[top]
000
FXUS63 KIWX 160254
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
952 PM EST THU JAN 15 2009
...INCREDIBLE COLD TONIGHT...
.UPDATE 2...
TEMPS CONT TO FREE FALL THIS EVENING...AND CLOSE TO PREV UPDATED
HACK DOWNWARD. WILL CUT NEARLY A CAT COLDER WHICH IS WHAT PREVIOUSLY
COMPUTED WAM NUMBERS CAME UP WITH. GIVEN OBSVD DEWPOINTS IN MESONET
OBS...COULD COME CLOSE TO BREAKING INDIANA/S ALL TIME STATE RECORD
(-28) MIN TONIGHT IN A LOCAL LOW SPOT ACRS THE SW CWA. FOR NOW WILL
TAKE THE KNOX/CULVER UP THROUGH KINGSBURY/NORTH LIBERTY AREA DOWN TO
-23 AND HOPE THAT HOLDS. CULVER AND KNOX CURRENTLY SITTING AT -19.
HWVR...BEGINNING TO RUN OUT OF CONTOUR ROOM IN GRIDS NXT TO THE LAKE.
&&
.AVIATION...
VFR CONDS EXPECTED THROUGH THE PD WITH EXCEPTION AT KSBN FOR SOME
MVFR BLSN FIRST FEW HOURS PER RECENT OBS. WIND DIRECTIONS WILL
STAY MAINLY IN THE 240-270 RANGE NEXT 24 HRS WITH SPDS AROUND
10-12 KTS LIKELY. CHC OF A BKN MVFR CIG AT KSBN ON SRN EDGE OF
LAKE EFFECT CLOUDS BUT WILL PRECLUDE WITH FLOW REMAINING LARGELY W
TO WSW AS STG HIGH PRESSURE SLIDES SOUTH OF TAF SITES.
&&
.PREV DISCUSSION... /ISSUED 639 PM EST THU JAN 15 2009/
..EXTREME COLD TONIGHT...
UPDATE...
AS TYPICAL W/FRESH SNOW AND ARCTIC HIGH PRES...MODEL GUIDANCE IS
LOST. TEMPS ALREADY NR GUIDANCE MINS/GRIDDED MINS AND POISED TO CRATER
OVERNIGHT AS ARCTIC RIDGE BLDS FURTHER. EARLY UPDATE TAKES MINS DOWN
TO CURRENT DEWPOINTS BUT PROBABLY STILL NOT ENOUGH. EXPERIMENTAL WAM
NUMBERS SUGGEST -20 TO -25 SW TO -15 TO -20 SOUTH OF THE IN/MI
BORDER. LK CLDS WILL HOLD ACRS BERRIEN/CASS BUT WILL CLEAR FURTHER
INLAND AND WILL DROP ERN MI COUNTIES FURTHER. OTHERWISE LT LK EFFECT
STILL CAUSING SLIDE OFFS/ACCIDENTS PER CALL TO BERRIEN COUNTY AND
WILL FOLLOW KGRR IN EXTENDING LAKE EFFECT SNOW WARNING UNTIL 10Z.
SHORT TERM...
TONIGHT THROUGH FRIDAY NIGHT...
LAKE EFFECT SNOW SHOWERS CONTINUE TO DIMINISH IN INTENSITY AS
STRONG MID LEVEL SUBSIDENCE COMBINES WITH DRYING LL AIR TO
WEAKEN THE MESOSCALE CIRCULATION ASSOCIATED WITH THE SNOW BANDS.
HAVE ELECTED TO KEEP UP THE LAKE EFFECT WARNING FOR BERRIEN/CASS
COUNTIES TO HIGHLIGHT A LITTLE MORE FALLING SNOW...BUT ALSO SOME
BLOWING AND DRIFTING GIVEN WINDS THAT HAVE BEEN OCCASIONALLY
REACHING 25 MPH. ELSEWHERE...MOSTLY CLEAR SKIES PREVAIL WITH
TEMPERATURES BETWEEN 5 BELOW AND 5 ABOVE ZERO.
DEWPOINTS ARE CRASHING OVER MY SOUTHWESTERN ZONES AND WITH BRAND
NEW SNOWPACK...WE WILL SEE THE COLDEST NIGHT OF THE SEASON...AND
THE COLDEST NIGHT IN A FEW YEARS OVER MUCH OF THE AREA. FOLLOWED
THE COLDER MET AND METBC GUIDANCE WITH LOWS 10 TO 15 BELOW OVER
MUCH OF THE AREA AND ONLY A LITTLE WARMER DOWNWIND OF LAKE
MICHIGAN WHERE SOME CLOUDS AND LIGHT SHSN OFF THE LAKE SHOULD
CONTINUE. WINDS WON/T BE THAT STRONG...10-15MPH...BUT GIVEN SUCH
COLD TEMPERATURES...WIND CHILL WARNING CRITERIA OF -25F WILL
EASILY BE MET WITH WIND CHILLS REACHING 35 BELOW ZERO IN THE
COLDEST SPOTS LATE TONIGHT. FWA AND SBN RECORD LOWS OF -19F LOOK
SAFE AT THIS TIME...BUT WE WON/T BE TOO FAR AWAY.
FRIDAY SHOULD FEATURE QUITE A BIT OF SUN AS A 1045 MB HIGH PULLS
SOUTH OF THE REGION AND THE LLEVEL FLOW GAINS AN INCREASINGLY
WESTERLY COMPONENT. THE LAKE EFFECT SHSN WILL BE LITTLE MORE THAN
FLURRIES...BUT WILL LIKELY CONTINUE GIVEN SUCH A COLD AIRMASS
ALOFT. ALTHOUGH H925 TEMPS WOULD SUGGEST 10F FULLY MIXED...BUFKIT
PROGS SUGGEST WE WILL ONLY MIX TO AROUND 960MB...WHICH INDICATES
THAT FOLLOWING THE CLOSER MET GUIDANCE IS IN ORDER. PREVIOUS FCST
HAD A GOOD HANDLE ON THIS AND WILL GO WITH HIGHS AROUND THE ZERO
MARK. GIVEN CONTINUED 10-15MPH WESTERLY WINDS...FULLY EXPECT THAT
AS THE WIND CHILL WARNING EXPIRES...WILL HAVE TO A CONTINUE A WIND
CHILL ADVISORY THROUGH AT LEAST FRIDAY NIGHT FOR CHILLS -15 TO
-25F.
TRENDS FOR THE NEXT SHORTWAVE THAT WILL BEGIN TO PUSH TOWARDS THE
AREA LATE FRIDAY NIGHT INDICATE A SLOWER ARRIVAL AND A SFC LOW
TRACK FURTHER TO THE NORTHEAST. 280K ISENTROPIC LIFT SUGGESTS THAT
WARM ADVECTION SHOULD DEVELOP AFTER MIDNIGHT. HAVE BACKED OFF THE
LIKELY POPS GIVEN THE SLOWING TREND AND THE DRY AIRMASS IN
PLACE...BUT WILL MAINTAIN CHANCE POPS OVER NORTHWESTERN AREAS
AFTER MIDNIGHT.
LONG TERM...
SATURDAY THROUGH THURSDAY...
MODEL HANDLING OF CLIPPER IMPACTING CWA AT BEGINNING OF EXTENDED
TRENDING SFC LOW INTO EXTREME SOUTHERN MICHIGAN. THIS TRACK KEEPS
BEST FORCING NORTH OF THE FORECAST AREA ALTHOUGH A BRIEF BURST OF
MODERATE SNOW APPEARS POSSIBLE IN WAA REGINE. TRENDED SNOW AMOUNTS
DOWN WITH AMOUNTS GENERALLY IN 1 TO 2 INCH RANGE AND HIGHEST ACROSS
NE PORTIONS TAPERING TO LESS THAN AN INCH EXTREME SOUTHERN
COUNTIES. MILD LAKE EFFECT APPEARS LIKELY SUNDAY BEHIND EXITING
SYSTEM BUT WITH MARGINAL SETUP AND WIND DIRECTIONS PRONE TO LARGE
DISCREPANCIES IN TIME WITH MINOR MODEL CHANGES IN TRACK OF LOW
COMING RIGHT OVER THE AREA HAVE BROADBRUHSED POPS IN THE USUAL REGION
WITHOUT ATTEMPTING TO PINPOINT SPECIFICS.
SIG DIFFERENCES BETWEEN MED RANGE MODELS WRT SUCCESSIVE WAVES
PROPAGATING IN NORTHERLY FLOW MON-TUES TIME FRAME. DIFFICULT TO
FAVOR ONE SOLUTION OVER ANOTHER WITH SUCH DISAGREEMENT AMONG OP
MODELS AND ENSEMBLE MEMBERS AND STAYED WITH A BLEND HEAVILY
WEIGHTING PERSISTENCE RESULTING IN SIMILAR GRIDS MON WITH CHC POPS
EXTENDED INTO TUESDAY. GFS/EC CONTINUE TO ADVERTISE WESTERN CONUS
RIDGE SHIFTING EAST AS IT FLATTENS...BRIEFLY WARMING H85 TEMPS ABV
FZ BY THU AHEAD OF NEXT FRONTAL PUSH SEEN AT END OF FCST PD.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR
INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 5 AM EST FRIDAY FOR MIZ077-078.
OH...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR OHZ001-002-004-005-
015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 12 PM EST FRIDAY FOR LMZ043-
046.
SMALL CRAFT ADVISORY UNTIL 12 PM EST FRIDAY FOR LMZ043-046.
&&
$$
SHORT TERM...ARNOTT
LONG TERM...LUDINGTON
AVIATION...SIMPSON
UPDATE...HOLSTEN
000
FXUS63 KIWX 152348
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
648 PM EST THU JAN 15 2009
.AVIATION...
VFR CONDS EXPECTED THROUGH THE PD WITH EXCEPTION AT KSBN FOR SOME
MVFR BLSN FIRST FEW HOURS PER RECENT OBS. WIND DIRECTIONS WILL
STAY MAINLY IN THE 240-270 RANGE NEXT 24 HRS WITH SPDS AROUND
10-12 KTS LIKELY. CHC OF A BKN MVFR CIG AT KSBN ON SRN EDGE OF
LAKE EFFECT CLOUDS BUT WILL PRECLUDE WITH FLOW REMAINING LARGELY W
TO WSW AS STG HIGH PRESSURE SLIDES SOUTH OF TAF SITES.
&&
.PREV DISCUSSION... /ISSUED 639 PM EST THU JAN 15 2009/
..EXTREME COLD TONIGHT...
UPDATE...
AS TYPICAL W/FRESH SNOW AND ARCTIC HIGH PRES...MODEL GUIDANCE IS
LOST. TEMPS ALREADY NR GUIDANCE MINS/GRIDDED MINS AND POISED TO CRATER
OVERNIGHT AS ARCTIC RIDGE BLDS FURTHER. EARLY UPDATE TAKES MINS DOWN
TO CURRENT DEWPOINTS BUT PROBABLY STILL NOT ENOUGH. EXPERIMENTAL WAM
NUMBERS SUGGEST -20 TO -25 SW TO -15 TO -20 SOUTH OF THE IN/MI
BORDER. LK CLDS WILL HOLD ACRS BERRIEN/CASS BUT WILL CLEAR FURTHER
INLAND AND WILL DROP ERN MI COUNTIES FURTHER. OTHERWISE LT LK EFFECT
STILL CAUSING SLIDE OFFS/ACCIDENTS PER CALL TO BERRIEN COUNTY AND
WILL FOLLOW KGRR IN EXTENDING LAKE EFFECT SNOW WARNING UNTIL 10Z.
SHORT TERM...
TONIGHT THROUGH FRIDAY NIGHT...
LAKE EFFECT SNOW SHOWERS CONTINUE TO DIMINISH IN INTENSITY AS
STRONG MID LEVEL SUBSIDENCE COMBINES WITH DRYING LL AIR TO
WEAKEN THE MESOSCALE CIRCULATION ASSOCIATED WITH THE SNOW BANDS.
HAVE ELECTED TO KEEP UP THE LAKE EFFECT WARNING FOR BERRIEN/CASS
COUNTIES TO HIGHLIGHT A LITTLE MORE FALLING SNOW...BUT ALSO SOME
BLOWING AND DRIFTING GIVEN WINDS THAT HAVE BEEN OCCASIONALLY
REACHING 25 MPH. ELSEWHERE...MOSTLY CLEAR SKIES PREVAIL WITH
TEMPERATURES BETWEEN 5 BELOW AND 5 ABOVE ZERO.
DEWPOINTS ARE CRASHING OVER MY SOUTHWESTERN ZONES AND WITH BRAND
NEW SNOWPACK...WE WILL SEE THE COLDEST NIGHT OF THE SEASON...AND
THE COLDEST NIGHT IN A FEW YEARS OVER MUCH OF THE AREA. FOLLOWED
THE COLDER MET AND METBC GUIDANCE WITH LOWS 10 TO 15 BELOW OVER
MUCH OF THE AREA AND ONLY A LITTLE WARMER DOWNWIND OF LAKE
MICHIGAN WHERE SOME CLOUDS AND LIGHT SHSN OFF THE LAKE SHOULD
CONTINUE. WINDS WON/T BE THAT STRONG...10-15MPH...BUT GIVEN SUCH
COLD TEMPERATURES...WIND CHILL WARNING CRITERIA OF -25F WILL
EASILY BE MET WITH WIND CHILLS REACHING 35 BELOW ZERO IN THE
COLDEST SPOTS LATE TONIGHT. FWA AND SBN RECORD LOWS OF -19F LOOK
SAFE AT THIS TIME...BUT WE WON/T BE TOO FAR AWAY.
FRIDAY SHOULD FEATURE QUITE A BIT OF SUN AS A 1045 MB HIGH PULLS
SOUTH OF THE REGION AND THE LLEVEL FLOW GAINS AN INCREASINGLY
WESTERLY COMPONENT. THE LAKE EFFECT SHSN WILL BE LITTLE MORE THAN
FLURRIES...BUT WILL LIKELY CONTINUE GIVEN SUCH A COLD AIRMASS
ALOFT. ALTHOUGH H925 TEMPS WOULD SUGGEST 10F FULLY MIXED...BUFKIT
PROGS SUGGEST WE WILL ONLY MIX TO AROUND 960MB...WHICH INDICATES
THAT FOLLOWING THE CLOSER MET GUIDANCE IS IN ORDER. PREVIOUS FCST
HAD A GOOD HANDLE ON THIS AND WILL GO WITH HIGHS AROUND THE ZERO
MARK. GIVEN CONTINUED 10-15MPH WESTERLY WINDS...FULLY EXPECT THAT
AS THE WIND CHILL WARNING EXPIRES...WILL HAVE TO A CONTINUE A WIND
CHILL ADVISORY THROUGH AT LEAST FRIDAY NIGHT FOR CHILLS -15 TO
-25F.
TRENDS FOR THE NEXT SHORTWAVE THAT WILL BEGIN TO PUSH TOWARDS THE
AREA LATE FRIDAY NIGHT INDICATE A SLOWER ARRIVAL AND A SFC LOW
TRACK FURTHER TO THE NORTHEAST. 280K ISENTROPIC LIFT SUGGESTS THAT
WARM ADVECTION SHOULD DEVELOP AFTER MIDNIGHT. HAVE BACKED OFF THE
LIKELY POPS GIVEN THE SLOWING TREND AND THE DRY AIRMASS IN
PLACE...BUT WILL MAINTAIN CHANCE POPS OVER NORTHWESTERN AREAS
AFTER MIDNIGHT.
LONG TERM...
SATURDAY THROUGH THURSDAY...
MODEL HANDLING OF CLIPPER IMPACTING CWA AT BEGINNING OF EXTENDED
TRENDING SFC LOW INTO EXTREME SOUTHERN MICHIGAN. THIS TRACK KEEPS
BEST FORCING NORTH OF THE FORECAST AREA ALTHOUGH A BRIEF BURST OF
MODERATE SNOW APPEARS POSSIBLE IN WAA REGINE. TRENDED SNOW AMOUNTS
DOWN WITH AMOUNTS GENERALLY IN 1 TO 2 INCH RANGE AND HIGHEST ACROSS
NE PORTIONS TAPERING TO LESS THAN AN INCH EXTREME SOUTHERN
COUNTIES. MILD LAKE EFFECT APPEARS LIKELY SUNDAY BEHIND EXITING
SYSTEM BUT WITH MARGINAL SETUP AND WIND DIRECTIONS PRONE TO LARGE
DISCREPANCIES IN TIME WITH MINOR MODEL CHANGES IN TRACK OF LOW
COMING RIGHT OVER THE AREA HAVE BROADBRUHSED POPS IN THE USUAL REGION
WITHOUT ATTEMPTING TO PINPOINT SPECIFICS.
SIG DIFFERENCES BETWEEN MED RANGE MODELS WRT SUCCESSIVE WAVES
PROPAGATING IN NORTHERLY FLOW MON-TUES TIME FRAME. DIFFICULT TO
FAVOR ONE SOLUTION OVER ANOTHER WITH SUCH DISAGREEMENT AMONG OP
MODELS AND ENSEMBLE MEMBERS AND STAYED WITH A BLEND HEAVILY
WEIGHTING PERSISTENCE RESULTING IN SIMILAR GRIDS MON WITH CHC POPS
EXTENDED INTO TUESDAY. GFS/EC CONTINUE TO ADVERTISE WESTERN CONUS
RIDGE SHIFTING EAST AS IT FLATTENS...BRIEFLY WARMING H85 TEMPS ABV
FZ BY THU AHEAD OF NEXT FRONTAL PUSH SEEN AT END OF FCST PD.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR
INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 5 AM EST FRIDAY FOR MIZ077-078.
OH...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR OHZ001-002-004-005-
015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 12 PM EST FRIDAY FOR LMZ043-
046.
SMALL CRAFT ADVISORY UNTIL 12 PM EST FRIDAY FOR LMZ043-046.
&&
$$
SHORT TERM...ARNOTT
LONG TERM...LUDINGTON
AVIATION...SIMPSON
UPDATE...HOLSTEN
000
FXUS63 KIWX 152342
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
639 PM EST THU JAN 15 2009...CORRECTION TO HEADLINES
...EXTREME COLD TONIGHT...
.UPDATE...
AS TYPICAL W/FRESH SNOW AND ARCTIC HIGH PRES...MODEL GUIDANCE IS
LOST. TEMPS ALREADY NR GUIDANCE MINS/GRIDDED MINS AND POISED TO CRATER
OVERNIGHT AS ARCTIC RIDGE BLDS FURTHER. EARLY UPDATE TAKES MINS DOWN
TO CURRENT DEWPOINTS BUT PROBABLY STILL NOT ENOUGH. EXPERIMENTAL WAM
NUMBERS SUGGEST -20 TO -25 SW TO -15 TO -20 SOUTH OF THE IN/MI
BORDER. LK CLDS WILL HOLD ACRS BERRIEN/CASS BUT WILL CLEAR FURTHER
INLAND AND WILL DROP ERN MI COUNTIES FURTHER. OTHERWISE LT LK EFFECT
STILL CAUSING SLIDE OFFS/ACCIDENTS PER CALL TO BERRIEN COUNTY AND
WILL FOLLOW KGRR IN EXTENDING LAKE EFFECT SNOW WARNING UNTIL 10Z.
&&
.SHORT TERM...
TONIGHT THROUGH FRIDAY NIGHT...
LAKE EFFECT SNOW SHOWERS CONTINUE TO DIMINISH IN INTENSITY AS
STRONG MID LEVEL SUBSIDENCE COMBINES WITH DRYING LL AIR TO
WEAKEN THE MESOSCALE CIRCULATION ASSOCIATED WITH THE SNOW BANDS.
HAVE ELECTED TO KEEP UP THE LAKE EFFECT WARNING FOR BERRIEN/CASS
COUNTIES TO HIGHLIGHT A LITTLE MORE FALLING SNOW...BUT ALSO SOME
BLOWING AND DRIFTING GIVEN WINDS THAT HAVE BEEN OCCASIONALLY
REACHING 25 MPH. ELSEWHERE...MOSTLY CLEAR SKIES PREVAIL WITH
TEMPERATURES BETWEEN 5 BELOW AND 5 ABOVE ZERO.
DEWPOINTS ARE CRASHING OVER MY SOUTHWESTERN ZONES AND WITH BRAND
NEW SNOWPACK...WE WILL SEE THE COLDEST NIGHT OF THE SEASON...AND
THE COLDEST NIGHT IN A FEW YEARS OVER MUCH OF THE AREA. FOLLOWED
THE COLDER MET AND METBC GUIDANCE WITH LOWS 10 TO 15 BELOW OVER
MUCH OF THE AREA AND ONLY A LITTLE WARMER DOWNWIND OF LAKE
MICHIGAN WHERE SOME CLOUDS AND LIGHT SHSN OFF THE LAKE SHOULD
CONTINUE. WINDS WON/T BE THAT STRONG...10-15MPH...BUT GIVEN SUCH
COLD TEMPERATURES...WIND CHILL WARNING CRITERIA OF -25F WILL
EASILY BE MET WITH WIND CHILLS REACHING 35 BELOW ZERO IN THE
COLDEST SPOTS LATE TONIGHT. FWA AND SBN RECORD LOWS OF -19F LOOK
SAFE AT THIS TIME...BUT WE WON/T BE TOO FAR AWAY.
FRIDAY SHOULD FEATURE QUITE A BIT OF SUN AS A 1045 MB HIGH PULLS
SOUTH OF THE REGION AND THE LLEVEL FLOW GAINS AN INCREASINGLY
WESTERLY COMPONENT. THE LAKE EFFECT SHSN WILL BE LITTLE MORE THAN
FLURRIES...BUT WILL LIKELY CONTINUE GIVEN SUCH A COLD AIRMASS
ALOFT. ALTHOUGH H925 TEMPS WOULD SUGGEST 10F FULLY MIXED...BUFKIT
PROGS SUGGEST WE WILL ONLY MIX TO AROUND 960MB...WHICH INDICATES
THAT FOLLOWING THE CLOSER MET GUIDANCE IS IN ORDER. PREVIOUS FCST
HAD A GOOD HANDLE ON THIS AND WILL GO WITH HIGHS AROUND THE ZERO
MARK. GIVEN CONTINUED 10-15MPH WESTERLY WINDS...FULLY EXPECT THAT
AS THE WIND CHILL WARNING EXPIRES...WILL HAVE TO A CONTINUE A WIND
CHILL ADVISORY THROUGH AT LEAST FRIDAY NIGHT FOR CHILLS -15 TO
-25F.
TRENDS FOR THE NEXT SHORTWAVE THAT WILL BEGIN TO PUSH TOWARDS THE
AREA LATE FRIDAY NIGHT INDICATE A SLOWER ARRIVAL AND A SFC LOW
TRACK FURTHER TO THE NORTHEAST. 280K ISENTROPIC LIFT SUGGESTS THAT
WARM ADVECTION SHOULD DEVELOP AFTER MIDNIGHT. HAVE BACKED OFF THE
LIKELY POPS GIVEN THE SLOWING TREND AND THE DRY AIRMASS IN
PLACE...BUT WILL MAINTAIN CHANCE POPS OVER NORTHWESTERN AREAS
AFTER MIDNIGHT.
&&
.LONG TERM...
SATURDAY THROUGH THURSDAY...
MODEL HANDLING OF CLIPPER IMPACTING CWA AT BEGINNING OF EXTENDED
TRENDING SFC LOW INTO EXTREME SOUTHERN MICHIGAN. THIS TRACK KEEPS
BEST FORCING NORTH OF THE FORECAST AREA ALTHOUGH A BRIEF BURST OF
MODERATE SNOW APPEARS POSSIBLE IN WAA REGINE. TRENDED SNOW AMOUNTS
DOWN WITH AMOUNTS GENERALLY IN 1 TO 2 INCH RANGE AND HIGHEST ACROSS
NE PORTIONS TAPERING TO LESS THAN AN INCH EXTREME SOUTHERN
COUNTIES. MILD LAKE EFFECT APPEARS LIKELY SUNDAY BEHIND EXITING
SYSTEM BUT WITH MARGINAL SETUP AND WIND DIRECTIONS PRONE TO LARGE
DISCREPANCIES IN TIME WITH MINOR MODEL CHANGES IN TRACK OF LOW
COMING RIGHT OVER THE AREA HAVE BROADBRUHSED POPS IN THE USUAL REGION
WITHOUT ATTEMPTING TO PINPOINT SPECIFICS.
SIG DIFFERENCES BETWEEN MED RANGE MODELS WRT SUCCESSIVE WAVES
PROPAGATING IN NORTHERLY FLOW MON-TUES TIME FRAME. DIFFICULT TO
FAVOR ONE SOLUTION OVER ANOTHER WITH SUCH DISAGREEMENT AMONG OP
MODELS AND ENSEMBLE MEMBERS AND STAYED WITH A BLEND HEAVILY
WEIGHTING PERSISTENCE RESULTING IN SIMILAR GRIDS MON WITH CHC POPS
EXTENDED INTO TUESDAY. GFS/EC CONTINUE TO ADVERTISE WESTERN CONUS
RIDGE SHIFTING EAST AS IT FLATTENS...BRIEFLY WARMING H85 TEMPS ABV
FZ BY THU AHEAD OF NEXT FRONTAL PUSH SEEN AT END OF FCST PD.
&&
.AVIATION...
CONDITIONS HAVE IMPROVED TO VFR AT FWA AND WILL LIKELY REMAIN SO
THROUGH THE TAF PERIOD AS THE LAKE CLOUDINESS SHOULD REMAIN NORTH OF
THE TERMINAL. AT SBN...IFR VSBYS ARE OCCURRING WITH SHSN AND BLSN.
THE BLSN SHOULD DIMINISH TOWARDS EVENING AS WINDS WEAKEN...BUT MVFR
CIGS WILL LIKELY REMAIN IN PLACE THROUGH THE EVENING BEFORE BREAKING
UP AND PULLING JUST NORTHEAST OF THE TERMINAL AFTER MIDNIGHT WITH
VFR CONDITIONS LIKELY THROUGH THE REMAINDER OF THE TAF PERIOD.
WESTERLY WINDS SHOULD REMAIN BETWEEN 10 AND 15 KNOTS THROUGH THE
PERIOD WITH GUSTS TO 18KTS THROUGH THIS AFTERNOON AT SBN.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR
INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 5 AM EST FRIDAY FOR MIZ077-078.
OH...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR OHZ001-002-004-005-
015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 12 PM EST FRIDAY FOR LMZ043-
046.
SMALL CRAFT ADVISORY UNTIL 12 PM EST FRIDAY FOR LMZ043-046.
&&
$$
SHORT TERM...ARNOTT
LONG TERM...LUDINGTON
AVIATION...ARNOTT
UPDATE...HOLSTEN
000
FXUS63 KIWX 152340
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
639 PM EST THU JAN 15 2009
...EXTREME COLD TONIGHT...
.UPDATE...
AS TYPICAL W/FRESH SNOW AND ARCTIC HIGH PRES...MODEL GUIDANCE IS
LOST. TEMPS ALREADY NR GUIDANCE MINS/GRIDDED MINS AND POISED TO CRATER
OVERNIGHT AS ARCTIC RIDGE BLDS FURTHER. EARLY UPDATE TAKES MINS DOWN
TO CURRENT DEWPOINTS BUT PROBABLY STILL NOT ENOUGH. EXPERIMENTAL WAM
NUMBERS SUGGEST -20 TO -25 SW TO -15 TO -20 SOUTH OF THE IN/MI
BORDER. LK CLDS WILL HOLD ACRS BERRIEN/CASS BUT WILL CLEAR FURTHER
INLAND AND WILL DROP ERN MI COUNTIES FURTHER. OTHERWISE LT LK EFFECT
STILL CAUSING SLIDE OFFS/ACCIDENTS PER CALL TO BERRIEN COUNTY AND
WILL FOLLOW KGRR IN EXTENDING LAKE EFFECT SNOW WARNING UNTIL 10Z.
&&
.SHORT TERM...
TONIGHT THROUGH FRIDAY NIGHT...
LAKE EFFECT SNOW SHOWERS CONTINUE TO DIMINISH IN INTENSITY AS
STRONG MID LEVEL SUBSIDENCE COMBINES WITH DRYING LL AIR TO
WEAKEN THE MESOSCALE CIRCULATION ASSOCIATED WITH THE SNOW BANDS.
HAVE ELECTED TO KEEP UP THE LAKE EFFECT WARNING FOR BERRIEN/CASS
COUNTIES TO HIGHLIGHT A LITTLE MORE FALLING SNOW...BUT ALSO SOME
BLOWING AND DRIFTING GIVEN WINDS THAT HAVE BEEN OCCASIONALLY
REACHING 25 MPH. ELSEWHERE...MOSTLY CLEAR SKIES PREVAIL WITH
TEMPERATURES BETWEEN 5 BELOW AND 5 ABOVE ZERO.
DEWPOINTS ARE CRASHING OVER MY SOUTHWESTERN ZONES AND WITH BRAND
NEW SNOWPACK...WE WILL SEE THE COLDEST NIGHT OF THE SEASON...AND
THE COLDEST NIGHT IN A FEW YEARS OVER MUCH OF THE AREA. FOLLOWED
THE COLDER MET AND METBC GUIDANCE WITH LOWS 10 TO 15 BELOW OVER
MUCH OF THE AREA AND ONLY A LITTLE WARMER DOWNWIND OF LAKE
MICHIGAN WHERE SOME CLOUDS AND LIGHT SHSN OFF THE LAKE SHOULD
CONTINUE. WINDS WON/T BE THAT STRONG...10-15MPH...BUT GIVEN SUCH
COLD TEMPERATURES...WIND CHILL WARNING CRITERIA OF -25F WILL
EASILY BE MET WITH WIND CHILLS REACHING 35 BELOW ZERO IN THE
COLDEST SPOTS LATE TONIGHT. FWA AND SBN RECORD LOWS OF -19F LOOK
SAFE AT THIS TIME...BUT WE WON/T BE TOO FAR AWAY.
FRIDAY SHOULD FEATURE QUITE A BIT OF SUN AS A 1045 MB HIGH PULLS
SOUTH OF THE REGION AND THE LLEVEL FLOW GAINS AN INCREASINGLY
WESTERLY COMPONENT. THE LAKE EFFECT SHSN WILL BE LITTLE MORE THAN
FLURRIES...BUT WILL LIKELY CONTINUE GIVEN SUCH A COLD AIRMASS
ALOFT. ALTHOUGH H925 TEMPS WOULD SUGGEST 10F FULLY MIXED...BUFKIT
PROGS SUGGEST WE WILL ONLY MIX TO AROUND 960MB...WHICH INDICATES
THAT FOLLOWING THE CLOSER MET GUIDANCE IS IN ORDER. PREVIOUS FCST
HAD A GOOD HANDLE ON THIS AND WILL GO WITH HIGHS AROUND THE ZERO
MARK. GIVEN CONTINUED 10-15MPH WESTERLY WINDS...FULLY EXPECT THAT
AS THE WIND CHILL WARNING EXPIRES...WILL HAVE TO A CONTINUE A WIND
CHILL ADVISORY THROUGH AT LEAST FRIDAY NIGHT FOR CHILLS -15 TO
-25F.
TRENDS FOR THE NEXT SHORTWAVE THAT WILL BEGIN TO PUSH TOWARDS THE
AREA LATE FRIDAY NIGHT INDICATE A SLOWER ARRIVAL AND A SFC LOW
TRACK FURTHER TO THE NORTHEAST. 280K ISENTROPIC LIFT SUGGESTS THAT
WARM ADVECTION SHOULD DEVELOP AFTER MIDNIGHT. HAVE BACKED OFF THE
LIKELY POPS GIVEN THE SLOWING TREND AND THE DRY AIRMASS IN
PLACE...BUT WILL MAINTAIN CHANCE POPS OVER NORTHWESTERN AREAS
AFTER MIDNIGHT.
&&
.LONG TERM...
SATURDAY THROUGH THURSDAY...
MODEL HANDLING OF CLIPPER IMPACTING CWA AT BEGINNING OF EXTENDED
TRENDING SFC LOW INTO EXTREME SOUTHERN MICHIGAN. THIS TRACK KEEPS
BEST FORCING NORTH OF THE FORECAST AREA ALTHOUGH A BRIEF BURST OF
MODERATE SNOW APPEARS POSSIBLE IN WAA REGINE. TRENDED SNOW AMOUNTS
DOWN WITH AMOUNTS GENERALLY IN 1 TO 2 INCH RANGE AND HIGHEST ACROSS
NE PORTIONS TAPERING TO LESS THAN AN INCH EXTREME SOUTHERN
COUNTIES. MILD LAKE EFFECT APPEARS LIKELY SUNDAY BEHIND EXITING
SYSTEM BUT WITH MARGINAL SETUP AND WIND DIRECTIONS PRONE TO LARGE
DISCREPANCIES IN TIME WITH MINOR MODEL CHANGES IN TRACK OF LOW
COMING RIGHT OVER THE AREA HAVE BROADBRUHSED POPS IN THE USUAL REGION
WITHOUT ATTEMPTING TO PINPOINT SPECIFICS.
SIG DIFFERENCES BETWEEN MED RANGE MODELS WRT SUCCESSIVE WAVES
PROPAGATING IN NORTHERLY FLOW MON-TUES TIME FRAME. DIFFICULT TO
FAVOR ONE SOLUTION OVER ANOTHER WITH SUCH DISAGREEMENT AMONG OP
MODELS AND ENSEMBLE MEMBERS AND STAYED WITH A BLEND HEAVILY
WEIGHTING PERSISTENCE RESULTING IN SIMILAR GRIDS MON WITH CHC POPS
EXTENDED INTO TUESDAY. GFS/EC CONTINUE TO ADVERTISE WESTERN CONUS
RIDGE SHIFTING EAST AS IT FLATTENS...BRIEFLY WARMING H85 TEMPS ABV
FZ BY THU AHEAD OF NEXT FRONTAL PUSH SEEN AT END OF FCST PD.
&&
.AVIATION...
CONDITIONS HAVE IMPROVED TO VFR AT FWA AND WILL LIKELY REMAIN SO
THROUGH THE TAF PERIOD AS THE LAKE CLOUDINESS SHOULD REMAIN NORTH OF
THE TERMINAL. AT SBN...IFR VSBYS ARE OCCURRING WITH SHSN AND BLSN.
THE BLSN SHOULD DIMINISH TOWARDS EVENING AS WINDS WEAKEN...BUT MVFR
CIGS WILL LIKELY REMAIN IN PLACE THROUGH THE EVENING BEFORE BREAKING
UP AND PULLING JUST NORTHEAST OF THE TERMINAL AFTER MIDNIGHT WITH
VFR CONDITIONS LIKELY THROUGH THE REMAINDER OF THE TAF PERIOD.
WESTERLY WINDS SHOULD REMAIN BETWEEN 10 AND 15 KNOTS THROUGH THE
PERIOD WITH GUSTS TO 18KTS THROUGH THIS AFTERNOON AT SBN.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR
INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ077-
078.
OH...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR OHZ001-002-004-005-
015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 12 PM EST FRIDAY FOR LMZ043-
046.
SMALL CRAFT ADVISORY UNTIL 12 PM EST FRIDAY FOR LMZ043-046.
&&
$$
SHORT TERM...ARNOTT
LONG TERM...LUDINGTON
AVIATION...ARNOTT
UPDATE...HOLSTEN
[top]
000
FXUS63 KIND 152225
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
525 PM EST THU JAN 15 2009
.AVIATION...DISCUSSION FOR 16/00Z TAFS
VFR EXPECTED THRU THE PD. SFC HI PRESSURE WILL KEEP VERY COLD AND
DRY AIR ACROSS THE SITES. THIS SHOULD KEEP SKIES CLEAR. WINDS WILL
SLOWLY DIMINISH OVERNIGHT AND BACK TO THE SW. SW WINDS AOB 10KT
EXPECTED ON FRI.
&&
.DISCUSSION...FCST FOCUS REMAINS ON TEMPS/WIND CHILLS NEXT 36 HRS.
06Z SFC MAP SHOWED 1049MB ARCTIC HIGH ACROSS THE DAKOTAS WITH A WEAK
LOW ACROSS VA. THE HIGH WILL REMAIN ITS STRENGTH AS IT MOVE THRU
INDIANA TONIGHT. CANT SEE WHERE THE GUIDANCE GETS WINDS AROUND 10
KTS. WITH HIGH MOVING OVER SHOULD BE LIGHTER. WITH THE CLEAR SKIES
SHOULD GIVE GOOD RADIATIONAL COOLING. 12Z GUIDANCE DOESN`T TAKE INTO
ACCOUNT SNOW THAT OCCURED OVERNIGHT. THIS WOULD CAUSE THEM TO NOT BE
COLD ENOUGH. THEY HAVE HAD A HISTORY OF NOT BEING COLD ENOUGH.
USUALLY SECOND NIGHT AFTER FROPA IS THE COLDEST. GUIDANCE WAS ABOUT
3 DEGREES T WARM LAST NIGHT. WITH TEMPS STARTING OUT MUCH COLDER
THEN YESTERDAY WILL GO COLDER THEN THIS MORNING BY AT LEAST 3
DEREES. WILL KEEP THE ADVSRYS AND WARNING.
ON FRIDAY THE HIGH WILL PULL EAST. THIS WILL BEGIN TO BRING IN SOME
WARM AIR ADVECTION. 850 TEMPS INCREASE AROUND 3 DEGREES. WITH
TEMPERATURES STARTING OUT MUCH BELOW GUIDANCE WILL GO NEAR THE
COLDER NAM.
ON SATURDAY A COLD FRONT MOVES THROUGH INDIANA. WILL GO WITH A
CHANCE OF SNOW. WITH A QUICK MOVEMENT OF SYSTEMS MOISTURE WILL NOT
HAVE MUCH OF A CHANCE OF MOVE INTO AREA. PRECIPITABLE WATER IS ONLY
.3 TO .4. NOT EXPECTING MUCH ACCUM WITH THIS SNOW.
FOR SUNDAY THERE CONTINUES TO BE CAA. THE GFS DOES NOT REFLECT THIS.
HAVE CONTINUED TO CUT GUIDANCE TEMPS. MON MONDAY 850 MB TEMPS
INCREASE AROUND 6 DEGREES. CLOUD COVER AHEAD OF NEXT SYSTEM MAY
INHIBIT TEMP INCREASE. ON TUESDAY ANOTHER COLD FRONT WILL MOVE
THROUGH INDIANA. WILL GO WITH A CHC OF SNOW WITH THIS SYSTEM BUT NOT
MUCH ACCUM DUE TO LACK OF MOISTURE.
HIGH PRESURE MOVES INTO INDIANA FOR THE END OF THE WORK WEEK. WITH
THE RETURN TO STRONG SOUTHERLY FLOW ON THE BACK SIDE OF THE HIGH
THERE WILL BE GOOD WAA ON THU WITH 850 MB TEMPS GOING ABOVE FREEZING
IN THE CNTRL AND SOUTH.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WIND CHILL WARNING UNTIL 1 PM EST FRIDAY FOR INZ021-028>031-035>049.
&&
$$
PUBLIC...SH
AVIATION...CS
000
FXUS63 KIND 152030
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
200 PM EST THU JAN 15 2009
.DISCUSSION...FCST FOCUS REMAINS ON TEMPS/WIND CHILLS NEXT 36 HRS.
06Z SFC MAP SHOWED 1049MB ARCTIC HIGH ACROSS THE DAKOTAS WITH A WEAK
LOW ACROSS VA. THE HIGH WILL REMAIN ITS STRENGTH AS IT MOVE THRU
INDIANA TONIGHT. CANT SEE WHERE THE GUIDANCE GETS WINDS AROUND 10
KTS. WITH HIGH MOVING OVER SHOULD BE LIGHTER. WITH THE CLEAR SKIES
SHOULD GIVE GOOD RADIATIONAL COOLING. 12Z GUIDANCE DOESN`T TAKE INTO
ACCOUNT SNOW THAT OCCURED OVERNIGHT. THIS WOULD CAUSE THEM TO NOT BE
COLD ENOUGH. THEY HAVE HAD A HISTORY OF NOT BEING COLD ENOUGH.
USUALLY SECOND NIGHT AFTER FROPA IS THE COLDEST. GUIDANCE WAS ABOUT
3 DEGREES T WARM LAST NIGHT. WITH TEMPS STARTING OUT MUCH COLDER
THEN YESTERDAY WILL GO COLDER THEN THIS MORNING BY AT LEAST 3
DEREES. WILL KEEP THE ADVSRYS AND WARNING.
ON FRIDAY THE HIGH WILL PULL EAST. THIS WILL BEGIN TO BRING IN SOME
WARM AIR ADVECTION. 850 TEMPS INCREASE AROUND 3 DEGREES. WITH
TEMPERATURES STARTING OUT MUCH BELOW GUIDANCE WILL GO NEAR THE
COLDER NAM.
ON SATURDAY A COLD FRONT MOVES THROUGH INDIANA. WILL GO WITH A
CHANCE OF SNOW. WITH A QUICK MOVEMENT OF SYSTEMS MOISTURE WILL NOT
HAVE MUCH OF A CHANCE OF MOVE INTO AREA. PRECIPITABLE WATER IS ONLY
.3 TO .4. NOT EXPECTING MUCH ACCUM WITH THIS SNOW.
FOR SUNDAY THERE CONTINUES TO BE CAA. THE GFS DOES NOT REFLECT THIS.
HAVE CONTINUED TO CUT GUIDANCE TEMPS. MON MONDAY 850 MB TEMPS
INCREASE AROUND 6 DEGREES. CLOUD COVER AHEAD OF NEXT SYSTEM MAY
INHIBIT TEMP INCREASE. ON TUESDAY ANOTHER COLD FRONT WILL MOVE
THROUGH INDIANA. WILL GO WITH A CHC OF SNOW WITH THIS SYSTEM BUT NOT
MUCH ACCUM DUE TO LACK OF MOISTURE.
HIGH PRESURE MOVES INTO INDIANA FOR THE END OF THE WORK WEEK. WITH
THE RETURN TO STRONG SOUTHERLY FLOW ON THE BACK SIDE OF THE HIGH
THERE WILL BE GOOD WAA ON THU WITH 850 MB TEMPS GOING ABOVE FREEZING
IN THE CNTRL AND SOUTH.
&&
.AVIATION...DISCUSSION FOR 151800Z TAF ISSUANCE. THIS MORNING/S UA
DATA SUGGEST A FEW SFC WND GUSTS 15-20KTS FM 280-300 DEG HEADINGS
PSBL THIS AFT. ANY GUSTINESS XPCTD TO END WITH SUNSET. OTRW...THERE
MAY BE ENOUGH LO LVL INSTABILITY/MOISTURE FOR SOME LIMITED DIURNAL
CLD DVLPMT THIS AFT BASED ARND 020...ESPECIALLY OVR THE SRN TERMINALS
CLOSE TO EDGE OF SNOWPACK.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WIND CHILL WARNING UNTIL 1 PM EST FRIDAY FOR INZ021-028>031-035>049.
&&
$$
PUBLIC...SH
AVIATION...JAS
000
FXUS63 KIND 152001
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
200 PM EST THU JAN 15 2009
.AVIATION...DISCUSSION FOR 151800Z TAF ISSUANCE. THIS MORNING/S UA
DATA SUGGEST A FEW SFC WND GUSTS 15-20KTS FM 280-300 DEG HEADINGS
PSBL THIS AFT. ANY GUSTINESS XPCTD TO END WITH SUNSET. OTRW...THERE
MAY BE ENOUGH LO LVL INSTABILITY/MOISTURE FOR SOME LIMITED DIURNAL
CLD DVLPMT THIS AFT BASED ARND 020...ESPECIALLY OVR THE SRN TERMINALS
CLOSE TO EDGE OF SNOWPACK.
&&
.DISCUSSION...FCST FOCUS REMAINS ON TEMPS/WIND CHILLS NEXT 36 HRS.
06Z SFC MAP SHOWED 1049MB ARCTIC HIGH ACROSS THE DAKOTAS WITH A WEAK
LOW ACROSS VA. THE HIGH WILL REMAIN ITS STRENGTH AS IT MOVE THRU
INDIANA TONIGHT. CANT SEE WHERE THE GUIDANCE GETS WINDS AROUND 10
KTS. WITH HIGH MOVING OVER SHOULD BE LIGHTER. WITH THE CLEAR SKIES
SHOULD GIVE GOOD RADIATIONAL COOLING. 12Z GUIDANCE DOESN`T TAKE INTO
ACCOUNT SNOW THAT OCCURED OVERNIGHT. THIS WOULD CAUSE THEM TO NOT BE
COLD ENOUGH. THEY HAVE HAD A HISTORY OF NOT BEING COLD ENOUGH.
USUALLY SECOND NIGHT AFTER FROPA IS THE COLDEST. GUIDANCE WAS ABOUT
3 DEGREES T WARM LAST NIGHT. WITH TEMPS STARTING OUT MUCH COLDER
THEN YESTERDAY WILL GO COLDER THEN THIS MORNING BY AT LEAST 3
DEREES. WILL KEEP THE ADVSRYS AND WARNING.
ON FRIDAY THE HIGH WILL PULL EAST. THIS WILL BEGIN TO BRING IN SOME
WARM AIR ADVECTION. 850 TEMPS INCREASE AROUND 3 DEGREES. WITH
TEMPERATURES STARTING OUT MUCH BELOW GUIDANCE WILL GO NEAR THE
COLDER NAM.
ON SATURDAY A COLD FRONT MOVES THROUGH INDIANA. WILL GO WITH A
CHANCE OF SNOW. WITH A QUICK MOVEMENT OF SYSTEMS MOISTURE WILL NOT
HAVE MUCH OF A CHANCE OF MOVE INTO AREA. PRECIPITABLE WATER IS ONLY
.3 TO .4. NOT EXPECTING MUCH ACCUM WITH THIS SNOW.
FOR SUNDAY THERE CONTINUES TO BE CAA. THE GFS DOES NOT REFLECT THIS.
HAVE CONTINUED TO CUT GUIDANCE TEMPS. MON MONDAY 850 MB TEMPS
INCREASE AROUND 6 DEGREES. CLOUD COVER AHEAD OF NEXT SYSTEM MAY
INHIBIT TEMP INCREASE. ON TUESDAY ANOTHER COLD FRONT WILL MOVE
THROUGH INDIANA. WILL GO WITH A CHC OF SNOW WITH THIS SYSTEM BUT NOT
MUCH ACCUM DUE TO LACK OF MOISTURE.
HIGH PRESURE MOVES INTO INDIANA FOR THE END OF THE WORK WEEK. WITH
THE RETURN TO STRONG SOUTHERLY FLOW ON THE BACK SIDE OF THE HIGH
THERE WILL BE GOOD WAA ON THU WITH 850 MB TEMPS GOING ABOVE FREEZING
IN THE CNTRL AND SOUTH.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WIND CHILL WARNING UNTIL 1 PM EST FRIDAY FOR INZ021-028>031-035>049.
&&
$$
PUBLIC...SH
AVIATION...JAS
000
FXUS63 KIWX 151951
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
251 PM EST THU JAN 15 2009
.SHORT TERM...
TONIGHT THROUGH FRIDAY NIGHT...
LAKE EFFECT SNOW SHOWERS CONTINUE TO DIMINISH IN INTENSITY AS
STRONG MID LEVEL SUBSIDENCE COMBINES WITH DRYING LLEVEL AIR TO
WEAKEN THE MESOSCALE CIRCULATION ASSOCIATED WITH THE SNOW BANDS.
HAVE ELECTED TO KEEP UP THE LAKE EFFECT WARNING FOR BERRIEN/CASS
COUNTIES TO HIGHLIGHT A LITTLE MORE FALLING SNOW...BUT ALSO SOME
BLOWING AND DRIFTING GIVEN WINDS THAT HAVE BEEN OCCASIONALLY
REACHING 25 MPH. ELSEWHERE...MOSTLY CLEAR SKIES PREVAIL WITH
TEMPERATURES BETWEEN 5 BELOW AND 5 ABOVE ZERO.
DEWPOINTS ARE CRASHING OVER MY SOUTHWESTERN ZONES AND WITH BRAND
NEW SNOWPACK...WE WILL SEE THE COLDEST NIGHT OF THE SEASON...AND
THE COLDEST NIGHT IN A FEW YEARS OVER MUCH OF THE AREA. FOLLOWED
THE COLDER MET AND METBC GUIDANCE WITH LOWS 10 TO 15 BELOW OVER
MUCH OF THE AREA AND ONLY A LITTLE WARMER DOWNWIND OF LAKE
MICHIGAN WHERE SOME CLOUDS AND LIGHT SHSN OFF THE LAKE SHOULD
CONTINUE. WINDS WON/T BE THAT STRONG...10-15MPH...BUT GIVEN SUCH
COLD TEMPERATURES...WIND CHILL WARNING CRITERIA OF -25F WILL
EASILY BE MET WITH WIND CHILLS REACHING 35 BELOW ZERO IN THE
COLDEST SPOTS LATE TONIGHT. FWA AND SBN RECORD LOWS OF -19F LOOK
SAFE AT THIS TIME...BUT WE WON/T BE TOO FAR AWAY.
FRIDAY SHOULD FEATURE QUITE A BIT OF SUN AS A 1045 MB HIGH PULLS
SOUTH OF THE REGION AND THE LLEVEL FLOW GAINS AN INCREASINGLY
WESTERLY COMPONENT. THE LAKE EFFECT SHSN WILL BE LITTLE MORE THAN
FLURRIES...BUT WILL LIKELY CONTINUE GIVEN SUCH A COLD AIRMASS
ALOFT. ALTHOUGH H925 TEMPS WOULD SUGGEST 10F FULLY MIXED...BUFKIT
PROGS SUGGEST WE WILL ONLY MIX TO AROUND 960MB...WHICH INDICATES
THAT FOLLOWING THE CLOSER MET GUIDANCE IS IN ORDER. PREVIOUS FCST
HAD A GOOD HANDLE ON THIS AND WILL GO WITH HIGHS AROUND THE ZERO
MARK. GIVEN CONTINUED 10-15MPH WESTERLY WINDS...FULLY EXPECT THAT
AS THE WIND CHILL WARNING EXPIRES...WILL HAVE TO A CONTINUE A WIND
CHILL ADVISORY THROUGH AT LEAST FRIDAY NIGHT FOR CHILLS -15 TO
-25F.
TRENDS FOR THE NEXT SHORTWAVE THAT WILL BEGIN TO PUSH TOWARDS THE
AREA LATE FRIDAY NIGHT INDICATE A SLOWER ARRIVAL AND A SFC LOW
TRACK FURTHER TO THE NORTHEAST. 280K ISENTROPIC LIFT SUGGESTS THAT
WARM ADVECTION SHOULD DEVELOP AFTER MIDNIGHT. HAVE BACKED OFF THE
LIKELY POPS GIVEN THE SLOWING TREND AND THE DRY AIRMASS IN
PLACE...BUT WILL MAINTAIN CHANCE POPS OVER NORTHWESTERN AREAS
AFTER MIDNIGHT.
&&
.LONG TERM...
SATURDAY THROUGH THURSDAY...
MODEL HANDLING OF CLIPPER IMPACTING CWA AT BEGINNING OF EXTENDED
TRENDING SFC LOW INTO EXTREME SOUTHERN MICHIGAN. THIS TRACK KEEPS
BEST FORCING NORTH OF THE FORECAST AREA ALTHOUGH A BRIEF BURST OF
MODERATE SNOW APPEARS POSSIBLE IN WAA REGINE. TRENDED SNOW AMOUNTS
DOWN WITH AMOUNTS GENERALLY IN 1 TO 2 INCH RANGE AND HIGHEST ACROSS
NE PORTIONS TAPERING TO LESS THAN AN INCH EXTREME SOUTHERN
COUNTIES. MILD LAKE EFFECT APPEARS LIKELY SUNDAY BEHIND EXITING
SYSTEM BUT WITH MARGINAL SETUP AND WIND DIRECTIONS PRONE TO LARGE
DISCREPANCIES IN TIME WITH MINOR MODEL CHANGES IN TRACK OF LOW
COMING RIGHT OVER THE AREA HAVE BROADBRUHSED POPS IN THE USUAL REGION
WITHOUT ATTEMPTING TO PINPOINT SPECIFICS.
SIG DIFFERENCES BETWEEN MED RANGE MODELS WRT SUCCESSIVE WAVES
PROPAGATING IN NORTHERLY FLOW MON-TUES TIME FRAME. DIFFICULT TO
FAVOR ONE SOLUTION OVER ANOTHER WITH SUCH DISAGREEMENT AMONG OP
MODELS AND ENSEMBLE MEMBERS AND STAYED WITH A BLEND HEAVILY
WEIGHTING PERSISTENCE RESULTING IN SIMILAR GRIDS MON WITH CHC POPS
EXTENDED INTO TUESDAY. GFS/EC CONTINUE TO ADVERTISE WESTERN CONUS
RIDGE SHIFTING EAST AS IT FLATTENS...BRIEFLY WARMING H85 TEMPS ABV
FZ BY THU AHEAD OF NEXT FRONTAL PUSH SEEN AT END OF FCST PD.
&&
.AVIATION...
CONDITIONS HAVE IMPROVED TO VFR AT FWA AND WILL LIKELY REMAIN SO
THROUGH THE TAF PERIOD AS THE LAKE CLOUDINESS SHOULD REMAIN NORTH OF
THE TERMINAL. AT SBN...IFR VSBYS ARE OCCURRING WITH SHSN AND BLSN.
THE BLSN SHOULD DIMINISH TOWARDS EVENING AS WINDS WEAKEN...BUT MVFR
CIGS WILL LIKELY REMAIN IN PLACE THROUGH THE EVENING BEFORE BREAKING
UP AND PULLING JUST NORTHEAST OF THE TERMINAL AFTER MIDNIGHT WITH
VFR CONDITIONS LIKELY THROUGH THE REMAINDER OF THE TAF PERIOD.
WESTERLY WINDS SHOULD REMAIN BETWEEN 10 AND 15 KNOTS THROUGH THE
PERIOD WITH GUSTS TO 18KTS THROUGH THIS AFTERNOON AT SBN.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR
INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ077-
078.
OH...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR OHZ001-002-004-005-
015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 12 PM EST FRIDAY FOR LMZ043-
046.
SMALL CRAFT ADVISORY UNTIL 12 PM EST FRIDAY FOR LMZ043-046.
&&
$$
SHORT TERM...ARNOTT
LONG TERM...LUDINGTON
AVIATION...ARNOTT
000
FXUS63 KIWX 151710
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1209 PM EST THU JAN 15 2009
.AVIATION...
CONDITIONS HAVE IMPROVED TO VFR AT FWA AND WILL LIKELY REMAIN SO
THROUGH THE TAF PERIOD AS THE LAKE CLOUDINESS SHOULD REMAIN NORTH OF
THE TERMINAL. AT SBN...IFR VSBYS ARE OCCURRING WITH SHSN AND BLSN.
THE BLSN SHOULD DIMINISH TOWARDS EVENING AS WINDS WEAKEN...BUT MVFR
CIGS WILL LIKELY REMAIN IN PLACE THROUGH THE EVENING BEFORE BREAKING
UP AND PULLING JUST NORTHEAST OF THE TERMINAL AFTER MIDNIGHT WITH
VFR CONDITIONS LIKELY THROUGH THE REMAINDER OF THE TAF PERIOD.
WESTERLY WINDS SHOULD REMAIN BETWEEN 10 AND 15 KNOTS THROUGH THE
PERIOD WITH GUSTS TO 18KTS THROUGH THIS AFTERNOON AT SBN.
&&
.PREV DISCUSSION... /ISSUED 942 AM EST THU JAN 15 2009/
.UPDATE...
GRR VWP NICELY SHOWING BACKING WINDS AHEAD OF WEAK H850 IMPULSE
THIS MORNING WHICH IS HELPING TO PULL LAKE EFFECT SNOWS TO THE
EAST. IN ADDITION...INCREASINGLY DRY LLEVEL AIR ALONG WITH A
SHORTER FETCH OVER THE LAKE IS ALLOWING THE BANDS TO BREAK UP WITH
SOME DECENT EMBEDDED SHSN BUT DIMINISHING THREAT FOR ACCUMS. HAVE
TAKEN DOWN WARNING FOR REMAINING INDIANA COUNTIES AS THREAT FOR
ADDITIONAL ACCUMS IS QUICKLY DIMINISHING. FURTHER NORTH...EXPECT
SHSN TO CONTINUE THROUGH MUCH OF THE DAY AND WHILE THE INTENSITY
HAS DIMINISHED...ANOTHER COUPLE OF INCHES OF FLUFF IS
POSSIBLE...SO HAVE LEFT THIS PART OF THE WARNING INTACT WITH A
FOOT OF TOTAL ACCUMS POSSIBLE IN A FEW PARTS OF BERRIEN COUNTY.
AFTER THE H850 WAVE PASSES THROUGH THIS AFTERNOON THE FLOW MAY GAIN A
LITTLE MORE OF A NORTHERLY COMPONENT WHICH COULD KEEP MY NWERN
INDIANA COUNTIES UNDER THE GUN FOR SOME ADDITIONAL SHSN...BUT
FEEL THAT ANY ACCUMS WILL BE HARD TO COME BY AS STRONG MID AND
UPPER LEVEL SUBSIDENCE ARRIVING AHEAD OF A 1045-1050 MB HIGH OVER
THE DAKOTAS WILL BE QUICKLY LOWERING INVERSION HEIGHTS OVER LAKE
MICHIGAN WITH THE RESULT BEING A WEAKENING MESOSCALE CIRCULATION.
WIND CHILLS ALREADY AT WARNING LEVELS OVER SOUTHWESTERN ZONES
WHERE TEMPS HAVE FALLEN TO -10.
UPDATED PRODUCTS/GRIDS ARE OUT.
&&
.PREV DISCUSSION... /ISSUED 645 AM EST THU JAN 15 2009/
SHORT TERM...
TODAY THROUGH FRIDAY NIGHT. TWO PRIMARY FCST CONCERNS WITH MORNING
ISSUANCE THOUGH CRNT FCST TRENDS APPEAR TO HAVE ALL WELL IN HAND.
FIRST WRT TWO EARLIER DEVELOPED BANDS MERGING INTO INTENSE SHORE
PARALLEL SNOWBAND INTO FAR NWRN CWA W/RESULTANT 2 IN/HR RATES
REPORTED AT KSBN BTWN 07-08 UTC...INDICATIVE OF AMAZING SNOW-LIQUID
RATIOS OF AT LEAST 30-40 TO 1. LOWEST 2-3KFT CBL COINCIDENT WITH DGZ
AND EXTREME UVM PUNCHING LKINDUCED EQL TO 11KFT CONFIRMED W/ WSR-88D
SAMPLING OF BAND IN 1.5 AND 2.5 DEG SLICES. BEST THERMAL DYNAMICS
WITH 925-8H LAPSE RATES GT 8C/KM PUSH PRIMARILY INTO MI COUNTIES BY
AFTN W/BEST CONVG SIGNALS. CURRENT WS WARNING END TIMES APPEAR ON
TRACK SAVE FOR EASY MONEY CAN FOR LAPORTE AND STARKE WITH AM
ISSUANCE. ST. JOE AND ELK COUNTIES MAY AS WELL BE AFFORDED AN EARLY
CAN BY LATE AM...THOUGH PREFER TO LET DAYSHIFT MAKE THAT
DETERMINATION AS STEERING FLOW RELATIVELY SLOW TO BACK. LAKE
AGGREGATE/THERMAL TROF CIRCULATION WELL ESTABLISHED RESULTING IN
KSBN 19F RISE FROM EARLIER EVE MIN UNDER CURRENT HVY SNOWBAND.
PREV TEMPS FOR TODAY APPEAR ON TRACK WITH LITTLE RISE. SECOND ISSUE
WRT IMMENSE HIGH AMP RIDGING ALONG EPAC EXNDG NWD INTO NW
TERRITORIES...TO USHER COLDEST AIRMASS IN DECADES INTO CWA WITH
COLDEST 1000-900MB TEMPS THIS AM ACRS CNTL MN/NRN WI TO SETTLE WITH
MINIMA M22-M23 INTO SRN CWA BY DAYBREAK FRI. UNFATHOMABLE TO CUT
TEMPS AS REALLY HOW OFTEN IS M15-16F NOT COLD ENOUGH. BUT WITH
STRONG 1049 ARCTIC HIGH DIVES INTO LWR OH VLY BY DAYBREAK FRI
W/STRONG SUBSIDENCE/DRYING AND FRESH SNOWPACK. SOME ALBEIT SLIGHT
ADDITION OF MOISTURE/SUBLIMATION INTO SHALLOW LYR WITH LOW
SUBSIDENCE INVERSION AND SFC BASED AM INVERSION GIVES RISE TO
CONCERN FOR POTNL FZFG. ADDITIONALLY WITH TEMPS FALLING 10-15F BLO
XOVER AND PATCHY M1/4SM AT KIRS THIS AM MAY BE FOREBODING OF AN
ADDED INSULT TO INJURY FOR DEADLY COLD AIRMASS TONIGHT. WITH LOW
CONFIDENCE THOUGH ESPCLY WITH DWPOINTS THIS AFTERNOON INTO TONIGHT
WL HOLD ON MENTION IN ZFP AND RELEGATE TO HWO MENTION OF PTCHY FZFG
PSBL. GIVEN SUCH COLD TEMPS FRI AM...HAVE LOWERED MAX TEMPS FOR FRI
BY SVRL DEGREES/BLO MOST GUID AS STRONG TEMP RECOVERY HIGHLY
UNLIKELY.
PREFERENCE LIES WITH GFS/ECMWF WITH HANDLING OF SHORTWAVE ROUNDING
HIGH AMP RIDGE WITH NAM TRACKING SURFACE LOW TOO FAR WEST/SOUTH. GFS
CONSISTENT WITH FEATURE. GIVEN INITIAL DRY AIRMASS HAVE DELAYED
ONSET MORE TOWARD DAYBREAK FOR RELATIVELY LIGHT SNOW/MOISTURE
STARVED CLIPPER EVENT.
LONG TERM...
SATURDAY THROUGH WEDNESDAY...THE MAIN CHALLENGES CONTINUE TO BE THE
TRACK AND TIMING OF CLIPPER TYPE OF SYSTEMS WITH SHORT WAVE TROFS
MOVING THROUGH THE LONG WAVE PATTERN OVER THE EASTERN CONUS. SOME
EARLIER GFS RUNS WERE TRYING TO MOUNT SUPPORT FOR A MORE ZONAL
FLOW...EVEN WITH THE LONG WAVE TROF BECOMING REESTABLISHED OVER THE
WESTERN UNITED STATES. HAVE NOT FOUND MUCH EVIDENCE FOR THIS TREND
AT LEAST THROUGH WEDNESDAY AS THE LONG WAVE TROF AXIS SHOULD REMAIN
OVER THE GREAT LAKES REGION TO THE EAST COAST. SOME MODERATION IS
POSSIBLE LATE IN THE PERIOD AHEAD OF A STRONG CLIPPER SYSTEM...BUT
ANOTHER SURGE OF COLD AIR IS EVIDENT JUST PAST THE END OF THE
FORECAST PERIOD PER ECMWF/GFS. ONGOING TIMING FOR THE SATURDAY
CLIPPER APPEARS ON TRACK...SO ONLY MINOR CHANGES MADE. A SECOND
WEAKER SYSTEM SHOULD PROVIDE A CHANCE FOR LIGHT SNOW SUNDAY AND
MONDAY. ONGOING GRIDS/ZPF APPEAR TO ADEQUATELY HANDLE THIS SYSTEM.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR
INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR
MIZ077>079.
OH...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR
OHZ001-002-004-005-015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR
LMZ043-046.
SMALL CRAFT ADVISORY UNTIL 12 PM EST FRIDAY FOR LMZ043-046.
&&
$$
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...ARNOTT
UPDATE...ARNOTT
000
FXUS63 KIND 151645
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1145 AM EST THU JAN 15 2009
.AVIATION...DISCUSSION FOR 151800Z TAF ISSUANCE. THIS MORNING/S UA
DATA SUGGEST A FEW SFC WND GUSTS 15-20KTS FM 280-300 DEG HEADINGS
PSBL THIS AFT. ANY GUSTINESS XPCTD TO END WITH SUNSET. OTRW...THERE
MAY BE ENOUGH LO LVL INSTABILITY/MOISTURE FOR SOME LIMITED DIURNAL
CLD DVLPMT THIS AFT BASED ARND 020...ESPECIALLY OVR THE SRN TERMINALS
CLOSE TO EDGE OF SNOWPACK.
&&
.PREV DISCUSSION...FCST FOCUS REMAINS ON TEMPS/WIND CHILLS NEXT 36
HRS.
06Z SFC MAP SHOWED 1047MB ARCTIC HIGH ACROSS THE DAKOTAS WITH A WEAK
LOW ACROSS VA. 3HR PRESSURE RISES OF 2MB CONTINUE TO OCCUR ACROSS
THE REGION AS THE STRONG HIGH MOVES SE TOWARD THE AREA. THIS SHOULD
ALLOW WINDS TO STAY UP AROUND 10KTS WITH SOME RISK FOR GUSTS TO
PERSIST INTO THE MORNING HOURS AS WELL. A QUICK CHECK OF THE TEMPS
SHOWS -5 TO -10F ACROSS CENTRAL IL AS OF 7Z WITH WIND CHILLS -20 TO
-25 ALSO OCCURRING ACROSS CENTRAL IL AT THIS TIME. MEANWHILE...LOW
CLDS DUE TO REMNANT LAKE MOISTURE CONTINUE TO LINGER ACROSS OUR CWA
HOWEVER THESE SHOULD DISSIPATE/MOVE EAST AS CAA/DRY ADVECTION
CONTINUES OVERNIGHT. THE LAKE MOISTURE HAS SLOWED OUR DROP IN AIR
TEMPS FOR THE MOMENT.
FOR THIS FCST WILL RELY ON A MIX OF NAM BUFKIT SFC TEMPS AND OBS TO
BEST ESTIMATE AIR TEMPS OVER THE NEXT 36 HRS. NOT RELYING HEAVILY ON
MOS AT THIS POINT ALTHOUGH I WOULD FAVOR THE COLDER NAM MOS AS
OTHERS APPEAR TOO WARM.
TODAY...CAA SHOULD CONTINUE THROUGH 18Z WHICH SUGGESTS THAT AIR
TEMPS MAY CONTINUE TO FALL THROUGH SUNRISE AND FOR A TIME INTO MID
MORNING THU. PRESSURE RISES AND WIND FIELDS ALSO SUGGEST THAT
SUSTAINED WINDS AOA 10KTS WITH GUSTS TO AROUND 20KTS WILL ALSO
OCCUR. GIVEN THIS SCENARIO I FAVOR THE COLDER NAM MOS TEMPS WHICH
ARE CLOSE TO OUR GOING FCST HIGHS. WIND CHILLS SHOULD FLIRT WITH
WARNING CRITERIA NORTH OF I-70 FOR A TIME THIS MORNING MAINLY FROM
12Z TO 17Z.
TONIGHT...AGAIN FAVOR A COLDER NAM MOS OR NAM BUFKIT SOUNDING SFC
TEMP WHICH SUGGESTS THAT LOWS SHOULD BOTTOM OUT IN THE -10 TO -20F
RANGE NORTH OF I-70. LIGHT WSW WINDS AROUND 5 TO 10KTS SHOULD KEEP
WIND CHILLS IN THE -20 TO -30F RANGE IN THE WARNING SO AT THIS POINT
WE WILL CONTINUE THE WIND CHILL WARNING THROUGH TONIGHT.
FRI...TEMPS MAY REBOUND SOMEWHAT AFTER A VERY COLD START. NAM
SOUNDINGS SHOW SINGLE DIGITS NORTH OF I-70 AS SOME WEAK WAA ATTEMPTS
TO DEVELOP BUT FEEL THIS WILL OCCUR ALOFT MORE THAN AT THE SFC.
FAVOR COLDER MOS AND CURRENT TEMPS APPEAR SUPERIOR TO MOS.
FRI NIGHT/SAT...STRONGER WAA WILL DEVELOP AND PERSIST INTO SAT.
TEMPS SHOULD BE STEADY OR RISE AFTER MIDNIGHT WITH SOME CHC FOR SNOW
ON SAT/SAT NIGHT ACROSS THE NE AS SATURATION OCCURS BY LATE DAY INTO
SAT NIGHT WITHIN THE WAA ZONE AHEAD OF A CLIPPER SYSTEM.
NO CHANGES WILL BE MADE BEYOND SAT.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WIND CHILL WARNING UNTIL 1 PM EST FRIDAY FOR INZ021-028>031-035>049.
&&
$$
PUBLIC...CO
AVIATION...JAS
000
FXUS63 KIWX 151442
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
942 AM EST THU JAN 15 2009
.UPDATE...
GRR VWP NICELY SHOWING BACKING WINDS AHEAD OF WEAK H850 IMPULSE
THIS MORNING WHICH IS HELPING TO PULL LAKE EFFECT SNOWS TO THE
EAST. IN ADDITION...INCREASINGLY DRY LLEVEL AIR ALONG WITH A
SHORTER FETCH OVER THE LAKE IS ALLOWING THE BANDS TO BREAK UP WITH
SOME DECENT EMBEDDED SHSN BUT DIMINISHING THREAT FOR ACCUMS. HAVE
TAKEN DOWN WARNING FOR REMAINING INDIANA COUNTIES AS THREAT FOR
ADDITIONAL ACCUMS IS QUICKLY DIMINISHING. FURTHER NORTH...EXPECT
SHSN TO CONTINUE THROUGH MUCH OF THE DAY AND WHILE THE INTENSITY
HAS DIMINISHED...ANOTHER COUPLE OF INCHES OF FLUFF IS
POSSIBLE...SO HAVE LEFT THIS PART OF THE WARNING INTACT WITH A
FOOT OF TOTAL ACCUMS POSSIBLE IN A FEW PARTS OF BERRIEN COUNTY.
AFTER THE H850 WAVE PASSES THROUGH THIS AFTERNOON THE FLOW MAY GAIN A
LITTLE MORE OF A NORTHERLY COMPONENT WHICH COULD KEEP MY NWERN
INDIANA COUNTIES UNDER THE GUN FOR SOME ADDITIONAL SHSN...BUT
FEEL THAT ANY ACCUMS WILL BE HARD TO COME BY AS STRONG MID AND
UPPER LEVEL SUBSIDENCE ARRIVING AHEAD OF A 1045-1050 MB HIGH OVER
THE DAKOTAS WILL BE QUICKLY LOWERING INVERSION HEIGHTS OVER LAKE
MICHIGAN WITH THE RESULT BEING A WEAKENING MESOSCALE CIRCULATION.
WIND CHILLS ALREADY AT WARNING LEVELS OVER SOUTHWESTERN ZONES
WHERE TEMPS HAVE FALLEN TO -10.
UPDATED PRODUCTS/GRIDS ARE OUT.
&&
.PREV DISCUSSION... /ISSUED 645 AM EST THU JAN 15 2009/
AVIATION...
FEW CHNGS WITH 12 UTC TAFS. LAST VESTIGES OF IFR SNOWBANDS ACRS NRN
INDIANA AS BANDS BEGIN TO SLIDE NEWD NORTH OF TERMINAL SITES. BEST
CHC FOR BRF PD OF IFR VSBYS AT KSBN NEXT FEW HOURS BEFORE INVERSION
HGHTS BEGIN TO CRASH...SPELLING END TO APPRECIABLE ACCUMULATING
SNOW. SUBSIDENCE IN EXTREMLY DRY AIRMASS TO BRING VFR TO KFWA BY
EARLY AFTN AND EVENING AT KSBN WHERE SLIGHTLY MOISTER LAKE ENHANCED
BOUNDARY LYR SHOULD REMAIN LOCKED BENEATH 3KFT INVERSION.
SHORT TERM...
TODAY THROUGH FRIDAY NIGHT. TWO PRIMARY FCST CONCERNS WITH MORNING
ISSUANCE THOUGH CRNT FCST TRENDS APPEAR TO HAVE ALL WELL IN HAND.
FIRST WRT TWO EARLIER DEVELOPED BANDS MERGING INTO INTENSE SHORE
PARALLEL SNOWBAND INTO FAR NWRN CWA W/RESULTANT 2 IN/HR RATES
REPORTED AT KSBN BTWN 07-08 UTC...INDICATIVE OF AMAZING SNOW-LIQUID
RATIOS OF AT LEAST 30-40 TO 1. LOWEST 2-3KFT CBL COINCIDENT WITH DGZ
AND EXTREME UVM PUNCHING LKINDUCED EQL TO 11KFT CONFIRMED W/ WSR-88D
SAMPLING OF BAND IN 1.5 AND 2.5 DEG SLICES. BEST THERMAL DYNAMICS
WITH 925-8H LAPSE RATES GT 8C/KM PUSH PRIMARILY INTO MI COUNTIES BY
AFTN W/BEST CONVG SIGNALS. CURRENT WS WARNING END TIMES APPEAR ON
TRACK SAVE FOR EASY MONEY CAN FOR LAPORTE AND STARKE WITH AM
ISSUANCE. ST. JOE AND ELK COUNTIES MAY AS WELL BE AFFORDED AN EARLY
CAN BY LATE AM...THOUGH PREFER TO LET DAYSHIFT MAKE THAT
DETERMINATION AS STEERING FLOW RELATIVELY SLOW TO BACK. LAKE
AGGREGATE/THERMAL TROF CIRCULATION WELL ESTABLISHED RESULTING IN
KSBN 19F RISE FROM EARLIER EVE MIN UNDER CURRENT HVY SNOWBAND.
PREV TEMPS FOR TODAY APPEAR ON TRACK WITH LITTLE RISE. SECOND ISSUE
WRT IMMENSE HIGH AMP RIDGING ALONG EPAC EXNDG NWD INTO NW
TERRITORIES...TO USHER COLDEST AIRMASS IN DECADES INTO CWA WITH
COLDEST 1000-900MB TEMPS THIS AM ACRS CNTL MN/NRN WI TO SETTLE WITH
MINIMA M22-M23 INTO SRN CWA BY DAYBREAK FRI. UNFATHOMABLE TO CUT
TEMPS AS REALLY HOW OFTEN IS M15-16F NOT COLD ENOUGH. BUT WITH
STRONG 1049 ARCTIC HIGH DIVES INTO LWR OH VLY BY DAYBREAK FRI
W/STRONG SUBSIDENCE/DRYING AND FRESH SNOWPACK. SOME ALBEIT SLIGHT
ADDITION OF MOISTURE/SUBLIMATION INTO SHALLOW LYR WITH LOW
SUBSIDENCE INVERSION AND SFC BASED AM INVERSION GIVES RISE TO
CONCERN FOR POTNL FZFG. ADDITIONALLY WITH TEMPS FALLING 10-15F BLO
XOVER AND PATCHY M1/4SM AT KIRS THIS AM MAY BE FOREBODING OF AN
ADDED INSULT TO INJURY FOR DEADLY COLD AIRMASS TONIGHT. WITH LOW
CONFIDENCE THOUGH ESPCLY WITH DWPOINTS THIS AFTERNOON INTO TONIGHT
WL HOLD ON MENTION IN ZFP AND RELEGATE TO HWO MENTION OF PTCHY FZFG
PSBL. GIVEN SUCH COLD TEMPS FRI AM...HAVE LOWERED MAX TEMPS FOR FRI
BY SVRL DEGREES/BLO MOST GUID AS STRONG TEMP RECOVERY HIGHLY
UNLIKELY.
PREFERENCE LIES WITH GFS/ECMWF WITH HANDLING OF SHORTWAVE ROUNDING
HIGH AMP RIDGE WITH NAM TRACKING SURFACE LOW TOO FAR WEST/SOUTH. GFS
CONSISTENT WITH FEATURE. GIVEN INITIAL DRY AIRMASS HAVE DELAYED
ONSET MORE TOWARD DAYBREAK FOR RELATIVELY LIGHT SNOW/MOISTURE
STARVED CLIPPER EVENT.
LONG TERM...
SATURDAY THROUGH WEDNESDAY...THE MAIN CHALLENGES CONTINUE TO BE THE
TRACK AND TIMING OF CLIPPER TYPE OF SYSTEMS WITH SHORT WAVE TROFS
MOVING THROUGH THE LONG WAVE PATTERN OVER THE EASTERN CONUS. SOME
EARLIER GFS RUNS WERE TRYING TO MOUNT SUPPORT FOR A MORE ZONAL
FLOW...EVEN WITH THE LONG WAVE TROF BECOMING REESTABLISHED OVER THE
WESTERN UNITED STATES. HAVE NOT FOUND MUCH EVIDENCE FOR THIS TREND
AT LEAST THROUGH WEDNESDAY AS THE LONG WAVE TROF AXIS SHOULD REMAIN
OVER THE GREAT LAKES REGION TO THE EAST COAST. SOME MODERATION IS
POSSIBLE LATE IN THE PERIOD AHEAD OF A STRONG CLIPPER SYSTEM...BUT
ANOTHER SURGE OF COLD AIR IS EVIDENT JUST PAST THE END OF THE
FORECAST PERIOD PER ECMWF/GFS. ONGOING TIMING FOR THE SATURDAY
CLIPPER APPEARS ON TRACK...SO ONLY MINOR CHANGES MADE. A SECOND
WEAKER SYSTEM SHOULD PROVIDE A CHANCE FOR LIGHT SNOW SUNDAY AND
MONDAY. ONGOING GRIDS/ZPF APPEAR TO ADEQUATELY HANDLE THIS SYSTEM.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR
INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR
MIZ077>079.
OH...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR OHZ001-002-004-005-
015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR
LMZ043-046.
SMALL CRAFT ADVISORY UNTIL 12 PM EST FRIDAY FOR LMZ043-046.
&&
$$
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...MURPHY
UPDATE...ARNOTT
000
FXUS63 KIWX 151149
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
645 AM EST THU JAN 15 2009
.AVIATION...
FEW CHNGS WITH 12 UTC TAFS. LAST VESTIGES OF IFR SNOWBANDS ACRS NRN
INDIANA AS BANDS BEGIN TO SLIDE NEWD NORTH OF TERMINAL SITES. BEST
CHC FOR BRF PD OF IFR VSBYS AT KSBN NEXT FEW HOURS BEFORE INVERSION
HGHTS BEGIN TO CRASH...SPELLING END TO APPRECIABLE ACCUMULATING
SNOW. SUBSIDENCE IN EXTREMLY DRY AIRMASS TO BRING VFR TO KFWA BY
EARLY AFTN AND EVENING AT KSBN WHERE SLIGHTLY MOISTER LAKE ENHANCED
BOUNDARY LYR SHOULD REMAIN LOCKED BENEATH 3KFT INVERSION.
&&
.SHORT TERM...
TODAY THROUGH FRIDAY NIGHT. TWO PRIMARY FCST CONCERNS WITH MORNING
ISSUANCE THOUGH CRNT FCST TRENDS APPEAR TO HAVE ALL WELL IN HAND.
FIRST WRT TWO EARLIER DEVELOPED BANDS MERGING INTO INTENSE SHORE
PARALLEL SNOWBAND INTO FAR NWRN CWA W/RESULTANT 2 IN/HR RATES
REPORTED AT KSBN BTWN 07-08 UTC...INDICATIVE OF AMAZING SNOW-LIQUID
RATIOS OF AT LEAST 30-40 TO 1. LOWEST 2-3KFT CBL COINCIDENT WITH DGZ
AND EXTREME UVM PUNCHING LKINDUCED EQL TO 11KFT CONFIRMED W/ WSR-88D
SAMPLING OF BAND IN 1.5 AND 2.5 DEG SLICES. BEST THERMAL DYNAMICS
WITH 925-8H LAPSE RATES GT 8C/KM PUSH PRIMARILY INTO MI COUNTIES BY
AFTN W/BEST CONVG SIGNALS. CURRENT WS WARNING END TIMES APPEAR ON
TRACK SAVE FOR EASY MONEY CAN FOR LAPORTE AND STARKE WITH AM
ISSUANCE. ST. JOE AND ELK COUNTIES MAY AS WELL BE AFFORDED AN EARLY
.CAN BY LATE AM...THOUGH PREFER TO LET DAYSHIFT MAKE THAT
DETERMINATION AS STEERING FLOW RELATIVELY SLOW TO BACK. LAKE
AGGREGATE/THERMAL TROF CIRCULATION WELL ESTABLISHED RESULTING IN
KSBN 19F RISE FROM EARLIER EVE MIN UNDER CURRENT HVY SNOWBAND.
PREV TEMPS FOR TODAY APPEAR ON TRACK WITH LITTLE RISE. SECOND ISSUE
WRT IMMENSE HIGH AMP RIDGING ALONG EPAC EXNDG NWD INTO NW
TERRITORIES...TO USHER COLDEST AIRMASS IN DECADES INTO CWA WITH
COLDEST 1000-900MB TEMPS THIS AM ACRS CNTL MN/NRN WI TO SETTLE WITH
MINIMA M22-M23 INTO SRN CWA BY DAYBREAK FRI. UNFATHOMABLE TO CUT
TEMPS AS REALLY HOW OFTEN IS M15-16F NOT COLD ENOUGH. BUT WITH
STRONG 1049 ARCTIC HIGH DIVES INTO LWR OH VLY BY DAYBREAK FRI
W/STRONG SUBSIDENCE/DRYING AND FRESH SNOWPACK. SOME ALBEIT SLIGHT
ADDITION OF MOISTURE/SUBLIMATION INTO SHALLOW LYR WITH LOW
SUBSIDENCE INVERSION AND SFC BASED AM INVERSION GIVES RISE TO
CONCERN FOR POTNL FZFG. ADDITIONALLY WITH TEMPS FALLING 10-15F BLO
XOVER AND PATCHY M1/4SM AT KIRS THIS AM MAY BE FOREBODING OF AN
ADDED INSULT TO INJURY FOR DEADLY COLD AIRMASS TONIGHT. WITH LOW
CONFIDENCE THOUGH ESPCLY WITH DWPOINTS THIS AFTERNOON INTO TONIGHT
WL HOLD ON MENTION IN ZFP AND RELEGATE TO HWO MENTION OF PTCHY FZFG
PSBL. GIVEN SUCH COLD TEMPS FRI AM...HAVE LOWERED MAX TEMPS FOR FRI
BY SVRL DEGREES/BLO MOST GUID AS STRONG TEMP RECOVERY HIGHLY
UNLIKELY.
PREFERENCE LIES WITH GFS/ECMWF WITH HANDLING OF SHORTWAVE ROUNDING
HIGH AMP RIDGE WITH NAM TRACKING SURFACE LOW TOO FAR WEST/SOUTH. GFS
CONSISTENT WITH FEATURE. GIVEN INITIAL DRY AIRMASS HAVE DELAYED
ONSET MORE TOWARD DAYBREAK FOR RELATIVELY LIGHT SNOW/MOISTURE
STARVED CLIPPER EVENT.
&&
.LONG TERM...
SATURDAY THROUGH WEDNESDAY...THE MAIN CHALLENGES CONTINUE TO BE THE
TRACK AND TIMING OF CLIPPER TYPE OF SYSTEMS WITH SHORT WAVE TROFS
MOVING THROUGH THE LONG WAVE PATTERN OVER THE EASTERN CONUS. SOME
EARLIER GFS RUNS WERE TRYING TO MOUNT SUPPORT FOR A MORE ZONAL
FLOW...EVEN WITH THE LONG WAVE TROF BECOMING REESTABLISHED OVER THE
WESTERN UNITED STATES. HAVE NOT FOUND MUCH EVIDENCE FOR THIS TREND
AT LEAST THROUGH WEDNESDAY AS THE LONG WAVE TROF AXIS SHOULD REMAIN
OVER THE GREAT LAKES REGION TO THE EAST COAST. SOME MODERATION IS
POSSIBLE LATE IN THE PERIOD AHEAD OF A STRONG CLIPPER SYSTEM...BUT
ANOTHER SURGE OF COLD AIR IS EVIDENT JUST PAST THE END OF THE
FORECAST PERIOD PER ECMWF/GFS. ONGOING TIMING FOR THE SATURDAY
CLIPPER APPEARS ON TRACK...SO ONLY MINOR CHANGES MADE. A SECOND
WEAKER SYSTEM SHOULD PROVIDE A CHANCE FOR LIGHT SNOW SUNDAY AND
MONDAY. ONGOING GRIDS/ZPF APPEAR TO ADEQUATELY HANDLE THIS SYSTEM.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR
INZ003>009-012>018-020-022>027-032>034.
LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR
INZ004-005-014.
MI...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR
MIZ077>079.
OH...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR
OHZ001-002-004-005-015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR
LMZ043-046.
SMALL CRAFT ADVISORY UNTIL 12 PM EST FRIDAY FOR LMZ043-046.
&&
$$
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...MURPHY
000
FXUS63 KIND 151102
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
601 AM EST THU JAN 15 2009
.AVIATION...DISCUSSION FOR 12Z TAFS.
HIGH PRESSURE WILL BUILD INTO CENTRAL INDIANA TODAY. TIME HTS
SHOW LOTS OF DRY AIR. CU RULE SLIGHTLY NEGATIVE DURING THE DAY AND
CONSIDERING THE SUNSHINE WL INCLUDE SCT CU AROUND 3KFT. COULD SEE A
BRIEF FLURRY AT ANY OF THE SITES BUT NOT ENUF TO INCLUDE. WINDS WILL
BE AROUND 12 KTS OUT OF THE WNW TODAY AND DROPPING TO AROUND 5KTS
OVERNIGHT.
&&
.PREV DISCUSSION...FCST FOCUS REMAINS ON TEMPS/WIND CHILLS NEXT 36
HRS.
06Z SFC MAP SHOWED 1047MB ARCTIC HIGH ACROSS THE DAKOTAS WITH A WEAK
LOW ACROSS VA. 3HR PRESSURE RISES OF 2MB CONTINUE TO OCCUR ACROSS
THE REGION AS THE STRONG HIGH MOVES SE TOWARD THE AREA. THIS SHOULD
ALLOW WINDS TO STAY UP AROUND 10KTS WITH SOME RISK FOR GUSTS TO
PERSIST INTO THE MORNING HOURS AS WELL. A QUICK CHECK OF THE TEMPS
SHOWS -5 TO -10F ACROSS CENTRAL IL AS OF 7Z WITH WIND CHILLS -20 TO
-25 ALSO OCCURRING ACROSS CENTRAL IL AT THIS TIME. MEANWHILE...LOW
CLDS DUE TO REMNANT LAKE MOISTURE CONTINUE TO LINGER ACROSS OUR CWA
HOWEVER THESE SHOULD DISSIPATE/MOVE EAST AS CAA/DRY ADVECTION
CONTINUES OVERNIGHT. THE LAKE MOISTURE HAS SLOWED OUR DROP IN AIR
TEMPS FOR THE MOMENT.
FOR THIS FCST WILL RELY ON A MIX OF NAM BUFKIT SFC TEMPS AND OBS TO
BEST ESTIMATE AIR TEMPS OVER THE NEXT 36 HRS. NOT RELYING HEAVILY ON
MOS AT THIS POINT ALTHOUGH I WOULD FAVOR THE COLDER NAM MOS AS
OTHERS APPEAR TOO WARM.
TODAY...CAA SHOULD CONTINUE THROUGH 18Z WHICH SUGGESTS THAT AIR
TEMPS MAY CONTINUE TO FALL THROUGH SUNRISE AND FOR A TIME INTO MID
MORNING THU. PRESSURE RISES AND WIND FIELDS ALSO SUGGEST THAT
SUSTAINED WINDS AOA 10KTS WITH GUSTS TO AROUND 20KTS WILL ALSO
OCCUR. GIVEN THIS SCENARIO I FAVOR THE COLDER NAM MOS TEMPS WHICH
ARE CLOSE TO OUR GOING FCST HIGHS. WIND CHILLS SHOULD FLIRT WITH
WARNING CRITERIA NORTH OF I-70 FOR A TIME THIS MORNING MAINLY FROM
12Z TO 17Z.
TONIGHT...AGAIN FAVOR A COLDER NAM MOS OR NAM BUFKIT SOUNDING SFC
TEMP WHICH SUGGESTS THAT LOWS SHOULD BOTTOM OUT IN THE -10 TO -20F
RANGE NORTH OF I-70. LIGHT WSW WINDS AROUND 5 TO 10KTS SHOULD KEEP
WIND CHILLS IN THE -20 TO -30F RANGE IN THE WARNING SO AT THIS POINT
WE WILL CONTINUE THE WIND CHILL WARNING THROUGH TONIGHT.
FRI...TEMPS MAY REBOUND SOMEWHAT AFTER A VERY COLD START. NAM
SOUNDINGS SHOW SINGLE DIGITS NORTH OF I-70 AS SOME WEAK WAA ATTEMPTS
TO DEVELOP BUT FEEL THIS WILL OCCUR ALOFT MORE THAN AT THE SFC.
FAVOR COLDER MOS AND CURRENT TEMPS APPEAR SUPERIOR TO MOS.
FRI NIGHT/SAT...STRONGER WAA WILL DEVELOP AND PERSIST INTO SAT.
TEMPS SHOULD BE STEADY OR RISE AFTER MIDNIGHT WITH SOME CHC FOR SNOW
ON SAT/SAT NIGHT ACROSS THE NE AS SATURATION OCCURS BY LATE DAY INTO
SAT NIGHT WITHIN THE WAA ZONE AHEAD OF A CLIPPER SYSTEM.
NO CHANGES WILL BE MADE BEYOND SAT.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WIND CHILL WARNING UNTIL 1 PM EST FRIDAY FOR INZ021-028>031-035>049.
&&
$$
PUBLIC...CO
AVIATION...CP
000
FXUS63 KIND 151102
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
601 AM EST THU JAN 15 2009
.AVIATION...DISCUSSION FOR 12Z TAFS.
HIGH PRESSURE WILL BUILD INTO CENTRAL INDIANA TODAY. TIME HTS
SHOW LOTS OF DRY AIR. CU RULE SLIGHTLY NEGATIVE DURING THE DAY AND
CONSIDERING THE SUNSHINE WL INCLUDE SCT CU AROUND 3KFT. COULD SEE A
BRIEF FLURRY AT ANY OF THE SITES BUT NOT ENUF TO INCLUDE. WINDS WILL
BE AROUND 12 KTS OUT OF THE WNW TODAY AND DROPPING TO AROUND 5KTS
OVERNIGHT.
&&
.PREV DISCUSSION...FCST FOCUS REMAINS ON TEMPS/WIND CHILLS NEXT 36
HRS.
06Z SFC MAP SHOWED 1047MB ARCTIC HIGH ACROSS THE DAKOTAS WITH A WEAK
LOW ACROSS VA. 3HR PRESSURE RISES OF 2MB CONTINUE TO OCCUR ACROSS
THE REGION AS THE STRONG HIGH MOVES SE TOWARD THE AREA. THIS SHOULD
ALLOW WINDS TO STAY UP AROUND 10KTS WITH SOME RISK FOR GUSTS TO
PERSIST INTO THE MORNING HOURS AS WELL. A QUICK CHECK OF THE TEMPS
SHOWS -5 TO -10F ACROSS CENTRAL IL AS OF 7Z WITH WIND CHILLS -20 TO
-25 ALSO OCCURRING ACROSS CENTRAL IL AT THIS TIME. MEANWHILE...LOW
CLDS DUE TO REMNANT LAKE MOISTURE CONTINUE TO LINGER ACROSS OUR CWA
HOWEVER THESE SHOULD DISSIPATE/MOVE EAST AS CAA/DRY ADVECTION
CONTINUES OVERNIGHT. THE LAKE MOISTURE HAS SLOWED OUR DROP IN AIR
TEMPS FOR THE MOMENT.
FOR THIS FCST WILL RELY ON A MIX OF NAM BUFKIT SFC TEMPS AND OBS TO
BEST ESTIMATE AIR TEMPS OVER THE NEXT 36 HRS. NOT RELYING HEAVILY ON
MOS AT THIS POINT ALTHOUGH I WOULD FAVOR THE COLDER NAM MOS AS
OTHERS APPEAR TOO WARM.
TODAY...CAA SHOULD CONTINUE THROUGH 18Z WHICH SUGGESTS THAT AIR
TEMPS MAY CONTINUE TO FALL THROUGH SUNRISE AND FOR A TIME INTO MID
MORNING THU. PRESSURE RISES AND WIND FIELDS ALSO SUGGEST THAT
SUSTAINED WINDS AOA 10KTS WITH GUSTS TO AROUND 20KTS WILL ALSO
OCCUR. GIVEN THIS SCENARIO I FAVOR THE COLDER NAM MOS TEMPS WHICH
ARE CLOSE TO OUR GOING FCST HIGHS. WIND CHILLS SHOULD FLIRT WITH
WARNING CRITERIA NORTH OF I-70 FOR A TIME THIS MORNING MAINLY FROM
12Z TO 17Z.
TONIGHT...AGAIN FAVOR A COLDER NAM MOS OR NAM BUFKIT SOUNDING SFC
TEMP WHICH SUGGESTS THAT LOWS SHOULD BOTTOM OUT IN THE -10 TO -20F
RANGE NORTH OF I-70. LIGHT WSW WINDS AROUND 5 TO 10KTS SHOULD KEEP
WIND CHILLS IN THE -20 TO -30F RANGE IN THE WARNING SO AT THIS POINT
WE WILL CONTINUE THE WIND CHILL WARNING THROUGH TONIGHT.
FRI...TEMPS MAY REBOUND SOMEWHAT AFTER A VERY COLD START. NAM
SOUNDINGS SHOW SINGLE DIGITS NORTH OF I-70 AS SOME WEAK WAA ATTEMPTS
TO DEVELOP BUT FEEL THIS WILL OCCUR ALOFT MORE THAN AT THE SFC.
FAVOR COLDER MOS AND CURRENT TEMPS APPEAR SUPERIOR TO MOS.
FRI NIGHT/SAT...STRONGER WAA WILL DEVELOP AND PERSIST INTO SAT.
TEMPS SHOULD BE STEADY OR RISE AFTER MIDNIGHT WITH SOME CHC FOR SNOW
ON SAT/SAT NIGHT ACROSS THE NE AS SATURATION OCCURS BY LATE DAY INTO
SAT NIGHT WITHIN THE WAA ZONE AHEAD OF A CLIPPER SYSTEM.
NO CHANGES WILL BE MADE BEYOND SAT.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WIND CHILL WARNING UNTIL 1 PM EST FRIDAY FOR INZ021-028>031-035>049.
&&
$$
PUBLIC...CO
AVIATION...CP
000
FXUS63 KIWX 151026
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
526 AM EST THU JAN 15 2009
.SHORT TERM...
TODAY THROUGH FRIDAY NIGHT. TWO PIRMARY FCST CONCERNS WITH MORNING
ISSUANCE THOUGH CRNT FCST TRENDS APPEAR TO HAVE ALL WELL IN HAND.
FIRST WRT TWO EARLIER DEVELOPED BANDS MERGING INTO INTENSE SHORE
PARALLEL SNOWBAND INTO FAR NWRN CWA W/RESULTANT 2 IN/HR RATES
REPORTED AT KSBN BTWN 07-08 UTC...INDICATIVE OF AMAZING SNOW-LIQUID
RATIOS OF AT LEAST 30-40 TO 1. LOWEST 2-3KFT CBL COINCIDENT WITH DGZ
AND EXTREME UVM PUNCHING LKINDUCED EQL TO 11KFT CONFIRMED W/ WSR-88D
SAMPLING OF BAND IN 1.5 AND 2.5 DEG SLICES. BEST THERMAL DYNAMICS
WITH 925-8H LAPSE RATES GT 8C/KM PUSH PRIMARILY INTO MI COUNTIES BY
AFTN W/BEST CONVG SIGNALS. CURRENT WS WARNING END TIMES APPEAR ON
TRACK SAVE FOR EASY MONEY CAN FOR LAPORTE AND STARKE WITH AM
ISSUANCE. ST. JOE AND ELK COUNTIES MAY AS WELL BE AFFORDED AN EARLY
.CAN BY LATE AM...THOUGH PREFER TO LET DAYSHIFT MAKE THAT
DETERMINATION AS STEERING FLOW RELATIVELY SLOW TO BACK. LAKE
AGGREGATE/THERMAL TROF CIRCULATION WELL ESTABLISHED RESULTING IN
KSBN 19F RISE FROM EARLIER EVE MIN UNDER CURRENT HVY SNOWBAND.
PREV TEMPS FOR TODAY APPEAR ON TRACK WITH LITTLE RISE. SECOND ISSUE
WRT IMMENSE HIGH AMP RIDGING ALONG EPAC EXNDG NWD INTO NW
TERRITORIES...TO USHER COLDEST AIRMASS IN DECADES INTO CWA WITH
COLDEST 1000-900MB TEMPS THIS AM ACRS CNTL MN/NRN WI TO SETTLE WITH
MINIMA M22-M23 INTO SRN CWA BY DAYBREAK FRI. UNFATHOMABLE TO CUT
TEMPS AS REALLY HOW OFTEN IS M15-16F NOT COLD ENOUGH. BUT WITH
STRONG 1049 ARCTIC HIGH DIVES INTO LWR OH VLY BY DAYBREAK FRI
W/STRONG SUBSIDENCE/DRYING AND FRESH SNOWPACK. SOME ALBEIT SLIGHT
ADDITION OF MOISTURE/SUBLIMATION INTO SHALLOW LYR WITH LOW
SUBSIDENCE INVERSION AND SFC BASED AM INVERSION GIVES RISE TO
CONCERN FOR POTNL FZFG. ADDITIONALLY WITH TEMPS FALLING 10-15F BLO
XOVER AND PATCHY M1/4SM AT KIRS THIS AM MAY BE FOREBODING OF AN
ADDED INSULT TO INJURY FOR DEADLY COLD AIRMASS TONIGHT. WITH LOW
CONFIDENCE THOUGH ESPCLY WITH DWPOINTS THIS AFTERNOON INTO TONIGHT
WL HOLD ON MENTION IN ZFP AND RELEGATE TO HWO MENTION OF PTCHY FZFG
PSBL. GIVEN SUCH COLD TEMPS FRI AM...HAVE LOWERED MAX TEMPS FOR FRI
BY SVRL DEGREES/BLO MOST GUID AS STRONG TEMP RECOVERY HIGHLY
UNLIKELY.
PREFERENCE LIES WITH GFS/ECMWF WITH HANDLING OF SHORTWAVE ROUNDING
HIGH AMP RIDGE WITH NAM TRACKING SURFACE LOW TOO FAR WEST/SOUTH. GFS
CONSISTENT WITH FEATURE. GIVEN INITIAL DRY AIRMASS HAVE DELAYED
ONSET MORE TOWARD DAYBREAK FOR RELATIVELY LIGHT SNOW/MOISTURE
STARVED CLIPPER EVENT.
&&
.LONG TERM...
SATURDAY THROUGH WEDNESDAY...THE MAIN CHALLENGES CONTINUE TO BE THE
TRACK AND TIMING OF CLIPPER TYPE OF SYSTEMS WITH SHORT WAVE TROFS
MOVING THROUGH THE LONG WAVE PATTERN OVER THE EASTERN CONUS. SOME
EARLIER GFS RUNS WERE TRYING TO MOUNT SUPPORT FOR A MORE ZONAL
FLOW...EVEN WITH THE LONG WAVE TROF BECOMING REESTABLISHED OVER THE
WESTERN UNITED STATES. HAVE NOT FOUND MUCH EVIDENCE FOR THIS TREND
AT LEAST THROUGH WEDNESDAY AS THE LONG WAVE TROF AXIS SHOULD REMAIN
OVER THE GREAT LAKES REGION TO THE EAST COAST. SOME MODERATION IS
POSSIBLE LATE IN THE PERIOD AHEAD OF A STRONG CLIPPER SYSTEM...BUT
ANOTHER SURGE OF COLD AIR IS EVIDENT JUST PAST THE END OF THE
FORECAST PERIOD PER ECMWF/GFS. ONGOING TIMING FOR THE SATURDAY
CLIPPER APPEARS ON TRACK...SO ONLY MINOR CHANGES MADE. A SECOND
WEAKER SYSTEM SHOULD PROVIDE A CHANCE FOR LIGHT SNOW SUNDAY AND
MONDAY. ONGOING GRIDS/ZPF APPEAR TO ADEQUATELY HANDLE THIS SYSTEM.
&&
.AVIATION...
MINOR TWEAKS TO KSBN TAF WRT TIMING OF INTENSE LES BAND NOW POINTED
FM BRIDGEMAN TOWARD KSBN. LIFR VSBYS AS 30 DBZ REFLECTIVITY IMPINGES
UPON AIRFIELD FOR NEXT TWO HOURS. MUCH LESS INTENSITY AS BAND
STRUGGLES TO OVERCOME DRY ENVIRONMENTAL AIR AS IT REACHES
KFWA...THOUGH BRIEF PD OF IFR VSBYS REMAIN PROBABLE AT TIMES...WITH
KASW EVEN DOWN AS LOW AS 1/2SM PAST HOUR. AS TEMPS CONT TO FALL SOME
CONCERN WRT PTCHY FREEZING FOG DVLPG...FOR NOW HAVE LEFT OUT AS LOW
PROBABILITY AND CONT TO MONITOR.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR
INZ003>009-012>018-020-022>027-032>034.
LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR
INZ004-005-014.
MI...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR
MIZ077>079.
OH...WIND CHILL WARNING UNTIL 12 PM EST FRIDAY FOR OHZ001-002-004-005-
015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR
LMZ043-046.
SMALL CRAFT ADVISORY UNTIL 12 PM EST FRIDAY FOR LMZ043-046.
&&
$$
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...MURPHY
000
FXUS63 KIND 150746
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
245 AM EST THU JAN 15 2009
.DISCUSSION...FCST FOCUS REMAINS ON TEMPS/WIND CHILLS NEXT 36 HRS.
06Z SFC MAP SHOWED 1047MB ARCTIC HIGH ACROSS THE DAKOTAS WITH A WEAK
LOW ACROSS VA. 3HR PRESSURE RISES OF 2MB CONTINUE TO OCCUR ACROSS
THE REGION AS THE STRONG HIGH MOVES SE TOWARD THE AREA. THIS SHOULD
ALLOW WINDS TO STAY UP AROUND 10KTS WITH SOME RISK FOR GUSTS TO
PERSIST INTO THE MORNING HOURS AS WELL. A QUICK CHECK OF THE TEMPS
SHOWS -5 TO -10F ACROSS CENTRAL IL AS OF 7Z WITH WIND CHILLS -20 TO
-25 ALSO OCCURRING ACROSS CENTRAL IL AT THIS TIME. MEANWHILE...LOW
CLDS DUE TO REMNANT LAKE MOISTURE CONTINUE TO LINGER ACROSS OUR CWA
HOWEVER THESE SHOULD DISSIPATE/MOVE EAST AS CAA/DRY ADVECTION
CONTINUES OVERNIGHT. THE LAKE MOISTURE HAS SLOWED OUR DROP IN AIR
TEMPS FOR THE MOMENT.
FOR THIS FCST WILL RELY ON A MIX OF NAM BUFKIT SFC TEMPS AND OBS TO
BEST ESTIMATE AIR TEMPS OVER THE NEXT 36 HRS. NOT RELYING HEAVILY ON
MOS AT THIS POINT ALTHOUGH I WOULD FAVOR THE COLDER NAM MOS AS
OTHERS APPEAR TOO WARM.
TODAY...CAA SHOULD CONTINUE THROUGH 18Z WHICH SUGGESTS THAT AIR
TEMPS MAY CONTINUE TO FALL THROUGH SUNRISE AND FOR A TIME INTO MID
MORNING THU. PRESSURE RISES AND WIND FIELDS ALSO SUGGEST THAT
SUSTAINED WINDS AOA 10KTS WITH GUSTS TO AROUND 20KTS WILL ALSO
OCCUR. GIVEN THIS SCENARIO I FAVOR THE COLDER NAM MOS TEMPS WHICH
ARE CLOSE TO OUR GOING FCST HIGHS. WIND CHILLS SHOULD FLIRT WITH
WARNING CRITERIA NORTH OF I-70 FOR A TIME THIS MORNING MAINLY FROM
12Z TO 17Z.
TONIGHT...AGAIN FAVOR A COLDER NAM MOS OR NAM BUFKIT SOUNDING SFC
TEMP WHICH SUGGESTS THAT LOWS SHOULD BOTTOM OUT IN THE -10 TO -20F
RANGE NORTH OF I-70. LIGHT WSW WINDS AROUND 5 TO 10KTS SHOULD KEEP
WIND CHILLS IN THE -20 TO -30F RANGE IN THE WARNING SO AT THIS POINT
WE WILL CONTINUE THE WIND CHILL WARNING THROUGH TONIGHT.
FRI...TEMPS MAY REBOUND SOMEWHAT AFTER A VERY COLD START. NAM
SOUNDINGS SHOW SINGLE DIGITS NORTH OF I-70 AS SOME WEAK WAA ATTEMPTS
TO DEVELOP BUT FEEL THIS WILL OCCUR ALOFT MORE THAN AT THE SFC.
FAVOR COLDER MOS AND CURRENT TEMPS APPEAR SUPERIOR TO MOS.
FRI NIGHT/SAT...STRONGER WAA WILL DEVELOP AND PERSIST INTO SAT.
TEMPS SHOULD BE STEADY OR RISE AFTER MIDNIGHT WITH SOME CHC FOR SNOW
ON SAT/SAT NIGHT ACROSS THE NE AS SATURATION OCCURS BY LATE DAY INTO
SAT NIGHT WITHIN THE WAA ZONE AHEAD OF A CLIPPER SYSTEM.
NO CHANGES WILL BE MADE BEYOND SAT.
&&
.AVIATION...DISCUSSION FOR 15/06Z TAFS
LOW VFR TO MVFR CIGS...WHICH ARE BEING INFLUENCED SOME BY FLOW OFF
OF LAKE MI...WILL GRADUALLY SHIFT E OVERNIGHT AS LOW LEVEL FLOW
BACKS TO THE W. CANNOT RULE OUT A SHSN EARLY IN THE TAF PD AT LAF OR
IND...BUT COVERAGE TOO LOW TO MENTION.
THESE CLOUDS SHOULD BE GONE FROM THE SITES BY 12Z LEAVING VFR CONDS
FOR THE REMAINDER OF THE PD AS A VERY COLD AND DRY AIRMASS MOVES IN.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WIND CHILL WARNING UNTIL 1 PM EST FRIDAY FOR INZ021-028>031-035>049.
&&
$$
PUBLIC...CO
AVIATION...CS/CP
000
FXUS63 KIWX 150556
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
100 AM EST THU JAN 15 2009
.AVIATION...
MINOR TWEAKS TO KSBN TAF WRT TIMING OF INTENSE LES BAND NOW POINTED
FM BRIDGEMAN TOWARD KSBN. LIFR VSBYS AS 30 DBZ REFLECTIVITY IMPINGES
UPON AIRFIELD FOR NEXT TWO HOURS. MUCH LESS INTENSITY AS BAND
STRUGGLES TO OVERCOME DRY ENVIRONMENTAL AIR AS IT REACHES
KFWA...THOUGH BRIEF PD OF IFR VSBYS REMAIN PROBABLE AT TIMES...WITH
KASW EVEN DOWN AS LOW AS 1/2SM PAST HOUR. AS TEMPS CONT TO FALL SOME
CONCERN WRT PTCHY FREEZING FOG DVLPG...FOR NOW HAVE LEFT OUT AS LOW
PROBABILITY AND CONT TO MONITOR.
&&
.PREV DISCUSSION...
AVIATION/UPDATE...
INTENSE LK EFFECT SNOW BAND HAS STRUGGLED THIS EVENING DUE TO A
MYRIAD OF EMBEDDED MESOLOWS DISRUPTING LL FLW AND FAILURE OF BAND
HOLDING IN ANY ONE SPOT FOR ANY SIG LENGTH OF TIME. HWVR OBSVD SNOW
INTENSITIES POINT TO 1 TO 2 INCH PER HOUR RATES AND BAND
REORGANIZING NORTH OF KBEH TO KMKG AND WHICH WILL BECOME THE
DOMINANT PLAYER THROUGH THU MORNING. OF NOTE HWVR ARE STG GRADIENT
WINDS UPSTREAM OF INTENSE LK BAND WHICH WILL SWING EWD BEHIND THIS
FTR OVERNIGHT AND THU MORNING AND WHICH WILL LEAD TO AREAS OF BLSN
AND EXTREME WIND CHILLS AS TEMPS DROP BACK BELOW ZERO WEST OF LK
CLOUD BAND. SMALL ADJUSTMENTS MADE TO ACCOUNT FOR OBSVD TRENDS THIS
EVE.
VFR CONDS AT THE TERMINALS WILL DETERIORATE AS LK BAND SHIFT
EWD...ESP AT KSBN W/PD OF LIFR LIKELY IN +SN. MORE QUESTIONABLE TO
KFWA AND WHETHER OR NOT BAND WILL EXTEND THAT FAR INLAND BUT
CERTAINLY PSBL GIVEN UPSTREAM FLW VECTORS AND TIGHTLY FOCUSED BNDRY
LYR CONVERGENCE.
SHORT TERM...
TONIGHT THROUGH THURS NIGHT
WEAK CLIPPER SYSTEM CENTERED OVER CENTRAL IN...IS CONTINUING TO
EXIT THE REGION. SNOW IS STARTING TO WIND DOWN ACROSS THE REGION AS
THE STRONGEST UPGLIDE AND LARGE SCALE ASCENT IS SHIFTING EAST INTO
OH. THIS WILL CONTINUE TO BE THE TREND THROUGH THE AFTERNOON AND
INTO THE EVENING. WILL LET THE ADV EXPIRE AT 4 PM WESTERN PORTION
/7PM EASTERN PORTION AS THE SNOW INTENSITY WILL CONTINUE TO WANE
ACROSS THE REGION...WITH THE WORST BEING OVER. FARTHER
UPSTREAM...MASSIVE HIGH PRESSURE CONTINUES TO SLIDE DOWN INTO THE
NORTHERN CONUS...WITH A CENTER CURRENTLY INDICATED AT AN IMPRESSIVE
1046MB. STRONG CAA COUPLED WITH BACKING LL FLOW...AND DELTA T/S
APPROACHING 23 C...WILL SUPPORT THE DEVELOPMENT OF LAKE SNOWS...WITH
A PERIOD OF INTENSE SNOWFALL LIKELY ACROSS PORTIONS OF THE REGION.
IN ADDITION...VERY COLD ARCTIC...WITH APPROX -22C AT H925 AT 00Z FRI
COUPLED WITH WINDS OF 10 TO 15 MPH WILL SUPPORT DANGEROUSLY COLD
WIND CHILLS...WITH READINGS DOWN TO -30F AT TIMES.
PERIOD WILL FEATURE SFC RIDGING AS THE CLIPPER SYSTEM PUSHES OUT OF
THE AREA. MORE IMPORTANTLY...FAVORED NORTHERLY FLOW WILL SUPPORT AN
INTENSE PERIOD OF LAKE SNOWS...ALLOWING SOME HIGH ACCUMS IN THE
NORTHWEST. GIVEN THE NATURE OF THE FORECAST CONCERN BEING LAKE
EFFECT PROCESSES...HAVE TRIED TO UTILIZED THE NAM/RUC WHERE POSSIBLE
MESOSCALE EFFECTS ARE MORE EASILY VIEWABLE. THE CAVEAT TO THIS
SITUATION IS THAT THE EXTREME INSTABILITY PRESENT WILL HIGHLY FAVOR
THERMODYNAMICAL ORGANIZATION OF THE LAKE SNOW EVENT...AS OPPOSED TO
SHEAR. THIS IS EVEN MORE TRUE SINCE THE FLOW IS NOW INDICATED TO BE
WEAKER THAN PROGS JUST 2 DAYS AGO INDICATED. BOTTOM LINE...TRYING TO
PINPOINT THE LOCATION OF THE HEAVIEST SNOW WILL BE VERY
DIFFICULT...AS ONE OR TWO MESO-LOWS WOULD CERTAINLY DISRUPT THE
FLOW...SHIFTING THINGS EAST OR WEST. HAVE STAYED VERY CLOSE TO NAM
12 PROGS AS THEY HAVE BEEN VERY HELPFUL WRT LAKE EFFECT EVENTS THIS
YEAR..OPTING TO BLEND IN QPF AREAL AMOUNTS FROM THE GFS AND RUC FOR
UNCERTAINTY PURPOSES.
TONIGHT...LAKE BANDING IS ALREADY IN PROGRESS ACROSS WESTERN
PORTIONS OF MI...EXTENDING SOUTH INTO GYY. LL FLOW WILL BACK
NORTHERLY AND ALLOW A PERIOD OF LONGER FETCH ENHANCEMENT. STRONG CAA
WITH DELTA T/S APPROACHING 23C WILL SUPPORT EXTREME INSTABILITY WITH
H925 OMEGA PROGGED AOA 27 MICROBARS/SEC. LAKE INDUCED EQUILIBRIUM
LEVELS PROGGED AT 12KFT WITH A LARGE PORTION OF UPWARD MOTION IN THE
DGZ WOULD LIKELY SUPPORT SNOWFALL RATES AT IMPRESSIVE VALUES OF 2
POSSIBLY 3 INCHES PER HOUR. CURRENT INDICATIONS SUPPORT THE HEAVIEST
SNOW ACROSS PORTIONS OF LA PORTE AND BERRIEN COUNTIES...AND POSSIBLY
WESTERN CASS. STRONGEST INTENSITY LOOKS TO FAVOR LA PORTE AND
POSSIBLY ST. JOE COUNTY IN...BUT THE BAND IS EXPECTED TO BE
TRANSIENT AS IT PUSHES INTO ST JOE COUNTY IN. SOUTHWEST MI COUNTIES
WILL SEE A PERIOD OF INTENSE SNOW. HOWEVER...VERY DRY AIR UPSTREAM
/DOWN 20 PERCENT AT H85/ COMBINED WITH FALLING INVERSION HEIGHTS
WILL TEND TO TRANSITION BANDS TO MULTIPLE SHORE PARALLEL
ORGANIZATION...BUT A LONG DURATION OF SNOWFALL WILL FAVOR HIGH
AMOUNTS. HAVE OPTED FOR AMOUNTS TO 12 INCHES IN BERRIEN COUNTY WHERE
DURATION WILL BE MAXIMIZED. HIGH AMOUNTS WILL BE POSSIBLE IN LA
PORTE...BUT UNCERTAINTY REMAINS ON HOW LONG THE BAND WILL SETUP OVER
THE AREA...PRECLUDES HIGH AMOUNT MENTION AT THIS TIME. LAKE SNOWS
WILL SHIFT NORTH INTO MI BY THU AFTERNOON...WITH LIGHT TO MODERATE
SNOWS CONTINUING OVER SOUTHWEST MI.
THE OTHER ISSUE WILL BE STRONG WINDS ON THE BACKSIDE OF ANY LONG
FETCH BANDS THAT DEVELOP IN REPONSE TO MOMENTUM ADJUSTMENT PER
CONVECTIVE INFLUENCES. DEEP MIXING AND ENHANCED FLOW COULD SUPPORT
20 TO 30 MPH WINDS OVER PORTIONS OF BERRIEN AND LA PORTE COUNTY WITH
HIGHER GUSTS. ESPECIALLY GIVEN 30 KNOTS PROGGED AT H925 BEING ABLE
TO TRANSLATE DOWN.
HAVE STARTED THE WIND CHILL ADV LATER GIVEN FORECAST
TEMPS/TD/WINDS...AND ALLOWED THE WARNING TO LAST INTO FRI WHERE THE
DATABASE INDICATES APPARENT T/S IN THE 25 TO 30 BELOW RANGE. HAVE
CONTINUED TO TREND THU HIGHS AND LOWS DOWN GIVEN MOS
TRENDS...TEMP/RH PROFILES ALOFT/AND MODEL 2M TEMPS. TEMPS AOA -20F
WILL BE POSSIBLE AT SOME LOCATIONS WHERE CLEARING AND CALM WINDS
WILL OVERLAP. TEMPS ARE LIKELY TO REMAIN BELOW ZERO AT MANY
LOCATIONS ON THU.
LONG TERM...
FRI THROUGH WED
STRONGLY POSITIVE PNA PATTERN WILL BEGIN THE PERIOD WITH LARGE
TROUGH IN THE EAST WELL ESTABLISHED. THIS PATTERN WILL PERSIST INTO
EARLY NEXT WEEK BEFORE THE EASTERN PACIFIC RIDGE BEGINS TO FLATTEN
AND PULL EAST BRINGING A SLOW MODERATING TREND TO OUR AREA.
GFS/GEFS/CMC/ECMWF ARE IN PRETTY GOOD AGREEMENT ON THIS OVERALL
EVOLUTION...WITH THE PRIMARY DIFFERENCES BEING ON THE HANDLING OF A
SERIES OF SHORTWAVES THAT WILL DROP THROUGH THE AREA DURING THE
PERIOD IN THE DEEP LAYER NORTHWESTERLY FLOW.
LAKE EFFECT SNOW WILL BE ONGOING TO START THE PERIOD WITH T850
AROUND -20C AND CONTINUED WESTERLY FLOW. HAVE KEPT CHC POPS FOR
SHSN OVER SOUTHERN MI AND THE NORTHERNMOST ROW OF COUNTIES IN IN.
THIS LINES UP A LITTLE BETTER WITH H925 AND H850 WINDS VS MODEL QPF
FIELDS. T925 WOULD SUGGEST HIGHS IN THE LOWER SINGLE DIGITS AND WILL
CONTINUE TO UNDERCUT THESE A LITTLE GIVEN SUCH COLD OVERNIGHT LOWS.
ANOTHER BRIEF BREAK OCCURS FRIDAY EVENING BEFORE MID AND HIGHS
CLOUDS ROLL BACK IN WITH SN LIKELY ARRIVING AFTER MIDNIGHT AHEAD OF
THE NEXT CLIPPER. HAVE GONE WITH NON DIURNAL TEMPERATURE TRENDS
FRIDAY NIGHT GIVEN THE INCREASING CLOUD COVER...BUT MOST SITES WILL
SEE LATE EVENING LOWS AGAIN BELOW ZERO.
CLIPPER FOR SATURDAY LOOKS LIKE A WIDESPREAD LIGHT SNOWFALL WITH A
LOW TRACK SOMEWHERE NEAR OVERHEAD AND A LOW TRACK TO THE SOUTHEAST
SUGGESTING THE MOST SNOW OVER NORTHEASTERN AREAS TAPERING OFF TO THE
SOUTH AND WEST. TEMPERATURES WILL RISE THROUGH THE EVENT INTO THE
LOWER 20S.
FOR SUNDAY DETAILS BECOME A LITTLE LESS CLEAR AS THE GFS SHOWS
ANOTHER WAVE DROPPING SOUTH IN THE NORTHWEST FLOW WITH THE ECMWF/CMC
AND QUITE A FEW GEFS MEMBERS VOID OF ANY DISTURBANCES WITH COLD
NORTHWEST FLOW SPAWNING LAKE EFFECT SHSN. WILL FOLLOW THIS LATTER
CONSENSUS...WHICH WAS WELL CAPTURED IN THE PREVIOUS SET OF GRIDS AND
RESTRICT CHC POPS TO THE NORTHEASTERN 2/3RDS OF THE CWA. HIGHS
SHOULD REACH THE LOWER 20S.
FOR THE MONDAY THROUGH WEDNESDAY TIMEFRAME...THE CONTINUED COLD
NORTHWESTERLY FLOW WILL GRADUALLY GIVE WAY TO INCREASING TEMPS ALOFT
AS THE WESTERN RIDGE BEGINS TO NUDGE TOWARDS THE AREA. LAST WAVE IN
THE NORTHWEST FLOW COULD BRING SOME LIGHT SNOW ON MONDAY WITH DRY
WEATHER BECOMING MORE LIKELY FOR TUESDAY AND WEDNESDAY AS TEMPS
ALOFT WILL WARM TO THE POINT WHERE ANY LAKE RESPONSE SHOULD FINALLY
BE OVER. TEMPERATURES WILL WARM INTO THE MID 20S FOR TUESDAY AND
THEN INTO THE LOWER 30S BY WEDNESDAY. WARMER TEMPS AT THIS RANGE
ARE POSSIBLE AS TEMPS ALOFT SHOULD WARM PRETTY QUICKLY WITH THE
RIDGE ARRIVAL...BUT AT THIS RANGE...HAVE TO GIVE SOME CREDENCE TO
CLIMATOLOGY.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ018-
026-027-033-034.
WIND CHILL WARNING FROM MIDNIGHT EST /11 PM CST/ TONIGHT TO 12
PM EST /11 AM CST/ FRIDAY FOR INZ003>009-012>018-020-
022>027-032>034.
LAKE EFFECT SNOW WARNING UNTIL 6 AM CST THURSDAY FOR INZ003-012.
LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THURSDAY FOR INZ004-005-
014.
WINTER WEATHER ADVISORY UNTIL 5 PM EST /4 PM CST/ THIS
AFTERNOON FOR INZ012>017-020-022>025-032.
MI...WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 12 PM EST FRIDAY
FOR MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THURSDAY FOR MIZ077.
LAKE EFFECT SNOW WARNING FROM 10 PM THIS EVENING TO 7 PM EST
THURSDAY FOR MIZ078-079.
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ015-
016-024-025.
WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 12 PM EST FRIDAY
FOR OHZ001-002-004-005-015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THURSDAY FOR LMZ043-
046.
GALE WARNING UNTIL 7 AM EST THURSDAY FOR LMZ043-046.
&&
$$
SHORT TERM...JC
LONG TERM...ARNOTT
AVIATION/UPDATE...HOLSTEN
AVIATION...MURPHY
000
FXUS63 KIND 150521
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1221 AM EST THU JAN 15 2009
.AVIATION...DISCUSSION FOR 15/06Z TAFS
LOW VFR TO MVFR CIGS...WHICH ARE BEING INFLUENCED SOME BY FLOW OFF
OF LAKE MI...WILL GRADUALLY SHIFT E OVERNIGHT AS LOW LEVEL FLOW
BACKS TO THE W. CANNOT RULE OUT A SHSN EARLY IN THE TAF PD AT LAF OR
IND...BUT COVERAGE TOO LOW TO MENTION.
THESE CLOUDS SHOULD BE GONE FROM THE SITES BY 12Z LEAVING VFR CONDS
FOR THE REMAINDER OF THE PD AS A VERY COLD AND DRY AIRMASS MOVES IN.
&&
.PREV DISCUSSION...FORECAST FOCUS WILL BE ON UPCOMING DANGEROUSLY
COLD TEMPERATURES.
SHORT TERM...SURFACE LOW WAS OVER WEST CENTRAL INDIANA AT 19Z AND
WILL MOVE EAST THROUGH THE STATE THIS AFTERNOON. A HEAVIER BAND OF
SNOW WAS MOVING ACROSS THE NORTHERN CWA IN AN ENHANCED AREA OF LIFT
THAT WILL QUICKLY MOVE EAST ALONG WITH THE SURFACE LOW AND UPPER
WAVE. TEMPS WERE FALLING QUICKLY BEHIND THE SURFACE FRONT AND WINDS
WERE INCREASING WITH GUSTS 25-35MPH. THERE WILL BE SOME ISSUES WITH
BLOWING SNOW...PARTICULARLY ALONG AND NORTH OF INTERSTATE 70. THAT
SAID WILL HANG ON TO THE WINTER WEATHER ADVISORY UNTIL EXPIRATION.
SNOW WILL TAPER OFF FROM WEST TO EAST STARTING AROUND 00Z. HAVE
LOWERED POPS TO CHANCE CAT AFTER THAT TIME THEN JUST FLURRIES AFTER
MIDNIGHT. WITH FRESH SNOW ON THE GROUND WILL GO BELOW MOS NUMBERS
TONIGHT. WITH SUB ZERO TEMPS AND WIND GUSTS TO 30 MPH WIND CHILL
VALUES WILL BE DANGEROUSLY COLD...ESPECIALLY NORTH OF INTERSTATE 70
WHERE WIND CHILL VALUES OF 20 BELOW ZERO TO 25 BELOW ZERO WILL
OCCUR. SOUTH OF THE INTERSTATE WHERE A WIND CHILL ADVISORY IS IN
EFFECT FOR VALUES AROUND 10 BELOW ALSO LOOKS GOOD. WIND CHILL
ADVISORY/WARNING START TIME OF MIDNIGHT STILL LOOKS GOOD SO NO
CHANGES WILL BE MADE.
ON THURSDAY STRONG COLD ADVECTION CONTINUES AND TEMPS ON THURSDAY
WILL NOT GET OUT OF THE SINGLE DIGITS ABOVE ZERO. SOME
AREAS...PARTICULARLY ALONG A LAF TO MIE LINE WILL REMAIN RIGHT
AROUND ZERO ALL DAY LONG.
THURSDAY NIGHT WILL BY FAR BE THE COLDEST NIGHT IN A VERY LONG
TIME. LOWS OF 10 TO 15 BELOW ZERO WILL BE COMMON NORTH OF
INTERSTATE 70 WHILE SOUTH OF THE INTERSTATE LOWS OF 3 TO 9 BELOW
ZERO WILL BE COMMON. WITH TEMPERATURES THAT LOW IT WONT TAKE MUCH
WIND AT ALL TO PRODUCE DANGEROUSLY COLD WIND CHILLS OF 25 TO 30
BELOW ZERO. WILL AGAIN CUT MOS NUMBERS TO ACCOUNT FOR SNOWPACK AND
STRONG COLD ADVECTION.
LONG TERM /FRIDAY TO WEDNESDAY/...STRONG H5 RIDGING OVER THE WEST
COAST OF THE CONUS WILL START TO MIGRATE EAST EARLY NEXT WEEK. THIS
RIDGING WILL KEEP INDIANA UNDER GENERAL NW FLOW AND TEMPERATURES
BELOW FREEZING FOR THE DURATION.
ON FRIDAY NIGHT/SATURDAY ANOTHER CLIPPER SYSTEM MOVES INTO THE
STATE. THE GFS SHOWS A MORE POTENT SWV ASSOCIATED THAN THE NAM BUT
TIMING IS SIMILAR. WILL GO SOMEWHERE IN BETWEEN AND RAISE POPS INTO
THE CHANCE CAT FROM SCHANCE. ON SUNDAY YET ANOTHER WAVE DROPS
THROUGH CENTRAL INDIANA WITHIN THE LARGER TROF. THE GFS/ECMWF ARE
IN GOOD ENOUGH AGREEMENT TO INCLUDE SOME POPS FOR THIS TIME.
THE GFS/ECMWF FOR THE MOST PART AGREE WITH KEEPING DEEP TROF OVER
THE EASTERN HALF OF THE CONUS INTO MID WEEK NEXT WEEK SO WILL ADJUST
TEMPS DOWN SLIGHTLY.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WINTER WEATHER ADVISORY UNTIL 4 AM EST THURSDAY FOR
INZ021-028>031-035>049.
WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ021-028>031-035>049.
&&
$$
SHORT TERM/LONG TERM...SALLY
AVIATION...CS/CP
000
FXUS63 KIWX 150336
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1035 PM EST WED JAN 14 2009
.AVIATION/UPDATE...
INTENSE LK EFFECT SNOW BAND HAS STRUGGLED THIS EVENING DUE TO A
MYRIAD OF EMBEDDED MESOLOWS DISRUPTING LL FLW AND FAILURE OF BAND
HOLDING IN ANY ONE SPOT FOR ANY SIG LENGTH OF TIME. HWVR OBSVD SNOW
INTENSITIES POINT TO 1 TO 2 INCH PER HOUR RATES AND BAND
REORGANIZING NORTH OF KBEH TO KMKG AND WHICH WILL BECOME THE
DOMINANT PLAYER THROUGH THU MORNING. OF NOTE HWVR ARE STG GRADIENT
WINDS UPSTREAM OF INTENSE LK BAND WHICH WILL SWING EWD BEHIND THIS
FTR OVERNIGHT AND THU MORNING AND WHICH WILL LEAD TO AREAS OF BLSN
AND EXTREME WIND CHILLS AS TEMPS DROP BACK BELOW ZERO WEST OF LK
CLOUD BAND. SMALL ADJUSTMENTS MADE TO ACCOUNT FOR OBSVD TRENDS THIS
EVE.
VFR CONDS AT THE TERMINALS WILL DETERIORATE AS LK BAND SHIFT
EWD...ESP AT KSBN W/PD OF LIFR LIKELY IN +SN. MORE QUESTIONABLE TO
KFWA AND WHETHER OR NOT BAND WILL EXTEND THAT FAR INLAND BUT
CERTAINLY PSBL GIVEN UPSTREAM FLW VECTORS AND TIGHTLY FOCUSED BNDRY
LYR CONVERGENCE.
&&
.SHORT TERM...
TONIGHT THROUGH THURS NIGHT
WEAK CLIPPER SYSTEM CENTERED OVER CENTRAL IN...IS CONTINUING TO
EXIT THE REGION. SNOW IS STARTING TO WIND DOWN ACROSS THE REGION AS
THE STRONGEST UPGLIDE AND LARGE SCALE ASCENT IS SHIFTING EAST INTO
OH. THIS WILL CONTINUE TO BE THE TREND THROUGH THE AFTERNOON AND
INTO THE EVENING. WILL LET THE ADV EXPIRE AT 4 PM WESTERN PORTION
/7PM EASTERN PORTION AS THE SNOW INTENSITY WILL CONTINUE TO WANE
ACROSS THE REGION...WITH THE WORST BEING OVER. FARTHER
UPSTREAM...MASSIVE HIGH PRESSURE CONTINUES TO SLIDE DOWN INTO THE
NORTHERN CONUS...WITH A CENTER CURRENTLY INDICATED AT AN IMPRESSIVE
1046MB. STRONG CAA COUPLED WITH BACKING LL FLOW...AND DELTA T/S
APPROACHING 23 C...WILL SUPPORT THE DEVELOPMENT OF LAKE SNOWS...WITH
A PERIOD OF INTENSE SNOWFALL LIKELY ACROSS PORTIONS OF THE REGION.
IN ADDITION...VERY COLD ARCTIC...WITH APPROX -22C AT H925 AT 00Z FRI
COUPLED WITH WINDS OF 10 TO 15 MPH WILL SUPPORT DANGEROUSLY COLD
WIND CHILLS...WITH READINGS DOWN TO -30F AT TIMES.
PERIOD WILL FEATURE SFC RIDGING AS THE CLIPPER SYSTEM PUSHES OUT OF
THE AREA. MORE IMPORTANTLY...FAVORED NORTHERLY FLOW WILL SUPPORT AN
INTENSE PERIOD OF LAKE SNOWS...ALLOWING SOME HIGH ACCUMS IN THE
NORTHWEST. GIVEN THE NATURE OF THE FORECAST CONCERN BEING LAKE EFFECT
PROCESSES...HAVE TRIED TO UTILIZED THE NAM/RUC WHERE POSSIBLE
MESOSCALE EFFECTS ARE MORE EASILY VIEWABLE. THE CAVEAT TO THIS
SITUATION IS THAT THE EXTREME INSTABILITY PRESENT WILL HIGHLY FAVOR
THERMODYNAMICAL ORGANIZATION OF THE LAKE SNOW EVENT...AS OPPOSED TO
SHEAR. THIS IS EVEN MORE TRUE SINCE THE FLOW IS NOW INDICATED TO BE
WEAKER THAN PROGS JUST 2 DAYS AGO INDICATED. BOTTOM LINE...TRYING TO
PINPOINT THE LOCATION OF THE HEAVIEST SNOW WILL BE VERY
DIFFICULT...AS ONE OR TWO MESO-LOWS WOULD CERTAINLY DISRUPT THE
FLOW...SHIFTING THINGS EAST OR WEST. HAVE STAYED VERY CLOSE TO NAM
12 PROGS AS THEY HAVE BEEN VERY HELPFUL WRT LAKE EFFECT EVENTS THIS
YEAR..OPTING TO BLEND IN QPF AREAL AMOUNTS FROM THE GFS AND RUC FOR
UNCERTAINTY PURPOSES.
TONIGHT...LAKE BANDING IS ALREADY IN PROGRESS ACROSS WESTERN
PORTIONS OF MI...EXTENDING SOUTH INTO GYY. LL FLOW WILL BACK
NORTHERLY AND ALLOW A PERIOD OF LONGER FETCH ENHANCEMENT. STRONG CAA
WITH DELTA T/S APPROACHING 23C WILL SUPPORT EXTREME INSTABILITY WITH
H925 OMEGA PROGGED AOA 27 MICROBARS/SEC. LAKE INDUCED EQUILIBRIUM
LEVELS PROGGED AT 12KFT WITH A LARGE PORTION OF UPWARD MOTION IN THE
DGZ WOULD LIKELY SUPPORT SNOWFALL RATES AT IMPRESSIVE VALUES OF 2
POSSIBLY 3 INCHES PER HOUR. CURRENT INDICATIONS SUPPORT THE HEAVIEST
SNOW ACROSS PORTIONS OF LA PORTE AND BERRIEN COUNTIES...AND POSSIBLY
WESTERN CASS. STRONGEST INTENSITY LOOKS TO FAVOR LA PORTE AND
POSSIBLY ST. JOE COUNTY IN...BUT THE BAND IS EXPECTED TO BE
TRANSIENT AS IT PUSHES INTO ST JOE COUNTY IN. SOUTHWEST MI COUNTIES
WILL SEE A PERIOD OF INTENSE SNOW. HOWEVER...VERY DRY AIR UPSTREAM
/DOWN 20 PERCENT AT H85/ COMBINED WITH FALLING INVERSION HEIGHTS
WILL TEND TO TRANSITION BANDS TO MULTIPLE SHORE PARALLEL
ORGANIZATION...BUT A LONG DURATION OF SNOWFALL WILL FAVOR HIGH
AMOUNTS. HAVE OPTED FOR AMOUNTS TO 12 INCHES IN BERRIEN COUNTY WHERE
DURATION WILL BE MAXIMIZED. HIGH AMOUNTS WILL BE POSSIBLE IN LA
PORTE...BUT UNCERTAINTY REMAINS ON HOW LONG THE BAND WILL SETUP OVER
THE AREA...PRECLUDES HIGH AMOUNT MENTION AT THIS TIME. LAKE SNOWS
WILL SHIFT NORTH INTO MI BY THU AFTERNOON...WITH LIGHT TO MODERATE
SNOWS CONTINUING OVER SOUTHWEST MI.
THE OTHER ISSUE WILL BE STRONG WINDS ON THE BACKSIDE OF ANY LONG
FETCH BANDS THAT DEVELOP IN REPONSE TO MOMENTUM ADJUSTMENT PER
CONVECTIVE INFLUENCES. DEEP MIXING AND ENHANCED FLOW COULD SUPPORT 20
TO 30 MPH WINDS OVER PORTIONS OF BERRIEN AND LA PORTE COUNTY WITH
HIGHER GUSTS. ESPECIALLY GIVEN 30 KNOTS PROGGED AT H925 BEING ABLE
TO TRANSLATE DOWN.
HAVE STARTED THE WIND CHILL ADV LATER GIVEN FORECAST
TEMPS/TD/WINDS...AND ALLOWED THE WARNING TO LAST INTO FRI WHERE THE
DATABASE INDICATES APPARENT T/S IN THE 25 TO 30 BELOW RANGE. HAVE
CONTINUED TO TREND THU HIGHS AND LOWS DOWN GIVEN MOS
TRENDS...TEMP/RH PROFILES ALOFT/AND MODEL 2M TEMPS. TEMPS AOA -20F
WILL BE POSSIBLE AT SOME LOCATIONS WHERE CLEARING AND CALM WINDS
WILL OVERLAP. TEMPS ARE LIKELY TO REMAIN BELOW ZERO AT MANY
LOCATIONS ON THU.
&&
.LONG TERM...
FRI THROUGH WED
STRONGLY POSITIVE PNA PATTERN WILL BEGIN THE PERIOD WITH LARGE
TROUGH IN THE EAST WELL ESTABLISHED. THIS PATTERN WILL PERSIST INTO
EARLY NEXT WEEK BEFORE THE EASTERN PACIFIC RIDGE BEGINS TO FLATTEN
AND PULL EAST BRINGING A SLOW MODERATING TREND TO OUR AREA.
GFS/GEFS/CMC/ECMWF ARE IN PRETTY GOOD AGREEMENT ON THIS OVERALL
EVOLUTION...WITH THE PRIMARY DIFFERENCES BEING ON THE HANDLING OF A
SERIES OF SHORTWAVES THAT WILL DROP THROUGH THE AREA DURING THE
PERIOD IN THE DEEP LAYER NORTHWESTERLY FLOW.
LAKE EFFECT SNOW WILL BE ONGOING TO START THE PERIOD WITH T850
AROUND -20C AND CONTINUED WESTERLY FLOW. HAVE KEPT CHC POPS FOR
SHSN OVER SOUTHERN MI AND THE NORTHERNMOST ROW OF COUNTIES IN IN.
THIS LINES UP A LITTLE BETTER WITH H925 AND H850 WINDS VS MODEL QPF
FIELDS. T925 WOULD SUGGEST HIGHS IN THE LOWER SINGLE DIGITS AND WILL
CONTINUE TO UNDERCUT THESE A LITTLE GIVEN SUCH COLD OVERNIGHT LOWS.
ANOTHER BRIEF BREAK OCCURS FRIDAY EVENING BEFORE MID AND HIGHS
CLOUDS ROLL BACK IN WITH SN LIKELY ARRIVING AFTER MIDNIGHT AHEAD OF
THE NEXT CLIPPER. HAVE GONE WITH NON DIURNAL TEMPERATURE TRENDS
FRIDAY NIGHT GIVEN THE INCREASING CLOUD COVER...BUT MOST SITES WILL
SEE LATE EVENING LOWS AGAIN BELOW ZERO.
CLIPPER FOR SATURDAY LOOKS LIKE A WIDESPREAD LIGHT SNOWFALL WITH A
LOW TRACK SOMEWHERE NEAR OVERHEAD AND A LOW TRACK TO THE SOUTHEAST
SUGGESTING THE MOST SNOW OVER NORTHEASTERN AREAS TAPERING OFF TO THE
SOUTH AND WEST. TEMPERATURES WILL RISE THROUGH THE EVENT INTO THE
LOWER 20S.
FOR SUNDAY DETAILS BECOME A LITTLE LESS CLEAR AS THE GFS SHOWS
ANOTHER WAVE DROPPING SOUTH IN THE NORTHWEST FLOW WITH THE ECMWF/CMC
AND QUITE A FEW GEFS MEMBERS VOID OF ANY DISTURBANCES WITH COLD
NORTHWEST FLOW SPAWNING LAKE EFFECT SHSN. WILL FOLLOW THIS LATTER
CONSENSUS...WHICH WAS WELL CAPTURED IN THE PREVIOUS SET OF GRIDS AND
RESTRICT CHC POPS TO THE NORTHEASTERN 2/3RDS OF THE CWA. HIGHS
SHOULD REACH THE LOWER 20S.
FOR THE MONDAY THROUGH WEDNESDAY TIMEFRAME...THE CONTINUED COLD
NORTHWESTERLY FLOW WILL GRADUALLY GIVE WAY TO INCREASING TEMPS ALOFT
AS THE WESTERN RIDGE BEGINS TO NUDGE TOWARDS THE AREA. LAST WAVE IN
THE NORTHWEST FLOW COULD BRING SOME LIGHT SNOW ON MONDAY WITH DRY
WEATHER BECOMING MORE LIKELY FOR TUESDAY AND WEDNESDAY AS TEMPS
ALOFT WILL WARM TO THE POINT WHERE ANY LAKE RESPONSE SHOULD FINALLY
BE OVER. TEMPERATURES WILL WARM INTO THE MID 20S FOR TUESDAY AND
THEN INTO THE LOWER 30S BY WEDNESDAY. WARMER TEMPS AT THIS RANGE
ARE POSSIBLE AS TEMPS ALOFT SHOULD WARM PRETTY QUICKLY WITH THE
RIDGE ARRIVAL...BUT AT THIS RANGE...HAVE TO GIVE SOME CREDENCE TO
CLIMATOLOGY.
&&
.AVIATION...
IFR SN CONTINUING ATTM AT SBN/FWA BUT IS IN A WEAKENING TREND WITH
THE BACK EDGE MOVING EAST. EXPECT IFR VSBYS WITH MVFR CIGS TO
PERSIST FOR THE NEXT FEW HOURS BEFORE IMPROVEMENT TO MVFR TOWARDS
EVENING. FOR THE OVERNIGHT AN INTENSE LAKE EFFECT SNOW BAND WILL
DEVELOP WEST OF SBN AND THEN PULL EAST. CAN/T RULE OUT A BRIEF
BREAK TO VFR AT FWA AROUND 6Z BUT CONFIDENCE IN THIS IS LOW SO HAVE
LEFT OUT AT THIS TIME. BEST CHANCE FOR BAND IMPACTING SBN IS IN THE
5-9Z TIMEFRAME WHEN OCCASIONAL LIFR CONDITIONS ARE LIKELY. BY
9Z...THE BAND MAY REACH AS FAR SOUTHEAST AS FWA WHERE OCCASIONAL IFR
VSBYS ARE POSSIBLE. TOWARDS AND AFTER DAYBREAK THURSDAY THE BAND
WILL PULL EAST WITH MVFR CONDITIONS /DUE TO CIGS/ RETURNING TO SBN
AND FWA SEEING POSSIBLE IMPROVEMENT TO VFR AS THE LOW CLOUDS SCATTER
OUT BY MID MORNING.
EAST NORTHEASTERLY WINDS AROUND 10KTS THIS AFTERNOON WILL BACK TO
NORTHERLY 10-15KTS THIS EVENING...AND CONTINUE TO BACK TO WESTERLY
BY THURSDAY MORNING AND INCREASE TO 12G18KTS. WITHIN THE LAKE
EFFECT SNOW BAND...WINDS WILL INCREASE TO 15G25KTS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ018-
026-027-033-034.
WIND CHILL WARNING FROM MIDNIGHT EST /11 PM CST/ TONIGHT TO 12
PM EST /11 AM CST/ FRIDAY FOR INZ003>009-012>018-020-
022>027-032>034.
LAKE EFFECT SNOW WARNING UNTIL 6 AM CST THURSDAY FOR INZ003-012.
LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THURSDAY FOR INZ004-005-
014.
WINTER WEATHER ADVISORY UNTIL 5 PM EST /4 PM CST/ THIS AFTERNOON
FOR INZ012>017-020-022>025-032.
MI...WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 12 PM EST FRIDAY FOR
MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THURSDAY FOR MIZ077.
LAKE EFFECT SNOW WARNING FROM 10 PM THIS EVENING TO 7 PM EST
THURSDAY FOR MIZ078-079.
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ015-
016-024-025.
WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 12 PM EST FRIDAY FOR
OHZ001-002-004-005-015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THURSDAY FOR LMZ043-
046.
GALE WARNING UNTIL 7 AM EST THURSDAY FOR LMZ043-046.
&&
$$
SHORT TERM...JC
LONG TERM...ARNOTT
AVIATION/UPDATE...HOLSTEN
000
FXUS63 KIND 142257
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
557 PM EST WED JAN 14 2009
.AVIATION...DISCUSSION FOR 15/00Z TAFS
PREVAILING MVFR CONDS EXPECTED THRU MUCH OF THE NIGHT ACROSS MOST
TAF SITES AS LOW PRESSURE EXITS THE AREA. LOOKS LIKE LAF MAY NOT SEE
AS MUCH MVFR PER UPSTREAM OBS...BUT CONFIDENCE NOT HIGH WITH THIS
FORECAST. BULK OF SNOW WILL BE OUT OF THE AREA BY ISSUANCE TIME
LEAVING BEHIND SCT SHSN. MVFR VSBYS CAN BE EXPECTED IN ANY
SHSN...AND THESE SHOULD DIMINISH EARLY IN THE PD. WINDS WILL GUST
NEAR 30KT OVERNIGHT AS COLD AIR RUSHES IN. THIS MAY CREATE LOCALIZED
REDUCED VISIBILITIES IN BLSN IN OUTLYING AREAS...BUT NOT EXPECTING
PREVAILING BLSN AT TAF SITES ATTM. WILL HAVE TO MONITOR.
EXPECT VFR CONDS ON THU AS HIGH PRESSURE AND VERY DRY AIR MOVE INTO
THE AREA.
&&
.DISCUSSION...FORECAST FOCUS WILL BE ON UPCOMING DANGEROUSLY COLD
TEMPERATURES.
SHORT TERM...SURFACE LOW WAS OVER WEST CENTRAL INDIANA AT 19Z AND
WILL MOVE EAST THROUGH THE STATE THIS AFTERNOON. A HEAVIER BAND OF
SNOW WAS MOVING ACROSS THE NORTHERN CWA IN AN ENHANCED AREA OF LIFT
THAT WILL QUICKLY MOVE EAST ALONG WITH THE SURFACE LOW AND UPPER
WAVE. TEMPS WERE FALLING QUICKLY BEHIND THE SURFACE FRONT AND WINDS
WERE INCREASING WITH GUSTS 25-35MPH. THERE WILL BE SOME ISSUES WITH
BLOWING SNOW...PARTICULARLY ALONG AND NORTH OF INTERSTATE 70. THAT
SAID WILL HANG ON TO THE WINTER WEATHER ADVISORY UNTIL EXPIRATION.
SNOW WILL TAPER OFF FROM WEST TO EAST STARTING AROUND 00Z. HAVE
LOWERED POPS TO CHANCE CAT AFTER THAT TIME THEN JUST FLURRIES AFTER
MIDNIGHT. WITH FRESH SNOW ON THE GROUND WILL GO BELOW MOS NUMBERS
TONIGHT. WITH SUB ZERO TEMPS AND WIND GUSTS TO 30 MPH WIND CHILL
VALUES WILL BE DANGEROUSLY COLD...ESPECIALLY NORTH OF INTERSTATE 70
WHERE WIND CHILL VALUES OF 20 BELOW ZERO TO 25 BELOW ZERO WILL
OCCUR. SOUTH OF THE INTERSTATE WHERE A WIND CHILL ADVISORY IS IN
EFFECT FOR VALUES AROUND 10 BELOW ALSO LOOKS GOOD. WIND CHILL
ADVISORY/WARNING START TIME OF MIDNIGHT STILL LOOKS GOOD SO NO
CHANGES WILL BE MADE.
ON THURSDAY STRONG COLD ADVECTION CONTINUES AND TEMPS ON THURSDAY
WILL NOT GET OUT OF THE SINGLE DIGITS ABOVE ZERO. SOME
AREAS...PARTICULARLY ALONG A LAF TO MIE LINE WILL REMAIN RIGHT
AROUND ZERO ALL DAY LONG.
THURSDAY NIGHT WILL BY FAR BE THE COLDEST NIGHT IN A VERY LONG
TIME. LOWS OF 10 TO 15 BELOW ZERO WILL BE COMMON NORTH OF
INTERSTATE 70 WHILE SOUTH OF THE INTERSTATE LOWS OF 3 TO 9 BELOW
ZERO WILL BE COMMON. WITH TEMPERATURES THAT LOW IT WONT TAKE MUCH
WIND AT ALL TO PRODUCE DANGEROUSLY COLD WIND CHILLS OF 25 TO 30
BELOW ZERO. WILL AGAIN CUT MOS NUMBERS TO ACCOUNT FOR SNOWPACK AND
STRONG COLD ADVECTION.
LONG TERM /FRIDAY TO WEDNESDAY/...STRONG H5 RIDGING OVER THE WEST
COAST OF THE CONUS WILL START TO MIGRATE EAST EARLY NEXT WEEK. THIS
RIDGING WILL KEEP INDIANA UNDER GENERAL NW FLOW AND TEMPERATURES
BELOW FREEZING FOR THE DURATION.
ON FRIDAY NIGHT/SATURDAY ANOTHER CLIPPER SYSTEM MOVES INTO THE
STATE. THE GFS SHOWS A MORE POTENT SWV ASSOCIATED THAN THE NAM BUT
TIMING IS SIMILAR. WILL GO SOMEWHERE IN BETWEEN AND RAISE POPS INTO
THE CHANCE CAT FROM SCHANCE. ON SUNDAY YET ANOTHER WAVE DROPS
THROUGH CENTRAL INDIANA WITHIN THE LARGER TROF. THE GFS/ECMWF ARE
IN GOOD ENOUGH AGREEMENT TO INCLUDE SOME POPS FOR THIS TIME.
THE GFS/ECMWF FOR THE MOST PART AGREE WITH KEEPING DEEP TROF OVER
THE EASTERN HALF OF THE CONUS INTO MID WEEK NEXT WEEK SO WILL ADJUST
TEMPS DOWN SLIGHTLY.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ021-
028>031-035>049.
WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ021-028>031-035>049.
&&
$$
SHORT TERM/LONG TERM...SALLY
AVIATION...CS
000
FXUS63 KIWX 142104
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
404 PM EST WED JAN 14 2009
.SHORT TERM...
TONIGHT THROUGH THURS NIGHT
WEAK CLIPPER SYSTEM CENTERED OVER CENTRAL IN...IS CONTINUING TO
EXIT THE REGION. SNOW IS STARTING TO WIND DOWN ACROSS THE REGION AS
THE STRONGEST UPGLIDE AND LARGE SCALE ASCENT IS SHIFTING EAST INTO
OH. THIS WILL CONTINUE TO BE THE TREND THROUGH THE AFTERNOON AND
INTO THE EVENING. WILL LET THE ADV EXPIRE AT 4 PM WESTERN PORTION
/7PM EASTERN PORTION AS THE SNOW INTENSITY WILL CONTINUE TO WANE
ACROSS THE REGION...WITH THE WORST BEING OVER. FARTHER
UPSTREAM...MASSIVE HIGH PRESSURE CONTINUES TO SLIDE DOWN INTO THE
NORTHERN CONUS...WITH A CENTER CURRENTLY INDICATED AT AN IMPRESSIVE
1046MB. STRONG CAA COUPLED WITH BACKING LL FLOW...AND DELTA T/S
APPROACHING 23 C...WILL SUPPORT THE DEVELOPMENT OF LAKE SNOWS...WITH
A PERIOD OF INTENSE SNOWFALL LIKELY ACROSS PORTIONS OF THE REGION.
IN ADDITION...VERY COLD ARCTIC...WITH APPROX -22C AT H925 AT 00Z FRI
COUPLED WITH WINDS OF 10 TO 15 MPH WILL SUPPORT DANGEROUSLY COLD
WIND CHILLS...WITH READINGS DOWN TO -30F AT TIMES.
PERIOD WILL FEATURE SFC RIDGING AS THE CLIPPER SYSTEM PUSHES OUT OF
THE AREA. MORE IMPORTANTLY...FAVORED NORTHERLY FLOW WILL SUPPORT AN
INTENSE PERIOD OF LAKE SNOWS...ALLOWING SOME HIGH ACCUMS IN THE
NORTHWEST. GIVEN THE NATURE OF THE FORECAST CONCERN BEING LAKE EFFECT
PROCESSES...HAVE TRIED TO UTILIZED THE NAM/RUC WHERE POSSIBLE
MESOSCALE EFFECTS ARE MORE EASILY VIEWABLE. THE CAVEAT TO THIS
SITUATION IS THAT THE EXTREME INSTABILITY PRESENT WILL HIGHLY FAVOR
THERMODYNAMICAL ORGANIZATION OF THE LAKE SNOW EVENT...AS OPPOSED TO
SHEAR. THIS IS EVEN MORE TRUE SINCE THE FLOW IS NOW INDICATED TO BE
WEAKER THAN PROGS JUST 2 DAYS AGO INDICATED. BOTTOM LINE...TRYING TO
PINPOINT THE LOCATION OF THE HEAVIEST SNOW WILL BE VERY
DIFFICULT...AS ONE OR TWO MESO-LOWS WOULD CERTAINLY DISRUPT THE
FLOW...SHIFTING THINGS EAST OR WEST. HAVE STAYED VERY CLOSE TO NAM
12 PROGS AS THEY HAVE BEEN VERY HELPFUL WRT LAKE EFFECT EVENTS THIS
YEAR..OPTING TO BLEND IN QPF AREAL AMOUNTS FROM THE GFS AND RUC FOR
UNCERTAINTY PURPOSES.
TONIGHT...LAKE BANDING IS ALREADY IN PROGRESS ACROSS WESTERN
PORTIONS OF MI...EXTENDING SOUTH INTO GYY. LL FLOW WILL BACK
NORTHERLY AND ALLOW A PERIOD OF LONGER FETCH ENHANCEMENT. STRONG CAA
WITH DELTA T/S APPROACHING 23C WILL SUPPORT EXTREME INSTABILITY WITH
H925 OMEGA PROGGED AOA 27 MICROBARS/SEC. LAKE INDUCED EQUILIBRIUM
LEVELS PROGGED AT 12KFT WITH A LARGE PORTION OF UPWARD MOTION IN THE
DGZ WOULD LIKELY SUPPORT SNOWFALL RATES AT IMPRESSIVE VALUES OF 2
POSSIBLY 3 INCHES PER HOUR. CURRENT INDICATIONS SUPPORT THE HEAVIEST
SNOW ACROSS PORTIONS OF LA PORTE AND BERRIEN COUNTIES...AND POSSIBLY
WESTERN CASS. STRONGEST INTENSITY LOOKS TO FAVOR LA PORTE AND
POSSIBLY ST. JOE COUNTY IN...BUT THE BAND IS EXPECTED TO BE
TRANSIENT AS IT PUSHES INTO ST JOE COUNTY IN. SOUTHWEST MI COUNTIES
WILL SEE A PERIOD OF INTENSE SNOW. HOWEVER...VERY DRY AIR UPSTREAM
/DOWN 20 PERCENT AT H85/ COMBINED WITH FALLING INVERSION HEIGHTS
WILL TEND TO TRANSITION BANDS TO MULTIPLE SHORE PARALLEL
ORGANIZATION...BUT A LONG DURATION OF SNOWFALL WILL FAVOR HIGH
AMOUNTS. HAVE OPTED FOR AMOUNTS TO 12 INCHES IN BERRIEN COUNTY WHERE
DURATION WILL BE MAXIMIZED. HIGH AMOUNTS WILL BE POSSIBLE IN LA
PORTE...BUT UNCERTAINTY REMAINS ON HOW LONG THE BAND WILL SETUP OVER
THE AREA...PRECLUDES HIGH AMOUNT MENTION AT THIS TIME. LAKE SNOWS
WILL SHIFT NORTH INTO MI BY THU AFTERNOON...WITH LIGHT TO MODERATE
SNOWS CONTINUING OVER SOUTHWEST MI.
THE OTHER ISSUE WILL BE STRONG WINDS ON THE BACKSIDE OF ANY LONG
FETCH BANDS THAT DEVELOP IN REPONSE TO MOMENTUM ADJUSTMENT PER
CONVECTIVE INFLUENCES. DEEP MIXING AND ENHANCED FLOW COULD SUPPORT 20
TO 30 MPH WINDS OVER PORTIONS OF BERRIEN AND LA PORTE COUNTY WITH
HIGHER GUSTS. ESPECIALLY GIVEN 30 KNOTS PROGGED AT H925 BEING ABLE
TO TRANSLATE DOWN.
HAVE STARTED THE WIND CHILL ADV LATER GIVEN FORECAST
TEMPS/TD/WINDS...AND ALLOWED THE WARNING TO LAST INTO FRI WHERE THE
DATABASE INDICATES APPARENT T/S IN THE 25 TO 30 BELOW RANGE. HAVE
CONTINUED TO TREND THU HIGHS AND LOWS DOWN GIVEN MOS
TRENDS...TEMP/RH PROFILES ALOFT/AND MODEL 2M TEMPS. TEMPS AOA -20F
WILL BE POSSIBLE AT SOME LOCATIONS WHERE CLEARING AND CALM WINDS
WILL OVERLAP. TEMPS ARE LIKELY TO REMAIN BELOW ZERO AT MANY
LOCATIONS ON THU.
&&
.LONG TERM...
FRI THROUGH WED
STRONGLY POSITIVE PNA PATTERN WILL BEGIN THE PERIOD WITH LARGE
TROUGH IN THE EAST WELL ESTABLISHED. THIS PATTERN WILL PERSIST INTO
EARLY NEXT WEEK BEFORE THE EASTERN PACIFIC RIDGE BEGINS TO FLATTEN
AND PULL EAST BRINGING A SLOW MODERATING TREND TO OUR AREA.
GFS/GEFS/CMC/ECMWF ARE IN PRETTY GOOD AGREEMENT ON THIS OVERALL
EVOLUTION...WITH THE PRIMARY DIFFERENCES BEING ON THE HANDLING OF A
SERIES OF SHORTWAVES THAT WILL DROP THROUGH THE AREA DURING THE
PERIOD IN THE DEEP LAYER NORTHWESTERLY FLOW.
LAKE EFFECT SNOW WILL BE ONGOING TO START THE PERIOD WITH T850
AROUND -20C AND CONTINUED WESTERLY FLOW. HAVE KEPT CHC POPS FOR
SHSN OVER SOUTHERN MI AND THE NORTHERNMOST ROW OF COUNTIES IN IN.
THIS LINES UP A LITTLE BETTER WITH H925 AND H850 WINDS VS MODEL QPF
FIELDS. T925 WOULD SUGGEST HIGHS IN THE LOWER SINGLE DIGITS AND WILL
CONTINUE TO UNDERCUT THESE A LITTLE GIVEN SUCH COLD OVERNIGHT LOWS.
ANOTHER BRIEF BREAK OCCURS FRIDAY EVENING BEFORE MID AND HIGHS
CLOUDS ROLL BACK IN WITH SN LIKELY ARRIVING AFTER MIDNIGHT AHEAD OF
THE NEXT CLIPPER. HAVE GONE WITH NON DIURNAL TEMPERATURE TRENDS
FRIDAY NIGHT GIVEN THE INCREASING CLOUD COVER...BUT MOST SITES WILL
SEE LATE EVENING LOWS AGAIN BELOW ZERO.
CLIPPER FOR SATURDAY LOOKS LIKE A WIDESPREAD LIGHT SNOWFALL WITH A
LOW TRACK SOMEWHERE NEAR OVERHEAD AND A LOW TRACK TO THE SOUTHEAST
SUGGESTING THE MOST SNOW OVER NORTHEASTERN AREAS TAPERING OFF TO THE
SOUTH AND WEST. TEMPERATURES WILL RISE THROUGH THE EVENT INTO THE
LOWER 20S.
FOR SUNDAY DETAILS BECOME A LITTLE LESS CLEAR AS THE GFS SHOWS
ANOTHER WAVE DROPPING SOUTH IN THE NORTHWEST FLOW WITH THE ECMWF/CMC
AND QUITE A FEW GEFS MEMBERS VOID OF ANY DISTURBANCES WITH COLD
NORTHWEST FLOW SPAWNING LAKE EFFECT SHSN. WILL FOLLOW THIS LATTER
CONSENSUS...WHICH WAS WELL CAPTURED IN THE PREVIOUS SET OF GRIDS AND
RESTRICT CHC POPS TO THE NORTHEASTERN 2/3RDS OF THE CWA. HIGHS
SHOULD REACH THE LOWER 20S.
FOR THE MONDAY THROUGH WEDNESDAY TIMEFRAME...THE CONTINUED COLD
NORTHWESTERLY FLOW WILL GRADUALLY GIVE WAY TO INCREASING TEMPS ALOFT
AS THE WESTERN RIDGE BEGINS TO NUDGE TOWARDS THE AREA. LAST WAVE IN
THE NORTHWEST FLOW COULD BRING SOME LIGHT SNOW ON MONDAY WITH DRY
WEATHER BECOMING MORE LIKELY FOR TUESDAY AND WEDNESDAY AS TEMPS
ALOFT WILL WARM TO THE POINT WHERE ANY LAKE RESPONSE SHOULD FINALLY
BE OVER. TEMPERATURES WILL WARM INTO THE MID 20S FOR TUESDAY AND
THEN INTO THE LOWER 30S BY WEDNESDAY. WARMER TEMPS AT THIS RANGE
ARE POSSIBLE AS TEMPS ALOFT SHOULD WARM PRETTY QUICKLY WITH THE
RIDGE ARRIVAL...BUT AT THIS RANGE...HAVE TO GIVE SOME CREDENCE TO
CLIMATOLOGY.
&&
.AVIATION...
IFR SN CONTINUING ATTM AT SBN/FWA BUT IS IN A WEAKENING TREND WITH
THE BACK EDGE MOVING EAST. EXPECT IFR VSBYS WITH MVFR CIGS TO
PERSIST FOR THE NEXT FEW HOURS BEFORE IMPROVEMENT TO MVFR TOWARDS
EVENING. FOR THE OVERNIGHT AN INTENSE LAKE EFFECT SNOW BAND WILL
DEVELOP WEST OF SBN AND THEN PULL EAST. CAN/T RULE OUT A BRIEF
BREAK TO VFR AT FWA AROUND 6Z BUT CONFIDENCE IN THIS IS LOW SO HAVE
LEFT OUT AT THIS TIME. BEST CHANCE FOR BAND IMPACTING SBN IS IN THE
5-9Z TIMEFRAME WHEN OCCASIONAL LIFR CONDITIONS ARE LIKELY. BY
9Z...THE BAND MAY REACH AS FAR SOUTHEAST AS FWA WHERE OCCASIONAL IFR
VSBYS ARE POSSIBLE. TOWARDS AND AFTER DAYBREAK THURSDAY THE BAND
WILL PULL EAST WITH MVFR CONDITIONS /DUE TO CIGS/ RETURNING TO SBN
AND FWA SEEING POSSIBLE IMPROVEMENT TO VFR AS THE LOW CLOUDS SCATTER
OUT BY MID MORNING.
EAST NORTHEASTERLY WINDS AROUND 10KTS THIS AFTERNOON WILL BACK TO
NORTHERLY 10-15KTS THIS EVENING...AND CONTINUE TO BACK TO WESTERLY
BY THURSDAY MORNING AND INCREASE TO 12G18KTS. WITHIN THE LAKE
EFFECT SNOW BAND...WINDS WILL INCREASE TO 15G25KTS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ018-
026-027-033-034.
WIND CHILL WARNING FROM MIDNIGHT EST /11 PM CST/ TONIGHT TO 12
PM EST /11 AM CST/ FRIDAY FOR INZ003>009-012>018-020-
022>027-032>034.
LAKE EFFECT SNOW WARNING UNTIL 6 AM CST THURSDAY FOR INZ003-012.
LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THURSDAY FOR INZ004-005-
014.
WINTER WEATHER ADVISORY UNTIL 5 PM EST /4 PM CST/ THIS AFTERNOON
FOR INZ012>017-020-022>025-032.
MI...WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 12 PM EST FRIDAY FOR
MIZ077>081.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THURSDAY FOR MIZ077.
LAKE EFFECT SNOW WARNING FROM 10 PM THIS EVENING TO 7 PM EST
THURSDAY FOR MIZ078-079.
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ015-
016-024-025.
WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 12 PM EST FRIDAY FOR
OHZ001-002-004-005-015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THURSDAY FOR LMZ043-
046.
GALE WARNING UNTIL 7 AM EST THURSDAY FOR LMZ043-046.
&&
$$
SHORT TERM...JC
LONG TERM...ARNOTT
AVIATION...ARNOTT
000
FXUS63 KIND 141951
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
351 PM EST WED JAN 14 2009
.DISCUSSION...FORECAST FOCUS WILL BE ON UPCOMING DANGEROUSLY COLD
TEMPERATURES.
SHORT TERM...SURFACE LOW WAS OVER WEST CENTRAL INDIANA AT 19Z AND
WILL MOVE EAST THROUGH THE STATE THIS AFTERNOON. A HEAVIER BAND OF
SNOW WAS MOVING ACROSS THE NORTHERN CWA IN AN ENHANCED AREA OF LIFT
THAT WILL QUICKLY MOVE EAST ALONG WITH THE SURFACE LOW AND UPPER
WAVE. TEMPS WERE FALLING QUICKLY BEHIND THE SURFACE FRONT AND WINDS
WERE INCREASING WITH GUSTS 25-35MPH. THERE WILL BE SOME ISSUES WITH
BLOWING SNOW...PARTICULARLY ALONG AND NORTH OF INTERSTATE 70. THAT
SAID WILL HANG ON TO THE WINTER WEATHER ADVISORY UNTIL EXPIRATION.
SNOW WILL TAPER OFF FROM WEST TO EAST STARTING AROUND 00Z. HAVE
LOWERED POPS TO CHANCE CAT AFTER THAT TIME THEN JUST FLURRIES AFTER
MIDNIGHT. WITH FRESH SNOW ON THE GROUND WILL GO BELOW MOS NUMBERS
TONIGHT. WITH SUB ZERO TEMPS AND WIND GUSTS TO 30 MPH WIND CHILL
VALUES WILL BE DANGEROUSLY COLD...ESPECIALLY NORTH OF INTERSTATE 70
WHERE WIND CHILL VALUES OF 20 BELOW ZERO TO 25 BELOW ZERO WILL
OCCUR. SOUTH OF THE INTERSTATE WHERE A WIND CHILL ADVISORY IS IN
EFFECT FOR VALUES AROUND 10 BELOW ALSO LOOKS GOOD. WIND CHILL
ADVISORY/WARNING START TIME OF MIDNIGHT STILL LOOKS GOOD SO NO
CHANGES WILL BE MADE.
ON THURSDAY STRONG COLD ADVECTION CONTINUES AND TEMPS ON THURSDAY
WILL NOT GET OUT OF THE SINGLE DIGITS ABOVE ZERO. SOME
AREAS...PARTICULARLY ALONG A LAF TO MIE LINE WILL REMAIN RIGHT
AROUND ZERO ALL DAY LONG.
THURSDAY NIGHT WILL BY FAR BE THE COLDEST NIGHT IN A VERY LONG
TIME. LOWS OF 10 TO 15 BELOW ZERO WILL BE COMMON NORTH OF
INTERSTATE 70 WHILE SOUTH OF THE INTERSTATE LOWS OF 3 TO 9 BELOW
ZERO WILL BE COMMON. WITH TEMPERATURES THAT LOW IT WONT TAKE MUCH
WIND AT ALL TO PRODUCE DANGEROUSLY COLD WIND CHILLS OF 25 TO 30
BELOW ZERO. WILL AGAIN CUT MOS NUMBERS TO ACCOUNT FOR SNOWPACK AND
STRONG COLD ADVECTION.
&&
LONG TERM /FRIDAY TO WEDNESDAY/...STRONG H5 RIDGING OVER THE WEST
COAST OF THE CONUS WILL START TO MIGRATE EAST EARLY NEXT WEEK. THIS
RIDGING WILL KEEP INDIANA UNDER GENERAL NW FLOW AND TEMPERATURES
BELOW FREEZING FOR THE DURATION.
ON FRIDAY NIGHT/SATURDAY ANOTHER CLIPPER SYSTEM MOVES INTO THE
STATE. THE GFS SHOWS A MORE POTENT SWV ASSOCIATED THAN THE NAM BUT
TIMING IS SIMILAR. WILL GO SOMEWHERE IN BETWEEN AND RAISE POPS INTO
THE CHANCE CAT FROM SCHANCE. ON SUNDAY YET ANOTHER WAVE DROPS
THROUGH CENTRAL INDIANA WITHIN THE LARGER TROF. THE GFS/ECMWF ARE
IN GOOD ENOUGH AGREEMENT TO INCLUDE SOME POPS FOR THIS TIME.
THE GFS/ECMWF FOR THE MOST PART AGREE WITH KEEPING DEEP TROF OVER
THE EASTERN HALF OF THE CONUS INTO MID WEEK NEXT WEEK SO WILL ADJUST
TEMPS DOWN SLIGHTLY.
.AVIATION...DISCUSSION FOR 18Z TAFS.
LOW PRESSURE IS APCHG LAF AT 17Z AND WILL CONTINUE TO MOVE EWD ACRS
CENTRAL INDIANA DURING THE NEXT 3-6 HOURS. AS THIS HAPPENS...WINDS
WILL SWING FROM THE NW INCREASING WITH GUSTS TO 30KT BY MID AFTN
THRU TNGT. MOSTLY MVFR CONDITIONS CAN BE EXPECTED THROUGH EARLY THIS
EVENING. AS STRONG HIGH PRESSURE THEN MOVES IN...SKIES WILL CLEAR
TO VFR WITH THE MAIN THREAT OF GUSTY WINDS CONTINUING INTO THU MRNG.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ021-
028>031-035>049.
WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ021-028>031-035>049.
&&
$$
SHORT TERM/LONG TERM...SALLY
AVIATION...DM
000
FXUS63 KIWX 141731
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1231 PM EST WED JAN 14 2009
.AVIATION...
IFR SN CONTINUING ATTM AT SBN/FWA BUT IS IN A WEAKENING TREND WITH
THE BACK EDGE MOVING EAST. EXPECT IFR VSBYS WITH MVFR CIGS TO
PERSIST FOR THE NEXT FEW HOURS BEFORE IMPROVEMENT TO MVFR TOWARDS
EVENING. FOR THE OVERNIGHT AN INTENSE LAKE EFFECT SNOW BAND WILL
DEVELOP WEST OF SBN AND THEN PULL EAST. CAN/T RULE OUT A BRIEF
BREAK TO VFR AT FWA AROUND 6Z BUT CONFIDENCE IN THIS IS LOW SO HAVE
LEFT OUT AT THIS TIME. BEST CHANCE FOR BAND IMPACTING SBN IS IN THE
5-9Z TIMEFRAME WHEN OCCASIONAL LIFR CONDITIONS ARE LIKELY. BY
9Z...THE BAND MAY REACH AS FAR SOUTHEAST AS FWA WHERE OCCASIONAL IFR
VSBYS ARE POSSIBLE. TOWARDS AND AFTER DAYBREAK THURSDAY THE BAND
WILL PULL EAST WITH MVFR CONDITIONS /DUE TO CIGS/ RETURNING TO SBN
AND FWA SEEING POSSIBLE IMPROVEMENT TO VFR AS THE LOW CLOUDS SCATTER
OUT BY MID MORNING.
EAST NORTHEASTERLY WINDS AROUND 10KTS THIS AFTERNOON WILL BACK TO
NORTHERLY 10-15KTS THIS EVENING...AND CONTINUE TO BACK TO WESTERLY
BY THURSDAY MORNING AND INCREASE TO 12G18KTS. WITHIN THE LAKE
EFFECT SNOW BAND...WINDS WILL INCREASE TO 15G25KTS.
&&
.PREV DISCUSSION... /ISSUED 658 AM EST WED JAN 14 2009/
SHORT TERM...
TODAY THROUGH THURSDAY NIGHT. PLETHORA OF HAZARDS IN SHORT TERM
FOR PROBLEMATIC MORNING ISSUANCE. TWO UPSTREAM SHORTWAVES EMBEDDED
IN BROAD LONGWAVE TROF COVERING WRN GRTLKS TO NEW ENGLAND. FIRST
INTO NRN IL WITH EXPANDING WAA SNOWFL ACRS CWA IN ADV OF SYSTEM.
FNTL SYSTEM UNDERGOING FRONTALYSIS PER UNFAVORABLE PRESS
COUPLET...HOWEVER I280-285K ISENT SFC UPGLIDE TO PROVIDE A BRIEF
SHOT OF LOCALLY HEAVY SNFL THIS AM PRIMARILY ACRS SRN CWA DESPITE
SLOW AND DIFFUSE AND SLOW TO SATURATE/PRECIP MODEL SOLNS EVEN PER
NAM12 AND RUC40. RAISED WINTER WX ADV FOR SNOW ALONG/S ROUTE 30
TO HIGHLIGHT RISK FOR AM COMMUTE/SCHOOLS/ETC. SECOND AND INCRSGLY
DOMINANT S/W ACRS NRN MANITOBA AND SURGING SWD TO SHARPEN TROF OVR
GRTLKS LTR TONIGHT. STRONG LES SIGNAL TONGIHT PER 925MB PLUME
ANALYSIS...LAKE/8H DELTA T INTO LWR 20S WITH LKBCAPES OF 600 J/KG
AND EQL GT 11KFT WITH MAX UVM GT 26 UBAR/S THROUGH DGZ SUGGESTS
INTENSE SNOWFALL RATES WITHIN CORE OF BAND OF 2 IN/HR AND SNOW-
LIQUID RATIOS IN LWR-MID 20S. CURRENT AMBIENT SATURATION OR LACK
THEREOF IS PRMARY NEG CONCERN WITH ENTRAINMENT INTO CBL...AND AS
SUCH HAVE TEMPERED SNOWFALL TOTALS SLIGHTLY. CURRENT PRESENCE OF
STRONG THERMAL TROF/CYCLONIC SPIN/LAND BREEZE CONVERGENCE ACRS FAR
NRN LK MI DRAWS ANOTHER CONCERN FOR AN INITIAL SINGLE BAND EVENT
DEVELOPING STRONG MESOVORTICY AS IT DRIVES S W/TIME LATE
AFTN/EARLY EVE. THOUGH SOMETHING OF NOTE MERELY ATTM AS THIS
TEMPORAL/SPATIAL DETAIL/RESOLUTION BETTER HANDLED BY DAYSHIFT.
UPG TO LAKE EFFECT SNOW WARNING WITH SOME TIMING AFFORDED TO END
WARNING SOONER FOR LAPORTE/STARKE COS. FINAL CONCERN WRT WINDCHILL
NEARING OR BLO WARNING CRITERIA AND HOISTED 17 HR DURATION
WINDCHILL WARNING ENTIRE CWA.
LONG TERM...
FRIDAY THROUGH WEDNESDAY...THE MAIN CHALLENGE THIS PERIOD IS THE
TRACK AND TIMING OF SHORT WAVE TROFS AND ASSOCIATED CLIPPER TYPE OF
SYSTEMS THAT TRACK OVER THE TOP OF THE UPSTREAM UPPER LEVEL RIDGE
AND DESCEND INTO THE GREAT LAKES REGION. FAVOR THE ECMWF THIS
PACKAGE. THE ECMWF HAS BEEN REASONABLY CONSISTENT FROM RUN TO RUN
WITH THIS PATTERN AND WITH THE TRACK OF THE CLIPPER SYSTEM LATE
FRIDAY NIGHT INTO SATURDAY. THE 00Z ECMWF RUN IS A LITTLE FARTHER
NORTHEAST WITH THE TRACK OF THE SFC LOW THAN THE PREVIOUS RUN...BUT
OTHERWISE HAS BEEN CONSISTENT. THE ECMWF IS SUPPORTED BY THE
CANADIAN GEM ENSEMBLES. MOST OF THE 00Z GFS ENSEMBLES HAVE ALSO COME
ON BOARD WITH THIS SOLUTION. GFS MRF PLUME DIAGRAM SHOWS REASONABLE
GFS ENSEMBLE TIMING WITH THIS SYSTEM FROM FRIDAY EVENING THROUGH
SATURDAY NIGHT. HAVE MADE SOME UPDATES TO THE GRIDS/FCST FRIDAY
NIGHT INTO SATURDAY BASED ON THIS EXPECTED SOLUTION. SNOW SHOULD
DEVELOP LATE FRIDAY NIGHT OR EARLY SATURDAY AND PERSIST AT LEAST
DURING THE DAY SATURDAY. RAISED SNOW CHANCES TO HIGH CHANCE
SATURDAY. OTHERWISE...CONTINUE TO PREFER THE ECMWF HANDLING OF THE
UPPER AIR PATTERN INTO EARLY NEXT WEEK. GIVEN THE STRENGTH AND
PERSISTENCE OF THE UPSTREAM BLOCK...FAVOR COLDER TEMPERATURES WITH
CHANCES FOR SNOW. THE ONGOING CHANCE FOR SNOW ON MONDAY APPEARS ON
TRACK.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 5 PM EST /4 PM CST/ THIS AFTERNOON
FOR INZ012>018-020-022>027-032>034.
WIND CHILL WARNING FROM 6 PM EST /5 PM CST/ THIS EVENING TO 11
AM EST /10 AM CST/ THURSDAY FOR INZ003>009-012>018-020-
022>027-032>034.
LAKE EFFECT SNOW WARNING FROM 4 PM THIS AFTERNOON TO 6 AM CST
THURSDAY FOR INZ003-012.
LAKE EFFECT SNOW WARNING FROM 7 PM THIS EVENING TO 1 PM EST
THURSDAY FOR INZ004-005-014.
MI...WIND CHILL WARNING FROM 6 PM THIS EVENING TO 11 AM EST THURSDAY
FOR MIZ077>081.
LAKE EFFECT SNOW WARNING FROM 7 PM THIS EVENING TO 7 PM EST
THURSDAY FOR MIZ077.
LAKE EFFECT SNOW WARNING FROM 10 PM THIS EVENING TO 7 PM EST
THURSDAY FOR MIZ078-079.
OH...WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR OHZ015-
016-024-025.
WIND CHILL WARNING FROM 6 PM THIS EVENING TO 11 AM EST THURSDAY
FOR OHZ001-002-004-005-015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING FROM 4 PM THIS AFTERNOON TO 7 PM
EST THURSDAY FOR LMZ043-046.
GALE WARNING FROM 4 PM THIS AFTERNOON TO 7 AM EST THURSDAY FOR
LMZ043-046.
&&
$$
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...ARNOTT
000
FXUS63 KIND 141709
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1215 PM EST WED JAN 14 2009
.AVIATION...DISCUSSION FOR 18Z TAFS.
LOW PRESSURE IS APCHG LAF AT 17Z AND WILL CONTINUE TO MOVE EWD ACRS
CENTRAL INDIANA DURING THE NEXT 3-6 HOURS. AS THIS HAPPENS...WINDS
WILL SWING FROM THE NW INCREASING WITH GUSTS TO 30KT BY MID AFTN
THRU TNGT. MOSTLY MVFR CONDITIONS CAN BE EXPECTED THROUGH EARLY THIS
EVENING. AS STRONG HIGH PRESSURE THEN MOVES IN...SKIES WILL CLEAR
TO VFR WITH THE MAIN THREAT OF GUSTY WINDS CONTINUING INTO THU MRNG.
&&
.PREV DISCUSSION...FOCUS ON SNOW TODAY AND BITTER COLD FOLLOWING
SNOW.
APPROACHING CLIPPER SYSTEM CONTINUES TO MOVE ESE TOWARD THE REGION.
06Z SFC MAP SHOWED THE LOW CENTER ACROSS SOUTH CENTRAL IA WITH THE
STRONGEST 3 HR PRESSURE FALLS NOW CENTERED ACROSS CENTRAL IL. THIS
SUGGESTS THE LOW SHOULD BEGIN A EASTWARD TURN. REGIONAL RADAR SHOWS
SNOW DEVELOPMENT DUE TO ISENTROPIC LIFT OCCURRING ACROSS CENTRAL IL
WITH PRECIP ASSOCIATED WITH DYNAMIC LIFT LAGGING BACK ACROSS SE IA.
THE CURRENT FCST LOOKS ON TRACK FOR SNOW AMOUNTS BASED ON RADAR AND
OB TRENDS.
BOTH GFS/NAM ARE IN GOOD AGREEMENT WITH THE TRACK OF THE SYSTEM
TODAY AND BOTH APPEAR CLOSE TO REALITY SO WILL USE A BLEND.
TODAY...SNOW WILL DEVELOP AND IMPACT MAINLY AREAS ALONG AND NORTH OF
I-70 TODAY. DURATION AND MAGNITUDE OF LIFT ALONG WITH SNOW RATIOS
AND AVAILABLE MOISTURE ALL SUGGEST THAT THE CURRENT FCST OF 2 TO 4
INCHES IS THE BEST BET. THE WILD CARD COULD BE THE RATIOS AND SOME
REPORTS OUT OF IL ARE POINTING TOWARD THE HIGHER END OF THIS RANGE.
ALONG THE I-70 CORRIDOR INCLUDING INDIANAPOLIS WE STILL EXPECT SNOW
ON THE ORDER OF 1 OR 2 INCHES OVER THE CITY TO 2 OR 3 INCHES ON THE
FAR NORTHSIDE WITH LOWER AMOUNTS SOUTH OF MARION COUNTY. DO NOT BUY
THE HEAVIER SNOW AMOUNTS FCST BY THE GFS OVER THE CITY AND FEEL THAT
THIS IS TOO FAR SOUTH GIVEN RECENT RADAR TRENDS. DESPITE LOWER SNOW
AMOUNTS ACROSS THE I-70 CORRIDOR FEEL IT MAY BE PRUDENT TO HOIST AN
ADVISORY GIVEN THE POTENTIAL FOR IMPACTS OF BLOWING/DRIFTING OF SNOW
LATER TODAY.
THE MAIN STORY/IMPACT WILL BE THE DANGEROUSLY COLD WIND CHILLS WHICH
WILL ARRIVE LATER TONIGHT AND PERSIST THROUGH FRI. ALL GUIDANCE
WINDS AND RAW MODEL TEMPS SHOW WIND CHILLS IN THE MINUS 10 TO MINUS
30 RANGE DURING THIS PERIOD. WE MAY RISE TO ABOVE WIND CHILL WARNING
CRITERIA FOR A TIME THU ONLY TO DROP BACK DOWN THU NIGHT. FOR
CLARITY I WILL NOT ATTEMPT TO BREAK THIS INTO WARNING/ADVISORY
PERIODS AND INSTEAD ISSUE ONE SIMPLE WARNING AND ADVISORY FOR WIND
CHILLS DURING THIS PERIOD.
THE COLDEST AIR TEMPS SHOULD OCCUR THU NIGHT INTO EARLY FRI WHEN
TEMPS MAY DROP INTO THE 10 TO 20 BELOW ZERO RANGE IF CURRENT
INDICATIONS ARE CORRECT. THIS WOULD BE THE COLDEST TEMPS AT IND
SINCE JAN OF 2004.
NO CHANGES TO THE FCST BEYOND FRI.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ021-
028>031-035>049.
WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ021-028>031-035>049.
&&
$$
PUBLIC...CO
AVIATION...DM
000
FXUS63 KIWX 141158
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
658 AM EST WED JAN 14 2009
.AVIATION...
AS SFC LOW CONTS TO TRACK ESE FM NEAR KUIN THIS AM ANTICIPATE LWST
CONDITIONS A BIT FURTHER S FOR KFWA WITH LIFR CONDS AT TIMES...
THOUGH IFR STILL LIKELY FOR A PD THIS AM AT KSBN. ONLY OTHER SIG
CHNG WAS TO DELAY TIMING A BIT FOR LIFR LAKE EFFECT SNOW BAND FOR
KSBN.
&&
.SHORT TERM...
TODAY THROUGH THURSDAY NIGHT. PLETHORA OF HAZARDS IN SHORT TERM
FOR PROBLEMATIC MORNING ISSUANCE. TWO UPSTREAM SHORTWAVES EMBEDDED
IN BROAD LONGWAVE TROF COVERING WRN GRTLKS TO NEW ENGLAND. FIRST
INTO NRN IL WITH EXPANDING WAA SNOWFL ACRS CWA IN ADV OF SYSTEM.
FNTL SYSTEM UNDERGOING FRONTALYSIS PER UNFAVORABLE PRESS
COUPLET...HOWEVER I280-285K ISENT SFC UPGLIDE TO PROVIDE A BRIEF
SHOT OF LOCALLY HEAVY SNFL THIS AM PRIMARILY ACRS SRN CWA DESPITE
SLOW AND DIFFUSE AND SLOW TO SATURATE/PRECIP MODEL SOLNS EVEN PER
NAM12 AND RUC40. RAISED WINTER WX ADV FOR SNOW ALONG/S ROUTE 30
TO HIGHLIGHT RISK FOR AM COMMUTE/SCHOOLS/ETC. SECOND AND INCRSGLY
DOMINANT S/W ACRS NRN MANITOBA AND SURGING SWD TO SHARPEN TROF OVR
GRTLKS LTR TONIGHT. STRONG LES SIGNAL TONGIHT PER 925MB PLUME
ANALYSIS...LAKE/8H DELTA T INTO LWR 20S WITH LKBCAPES OF 600 J/KG
AND EQL GT 11KFT WITH MAX UVM GT 26 UBAR/S THROUGH DGZ SUGGESTS
INTENSE SNOWFALL RATES WITHIN CORE OF BAND OF 2 IN/HR AND SNOW-
LIQUID RATIOS IN LWR-MID 20S. CURRENT AMBIENT SATURATION OR LACK
THEREOF IS PRMARY NEG CONCERN WITH ENTRAINMENT INTO CBL...AND AS
SUCH HAVE TEMPERED SNOWFALL TOTALS SLIGHTLY. CURRENT PRESENCE OF
STRONG THERMAL TROF/CYCLONIC SPIN/LAND BREEZE CONVERGENCE ACRS FAR
NRN LK MI DRAWS ANOTHER CONCERN FOR AN INITIAL SINGLE BAND EVENT
DEVELOPING STRONG MESOVORTICY AS IT DRIVES S W/TIME LATE
AFTN/EARLY EVE. THOUGH SOMETHING OF NOTE MERELY ATTM AS THIS
TEMPORAL/SPATIAL DETAIL/RESOLUTION BETTER HANDLED BY DAYSHIFT.
UPG TO LAKE EFFECT SNOW WARNING WITH SOME TIMING AFFORDED TO END
WARNING SOONER FOR LAPORTE/STARKE COS. FINAL CONCERN WRT WINDCHILL
NEARING OR BLO WARNING CRITERIA AND HOISTED 17 HR DURATION
WINDCHILL WARNING ENTIRE CWA.
&&
.LONG TERM...
FRIDAY THROUGH WEDNESDAY...THE MAIN CHALLENGE THIS PERIOD IS THE
TRACK AND TIMING OF SHORT WAVE TROFS AND ASSOCIATED CLIPPER TYPE OF
SYSTEMS THAT TRACK OVER THE TOP OF THE UPSTREAM UPPER LEVEL RIDGE
AND DESCEND INTO THE GREAT LAKES REGION. FAVOR THE ECMWF THIS
PACKAGE. THE ECMWF HAS BEEN REASONABLY CONSISTENT FROM RUN TO RUN
WITH THIS PATTERN AND WITH THE TRACK OF THE CLIPPER SYSTEM LATE
FRIDAY NIGHT INTO SATURDAY. THE 00Z ECMWF RUN IS A LITTLE FARTHER
NORTHEAST WITH THE TRACK OF THE SFC LOW THAN THE PREVIOUS RUN...BUT
OTHERWISE HAS BEEN CONSISTENT. THE ECMWF IS SUPPORTED BY THE
CANADIAN GEM ENSEMBLES. MOST OF THE 00Z GFS ENSEMBLES HAVE ALSO COME
ON BOARD WITH THIS SOLUTION. GFS MRF PLUME DIAGRAM SHOWS REASONABLE
GFS ENSEMBLE TIMING WITH THIS SYSTEM FROM FRIDAY EVENING THROUGH
SATURDAY NIGHT. HAVE MADE SOME UPDATES TO THE GRIDS/FCST FRIDAY
NIGHT INTO SATURDAY BASED ON THIS EXPECTED SOLUTION. SNOW SHOULD
DEVELOP LATE FRIDAY NIGHT OR EARLY SATURDAY AND PERSIST AT LEAST
DURING THE DAY SATURDAY. RAISED SNOW CHANCES TO HIGH CHANCE
SATURDAY. OTHERWISE...CONTINUE TO PREFER THE ECMWF HANDLING OF THE
UPPER AIR PATTERN INTO EARLY NEXT WEEK. GIVEN THE STRENGTH AND
PERSISTENCE OF THE UPSTREAM BLOCK...FAVOR COLDER TEMPERATURES WITH
CHANCES FOR SNOW. THE ONGOING CHANCE FOR SNOW ON MONDAY APPEARS ON
TRACK.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
INZ018-026-027-033-034.
WIND CHILL WARNING FROM 6 PM EST /5 PM CST/ THIS EVENING TO 11
AM EST /10 AM CST/ THURSDAY FOR INZ003>009-012>018-020-
022>027-032>034.
LAKE EFFECT SNOW WARNING FROM 2 PM THIS AFTERNOON TO 6 AM CST
THURSDAY FOR INZ003-012.
LAKE EFFECT SNOW WARNING FROM 5 PM THIS AFTERNOON TO 1 PM EST
THURSDAY FOR INZ004-005-014.
WINTER WEATHER ADVISORY UNTIL 11 AM EST /10 AM CST/ THIS
MORNING FOR INZ012>017-020-022>025-032.
MI...WIND CHILL WARNING FROM 6 PM THIS EVENING TO 11 AM EST THURSDAY
FOR MIZ077>081.
LAKE EFFECT SNOW WARNING FROM 5 PM THIS AFTERNOON TO 1 PM EST
THURSDAY FOR MIZ079.
LAKE EFFECT SNOW WARNING FROM 3 PM THIS AFTERNOON TO 1 PM EST
THURSDAY FOR MIZ077-078.
OH...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
OHZ015-016-024-025.
WIND CHILL WARNING FROM 6 PM THIS EVENING TO 11 AM EST THURSDAY
FOR OHZ001-002-004-005-015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 PM EST
THURSDAY FOR LMZ043-046.
GALE WARNING FROM 4 PM THIS AFTERNOON TO 7 AM EST THURSDAY FOR
LMZ043-046.
&&
$$
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...MURPHY
000
FXUS63 KIWX 141122
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
622 AM EST WED JAN 14 2009
.SHORT TERM...
TODAY THROUGH THURSDAY NIGHT. PLETHORA OF HAZARDS IN SHORT TERM
FOR PROBLEMATIC MORNING ISSUANCE. TWO UPSTREAM SHORTWAVES EMBEDDED
IN BROAD LONGWAVE TROF COVERING WRN GRTLKS TO NEW ENGLAND. FIRST
INTO NRN IL WITH EXPANDING WAA SNOWFL ACRS CWA IN ADV OF SYSTEM.
FNTL SYSTEM UNDERGOING FRONTALYSIS PER UNFAVORABLE PRESS
COUPLET...HOWEVER I280-285K ISENT SFC UPGLIDE TO PROVIDE A BRIEF
SHOT OF LOCALLY HEAVY SNFL THIS AM PRIMARILY ACRS SRN CWA DESPITE
SLOW AND DIFFUSE AND SLOW TO SATURATE/PRECIP MODEL SOLNS EVEN PER
NAM12 AND RUC40. RAISED WINTER WX ADV FOR SNOW ALONG/S ROUTE 30
TO HIGHLIGHT RISK FOR AM COMMUTE/SCHOOLS/ETC. SECOND AND INCRSGLY
DOMINANT S/W ACRS NRN MANITOBA AND SURGING SWD TO SHARPEN TROF OVR
GRTLKS LTR TONIGHT. STRONG LES SIGNAL TONGIHT PER 925MB PLUME
ANALYSIS...LAKE/8H DELTA T INTO LWR 20S WITH LKBCAPES OF 600 J/KG
AND EQL GT 11KFT WITH MAX UVM GT 26 UBAR/S THROUGH DGZ SUGGESTS
INTENSE SNOWFALL RATES WITHIN CORE OF BAND OF 2 IN/HR AND SNOW-
LIQUID RATIOS IN LWR-MID 20S. CURRENT AMBIENT SATURATION OR LACK
THEREOF IS PRMARY NEG CONCERN WITH ENTRAINMENT INTO CBL...AND AS
SUCH HAVE TEMPERED SNOWFALL TOTALS SLIGHTLY. CURRENT PRESENCE OF
STRONG THERMAL TROF/CYCLONIC SPIN/LAND BREEZE CONVERGENCE ACRS FAR
NRN LK MI DRAWS ANOTHER CONCERN FOR AN INITIAL SINGLE BAND EVENT
DEVELOPING STRONG MESOVORTICY AS IT DRIVES S W/TIME LATE
AFTN/EARLY EVE. THOUGH SOMETHING OF NOTE MERELY ATTM AS THIS
TEMPORAL/SPATIAL DETAIL/RESOLUTION BETTER HANDLED BY DAYSHIFT.
UPG TO LAKE EFFECT SNOW WARNING WITH SOME TIMING AFFORDED TO END
WARNING SOONER FOR LAPORTE/STARKE COS. FINAL CONCERN WRT WINDCHILL
NEARING OR BLO WARNING CRITERIA AND HOISTED 17 HR DURATION
WINDCHILL WARNING ENTIRE CWA.
&&
.LONG TERM...
FRIDAY THROUGH WEDNESDAY...THE MAIN CHALLENGE THIS PERIOD IS THE
TRACK AND TIMING OF SHORT WAVE TROFS AND ASSOCIATED CLIPPER TYPE OF
SYSTEMS THAT TRACK OVER THE TOP OF THE UPSTREAM UPPER LEVEL RIDGE
AND DESCEND INTO THE GREAT LAKES REGION. FAVOR THE ECMWF THIS
PACKAGE. THE ECMWF HAS BEEN REASONABLY CONSISTENT FROM RUN TO RUN
WITH THIS PATTERN AND WITH THE TRACK OF THE CLIPPER SYSTEM LATE
FRIDAY NIGHT INTO SATURDAY. THE 00Z ECMWF RUN IS A LITTLE FARTHER
NORTHEAST WITH THE TRACK OF THE SFC LOW THAN THE PREVIOUS RUN...BUT
OTHERWISE HAS BEEN CONSISTENT. THE ECMWF IS SUPPORTED BY THE
CANADIAN GEM ENSEMBLES. MOST OF THE 00Z GFS ENSEMBLES HAVE ALSO COME
ON BOARD WITH THIS SOLUTION. GFS MRF PLUME DIAGRAM SHOWS REASONABLE
GFS ENSEMBLE TIMING WITH THIS SYSTEM FROM FRIDAY EVENING THROUGH
SATURDAY NIGHT. HAVE MADE SOME UPDATES TO THE GRIDS/FCST FRIDAY
NIGHT INTO SATURDAY BASED ON THIS EXPECTED SOLUTION. SNOW SHOULD
DEVELOP LATE FRIDAY NIGHT OR EARLY SATURDAY AND PERSIST AT LEAST
DURING THE DAY SATURDAY. RAISED SNOW CHANCES TO HIGH CHANCE
SATURDAY. OTHERWISE...CONTINUE TO PREFER THE ECMWF HANDLING OF THE
UPPER AIR PATTERN INTO EARLY NEXT WEEK. GIVEN THE STRENGTH AND
PERSISTENCE OF THE UPSTREAM BLOCK...FAVOR COLDER TEMPERATURES WITH
CHANCES FOR SNOW. THE ONGOING CHANCE FOR SNOW ON MONDAY APPEARS ON
TRACK.
&&
.AVIATION...
PRIMARY FOCUS ON FASTER TIMING WRT SHORTWAVE INDUCED SN RACING EWD
ACRS NRN IL INTO NW IN ERLY THIS AM. ANTICIPATE EASY/RAPID
SATURATION TO IFR LVLS IN COLD AIRMASS ABOUT AN HR AFT SNOW BEGINS
WITH FURTHER DETERIORATION TO LIFR NR DAYBREAK. ANTICIPATE GRDL
IMPROVEMENT INTO AFTN HRS IN WAKE OF SFC LOW PASSING THRU SRN IN.
CAVEAT REMAINS INVOF KSBN WITH STRONG/HEAVY LAKE EFFECT SNOW SIGNALS
LTR THIS EVE. WHILE EXACT PLACEMENT/TIMING OF STRONGEST SINGLE BAND
DIFFICULT AT BEST...HAVE PLACED LIFR TEMPO GRP FOR KSBN PRIMARILY AS
AN MED CONFIDENCE OUTLOOK 23-03 UTC TONIGHT.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR INZ018-
026-027-033-034.
WIND CHILL WARNING FROM 6 PM EST /5 PM CST/ THIS EVENING TO 11
AM EST /10 AM CST/ THURSDAY FOR INZ003>009-012>018-020-
022>027-032>034.
LAKE EFFECT SNOW WARNING FROM 2 PM THIS AFTERNOON TO 6 AM CST
THURSDAY FOR INZ003-012.
LAKE EFFECT SNOW WARNING FROM 5 PM THIS AFTERNOON TO 1 PM EST
THURSDAY FOR INZ004-005-014.
WINTER WEATHER ADVISORY UNTIL 11 AM EST /10 AM CST/ THIS MORNING
FOR INZ012>017-020-022>025-032.
MI...WIND CHILL WARNING FROM 6 PM THIS EVENING TO 11 AM EST THURSDAY
FOR MIZ077>081.
LAKE EFFECT SNOW WARNING FROM 5 PM THIS AFTERNOON TO 1 PM EST
THURSDAY FOR MIZ079.
LAKE EFFECT SNOW WARNING FROM 3 PM THIS AFTERNOON TO 1 PM EST
THURSDAY FOR MIZ077-078.
OH...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR OHZ015-
016-024-025.
WIND CHILL WARNING FROM 6 PM THIS EVENING TO 11 AM EST THURSDAY
FOR OHZ001-002-004-005-015-016-024-025.
LM...HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 PM EST
THURSDAY FOR LMZ043-046.
GALE WARNING FROM 4 PM THIS AFTERNOON TO 7 AM EST THURSDAY FOR
LMZ043-046.
&&
$$
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...MURPHY
000
FXUS63 KIND 141101
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
601 AM EST WED JAN 14 2009
.AVIATION...DISCUSSION FOR 12Z TAFS.
A LOW PRESSURE SYSTEM CENTERED OVR THE IA/MO BORDER AT 11Z WILL MOVE
EAST ACRS IL AND INDIANA TODAY. FORCING AHEAD OF THIS SYSTEM WL
CAUSE SNOW AND LIFR CIGS/VSBYS AT KLAF...IFR AT KIND AND KHUF...AND
MVFR AT KBMG AS THE SYSTEM APPROACHES. AS IT PASSES WINDS WILL SWING
AROUND TO OUT OF THE NW AND INCREASE IN SPEED WITH GUSTS TO 25-30KTS
AS WELL AS FORCE ANOTHER COUPLE HOURS OF LIGHT SNOW SHOWERS. THE
GUSTS SHUD CONTINUE THRU THE PD AS WELL AS MVFR CIGS OVRNIGHT.
&&
.PREV DISCUSSION...FOCUS ON SNOW TODAY AND BITTER COLD FOLLOWING
SNOW.
APPROACHING CLIPPER SYSTEM CONTINUES TO MOVE ESE TOWARD THE REGION.
06Z SFC MAP SHOWED THE LOW CENTER ACROSS SOUTH CENTRAL IA WITH THE
STRONGEST 3 HR PRESSURE FALLS NOW CENTERED ACROSS CENTRAL IL. THIS
SUGGESTS THE LOW SHOULD BEGIN A EASTWARD TURN. REGIONAL RADAR SHOWS
SNOW DEVELOPMENT DUE TO ISENTROPIC LIFT OCCURRING ACROSS CENTRAL IL
WITH PRECIP ASSOCIATED WITH DYNAMIC LIFT LAGGING BACK ACROSS SE IA.
THE CURRENT FCST LOOKS ON TRACK FOR SNOW AMOUNTS BASED ON RADAR AND
OB TRENDS.
BOTH GFS/NAM ARE IN GOOD AGREEMENT WITH THE TRACK OF THE SYSTEM
TODAY AND BOTH APPEAR CLOSE TO REALITY SO WILL USE A BLEND.
TODAY...SNOW WILL DEVELOP AND IMPACT MAINLY AREAS ALONG AND NORTH OF
I-70 TODAY. DURATION AND MAGNITUDE OF LIFT ALONG WITH SNOW RATIOS
AND AVAILABLE MOISTURE ALL SUGGEST THAT THE CURRENT FCST OF 2 TO 4
INCHES IS THE BEST BET. THE WILD CARD COULD BE THE RATIOS AND SOME
REPORTS OUT OF IL ARE POINTING TOWARD THE HIGHER END OF THIS RANGE.
ALONG THE I-70 CORRIDOR INCLUDING INDIANAPOLIS WE STILL EXPECT SNOW
ON THE ORDER OF 1 OR 2 INCHES OVER THE CITY TO 2 OR 3 INCHES ON THE
FAR NORTHSIDE WITH LOWER AMOUNTS SOUTH OF MARION COUNTY. DO NOT BUY
THE HEAVIER SNOW AMOUNTS FCST BY THE GFS OVER THE CITY AND FEEL THAT
THIS IS TOO FAR SOUTH GIVEN RECENT RADAR TRENDS. DESPITE LOWER SNOW
AMOUNTS ACROSS THE I-70 CORRIDOR FEEL IT MAY BE PRUDENT TO HOIST AN
ADVISORY GIVEN THE POTENTIAL FOR IMPACTS OF BLOWING/DRIFTING OF SNOW
LATER TODAY.
THE MAIN STORY/IMPACT WILL BE THE DANGEROUSLY COLD WIND CHILLS WHICH
WILL ARRIVE LATER TONIGHT AND PERSIST THROUGH FRI. ALL GUIDANCE
WINDS AND RAW MODEL TEMPS SHOW WIND CHILLS IN THE MINUS 10 TO MINUS
30 RANGE DURING THIS PERIOD. WE MAY RISE TO ABOVE WIND CHILL WARNING
CRITERIA FOR A TIME THU ONLY TO DROP BACK DOWN THU NIGHT. FOR
CLARITY I WILL NOT ATTEMPT TO BREAK THIS INTO WARNING/ADVISORY
PERIODS AND INSTEAD ISSUE ONE SIMPLE WARNING AND ADVISORY FOR WIND
CHILLS DURING THIS PERIOD.
THE COLDEST AIR TEMPS SHOULD OCCUR THU NIGHT INTO EARLY FRI WHEN
TEMPS MAY DROP INTO THE 10 TO 20 BELOW ZERO RANGE IF CURRENT
INDICATIONS ARE CORRECT. THIS WOULD BE THE COLDEST TEMPS AT IND
SINCE JAN OF 2004.
NO CHANGES TO THE FCST BEYOND FRI.
&&
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ021-
028>031-035>049.
WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ021-028>031-035>049.
&&
$$
PUBLIC...CO
AVIATION...CP
000
FXUS63 KIND 140852
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
355 AM EST WED JAN 14 2009
.DISCUSSION...FOCUS ON SNOW TODAY AND BITTER COLD FOLLOWING SNOW.
APPROACHING CLIPPER SYSTEM CONTINUES TO MOVE ESE TOWARD THE REGION.
06Z SFC MAP SHOWED THE LOW CENTER ACROSS SOUTH CENTRAL IA WITH THE
STRONGEST 3 HR PRESSURE FALLS NOW CENTERED ACROSS CENTRAL IL. THIS
SUGGESTS THE LOW SHOULD BEGIN A EASTWARD TURN. REGIONAL RADAR SHOWS
SNOW DEVELOPMENT DUE TO ISENTROPIC LIFT OCCURRING ACROSS CENTRAL IL
WITH PRECIP ASSOCIATED WITH DYNAMIC LIFT LAGGING BACK ACROSS SE IA.
THE CURRENT FCST LOOKS ON TRACK FOR SNOW AMOUNTS BASED ON RADAR AND
OB TRENDS.
BOTH GFS/NAM ARE IN GOOD AGREEMENT WITH THE TRACK OF THE SYSTEM
TODAY AND BOTH APPEAR CLOSE TO REALITY SO WILL USE A BLEND.
TODAY...SNOW WILL DEVELOP AND IMPACT MAINLY AREAS ALONG AND NORTH OF
I-70 TODAY. DURATION AND MAGNITUDE OF LIFT ALONG WITH SNOW RATIOS
AND AVAILABLE MOISTURE ALL SUGGEST THAT THE CURRENT FCST OF 2 TO 4
INCHES IS THE BEST BET. THE WILD CARD COULD BE THE RATIOS AND SOME
REPORTS OUT OF IL ARE POINTING TOWARD THE HIGHER END OF THIS RANGE.
ALONG THE I-70 CORRIDOR INCLUDING INDIANAPOLIS WE STILL EXPECT SNOW
ON THE ORDER OF 1 OR 2 INCHES OVER THE CITY TO 2 OR 3 INCHES ON THE
FAR NORTHSIDE WITH LOWER AMOUNTS SOUTH OF MARION COUNTY. DO NOT BUY
THE HEAVIER SNOW AMOUNTS FCST BY THE GFS OVER THE CITY AND FEEL THAT
THIS IS TOO FAR SOUTH GIVEN RECENT RADAR TRENDS. DESPITE LOWER SNOW
AMOUNTS ACROSS THE I-70 CORRIDOR FEEL IT MAY BE PRUDENT TO HOIST AN
ADVISORY GIVEN THE POTENTIAL FOR IMPACTS OF BLOWING/DRIFTING OF SNOW
LATER TODAY.
THE MAIN STORY/IMPACT WILL BE THE DANGEROUSLY COLD WIND CHILLS WHICH
WILL ARRIVE LATER TONIGHT AND PERSIST THROUGH FRI. ALL GUIDANCE
WINDS AND RAW MODEL TEMPS SHOW WIND CHILLS IN THE MINUS 10 TO MINUS
30 RANGE DURING THIS PERIOD. WE MAY RISE TO ABOVE WIND CHILL WARNING
CRITERIA FOR A TIME THU ONLY TO DROP BACK DOWN THU NIGHT. FOR
CLARITY I WILL NOT ATTEMPT TO BREAK THIS INTO WARNING/ADVISORY
PERIODS AND INSTEAD ISSUE ONE SIMPLE WARNING AND ADVISORY FOR WIND
CHILLS DURING THIS PERIOD.
THE COLDEST AIR TEMPS SHOULD OCCUR THU NIGHT INTO EARLY FRI WHEN
TEMPS MAY DROP INTO THE 10 TO 20 BELOW ZERO RANGE IF CURRENT
INDICATIONS ARE CORRECT. THIS WOULD BE THE COLDEST TEMPS AT IND
SINCE JAN OF 2004.
NO CHANGES TO THE FCST BEYOND FRI.
IND WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ051>057-060>065-067>072.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ021-
028>031-035>049.
WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 1 PM EST FRIDAY FOR
INZ021-028>031-035>049.
&&
$$
PUBLIC...CO
AVIATION...CS/CP
000
FXUS63 KIWX 140614
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
105 AM EST WED JAN 14 2009
.AVIATION...
PRIMARY FOCUS ON FASTER TIMING WRT SHORTWAVE INDUCED SN RACING EWD
ACRS NRN IL INTO NW IN ERLY THIS AM. ANTICIPATE EASY/RAPID
SATURATION TO IFR LVLS IN COLD AIRMASS ABOUT AN HR AFT SNOW BEGINS
WITH FURTHER DETERIORATION TO LIFR NR DAYBREAK. ANTICIPATE GRDL
IMPROVEMENT INTO AFTN HRS IN WAKE OF SFC LOW PASSING THRU SRN IN.
CAVEAT REMAINS INVOF KSBN WITH STRONG/HEAVY LAKE EFFECT SNOW SIGNALS
LTR THIS EVE. WHILE EXACT PLACEMENT/TIMING OF STRONGEST SINGLE BAND
DIFFICULT AT BEST...HAVE PLACED LIFR TEMPO GRP FOR KSBN PRIMARILY AS
AN MED CONFIDENCE OUTLOOK 23-03 UTC TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 339 PM EST TUE JAN 13 2009/
SHORT TERM...
TONIGHT THROUGH THURSDAY...
LAKE EFFECT GAINING A MORE CELLULAR NATURE THIS AFTERNOON GIVEN
INCREASING LLEVEL INSTABILITY. MOST OF THE ACCUMULATING SNOW IS NOW
OVER...BUT SOME HEAVIER CELLS ARE CERTAINLY POSSIBLE GIVEN WHAT HAS
OCCURRED THIS MORNING AND MODERATE LEVELS OF INSTABILITY.
TONIGHT...THE LLEVEL FLOW WILL BACK...FETCH OVER THE LAKE WILL
DECREASE AND AS DRIER AIR WORKS IN FROM THE WEST...WE SHOULD SEE
SNOWS WEAKEN AND PULL EAST.
TONIGHT WE WILL ONCE AGAIN GET A VERY BRIEF BREAK AS A WEAK H850
RIDGE MOVES OVERHEAD AND IS QUICKLY REPLACED BY AN ARRIVING SHOT OF
STRONG ISENTROPIC LIFT. WILL UP POPS TO LIKELY AFTER ABOUT 9Z OVER
WESTERN AREAS AS THE GFS/NAM AGREE ON AREA OF ISENTROPIC LIFT BEING
OVERHEAD WELL BEFORE DAYBREAK. TEMPS WILL FALL QUICKLY THIS EVENING
BUT WILL LIKELY LEVEL OFF OR EVEN RISE SOME AS MID AND UPPER LEVEL
CLOUDINESS SPREADS BACK OVERHEAD AHEAD OF THE SNOW.
GFS NAM ARE QUITE SIMILAR WITH TRACK OF LOW FOR WEDNESDAY...WITH
BOTH HAVING A TRACK FURTHER SOUTH THAN THIS PAST SYSTEM WITH THE GFS
A LITTLE BIT SOUTH OF THE NAM/SREFS. WILL LEAN TOWARDS A NAM-LIKE
SOLUTION FOR WEDNESDAY AND BEYOND WHICH FAVORS A LOW TRACK PRETTY
MUCH DIRECTLY OVERHEAD ON WEDNESDAY. GIVEN THAT THIS CLIPPER WILL
BE QUITE MOISTURE STARVED /DEWPOINTS WILL LIKELY NOT REACH MUCH
ABOVE 10F DURING THE EVENT/ WE WILL NOT SEE MUCH QPF...ONE TO TWO
TENTHS. THE DENDRITIC GROWTH ZONE IS WELL SITUATED FOR HIGH
SNOW:LIQUID RATIOS...SO EXPECT A WIDESPREAD 2-3 INCH SNOWFALL.
WINDS DURING THE DAY WILL BE LIGHT...GIVEN THE LOW TRACK OVERHEAD.
HAVE OPTED FOR NO HEADLINES DURING THE DAY AS 2-3 INCHES WILL FALL
BELOW CRITERIA...BUT WILL MENTION TRAVEL IMPACTS IN THE HWO.
WEDNESDAY NIGHT IS WHEN THINGS GET MORE INTERESTING AS LOW DEPARTS
AND 1045 HIGH MOVES INTO THE NORTHERN PLAINS. T850 FALLS BELOW -20C
AND BUFKIT PROFILES SUGGEST TERRIFIC CONDITIONS FOR FLUFFY LAKE
EFFECT SNOW...AND LOTS OF IT. EXPECT SNOW:LIQUID RATIOS TO APPROACH
20:1 AND GIVEN EXTREME INSTABILITY...EXPECT HEAVY LAKE SNOWS.
CURRENT TRAJECTORY FAVORS BERRIEN/CASS/ST JOE COUNTIES. CERTAINLY
EXPECT WARNING LEVEL SNOWFALLS FROM THE EVENT...BUT GIVEN SOME
UNCERTAINTY IN BAND LOCATION GIVEN A BACKING WIND PROFILES AND THE
AMOUNT OF TIME UNTIL THE EVENT...WILL PAINT A BROADER LES WATCH FOR
THE COUNTIES MENTIONED ABOVE AND A SURROUNDING SET. ONE FOOT SNOW
TOTALS APPEAR LIKELY. WINDS ARE MORE OF A QUESTION. RISE FALL
COUPLET IS MORE WELL ALIGNED AND SOMEWHAT STRONGER THAN TODAY...BUT
ARRIVES AT NIGHT AND H925/H850 FLOW IS NO MORE THAN 25-30KTS.
SO...EXPECT BLOWING SNOW ALONG WITH THE LAKE EFFECT...BUT FEEL THAT
WIDESPREAD BLIZZARD CONDITIONS ARE NOT LIKELY. SO HAVE CANCELLED
THE BLIZZARD WATCH BUT WILL MENTION LOCAL BLIZZARD CONDITIONS
POSSIBLE IN LAKE SNOW BANDS.
ON THURSDAY THE LAKE SNOWS WILL SLOWLY WEAKEN AND PULL EAST...BUT
ADDITIONAL LIGHT ACCUMS LOOK POSSIBLE. WILL ALSO LIKELY SEE WIND
CHILLS APPROACHING ADVISORY LEVELS...BUT WILL HOLD OFF ON FLAGS AT
THIS TIME GIVEN ACTIVE SHORT TERM WEATHER.
LONG TERM...
THURSDAY NIGHT THROUGH TUESDAY
ARCTIC CHILL STILL ON THE WAY WITH TEMPS EXPECTED TO BE WELL BELOW
NORMAL BY FRI MORNING. ACTIVE NORTHWEST FLOW WILL CONTINUE INTO
THE WEEKEND SUPPORTING AT LEAST TWO MORE CLIPPER SYSTEMS EACH WITH
THE POTENTIAL OF BRINGING SNOWFALL TO THE REGION. CURRENT MEAN
ENSEMBLE AS WELL AS THE LATEST 12Z GFS AND ECMWF...CONTINUE TO
SUPPORT BREAKDOWN OF THE THE POTENT EAST ASIAN JET...WITH A
TRANSITION TO HIGHLY AMPLIFIED FLOW OVER THE PACIFIC. THESE TWO
FEATURES WILL ALLOW A PATTERN TRANSITION LIKELY BACK TO A NEGATIVE
PNA REGIME AS THE EASTERN PACIFIC RIDGE BREAKS DOWN ALLOWING
RESURGENCE OF THE EASTERN CONUS RIDGE WITH TROUGHING SETTING UP IN
THE WEST. THIS COULD SPELL ANOTHER ROUND OF ACTIVE WEATHER AS
SOUTHWEST FLOW LOOKS TO SETUP ONCE AGAIN. THIS FITS THE BILL FOR A
LA NINA PATTERN...WHICH IS GAINING STRENGTH IN THE PAC. BOTTOM
LINE...EXPECT TEMPS TO GRADUALLY WARM BACK TO CLIMO NORMS...AND
POSSIBLY ABOVE AT SOME POINT. FELT THE BEST SOLUTION WAS TO MODIFIED
THE DATABASE WITH A BLEND OF THE NAEFS/GEFS/AND 12Z-00Z ECMWF WHICH
HAS THE SUPPORT FROM THE AFOREMENTIONED GUIDANCE.
COLDEST DAY LOOKING TO BE FRIDAY AS A AN ARCTIC HIGH WILL SHIFT JUST
SOUTH OF THE AREA...AN OPTIMAL LOCATION FOR EXCELLENT RADIATIONAL
COOLING AND COLD TEMPS. TEMPS THU NIGHT WILL FALL OFF
DRAMATICALLY...ESPECIALLY WHERE CLEAR SKIES AND LIGHT WINDS OVERLAP
THE LONGEST. THIS LOOKS TO FAVOR THE SOUTHWEST CWA. HAVE ADJUSTED
TEMPS DOWN SOME FRI...IN LINE WITH SHALLOW MIXING TYPICAL IN AN
ARCTIC INTRUSION. FEEL MANY PLACES WILL STRUGGLE TO GET ABOVE
ZERO...ESPECIALLY WHERE THE SNOW PACK IS DEEP AND GIVEN H925 TEMPS
AROUND -17C. NEXT CLIPPER WILL ARRIVE FRI NIGHT...BRINGING CHANCES
OF SNOW TO THE REGION INTO SAT. HAVE OPTED FOR FASTER ENSEMBLE
MEANS...WHICH SUPPORT SNOW ARRIVAL FRIDAY NIGHT AND ENDS THINGS BY
SAT NIGHT WITH POSSIBLE LAKE SNOW CHANCES IN THE NW. ANOTHER SYSTEM
IS EXPECTED IN THE SUNDAY NIGHT MON TIME FRAME...AND AGAIN HAVE
PREFERRED THE FASTER NAEFS/GEFS MEAN SOLUTIONS...DO TO TYPICAL SLOW
FORECAST MODEL BIAS WRT CLIPPERS.
RIDGING WILL BE ONGOING EARLY NEXT WEEK AS THE WESTERN RIDGE SHIFTS
SLOWLY EAST. HAVE KEPT TEMPS AT OR JUST BELOW CLIMO NORMS. STILL
POSSIBLE THAT ONE MORE CLIPPER SYSTEMS COULD AFFECT THE REGION AS
PREFERRED BY THE GFS...BUT FEEL AN ADJUSTMENT TOWARD THE EXPECTED
PATTERN SHIFT...SUPPORTED BY THE MEAN ENSEMBLE PROGS...IS PRUDENT.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...LAKE EFFECT SNOW WATCH FROM WEDNESDAY AFTERNOON THROUGH
THURSDAY AFTERNOON FOR INZ003>005-012-014.
MI...LAKE EFFECT SNOW WATCH FROM WEDNESDAY AFTERNOON THROUGH
THURSDAY AFTERNOON FOR MIZ077>079.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 4 AM EST WEDNESDAY FOR LMZ043-046.
&&
$$
SHORT TERM...ARNOTT
LONG TERM...JC
AVIATION...MURPHY
000
FXUS63 KIND 140517
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1217 AM EST WED JAN 14 2009
.AVIATION...DISCUSSION FOR 14/06Z TAFS
SNOW WILL SPREAD QUICKLY INTO THE AREA BEFORE 12Z. THERE WILL BE A
TIGHT GRADIENT BETWEEN LIFR CONDS TO MVFR CONDS...WITH HUF/IND IN
THE MOST UNCERTAIN ZONE. LAF WILL LIKELY DETERIORATE TO LIFR CONDS
AROUND 12Z WITH THOSE CONDITIONS PERSISTING THROUGH THE MORNING WITH
BEST FORCING OCCURRING IN THIS AREA. IND WILL LIKELY GO DOWN TO IFR
IN SNOW BY MID MORNING WITH LOW MVFR RETURNING DURING THE AFTN.
BELIEVE BULK OF THE SNOW WILL STAY N OF HUF SO ONLY WENT MVFR THERE.
BMG LOOKS TO STAY MVFR AS WELL. SNOW WILL TAPER OFF DURING THE AFTN.
AFT SFC LOW EXITS THE AREA DURING THE AFTN ARCTIC AIRMASS WILL FLOW
IN WITH GUSTY NW WINDS. EXPECT MVFR CIGS TO CONTINUE INTO THE
OVERNIGHT PD.
&&
.DISCUSSION...FOCUS ON SNOW WEDNESDAY AND BITTER COLD FOLLOWING SNOW.
SNOW SHOWERS WILL HAVE ENDED AND SKIES PARTIALLY CLEARED BY THIS
WITH TEMPS FROM NEAR 10 TO 20 ACROSS FCST AREA.
NEXT CLIPPER SYSTEM CLOUDS ALREADY INTO WRN IOWA AND AFTER CLEAR
SKIES BRIEFLY THIS EVENING WE SHOULD CLOUD OVER. SNOWS ALREADY IN
ERN SOUTH DAKOTA WILL REACH MUCH OF CENTRAL INDIANA BEFORE DAYBREAK.
MODELS HAVE ALL TRACKED BIT FURTHER SOUTH ON CLIPPER SYSTEM AND
TOWARDS 00Z EURO RUN SO WILL LEAN IN THAT DIRECTION. GIVEN A MERGE
OF MODEL QPF`S APPEARS A SWATH OF 2-4 INCH SNOW SHOULD OCCUR ALONG A
KLAF TO MUNCIE LINE WITH AMOUNTS OF 1-2 NEAR AND NORTH OF THE I-70
CORRIDOR. WILL INCLUDE WINTER WEATHER ADVISORY FOR SNOW GIVEN THE
AVERAGE IS 3 INCHES AND ADVISORIES ARE FOR EVENTS AVERAGING 3 OR 4
OR 5 INCHES.
MODELS ALSO CONTINUE ON TRACK WITH ARCTIC AIR FOLLOWING CLIPPER.
CURRENT SFC TEMP FCSTS FROM MODELS APPEARED TAD COLDER/BETTER THAN
MOS AND HAVE FOLLOWED. COMBINED WITH STRONG BUT SUB WIND ADVISORY
GUSTY WINDS...WIND CHILLS WILL BE INTO ADVISORY OR WARNING CRITERIA
WEDNESDAY NIGHT INTO FRIDAY. HAVE THUS INTRODUCED WIND CHILL WATCH
FOR MOST COUNTIES FOR THAT TIME FRAME. SUBZERO LOWS FOR MOST
COUNTIES WILL MAKE FOR COLDEST TEMPS THIS SEASON.
ALL MODELS LIFT ARCTIC AIR OUT BY SATURDAY AS YET ANOTHER CLIPPER
MOVES INTO LAKES REGION. HAVE THUS TEMPERED READINGS BEGINNING
SATURDAY AND CONTINUE THROUGH REMAINDER OF FCST. HAVE ALSO
INTRODUCED CHC SNOW FOR SATURDAY WITH SAID CLIPPER SYSTEM.
&&
.IND WATCHES/WARNINGS/ADVISORIES...SNOW ADVISORY WEDNESDAY FOR
INDIANA ZONES INZ021-028>031-035>042
WIND CHILL WATCHES ARE IN EFFECT WEDNESDAY NIGHT INTO FRIDAY FOR
INZ021-028>031-035>042>049-051>057-062>065
&&
$$
PUBLIC...DT
AVIATION...CS/CP
000
FXUS63 KIND 140517
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1217 AM EST WED JAN 14 2009
.AVIATION...DISCUSSION FOR 14/06Z TAFS
SNOW WILL SPREAD QUICKLY INTO THE AREA BEFORE 12Z. THERE WILL BE A
TIGHT GRADIENT BETWEEN LIFR CONDS TO MVFR CONDS...WITH HUF/IND IN
THE MOST UNCERTAIN ZONE. LAF WILL LIKELY DETERIORATE TO LIFR CONDS
AROUND 12Z WITH THOSE CONDITIONS PERSISTING THROUGH THE MORNING WITH
BEST FORCING OCCURRING IN THIS AREA. IND WILL LIKELY GO DOWN TO IFR
IN SNOW BY MID MORNING WITH LOW MVFR RETURNING DURING THE AFTN.
BELIEVE BULK OF THE SNOW WILL STAY N OF HUF SO ONLY WENT MVFR THERE.
BMG LOOKS TO STAY MVFR AS WELL. SNOW WILL TAPER OFF DURING THE AFTN.
AFT SFC LOW EXITS THE AREA DURING THE AFTN ARCTIC AIRMASS WILL FLOW
IN WITH GUSTY NW WINDS. EXPECT MVFR CIGS TO CONTINUE INTO THE
OVERNIGHT PD.
&&
.DISCUSSION...FOCUS ON SNOW WEDNESDAY AND BITTER COLD FOLLOWING SNOW.
SNOW SHOWERS WILL HAVE ENDED AND SKIES PARTIALLY CLEARED BY THIS
WITH TEMPS FROM NEAR 10 TO 20 ACROSS FCST AREA.
NEXT CLIPPER SYSTEM CLOUDS ALREADY INTO WRN IOWA AND AFTER CLEAR
SKIES BRIEFLY THIS EVENING WE SHOULD CLOUD OVER. SNOWS ALREADY IN
ERN SOUTH DAKOTA WILL REACH MUCH OF CENTRAL INDIANA BEFORE DAYBREAK.
MODELS HAVE ALL TRACKED BIT FURTHER SOUTH ON CLIPPER SYSTEM AND
TOWARDS 00Z EURO RUN SO WILL LEAN IN THAT DIRECTION. GIVEN A MERGE
OF MODEL QPF`S APPEARS A SWATH OF 2-4 INCH SNOW SHOULD OCCUR ALONG A
KLAF TO MUNCIE LINE WITH AMOUNTS OF 1-2 NEAR AND NORTH OF THE I-70
CORRIDOR. WILL INCLUDE WINTER WEATHER ADVISORY FOR SNOW GIVEN THE
AVERAGE IS 3 INCHES AND ADVISORIES ARE FOR EVENTS AVERAGING 3 OR 4
OR 5 INCHES.
MODELS ALSO CONTINUE ON TRACK WITH ARCTIC AIR FOLLOWING CLIPPER.
CURRENT SFC TEMP FCSTS FROM MODELS APPEARED TAD COLDER/BETTER THAN
MOS AND HAVE FOLLOWED. COMBINED WITH STRONG BUT SUB WIND ADVISORY
GUSTY WINDS...WIND CHILLS WILL BE INTO ADVISORY OR WARNING CRITERIA
WEDNESDAY NIGHT INTO FRIDAY. HAVE THUS INTRODUCED WIND CHILL WATCH
FOR MOST COUNTIES FOR THAT TIME FRAME. SUBZERO LOWS FOR MOST
COUNTIES WILL MAKE FOR COLDEST TEMPS THIS SEASON.
ALL MODELS LIFT ARCTIC AIR OUT BY SATURDAY AS YET ANOTHER CLIPPER
MOVES INTO LAKES REGION. HAVE THUS TEMPERED READINGS BEGINNING
SATURDAY AND CONTINUE THROUGH REMAINDER OF FCST. HAVE ALSO
INTRODUCED CHC SNOW FOR SATURDAY WITH SAID CLIPPER SYSTEM.
&&
.IND WATCHES/WARNINGS/ADVISORIES...SNOW ADVISORY WEDNESDAY FOR
INDIANA ZONES INZ021-028>031-035>042
WIND CHILL WATCHES ARE IN EFFECT WEDNESDAY NIGHT INTO FRIDAY FOR
INZ021-028>031-035>042>049-051>057-062>065
&&
$$
PUBLIC...DT
AVIATION...CS/CP
| 
