000
FXUS63 KLOT 201622
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1022 AM CST TUE JAN 20 2009
.DISCUSSION...
1019 AM CST
MAIN CONCERN THIS MORNING IS ON MAGNITUDE OF LAKE EFFECT SNOW
ACCUMULATION FOR FAR NORTHEAST ILLINOIS NORTHWEST INDIANA. LAKE
EFFECT BAND HAS BECOME NEARLY STATIONARY THIS MORNING WITH MOST
INTENSE BANDING ACROSS NORTHERN LAKE COUNTY IN NORTHEAST ILLINOIS.
A MORE WIDESPREAD AREA OF LAKE EFFECT SNOW SHOWERS EXTENDS BACK
WESTWARD INTO COOK COUNTY. AT 7 AM THIS MORNING...HAD SOME REPORTS
OF 4 TO 5 INCH SNOW ACCUMULATIONS IN THE BURNAM AREA EXTENDING TO
HAMMOND. BASED ON EXPECTED ADDITIONAL 2 TO 5 INCH ACCUMULATIONS
TODAY ACROSS LAKE COUNTY INDIANA...HAVE ISSUED A LAKE EFFECT SNOW
WARNING FOR LAKE COUNTY INDIANA THROUGH 6 PM THIS EVENING. ACROSS
FAR SOUTHEAST COOK COUNTY...WILL LIKELY HAVE LOCALIZED LOCATIONS
REACH WARNING CRITERIA ACCUMULATIONS BUT EXPECTING THE GREATER
LIKELIHOOD OF THIS CLOSER TO THE INDIANA STATELINE. HAVE ISSUED A
LAKE EFFECT SNOW ADVISORY FOR COOK COUNTY TO MENTION SNOW
ACCUMULATIONS OF 4 TO 7 INCHES BY THE TIME THE SNOW BEGINS TO WIND
DOWN MID AFTERNOON. A SHEARED VORTICITY MAXIMUM DROPPING SOUTHEAST
OUT OF WESTERN ILLINOIS AND SOUTHWEST WISCONSIN WILL TRACK ACROSS
LAKE MICHIGAN THIS AFTERNOON. THE PASSAGE OF THIS SHORT WAVE WILL
ALLOW A SFC RIDGE AXIS TO BEGIN TO BUILD INTO THE AREA...ALLOWING
WINDS TO BACK MORE NORTHWEST THIS AFTERNOON AND RESULTING IN LAKE
EFFECT SNOW BAND TO BEGIN TO SHIFT BACK EASTWARD AND BECOME MORE
PROGRESSIVE. THE PROGRESSIVE NATURE OF THE BANDING THIS AFTERNOON
SHOULD LIMIT ADDITIONAL ACCUMS SOMEWHAT ACROSS PORTER COUNTY.
UPDATED FORECAST HAS BEEN SENT.
MARSILI
&&
.PREV DISCUSSION...
330 PM CST
MAIN CONCERN FOR THE MORNING FORECAST UPDATE CONTINUES TO FOCUS ON
THE ONGOING LAKE EFFECT SNOW EVENT.
LATEST RADAR IMAGERY SHOWS THE LAKE EFFECT SNOW BAND MOVING OVER
ERN COOK COUNTY AND FAR ERN WILL COUNTY WITH SNOW CONTINUING OVER
LAKE COUNTY IN NWRN INDIANA. SFC WIND FIELD NICELY SHOWS THE
CONVERGENCE AREA ASSOCIATED WITH THE SNOW BAND WITH NNWLY WINDS
OVER NERN IL AND NNELY WINDS OVER NWRN INDIANA. THE FIRST SEVERAL
HOURS OF THE NAM12...AND WRFARW DO NOT INDICATE THE CONVERGENCE
ZONE MOVING MUCH FARTHER INLAND THIS MORNING...SO DO NOT
ANTICIPATE ANY CHANGES TO THE CURRENT HEADLINES IN EFFECT. GIVEN
THE VERY HIGH SNOW TO LIQUID RATIOS EXPECTED...EVEN WITH LITTLE
ANTICIPATED ASSOCIATED LIQUID EQUIVALENT QPF...THE ERN AND SRN
PORTIONS OF THE METRO AREA COULD SEE UPWARDS OF 1 TO 3 INCHES OF
VERY LIGHT...FLUFFY SNOWFALL THIS MORNING. ALSO BASED ON THE SHORT
TERM WIND FORECAST...EXPECT THAT THE SNOW BAND WILL BEGIN TO SHIFT
BACK EWD AGAIN BY LATE MORNING OR AROUND NOON...ENDING THE SNOW
OVER ERN COOK/WILL COUNTIES. HOWEVER...THE LAKE PLUME WILL
CONTINUE TO DROP SNOW OVER LAKE AND PORTER COUNTIES...WITH SOME
SPREADING INTO JASPER...NEWTON AND NRN BENTON COUNTIES. STILL
EXPECT THE HEAVIEST SNOW OVER LAKE AND PORTER COUNTIES...SO WILL
NOT EXPAND THE HEADLINES INTO NEWTON OR JASPER COUNTIES AT THIS
TIME.
THE REMAINDER OF THE SHORT TERM FORECAST PERIOD LOOKS RATHER
QUIET. THE HIGH AMPLITUDE PATTERN OVER THE CONUS WITH THE MAIN
UPPER TROUGH OVER THE ERN CONUS BECOMING SLOWLY PROGRESSIVE WHILE
THE UPPER RIDGE OVER THE ROCKIES FLATTENS CONSIDERABLY...WITH WEAK
RIDGING BUILDING OVER THE MIDDLE AND LOWER MISSISSIPPI VALLEY. THE
SHORT TERM MODELS ARE IN RATHER GOOD AGREEMENT ON KEEPING THE
UPPER MIDWEST UNDER NWLY FLOW ALOFT...WITH INCREASING HEIGHTS
ENCROACHING ON THE LOCAL AREA. THUS EXPECT SOME MODERATION TO
TEMPERATURES THROUGH THE SHORT TERM WITH DAYTIME HIGHS ACTUALLY
GETTING ABOVE FREEZING FOR THE FIRST TIME IN TWO WEEKS. THIS
WARMING TREND WILL BE SHORT LIVED AS THE MODELS ARE INDICATING
ANOTHER POLAR VORTEX PUSHING SOUTH OF HUDSON BAY BRINGING A
RESURGENCE OF ARCTIC AIR FOR THE WEEKEND. NOT EXPECTING THE EXTREME
COLD OF LAST WEEK...BUT STILL LOOKING AT HIGHS IN THE TEENS TO LOW
20S AND LOWS APPROACHING 0F FOR MUCH OF THE CWA. THE DEVELOPING
PATTERN OVER THE AREA LOOKS TO BE RATHER MOISTURE STARVED...SO DO
NOT EXPECT ANY SIGNIFICANT PCPN THROUGH THE PERIOD.
KREIN
&&
.AVIATION...
1200 UTC TAFS...ONLY REAL CONTENDER TODAY AND TONIGHT WILL BE LAKE
EFFECT SNOWS STREAMING DOWN LAKE MICHIGAN. THE SURGE INLAND TO
OHARE IS DIMINISHING THIS MRNG AND THINK ONLY A COUPLE MORE HOURS
OF SNOW THREAT THERE FOR THE DAY. MDW AND ESPECIALLY GYY WILL
CONTEND WITH SNOW PAST SUNUP. HIGH PRESSURE BLDG ACROSS THE MID MS
VLY WILL FORCE SFC WINDS TO BACK MORE TO THE WEST TODAY. THIS WILL
PUSH LAKE PLUMES OVER TO THE MICHIGAN SIDE AND AWAY FROM ILLINOIS
TERMINALS. GYY MAY SEE SNOW SHOWERS UP TO 21Z THIS AFTN WITH MDW
SCATTERING OUT ARND NOONTIME. WINDS SHUD CONTINUE TO BACK TO SW
THIS EVENING AND CONTINUE SW THRU WEDNESDAY MRNG. WAA CIRRUS SHUD
BE THE ONLY CIGS IN TERMINAL FCSTS OUTSIDE OF THE THOSE ASSOCIATED
WITH THE LAKE EFFECT SNOW SHOWERS.
RLB
&&
.MARINE...
155 AM CST
NORTH WINDS ON THE EAST SIDE OF BUILDING HIGH PRESSURE WILL BACK
WEST LATER TODAY WITH RIDGE PASSAGE TO THE SOUTH OF THE LAKES.
WINDS BACK EVEN FURTHER TO THE SOUTHWEST BY WEDNESDAY AS A LOW
PRESSURE TROF DROPS OUT OF ONTARIO THURS NGT INTO FRIDAY. TROF
PASSAGE VEERS WINDS BACK TO THE NW FOR THE REMAINDER OF THE WEEK.
HAVE OPTED FOR ONLY INCREASING WINDS TO 25 KTS VERSUS 30 KTS
FRIDAY AND SATURDAY.
RLB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKE EFFECT SNOW ADVISORY...ILZ014 UNTIL 6 PM TUESDAY.
IN...LAKE EFFECT SNOW WARNING...INZ001-INZ002 UNTIL 6 PM TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 201102
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
502 AM CST TUE JAN 20 2009
.DISCUSSION...
330 PM CST
MAIN CONCERN FOR THE MORNING FORECAST UPDATE CONTINUES TO FOCUS ON
THE ONGOING LAKE EFFECT SNOW EVENT.
LATEST RADAR IMAGERY SHOWS THE LAKE EFFECT SNOW BAND MOVING OVER
ERN COOK COUNTY AND FAR ERN WILL COUNTY WITH SNOW CONTINUING OVER
LAKE COUNTY IN NWRN INDIANA. SFC WIND FIELD NICELY SHOWS THE
CONVERGENCE AREA ASSOCIATED WITH THE SNOW BAND WITH NNWLY WINDS
OVER NERN IL AND NNELY WINDS OVER NWRN INDIANA. THE FIRST SEVERAL
HOURS OF THE NAM12...AND WRFARW DO NOT INDICATE THE CONVERGENCE
ZONE MOVING MUCH FARTHER INLAND THIS MORNING...SO DO NOT
ANTICIPATE ANY CHANGES TO THE CURRENT HEADLINES IN EFFECT. GIVEN
THE VERY HIGH SNOW TO LIQUID RATIOS EXPECTED...EVEN WITH LITTLE
ANTICIPATED ASSOCIATED LIQUID EQUIVALENT QPF...THE ERN AND SRN
PORTIONS OF THE METRO AREA COULD SEE UPWARDS OF 1 TO 3 INCHES OF
VERY LIGHT...FLUFFY SNOWFALL THIS MORNING. ALSO BASED ON THE SHORT
TERM WIND FORECAST...EXPECT THAT THE SNOW BAND WILL BEGIN TO SHIFT
BACK EWD AGAIN BY LATE MORNING OR AROUND NOON...ENDING THE SNOW
OVER ERN COOK/WILL COUNTIES. HOWEVER...THE LAKE PLUME WILL
CONTINUE TO DROP SNOW OVER LAKE AND PORTER COUNTIES...WITH SOME
SPREADING INTO JASPER...NEWTON AND NRN BENTON COUNTIES. STILL
EXPECT THE HEAVIEST SNOW OVER LAKE AND PORTER COUNTIES...SO WILL
NOT EXPAND THE HEADLINES INTO NEWTON OR JASPER COUNTIES AT THIS
TIME.
THE REMAINDER OF THE SHORT TERM FORECAST PERIOD LOOKS RATHER
QUIET. THE HIGH AMPLITUDE PATTERN OVER THE CONUS WITH THE MAIN
UPPER TROUGH OVER THE ERN CONUS BECOMING SLOWLY PROGRESSIVE WHILE
THE UPPER RIDGE OVER THE ROCKIES FLATTENS CONSIDERABLY...WITH WEAK
RIDGING BUILDING OVER THE MIDDLE AND LOWER MISSISSIPPI VALLEY. THE
SHORT TERM MODELS ARE IN RATHER GOOD AGREEMENT ON KEEPING THE
UPPER MIDWEST UNDER NWLY FLOW ALOFT...WITH INCREASING HEIGHTS
ENCROACHING ON THE LOCAL AREA. THUS EXPECT SOME MODERATION TO
TEMPERATURES THROUGH THE SHORT TERM WITH DAYTIME HIGHS ACTUALLY
GETTING ABOVE FREEZING FOR THE FIRST TIME IN TWO WEEKS. THIS
WARMING TREND WILL BE SHORT LIVED AS THE MODELS ARE INDICATING
ANOTHER POLAR VORTEX PUSHING SOUTH OF HUDSON BAY BRINGING A
RESURGENCE OF ARCTIC AIR FOR THE WEEKEND. NOT EXPECTING THE EXTREME
COLD OF LAST WEEK...BUT STILL LOOKING AT HIGHS IN THE TEENS TO LOW
20S AND LOWS APPROACHING 0F FOR MUCH OF THE CWA. THE DEVELOPING
PATTERN OVER THE AREA LOOKS TO BE RATHER MOISTURE STARVED...SO DO
NOT EXPECT ANY SIGNIFICANT PCPN THROUGH THE PERIOD.
KREIN
&&
.AVIATION...
1200 UTC TAFS...ONLY REAL CONTENDER TODAY AND TONIGHT WILL BE LAKE
EFFECT SNOWS STREAMING DOWN LAKE MICHIGAN. THE SURGE INLAND TO
OHARE IS DIMINISHING THIS MRNG AND THINK ONLY A COUPLE MORE HOURS
OF SNOW THREAT THERE FOR THE DAY. MDW AND ESPECIALLY GYY WILL
CONTEND WITH SNOW PAST SUNUP. HIGH PRESSURE BLDG ACROSS THE MID MS
VLY WILL FORCE SFC WINDS TO BACK MORE TO THE WEST TODAY. THIS WILL
PUSH LAKE PLUMES OVER TO THE MICHIGAN SIDE AND AWAY FROM ILLINOIS
TERMINALS. GYY MAY SEE SNOW SHOWERS UP TO 21Z THIS AFTN WITH MDW
SCATTERING OUT ARND NOONTIME. WINDS SHUD CONTINUE TO BACK TO SW
THIS EVENING AND CONTINUE SW THRU WEDNESDAY MRNG. WAA CIRRUS SHUD
BE THE ONLY CIGS IN TERMINAL FCSTS OUTSIDE OF THE THOSE ASSOCIATED
WITH THE LAKE EFFECT SNOW SHOWERS.
RLB
&&
.MARINE...
155 AM CST
NORTH WINDS ON THE EAST SIDE OF BUILDING HIGH PRESSURE WILL BACK
WEST LATER TODAY WITH RIDGE PASSAGE TO THE SOUTH OF THE LAKES.
WINDS BACK EVEN FURTHER TO THE SOUTHWEST BY WEDNESDAY AS A LOW
PRESSURE TROF DROPS OUT OF ONTARIO THURS NGT INTO FRIDAY. TROF
PASSAGE VEERS WINDS BACK TO THE NW FOR THE REMAINDER OF THE WEEK.
HAVE OPTED FOR ONLY INCREASING WINDS TO 25 KTS VERSUS 30 KTS
FRIDAY AND SATURDAY.
RLB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 6 PM TUESDAY.
LAKE EFFECT SNOW ADVISORY...INZ001 UNTIL 6 PM TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 200936
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
336 AM CST TUE JAN 20 2009
.DISCUSSION...
330 PM CST
MAIN CONCERN FOR THE MORNING FORECAST UPDATE CONTINUES TO FOCUS ON
THE ONGOING LAKE EFFECT SNOW EVENT.
LATEST RADAR IMAGERY SHOWS THE LAKE EFFECT SNOW BAND MOVING OVER
ERN COOK COUNTY AND FAR ERN WILL COUNTY WITH SNOW CONTINUING OVER
LAKE COUNTY IN NWRN INDIANA. SFC WIND FIELD NICELY SHOWS THE
CONVERGENCE AREA ASSOCIATED WITH THE SNOW BAND WITH NNWLY WINDS
OVER NERN IL AND NNELY WINDS OVER NWRN INDIANA. THE FIRST SEVERAL
HOURS OF THE NAM12...AND WRFARW DO NOT INDICATE THE CONVERGENCE
ZONE MOVING MUCH FARTHER INLAND THIS MORNING...SO DO NOT
ANTICIPATE ANY CHANGES TO THE CURRENT HEADLINES IN EFFECT. GIVEN
THE VERY HIGH SNOW TO LIQUID RATIOS EXPECTED...EVEN WITH LITTLE
ANTICIPATED ASSOCIATED LIQUID EQUIVALENT QPF...THE ERN AND SRN
PORTIONS OF THE METRO AREA COULD SEE UPWARDS OF 1 TO 3 INCHES OF
VERY LIGHT...FLUFFY SNOWFALL THIS MORNING. ALSO BASED ON THE SHORT
TERM WIND FORECAST...EXPECT THAT THE SNOW BAND WILL BEGIN TO SHIFT
BACK EWD AGAIN BY LATE MORNING OR AROUND NOON...ENDING THE SNOW
OVER ERN COOK/WILL COUNTIES. HOWEVER...THE LAKE PLUME WILL
CONTINUE TO DROP SNOW OVER LAKE AND PORTER COUNTIES...WITH SOME
SPREADING INTO JASPER...NEWTON AND NRN BENTON COUNTIES. STILL
EXPECT THE HEAVIEST SNOW OVER LAKE AND PORTER COUNTIES...SO WILL
NOT EXPAND THE HEADLINES INTO NEWTON OR JASPER COUNTIES AT THIS
TIME.
THE REMAINDER OF THE SHORT TERM FORECAST PERIOD LOOKS RATHER
QUIET. THE HIGH AMPLITUDE PATTERN OVER THE CONUS WITH THE MAIN
UPPER TROUGH OVER THE ERN CONUS BECOMING SLOWLY PROGRESSIVE WHILE
THE UPPER RIDGE OVER THE ROCKIES FLATTENS CONSIDERABLY...WITH WEAK
RIDGING BUILDING OVER THE MIDDLE AND LOWER MISSISSIPPI VALLEY. THE
SHORT TERM MODELS ARE IN RATHER GOOD AGREEMENT ON KEEPING THE
UPPER MIDWEST UNDER NWLY FLOW ALOFT...WITH INCREASING HEIGHTS
ENCROACHING ON THE LOCAL AREA. THUS EXPECT SOME MODERATION TO
TEMPERATURES THROUGH THE SHORT TERM WITH DAYTIME HIGHS ACTUALLY
GETTING ABOVE FREEZING FOR THE FIRST TIME IN TWO WEEKS. THIS
WARMING TREND WILL BE SHORT LIVED AS THE MODELS ARE INDICATING
ANOTHER POLAR VORTEX PUSHING SOUTH OF HUDSON BAY BRINGING A
RESURGENCE OF ARCTIC AIR FOR THE WEEKEND. NOT EXPECTING THE EXTREME
COLD OF LAST WEEK...BUT STILL LOOKING AT HIGHS IN THE TEENS TO LOW
20S AND LOWS APPROACHING 0F FOR MUCH OF THE CWA. THE DEVELOPING
PATTERN OVER THE AREA LOOKS TO BE RATHER MOISTURE STARVED...SO DO
NOT EXPECT ANY SIGNIFICANT PCPN THROUGH THE PERIOD.
KREIN
&&
.AVIATION...
1100 PM CST
06Z TAFORS...SHORT WAVE TROUGH HAS PASSED SOUTH OVER NORTHERN AND
INTO CENTRAL IL AT LATE EVENING ENDING SNOW ACROSS THE LOCAL
TERMINALS AND RAPIDLY SCATTERING OUT CLOUDS. EXPECT ONLY
SCATTERED PATCHES OF STRATOCU OVERNIGHT. WITH SHORT WAVE TROUGH
PASSING FURTHER SOUTH TOWARD THE LOWER OH VALLEY FLOW DOWN LAKE MI
HAS VEERED RESULTING IN ITS MIGRATION BACK ACROSS MID LAKE AND
CROSSING INTO IL WATERS PER RADAR AND SATELLITE. LATEST MODEL
OUTPUT CONTINUES TO FORECAST NNE-NE FLOW AT LAKE EFFECT CLOUD
PRODUCTION LEVEL AND EXPECT THE TAIL OF THE LES BAND TO CONTINUE
TO WESTWARD TO THE IL-IN STATE LINE BETWEEN 09Z AND 12Z. EDGE OF
LES MAY GET FAR ENOUGH WEST INTO SOUTHERN COOK CO FOR KMDW TO GET
CLIPPED BY SOME -SHSN 12Z-15Z. THEREAFTER...BACKING FLOW SHOVES
THE LES BAND BACK OFF OF THE IL SHORE AND EASTWARD PAST KGYY AND
EVENTUALLY INTO SOUTHWEST LOWER MI AND NORTH CENTRAL IN BY LATE
TUE AFTERNOON.
TRS
&&
.MARINE...
155 AM CST
NORTH WINDS ON THE EAST SIDE OF BUILDING HIGH PRESSURE WILL BACK
WEST LATER TODAY WITH RIDGE PASSAGE TO THE SOUTH OF THE LAKES.
WINDS BACK EVEN FURTHER TO THE SOUTHWEST BY WEDNESDAY AS A LOW
PRESSURE TROF DROPS OUT OF ONTARIO THURS NGT INTO FRIDAY. TROF
PASSAGE VEERS WINDS BACK TO THE NW FOR THE REMAINDER OF THE WEEK.
HAVE OPTED FOR ONLY INCREASING WINDS TO 25 KTS VERSUS 30 KTS
FRIDAY AND SATURDAY.
RLB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 6 PM TUESDAY.
LAKE EFFECT SNOW ADVISORY...INZ001 UNTIL 6 PM TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 200755
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
155 AM CST TUE JAN 20 2009
.DISCUSSION...
955 PM CST
UPDATE FOR OVERNIGHT AND TUESDAY...SHORT WAVE TROUGH HAS DROPPED
SOUTH OVER NORTHERN IL THIS EVENING AND IS NOW APPROACHING CENTRAL
IL. SNOW WILL BE QUICKLY WINDING DOWN ACROSS NORTH CENTRAL IL OVER
THE NEXT HR OR SO WITH JUST SOME LINGERING -SHSN THEREAFTER. AS
THE SHORT WAVE HAS MOVED SOUTHWARD TONIGHT THE LOW LEVEL FLOW IN
ITS WAKE HAS VEERED RESULTING IN THE LAKE EFFECT BAND DRIFTING
WESTWARD FROM NEAR THE MI SHORE BACK OUT TO MID LAKE. TAIL OF LES
BAND HAS ALREADY MOVED BACK TO EASTERN PORTER COUNTY AND WILL
CONTINUE TO SHIFT WEST OVERNIGHT AS LATEST MODEL OUTPUT SIMILAR
WITH A NNE-NE FLOW IN THE LAKE EFFECT PRODUCTION LAYER PUSHING THE
LES BAND TO THE IL-IN STATE LINE BY 12Z TUE. WESTERN EDGE OF LES
EXPECTED TO SPILL OVER INTO SOUTHERN COOK AND EASTERN PORTIONS OF
WILL AND KANKAKEE COUNTIES FOR TUE MORNING BEFORE FLOW STARTS TO
BACK AND THE TAIL OF THE LES MIGRATES BACK EASTWARD...EVENTUALLY
BACK TO SOUTHWEST LOWER MI AND NORTH CENTRAL IN BY LATE AFTERNOON.
TRS
PREVIOUS DISCUSSION
401 PM CST
LAKE EFFECT SNOW WILL DIMINISH A LITTLE THIS EVENING AND
THEN RETURN LATE TONIGHT. A LAKE EFFECT SNOW WARNING AND
ADVISORY ARE POSTED FOR NORTHWEST INDIANA THROUGH TUESDAY.
OCCASIONAL LIGHT SNOW WILL OCCUR THIS EVENING.
TONIGHT...A SHORT WAVE OVER WESTERN ONTARIO WILL MOVE SOUTH INTO
NORTHERN ILLINOIS BY 02 UTC. THIS WILL BRING ENOUGH LIFT FOR SOME
LIGHT SNOW. WE EXPECT LITTLE IF ANY ACCUMULATION WITH THIS SNOW.
WE USED THE ECMWF MODEL AND A LOCALLY RUN WRF MODEL. THIS SHORT
WAVE TROUGH WILL MOVE INTO THE LOWER OHIO VALLEY BY TUESDAY
MORNING. THE SATELLITE SHOWS THE CLOUDS MOVING INTO WESTERN
ILLINOIS RAPIDLY WITH THIS TROUGH. THE WIND WILL BE NORTHWEST TO
NORTH OVER LAKE MICHIGAN TONIGHT. WITH THE FETCH OVER WARM
WATER...LAKE EFFECT SNOW WILL SET UP AGAIN FOR TONIGHT. WE WILL
KEEP THE ADVISORY AND WARNING GOING OVERNIGHT. THESE PRODUCTS ARE
FOR THE TOTAL SNOW ACCUMULATION FROM LAST NIGHT TO TUESDAY
EVENING. THE LOW TEMPERATURE WILL REACH THE MIDDLE TEENS TONIGHT.
TUESDAY THROUGH MONDAY...THE LAKE EFFECT SNOW WILL CONTINUE
DURING THE DAY TUESDAY. BY TUESDAY EVENING THE BAND OF SNOW WILL
MOVE EAST. THE LOW TEMPERATURES FOR TUESDAY EVENING WILL BE IN THE
TEENS. A LARGE SURFACE RIDGE WILL LIE FROM TEXAS TO SOUTHERN
ONTARIO TUESDAY. BY WEDNESDAY MORNING THE GFS AND ECMWF MODELS
SHOW A SURFACE TROUGH FROM SOUTHERN ONTARIO TO OKLAHOMA. THIS
TROUGH HAS MORE MERIDIONAL AMPLITUDE ON THE GFS. WE EXPECT CLOUDY
SKIES IN OUR NORTHERN TWO THIRDS OF OUR FORECAST AREA AND PARTLY
CLOUDY SKIES IN OUR SOUTHERN THIRD OF THE FORECAST AREA. THE REST
OF THE WEEK LOOKS TO BE MAINLY DRY WEATHER. THE AIR WILL BECOME
COLDER THROUGH THE WEEK. THE HIGH TEMPERATURES WILL BE IN THE
TEENS AND LOWS IN THE SINGLE DIGITS BY SUNDAY. THE NEXT CHANCE OF
PRECIPITATION MAY BE SUNDAY AND MONDAY.
&&
.AVIATION...
1100 PM CST
06Z TAFORS...SHORT WAVE TROUGH HAS PASSED SOUTH OVER NORTHERN AND
INTO CENTRAL IL AT LATE EVENING ENDING SNOW ACROSS THE LOCAL
TERMINALS AND RAPIDLY SCATTERING OUT CLOUDS. EXPECT ONLY
SCATTERED PATCHES OF STRATOCU OVERNIGHT. WITH SHORT WAVE TROUGH
PASSING FURTHER SOUTH TOWARD THE LOWER OH VALLEY FLOW DOWN LAKE MI
HAS VEERED RESULTING IN ITS MIGRATION BACK ACROSS MID LAKE AND
CROSSING INTO IL WATERS PER RADAR AND SATELLITE. LATEST MODEL
OUTPUT CONTINUES TO FORECAST NNE-NE FLOW AT LAKE EFFECT CLOUD
PRODUCTION LEVEL AND EXPECT THE TAIL OF THE LES BAND TO CONTINUE
TO WESTWARD TO THE IL-IN STATE LINE BETWEEN 09Z AND 12Z. EDGE OF
LES MAY GET FAR ENOUGH WEST INTO SOUTHERN COOK CO FOR KMDW TO GET
CLIPPED BY SOME -SHSN 12Z-15Z. THEREAFTER...BACKING FLOW SHOVES
THE LES BAND BACK OFF OF THE IL SHORE AND EASTWARD PAST KGYY AND
EVENTUALLY INTO SOUTHWEST LOWER MI AND NORTH CENTRAL IN BY LATE
TUE AFTERNOON.
TRS
&&
.MARINE...
155 AM CST
NORTH WINDS ON THE EAST SIDE OF BUILDING HIGH PRESSURE WILL BACK
WEST LATER TODAY WITH RIDGE PASSAGE TO THE SOUTH OF THE LAKES.
WINDS BACK EVEN FURTHER TO THE SOUTHWEST BY WEDNESDAY AS A LOW
PRESSURE TROF DROPS OUT OF ONTARIO THURS NGT INTO FRIDAY. TROF
PASSAGE VEERS WINDS BACK TO THE NW FOR THE REMAINDER OF THE WEEK.
HAVE OPTED FOR ONLY INCREASING WINDS TO 25 KTS VERSUS 30 KTS
FRIDAY AND SATURDAY.
RLB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 6 PM TUESDAY.
LAKE EFFECT SNOW ADVISORY...INZ001 UNTIL 6 PM TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 200503
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1103 PM CST MON JAN 19 2009
.DISCUSSION...
955 PM CST
UPDATE FOR OVERNIGHT AND TUESDAY...SHORT WAVE TROUGH HAS DROPPED
SOUTH OVER NORTHERN IL THIS EVENING AND IS NOW APPROACHING CENTRAL
IL. SNOW WILL BE QUICKLY WINDING DOWN ACROSS NORTH CENTRAL IL OVER
THE NEXT HR OR SO WITH JUST SOME LINGERING -SHSN THEREAFTER. AS
THE SHORT WAVE HAS MOVED SOUTHWARD TONIGHT THE LOW LEVEL FLOW IN
ITS WAKE HAS VEERED RESULTING IN THE LAKE EFFECT BAND DRIFTING
WESTWARD FROM NEAR THE MI SHORE BACK OUT TO MID LAKE. TAIL OF LES
BAND HAS ALREADY MOVED BACK TO EASTERN PORTER COUNTY AND WILL
CONTINUE TO SHIFT WEST OVERNIGHT AS LATEST MODEL OUTPUT SIMILAR
WITH A NNE-NE FLOW IN THE LAKE EFFECT PRODUCTION LAYER PUSHING THE
LES BAND TO THE IL-IN STATE LINE BY 12Z TUE. WESTERN EDGE OF LES
EXPECTED TO SPILL OVER INTO SOUTHERN COOK AND EASTERN PORTIONS OF
WILL AND KANKAKEE COUNTIES FOR TUE MORNING BEFORE FLOW STARTS TO
BACK AND THE TAIL OF THE LES MIGRATES BACK EASTWARD...EVENTUALLY
BACK TO SOUTHWEST LOWER MI AND NORTH CENTRAL IN BY LATE AFTERNOON.
TRS
PREVIOUS DISCUSSION
401 PM CST
LAKE EFFECT SNOW WILL DIMINISH A LITTLE THIS EVENING AND
THEN RETURN LATE TONIGHT. A LAKE EFFECT SNOW WARNING AND
ADVISORY ARE POSTED FOR NORTHWEST INDIANA THROUGH TUESDAY.
OCCASIONAL LIGHT SNOW WILL OCCUR THIS EVENING.
TONIGHT...A SHORT WAVE OVER WESTERN ONTARIO WILL MOVE SOUTH INTO
NORTHERN ILLINOIS BY 02 UTC. THIS WILL BRING ENOUGH LIFT FOR SOME
LIGHT SNOW. WE EXPECT LITTLE IF ANY ACCUMULATION WITH THIS SNOW.
WE USED THE ECMWF MODEL AND A LOCALLY RUN WRF MODEL. THIS SHORT
WAVE TROUGH WILL MOVE INTO THE LOWER OHIO VALLEY BY TUESDAY
MORNING. THE SATELLITE SHOWS THE CLOUDS MOVING INTO WESTERN
ILLINOIS RAPIDLY WITH THIS TROUGH. THE WIND WILL BE NORTHWEST TO
NORTH OVER LAKE MICHIGAN TONIGHT. WITH THE FETCH OVER WARM
WATER...LAKE EFFECT SNOW WILL SET UP AGAIN FOR TONIGHT. WE WILL
KEEP THE ADVISORY AND WARNING GOING OVERNIGHT. THESE PRODUCTS ARE
FOR THE TOTAL SNOW ACCUMULATION FROM LAST NIGHT TO TUESDAY
EVENING. THE LOW TEMPERATURE WILL REACH THE MIDDLE TEENS TONIGHT.
TUESDAY THROUGH MONDAY...THE LAKE EFFECT SNOW WILL CONTINUE
DURING THE DAY TUESDAY. BY TUESDAY EVENING THE BAND OF SNOW WILL
MOVE EAST. THE LOW TEMPERATURES FOR TUESDAY EVENING WILL BE IN THE
TEENS. A LARGE SURFACE RIDGE WILL LIE FROM TEXAS TO SOUTHERN
ONTARIO TUESDAY. BY WEDNESDAY MORNING THE GFS AND ECMWF MODELS
SHOW A SURFACE TROUGH FROM SOUTHERN ONTARIO TO OKLAHOMA. THIS
TROUGH HAS MORE MERIDIONAL AMPLITUDE ON THE GFS. WE EXPECT CLOUDY
SKIES IN OUR NORTHERN TWO THIRDS OF OUR FORECAST AREA AND PARTLY
CLOUDY SKIES IN OUR SOUTHERN THIRD OF THE FORECAST AREA. THE REST
OF THE WEEK LOOKS TO BE MAINLY DRY WEATHER. THE AIR WILL BECOME
COLDER THROUGH THE WEEK. THE HIGH TEMPERATURES WILL BE IN THE
TEENS AND LOWS IN THE SINGLE DIGITS BY SUNDAY. THE NEXT CHANCE OF
PRECIPITATION MAY BE SUNDAY AND MONDAY.
&&
.AVIATION...
1100 PM CST
06Z TAFORS...SHORT WAVE TROUGH HAS PASSED SOUTH OVER NORTHERN AND
INTO CENTRAL IL AT LATE EVENING ENDING SNOW ACROSS THE LOCAL
TERMINALS AND RAPIDLY SCATTERING OUT CLOUDS. EXPECT ONLY
SCATTERED PATCHES OF STRATOCU OVERNIGHT. WITH SHORT WAVE TROUGH
PASSING FURTHER SOUTH TOWARD THE LOWER OH VALLEY FLOW DOWN LAKE MI
HAS VEERED RESULTING IN ITS MIGRATION BACK ACROSS MID LAKE AND
CROSSING INTO IL WATERS PER RADAR AND SATELLITE. LATEST MODEL
OUTPUT CONTINUES TO FORECAST NNE-NE FLOW AT LAKE EFFECT CLOUD
PRODUCTION LEVEL AND EXPECT THE TAIL OF THE LES BAND TO CONTINUE
TO WESTWARD TO THE IL-IN STATE LINE BETWEEN 09Z AND 12Z. EDGE OF
LES MAY GET FAR ENOUGH WEST INTO SOUTHERN COOK CO FOR KMDW TO GET
CLIPPED BY SOME -SHSN 12Z-15Z. THEREAFTER...BACKING FLOW SHOVES
THE LES BAND BACK OFF OF THE IL SHORE AND EASTWARD PAST KGYY AND
EVENTUALLY INTO SOUTHWEST LOWER MI AND NORTH CENTRAL IN BY LATE
TUE AFTERNOON.
TRS
&&
.MARINE...
215 PM CST
A RELATIVELY QUIET PERIOD ANTICIPATED FOR LAKE MICHIGAN WITH
THE MAIN CONCERN ON FRIDAY AND POTENTIAL FOR SOME STRONG NORTHWEST
GUSTS BEHIND A COLD FRONT. A TROUGH OF LOW PRESSURE ACROSS
CENTRAL/NORTHERN SECTIONS OF LAKE MICHIGAN WILL TRACK SOUTHWARD
TONIGHT MAINTAINING NORTH WINDS. WINDS WILL BACK TO THE WEST
TUESDAY AFTERNOON INTO TUESDAY EVENING AS A SFC RIDGE AXIS BUILDS
ACROSS THE LOWER/MID MISSISSIPPI RIVER VALLEY. THIS RIDGE WILL
MOVE OFF TO THE EAST EARLY WEDNESDAY AS AN AREA OF LOW PRESSURE
TRACKS ACROSS HUDSON BAY. THIS COMBINATION WILL PRODUCE WEST
SOUTHWEST WINDS ON WEDNESDAY WITH GUSTS AROUND 20 KNOTS. WEST
WINDS WILL CONTINUE INTO THURSDAY AND THEN FOCUS WILL BE ON POTENTIAL
OF STRONGER NORTHWEST WINDS FOR FRIDAY AS A FAIRLY STRONG COLD
FRONT TRACKS SOUTHWARD ACROSS THE LAKE. GUSTS TO 30 KNOTS SEEM
REASONABLE AT THIS TIME...ALTHOUGH WOULD SUSPECT GUSTS TO GALES
NOT OUT OF THE QUESTION BASED ON EXPECTED STRENGTH OF COLD
ADVECTION. WINDS WILL SUBSIDE THIS WEEKEND AS A STRONG RIDGE OF
HIGH PRESSURE OUT OF SOUTHWEST CANADA BUILDS ACROSS THE WESTERN
GREAT LAKES.
MARSILI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 6 PM TUESDAY.
LAKE EFFECT SNOW ADVISORY...INZ001 UNTIL 6 PM TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 200359
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
959 PM CST MON JAN 19 2009
.DISCUSSION...
955 PM CST
UPDATE FOR OVERNIGHT AND TUESDAY...SHORT WAVE TROUGH HAS DROPPED
SOUTH OVER NORTHERN IL THIS EVENING AND IS NOW APPROACHING CENTRAL
IL. SNOW WILL BE QUICKLY WINDING DOWN ACROSS NORTH CENTRAL IL OVER
THE NEXT HR OR SO WITH JUST SOME LINGERING -SHSN THEREAFTER. AS
THE SHORT WAVE HAS MOVED SOUTHWARD TONIGHT THE LOW LEVEL FLOW IN
ITS WAKE HAS VEERED RESULTING IN THE LAKE EFFECT BAND DRIFTING
WESTWARD FROM NEAR THE MI SHORE BACK OUT TO MID LAKE. TAIL OF LES
BAND HAS ALREADY MOVED BACK TO EASTERN PORTER COUNTY AND WILL
CONTINUE TO SHIFT WEST OVERNIGHT AS LATEST MODEL OUTPUT SIMILAR
WITH A NNE-NE FLOW IN THE LAKE EFFECT PRODUCTION LAYER PUSHING THE
LES BAND TO THE IL-IN STATE LINE BY 12Z TUE. WESTERN EDGE OF LES
EXPECTED TO SPILL OVER INTO SOUTHERN COOK AND EASTERN PORTIONS OF
WILL AND KANKAKEE COUNTIES FOR TUE MORNING BEFORE FLOW STARTS TO
BACK AND THE TAIL OF THE LES MIGRATES BACK EASTWARD...EVENTUALLY
BACK TO SOUTHWEST LOWER MI AND NORTH CENTRAL IN BY LATE AFTERNOON.
TRS
PREVIOUS DISCUSSION
401 PM CST
LAKE EFFECT SNOW WILL DIMINISH A LITTLE THIS EVENING AND
THEN RETURN LATE TONIGHT. A LAKE EFFECT SNOW WARNING AND
ADVISORY ARE POSTED FOR NORTHWEST INDIANA THROUGH TUESDAY.
OCCASIONAL LIGHT SNOW WILL OCCUR THIS EVENING.
TONIGHT...A SHORT WAVE OVER WESTERN ONTARIO WILL MOVE SOUTH INTO
NORTHERN ILLINOIS BY 02 UTC. THIS WILL BRING ENOUGH LIFT FOR SOME
LIGHT SNOW. WE EXPECT LITTLE IF ANY ACCUMULATION WITH THIS SNOW.
WE USED THE ECMWF MODEL AND A LOCALLY RUN WRF MODEL. THIS SHORT
WAVE TROUGH WILL MOVE INTO THE LOWER OHIO VALLEY BY TUESDAY
MORNING. THE SATELLITE SHOWS THE CLOUDS MOVING INTO WESTERN
ILLINOIS RAPIDLY WITH THIS TROUGH. THE WIND WILL BE NORTHWEST TO
NORTH OVER LAKE MICHIGAN TONIGHT. WITH THE FETCH OVER WARM
WATER...LAKE EFFECT SNOW WILL SET UP AGAIN FOR TONIGHT. WE WILL
KEEP THE ADVISORY AND WARNING GOING OVERNIGHT. THESE PRODUCTS ARE
FOR THE TOTAL SNOW ACCUMULATION FROM LAST NIGHT TO TUESDAY
EVENING. THE LOW TEMPERATURE WILL REACH THE MIDDLE TEENS TONIGHT.
TUESDAY THROUGH MONDAY...THE LAKE EFFECT SNOW WILL CONTINUE
DURING THE DAY TUESDAY. BY TUESDAY EVENING THE BAND OF SNOW WILL
MOVE EAST. THE LOW TEMPERATURES FOR TUESDAY EVENING WILL BE IN THE
TEENS. A LARGE SURFACE RIDGE WILL LIE FROM TEXAS TO SOUTHERN
ONTARIO TUESDAY. BY WEDNESDAY MORNING THE GFS AND ECMWF MODELS
SHOW A SURFACE TROUGH FROM SOUTHERN ONTARIO TO OKLAHOMA. THIS
TROUGH HAS MORE MERIDIONAL AMPLITUDE ON THE GFS. WE EXPECT CLOUDY
SKIES IN OUR NORTHERN TWO THIRDS OF OUR FORECAST AREA AND PARTLY
CLOUDY SKIES IN OUR SOUTHERN THIRD OF THE FORECAST AREA. THE REST
OF THE WEEK LOOKS TO BE MAINLY DRY WEATHER. THE AIR WILL BECOME
COLDER THROUGH THE WEEK. THE HIGH TEMPERATURES WILL BE IN THE
TEENS AND LOWS IN THE SINGLE DIGITS BY SUNDAY. THE NEXT CHANCE OF
PRECIPITATION MAY BE SUNDAY AND MONDAY.
&&
.AVIATION...
619 PM CST
00Z TAFORS...SHORT WAVE HAS BEEN DROPPED FROM THE MN ARROWHEAD
AND WESTERN LAKE SUPERIOR SOUTHWARD DOWN WI DURING THE DAY. SHORT
WAVE TROUGH JUST NORTH OF THE WI STATE LINE AT 23Z. SNOW AHEAD OF
THE SHORT WAVE HAS BEEN QUICKLY SPREADING SOUTHWARD ACROSS
NORTHWEST AND NORTH CENTRAL IL. WITH MODELS CONTINUING SOUTHWARD
MOVEMENT OF THE SHORT WAVE TO OVER FAR SOUTHERN PORTIONS OF IN
AND IL BY 06Z THE MAIN AREA OF SNOW TO STAY OUT OF CHI AREA
TERMINALS AND TO BE EXITING THE KRFD AREA BY 02Z. OTHERWISE...ONLY
SOME FLURRIES AND SCATTERED -SHSN DURING THE EVENING WITH
LINGERING STRATOCU CLOUDS.
LAKE EFFECT SNOW BAND HAS SHIFTED EAST WITH BACKING FLOW PRECEDING
THE SHORT WAVE. RADAR AND SATELLITE SHOWS THAT WITH VEERING OF THE
LOW LEVEL FLOW WITH THE SHORT WAVE PASSAGE THAT THE BAND ACROSS
CENTRAL LAKE MICHIGAN STARTING TO MIGRATE BACK FROM NEAR THE MI
SHORELINE OUT TOWARD MID LAKE AGAIN. MODELS SHOWING A NNE-NE FLOW
AT LAKE EFFECT CLOUD PRODUCTION AND EXPECT TAIL OF BAND TO SHIFT
ACROSS KGYY AROUND 09Z AND TO THE IL-IN STATE LINE BY 12Z. EDGE OF
BAND MAY GET FAR ENOUGH WEST INTO SOUTHERN COOK CO FOR KMDW TO SEE
SOME LAKE EFFECT SHSN BETWEEN 12Z AND 15Z. THEREAFTER...BACKING
FLOW SHOVES THE LES BAND BACK OFF OF THE IL SHORE AND EASTWARD
PAST KGYY.
TRS
&&
.MARINE...
215 PM CST
A RELATIVELY QUIET PERIOD ANTICIPATED FOR LAKE MICHIGAN WITH
THE MAIN CONCERN ON FRIDAY AND POTENTIAL FOR SOME STRONG NORTHWEST
GUSTS BEHIND A COLD FRONT. A TROUGH OF LOW PRESSURE ACROSS
CENTRAL/NORTHERN SECTIONS OF LAKE MICHIGAN WILL TRACK SOUTHWARD
TONIGHT MAINTAINING NORTH WINDS. WINDS WILL BACK TO THE WEST
TUESDAY AFTERNOON INTO TUESDAY EVENING AS A SFC RIDGE AXIS BUILDS
ACROSS THE LOWER/MID MISSISSIPPI RIVER VALLEY. THIS RIDGE WILL
MOVE OFF TO THE EAST EARLY WEDNESDAY AS AN AREA OF LOW PRESSURE
TRACKS ACROSS HUDSON BAY. THIS COMBINATION WILL PRODUCE WEST
SOUTHWEST WINDS ON WEDNESDAY WITH GUSTS AROUND 20 KNOTS. WEST
WINDS WILL CONTINUE INTO THURSDAY AND THEN FOCUS WILL BE ON POTENTIAL
OF STRONGER NORTHWEST WINDS FOR FRIDAY AS A FAIRLY STRONG COLD
FRONT TRACKS SOUTHWARD ACROSS THE LAKE. GUSTS TO 30 KNOTS SEEM
REASONABLE AT THIS TIME...ALTHOUGH WOULD SUSPECT GUSTS TO GALES
NOT OUT OF THE QUESTION BASED ON EXPECTED STRENGTH OF COLD
ADVECTION. WINDS WILL SUBSIDE THIS WEEKEND AS A STRONG RIDGE OF
HIGH PRESSURE OUT OF SOUTHWEST CANADA BUILDS ACROSS THE WESTERN
GREAT LAKES.
MARSILI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 6 PM TUESDAY.
LAKE EFFECT SNOW ADVISORY...INZ001 UNTIL 6 PM TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 200021
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
621 PM CST MON JAN 19 2009
.DISCUSSION...
401 PM CST
LAKE EFFECT SNOW WILL DIMINISH A LITTLE THIS EVENING AND
THEN RETURN LATE TONIGHT. A LAKE EFFECT SNOW WARNING AND
ADVISORY ARE POSTED FOR NORTHWEST INDIANA THROUGH TUESDAY.
OCCASIONAL LIGHT SNOW WILL OCCUR THIS EVENING.
TONIGHT...A SHORT WAVE OVER WESTERN ONTARIO WILL MOVE SOUTH INTO
NORTHERN ILLINOIS BY 02 UTC. THIS WILL BRING ENOUGH LIFT FOR SOME
LIGHT SNOW. WE EXPECT LITTLE IF ANY ACCUMULATION WITH THIS SNOW.
WE USED THE ECMWF MODEL AND A LOCALLY RUN WRF MODEL. THIS SHORT
WAVE TROUGH WILL MOVE INTO THE LOWER OHIO VALLEY BY TUESDAY
MORNING. THE SATELLITE SHOWS THE CLOUDS MOVING INTO WESTERN
ILLINOIS RAPIDLY WITH THIS TROUGH. THE WIND WILL BE NORTHWEST TO
NORTH OVER LAKE MICHIGAN TONIGHT. WITH THE FETCH OVER WARM
WATER...LAKE EFFECT SNOW WILL SET UP AGAIN FOR TONIGHT. WE WILL
KEEP THE ADVISORY AND WARNING GOING OVERNIGHT. THESE PRODUCTS ARE
FOR THE TOTAL SNOW ACCUMULATION FROM LAST NIGHT TO TUESDAY
EVENING. THE LOW TEMPERATURE WILL REACH THE MIDDLE TEENS TONIGHT.
TUESDAY THROUGH MONDAY...THE LAKE EFFECT SNOW WILL CONTINUE
DURING THE DAY TUESDAY. BY TUESDAY EVENING THE BAND OF SNOW WILL
MOVE EAST. THE LOW TEMPERATURES FOR TUESDAY EVENING WILL BE IN THE
TEENS. A LARGE SURFACE RIDGE WILL LIE FROM TEXAS TO SOUTHERN
ONTARIO TUESDAY. BY WEDNESDAY MORNING THE GFS AND ECMWF MODELS
SHOW A SURFACE TROUGH FROM SOUTHERN ONTARIO TO OKLAHOMA. THIS
TROUGH HAS MORE MERIDIONAL AMPLITUDE ON THE GFS. WE EXPECT CLOUDY
SKIES IN OUR NORTHERN TWO THIRDS OF OUR FORECAST AREA AND PARTLY
CLOUDY SKIES IN OUR SOUTHERN THIRD OF THE FORECAST AREA. THE REST
OF THE WEEK LOOKS TO BE MAINLY DRY WEATHER. THE AIR WILL BECOME
COLDER THROUGH THE WEEK. THE HIGH TEMPERATURES WILL BE IN THE
TEENS AND LOWS IN THE SINGLE DIGITS BY SUNDAY. THE NEXT CHANCE OF
PRECIPITATION MAY BE SUNDAY AND MONDAY.
&&
.AVIATION...
619 PM CST
00Z TAFORS...SHORT WAVE HAS BEEN DROPPED FROM THE MN ARROWHEAD
AND WESTERN LAKE SUPERIOR SOUTHWARD DOWN WI DURING THE DAY. SHORT
WAVE TROUGH JUST NORTH OF THE WI STATE LINE AT 23Z. SNOW AHEAD OF
THE SHORT WAVE HAS BEEN QUICKLY SPREADING SOUTHWARD ACROSS
NORTHWEST AND NORTH CENTRAL IL. WITH MODELS CONTINUING SOUTHWARD
MOVEMENT OF THE SHORT WAVE TO OVER FAR SOUTHERN PORTIONS OF IN
AND IL BY 06Z THE MAIN AREA OF SNOW TO STAY OUT OF CHI AREA
TERMINALS AND TO BE EXITING THE KRFD AREA BY 02Z. OTHERWISE...ONLY
SOME FLURRIES AND SCATTERED -SHSN DURING THE EVENING WITH
LINGERING STRATOCU CLOUDS.
LAKE EFFECT SNOW BAND HAS SHIFTED EAST WITH BACKING FLOW PRECEDING
THE SHORT WAVE. RADAR AND SATELLITE SHOWS THAT WITH VEERING OF THE
LOW LEVEL FLOW WITH THE SHORT WAVE PASSAGE THAT THE BAND ACROSS
CENTRAL LAKE MICHIGAN STARTING TO MIGRATE BACK FROM NEAR THE MI
SHORELINE OUT TOWARD MID LAKE AGAIN. MODELS SHOWING A NNE-NE FLOW
AT LAKE EFFECT CLOUD PRODUCTION AND EXPECT TAIL OF BAND TO SHIFT
ACROSS KGYY AROUND 09Z AND TO THE IL-IN STATE LINE BY 12Z. EDGE OF
BAND MAY GET FAR ENOUGH WEST INTO SOUTHERN COOK CO FOR KMDW TO SEE
SOME LAKE EFFECT SHSN BETWEEN 12Z AND 15Z. THEREAFTER...BACKING
FLOW SHOVES THE LES BAND BACK OFF OF THE IL SHORE AND EASTWARD
PAST KGYY.
TRS
&&
.MARINE...
215 PM CST
A RELATIVELY QUIET PERIOD ANTICIPATED FOR LAKE MICHIGAN WITH
THE MAIN CONCERN ON FRIDAY AND POTENTIAL FOR SOME STRONG NORTHWEST
GUSTS BEHIND A COLD FRONT. A TROUGH OF LOW PRESSURE ACROSS
CENTRAL/NORTHERN SECTIONS OF LAKE MICHIGAN WILL TRACK SOUTHWARD
TONIGHT MAINTAINING NORTH WINDS. WINDS WILL BACK TO THE WEST
TUESDAY AFTERNOON INTO TUESDAY EVENING AS A SFC RIDGE AXIS BUILDS
ACROSS THE LOWER/MID MISSISSIPPI RIVER VALLEY. THIS RIDGE WILL
MOVE OFF TO THE EAST EARLY WEDNESDAY AS AN AREA OF LOW PRESSURE
TRACKS ACROSS HUDSON BAY. THIS COMBINATION WILL PRODUCE WEST
SOUTHWEST WINDS ON WEDNESDAY WITH GUSTS AROUND 20 KNOTS. WEST
WINDS WILL CONTINUE INTO THURSDAY AND THEN FOCUS WILL BE ON POTENTIAL
OF STRONGER NORTHWEST WINDS FOR FRIDAY AS A FAIRLY STRONG COLD
FRONT TRACKS SOUTHWARD ACROSS THE LAKE. GUSTS TO 30 KNOTS SEEM
REASONABLE AT THIS TIME...ALTHOUGH WOULD SUSPECT GUSTS TO GALES
NOT OUT OF THE QUESTION BASED ON EXPECTED STRENGTH OF COLD
ADVECTION. WINDS WILL SUBSIDE THIS WEEKEND AS A STRONG RIDGE OF
HIGH PRESSURE OUT OF SOUTHWEST CANADA BUILDS ACROSS THE WESTERN
GREAT LAKES.
MARSILI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 6 PM TUESDAY.
LAKE EFFECT SNOW ADVISORY...INZ001...MIDNIGHT TUESDAY TO 6 PM
TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 192206
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
406 PM CST MON JAN 19 2009
.DISCUSSION...
401 PM CST
LAKE EFFECT SNOW WILL DIMINISH A LITTLE THIS EVENING AND
THEN RETURN LATE TONIGHT. A LAKE EFFECT SNOW WARNING AND
ADVISORY ARE POSTED FOR NORTHWEST INDIANA THROUGH TUESDAY.
OCCASIONAL LIGHT SNOW WILL OCCUR THIS EVENING.
TONIGHT...A SHORT WAVE OVER WESTERN ONTARIO WILL MOVE SOUTH INTO
NORTHERN ILLINOIS BY 02 UTC. THIS WILL BRING ENOUGH LIFT FOR SOME
LIGHT SNOW. WE EXPECT LITTLE IF ANY ACCUMULATION WITH THIS SNOW.
WE USED THE ECMWF MODEL AND A LOCALLY RUN WRF MODEL. THIS SHORT
WAVE TROUGH WILL MOVE INTO THE LOWER OHIO VALLEY BY TUESDAY
MORNING. THE SATELLITE SHOWS THE CLOUDS MOVING INTO WESTERN
ILLINOIS RAPIDLY WITH THIS TROUGH. THE WIND WILL BE NORTHWEST TO
NORTH OVER LAKE MICHIGAN TONIGHT. WITH THE FETCH OVER WARM
WATER...LAKE EFFECT SNOW WILL SET UP AGAIN FOR TONIGHT. WE WILL
KEEP THE ADVISORY AND WARNING GOING OVERNIGHT. THESE PRODUCTS ARE
FOR THE TOTAL SNOW ACCUMULATION FROM LAST NIGHT TO TUESDAY
EVENING. THE LOW TEMPERATURE WILL REACH THE MIDDLE TEENS TONIGHT.
TUESDAY THROUGH MONDAY...THE LAKE EFFECT SNOW WILL CONTINUE
DURING THE DAY TUESDAY. BY TUESDAY EVENING THE BAND OF SNOW WILL
MOVE EAST. THE LOW TEMPERATURES FOR TUESDAY EVENING WILL BE IN THE
TEENS. A LARGE SURFACE RIDGE WILL LIE FROM TEXAS TO SOUTHERN
ONTARIO TUESDAY. BY WEDNESDAY MORNING THE GFS AND ECMWF MODELS
SHOW A SURFACE TROUGH FROM SOUTHERN ONTARIO TO OKLAHOMA. THIS
TROUGH HAS MORE MERIDIONAL AMPLITUDE ON THE GFS. WE EXPECT CLOUDY
SKIES IN OUR NORTHERN TWO THIRDS OF OUR FORECAST AREA AND PARTLY
CLOUDY SKIES IN OUR SOUTHERN THIRD OF THE FORECAST AREA. THE REST
OF THE WEEK LOOKS TO BE MAINLY DRY WEATHER. THE AIR WILL BECOME
COLDER THROUGH THE WEEK. THE HIGH TEMPERATURES WILL BE IN THE
TEENS AND LOWS IN THE SINGLE DIGITS BY SUNDAY. THE NEXT CHANCE OF
PRECIPITATION MAY BE SUNDAY AND MONDAY.
&&
.AVIATION...
1205 PM CST
1800 UTC TAFS...MAIN AVIATION FORECAST CONCERNS WILL CONTINUE TO
BE LAKE EFFECT SNOW ACROSS NORTHERN INDIANA...AND THEN INCREASING
LIGHT SNOW CHANCES TOWARD EVENING WITH A DISTURBANCE APPROACHING
IN NORTHWEST FLOW.
RADAR/SATELLITE IMAGERY CONTINUES TO SUGGEST MAIN LAKE EFFECT SNOW
BAND TO AFFECT AREAS EAST OF GYY INTO THIS AFTERNOON. DID CONFINE
MENTION OF SNOW AT GYY TO THE 18Z-19Z TIME PERIOD WHEN SOME LIGHT
SNOW SHOWERS WILL STILL BE POSSIBLE WITH SOME MVFR CIGS AROUND
1500 FT. OTHERWISE...REMAINDER OF TERMINALS SHOULD BE DRY THROUGH
THE AFTERNOON HOURS. FOCUS FOR LATE AFTERNOON INTO EARLY THIS
EVENING WILL TURN TO UPPER LEVEL VORT MAX DIGGING SOUTHWARD ACROSS
EAST CENTRAL MINNESOTA. THE STRONGEST UPPER FORCING WITH THIS WAVE
SHOULD AFFECT MAINLY NORTHWEST ILLINOIS BASED ON STRAIGHT
SOUTHWARD TRACK...BUT EXPECTING SOME SCATTERED SNOW SHOWERS TO
AFFECT MOST OF THE AREA THIS EVENING. HAVE MAINTAINED IDEA OF MVFR
VSBYS WITH THE SNOW SHOWERS THIS EVENING...AND ONLY INCLUSION OF
IFR VSBYS AT THIS TIME FOR THE RFD AREA IN CLOSER PROXIMITY TO THE
MAIN VORT MAX. MID LEVEL CLOUDS AHEAD OF THIS VORT WILL OVERSPREAD
TERMINALS THIS AFTERNOON...WITH MVFR CIGS LIKELY BY EARLY THIS
EVENING. WINDS WILL REMAIN NORTHWEST AROUND 10 KNOTS THROUGH THE
EVENING HOURS.
SNOW CHANCES SHOULD DIMINISH AFTER MIDNIGHT AS THIS VORT MAX
SLIDES SOUTHWARD...BUT LOW LEVEL WINDS WILL LIKELY BACK SLIGHTLY
LATE EVENING WHICH SHOULD ALLOW LAKE EFFECT SNOW BAND TO SHIFT
BACK WESTWARD ACROSS NORTHWEST INDIANA AND EVENTUALLY INTO FAR
NORTHEAST ILLINOIS. HAVE CONTINUED SNOW SHOWER MENTION THROUGH THE
REMAINDER OF THE FORECAST PERIOD AT GYY. CONFIDENCE IN LAKE EFFECT
SNOW POTENTIAL AS FAR WEST AS MDW IS SOMEWHAT LOWER AND CURRENT
TAF REFLECTS SNOW MORE WITH THE SYNOPTIC WAVE AS OPPOSED TO LAKE
EFFECT...BUT FUTURE FORECASTS WILL LIKELY NEED TO EXAMINE
POTENTIAL FOR LAKE EFFECT SNOW SHOWERS AFFECTING MDW EARLY TUESDAY
MORNING.
MARSILI
&&
.MARINE...
215 PM CST
A RELATIVELY QUIET PERIOD ANTICIPATED FOR LAKE MICHIGAN WITH
THE MAIN CONCERN ON FRIDAY AND POTENTIAL FOR SOME STRONG NORTHWEST
GUSTS BEHIND A COLD FRONT. A TROUGH OF LOW PRESSURE ACROSS
CENTRAL/NORTHERN SECTIONS OF LAKE MICHIGAN WILL TRACK SOUTHWARD
TONIGHT MAINTAINING NORTH WINDS. WINDS WILL BACK TO THE WEST
TUESDAY AFTERNOON INTO TUESDAY EVENING AS A SFC RIDGE AXIS BUILDS
ACROSS THE LOWER/MID MISSISSIPPI RIVER VALLEY. THIS RIDGE WILL
MOVE OFF TO THE EAST EARLY WEDNESDAY AS AN AREA OF LOW PRESSURE
TRACKS ACROSS HUDSON BAY. THIS COMBINATION WILL PRODUCE WEST
SOUTHWEST WINDS ON WEDNESDAY WITH GUSTS AROUND 20 KNOTS. WEST
WINDS WILL CONTINUE INTO THURSDAY AND THEN FOCUS WILL BE ON POTENTIAL
OF STRONGER NORTHWEST WINDS FOR FRIDAY AS A FAIRLY STRONG COLD
FRONT TRACKS SOUTHWARD ACROSS THE LAKE. GUSTS TO 30 KNOTS SEEM
REASONABLE AT THIS TIME...ALTHOUGH WOULD SUSPECT GUSTS TO GALES
NOT OUT OF THE QUESTION BASED ON EXPECTED STRENGTH OF COLD
ADVECTION. WINDS WILL SUBSIDE THIS WEEKEND AS A STRONG RIDGE OF
HIGH PRESSURE OUT OF SOUTHWEST CANADA BUILDS ACROSS THE WESTERN
GREAT LAKES.
MARSILI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 6 PM TUESDAY.
LAKE EFFECT SNOW ADVISORY...INZ001...MIDNIGHT TUESDAY TO 6 PM
TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 192016
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
216 PM CST MON JAN 19 2009
.DISCUSSION...
925 AM CST
HAVE UPGRADED THE LAKE EFFECT SNOW ADVISORY FOR PORTER COUNTY TO A
WARNING. SPOTTER REPORTS INDICATE SNOW ACCUMULATIONS OF 3 TO 6
INCHES ACROSS NORTHERN PORTER COUNTY WITH INTEGRITY OF BANDING
CONTINUING TO BE MAINTAINED PER RADAR IMAGERY/SATELLITE. RADAR
ALSO SUGGEST POSSIBLE DEVELOPMENT OF MESOVORTICES OVER SOUTHERN
LAKE MICHIGAN THAT WILL LIKELY ENHANCE SNOWFALL AMOUNTS ACROSS
PORTER COUNTY. HAVE MENTIONED ACCUMS OF 2 TO 4 INCHES FOR REST OF
TODAY...ALTHOUGH SOME LOCALLY HIGHER AMOUNTS ARE POSSIBLE. MAIN
LAKE EFFECT BAND IS EXPECTED TO SHIFT EAST THIS AFTERNOON...BUT
THEN RETURN BACK WEST LATER TONIGHT AS UPPER LEVEL SHORT WAVE
DROPS INTO THE MID MS RVR VALLEY ALLOWING WINDS TO BACK. HAVE
ALSO INCLUDED LAKE COUNTY INDIANA IN LAKE EFFECT SNOW ADVISORY
WITH 3 TO 5 INCHES OF SNOW EXPECTED FROM LATE TONIGHT INTO TUESDAY
AFTERNOON. SOME CONCERN FOR FAR SOUTHERN COOK COUNTY BUT WILL
MAINTAIN ACCUMS BELOW ADVISORY LEVEL AT THIS TIME.
&&
.PREV DISCUSSION...
302 AM CST
POST TROF VEERING OF WINDS ON SCHEDULE WITH PUSHING LAKE PLUMES SWD
INTO NW INDIANA. BELIEVE A FEW INCHES IN LAKE COUNTY WILL SUFFICE
BEFORE WINDS BACK AGAIN TO THE NW. ALREADY PLUME APPEARS TO BE
SHIFTING EAST MID LAKE OFF OF MKE. WILL PROBLY GO AHEAD AND KEEP
ADVISORY FOR 3-5 INCHES GOING FOR PORTER COUNTY TODAY...ESP FOR THAT
NORTHEAST CORNER NEAR CHESTERTON. WINDS BACK THIS AFTN TO A POINT
WHERE LAKE EFFECT SNOWS SHIFT EAST OF PORTER COUNTY.
WINDS HAVE ALSO VEERED BEHIND A TROF SWINGING AROUND AN UPPER
VORTEX LOCATED NEAR HUDSON BAY. ANOTHER JET VISUALIZED ON WATER
VAPOR IMAGERY DIVING SOUTH THRU WESTERN ONTARIO THIS MRNG. THIS
JET DEEPENS ANOTHER WAVE AROUND THIS VORTEX THIS AFTN AND SWINGS
ANOTHER UPR TROF DOWN THE LAKE BY EVENING. THE SHORT OF IT IS THAT
WE ARE LIKELY IN FOR A REPEAT PERFORMANCE OF LAKE EFFECT TONIGHT
AS WINDS VEER AGAIN MORE NORTHEASTERLY DOWN THE LAKE. LIFT AROUND
THE LFQ OF THIS JET WILL DEVELOP SNOW SHOWERS IN NW ILLINOIS...WITH
PSBL FLURRIES THE REST OF NRN IL TONIGHT. BUT THE MAIN FOCUS WILL
BE THE CONVECTIVE PLUMES SHIFTING WEST INTO SRN COOK COUNTY AND NW
INDIANA AGAIN. MODEL SOUNDINGS STILL INDICATE THAT THE HEIGHT OF
THE INVERSION BEGINS AROUND 800 MB WHICH LIMITS THE DEEPENING OF
MSTR AND IN EFFECT LESSENS THE IMPACT OF THESE LAKE EFFECT
PLUMES. SO AT BEST LOOKING ONLY AT ANOTHER ADVISORY ISSUANCE
MONDAY NIGHT INTO TUESDAY FOR 3 TO 5 INCHES FOR LAKE AND PORTER
COUNTIES WITH PSBLY 2-3 INCHES FOR SERN COOK COUNTY. WILL LET DAY
SHIFT MAKE THIS CALL SINCE ALREADY HAVE A LAKE EFFECT SNOW
ADVISORY IN EFFECT FOR THE SAME AREA. THIS CURRENT ADVISORY MAY
NEED TO BE CANCELLED EARLY TODAY.
WINDS BACK AGAIN TO THE NW TUESDAY MRNG WHILE THE MAIN POLAR VORTEX
NEAR HUDSON BAY KICKS OUT TO THE EAST. UPR FLOW FLATTENS A LITTLE
MORE TO NW FLOW ON WED AND THURS TO ALMOST STRAIGHT EAST WEST OR
ZONAL FLOW ON FRIDAY. THIS DRY PERIOD FROM TUES NIGHT THRU FRIDAY
WITH TEMPS WARMING DURING THE DAY INTO THE MID 20S TO LOWER 30S WILL
HELP GET RID OF SOME OF THIS ACCUMULATED SNOW. WEAK TROFFING SLIPS
ACROSS THE REGION FRI NGT INTO SATURDAY AND LOWERS HIGH AND LOW
TEMPS INTO THE TEENS AND SINGLE DIGITS THRU THE WEEKEND. SOME LIGHT
OVERRUNNING SNOWS MAY BE PSBL OVER THE WEEKEND AS WELL BUT WILL LEAVE
DRY IN GOING ALONG WITH CURRENT FCST PACKAGE.
RLB
&&
.AVIATION...
1205 PM CST
1800 UTC TAFS...MAIN AVIATION FORECAST CONCERNS WILL CONTINUE TO
BE LAKE EFFECT SNOW ACROSS NORTHERN INDIANA...AND THEN INCREASING
LIGHT SNOW CHANCES TOWARD EVENING WITH A DISTURBANCE APPROACHING
IN NORTHWEST FLOW.
RADAR/SATELLITE IMAGERY CONTINUES TO SUGGEST MAIN LAKE EFFECT SNOW
BAND TO AFFECT AREAS EAST OF GYY INTO THIS AFTERNOON. DID CONFINE
MENTION OF SNOW AT GYY TO THE 18Z-19Z TIME PERIOD WHEN SOME LIGHT
SNOW SHOWERS WILL STILL BE POSSIBLE WITH SOME MVFR CIGS AROUND
1500 FT. OTHERWISE...REMAINDER OF TERMINALS SHOULD BE DRY THROUGH
THE AFTERNOON HOURS. FOCUS FOR LATE AFTERNOON INTO EARLY THIS
EVENING WILL TURN TO UPPER LEVEL VORT MAX DIGGING SOUTHWARD ACROSS
EAST CENTRAL MINNESOTA. THE STRONGEST UPPER FORCING WITH THIS WAVE
SHOULD AFFECT MAINLY NORTHWEST ILLINOIS BASED ON STRAIGHT
SOUTHWARD TRACK...BUT EXPECTING SOME SCATTERED SNOW SHOWERS TO
AFFECT MOST OF THE AREA THIS EVENING. HAVE MAINTAINED IDEA OF MVFR
VSBYS WITH THE SNOW SHOWERS THIS EVENING...AND ONLY INCLUSION OF
IFR VSBYS AT THIS TIME FOR THE RFD AREA IN CLOSER PROXIMITY TO THE
MAIN VORT MAX. MID LEVEL CLOUDS AHEAD OF THIS VORT WILL OVERSPREAD
TERMINALS THIS AFTERNOON...WITH MVFR CIGS LIKELY BY EARLY THIS
EVENING. WINDS WILL REMAIN NORTHWEST AROUND 10 KNOTS THROUGH THE
EVENING HOURS.
SNOW CHANCES SHOULD DIMINISH AFTER MIDNIGHT AS THIS VORT MAX
SLIDES SOUTHWARD...BUT LOW LEVEL WINDS WILL LIKELY BACK SLIGHTLY
LATE EVENING WHICH SHOULD ALLOW LAKE EFFECT SNOW BAND TO SHIFT
BACK WESTWARD ACROSS NORTHWEST INDIANA AND EVENTUALLY INTO FAR
NORTHEAST ILLINOIS. HAVE CONTINUED SNOW SHOWER MENTION THROUGH THE
REMAINDER OF THE FORECAST PERIOD AT GYY. CONFIDENCE IN LAKE EFFECT
SNOW POTENTIAL AS FAR WEST AS MDW IS SOMEWHAT LOWER AND CURRENT
TAF REFLECTS SNOW MORE WITH THE SYNOPTIC WAVE AS OPPOSED TO LAKE
EFFECT...BUT FUTURE FORECASTS WILL LIKELY NEED TO EXAMINE
POTENTIAL FOR LAKE EFFECT SNOW SHOWERS AFFECTING MDW EARLY TUESDAY
MORNING.
MARSILI
&&
.MARINE...
215 PM CST
A RELATIVELY QUIET PERIOD ANTICIPATED FOR LAKE MICHIGAN WITH
THE MAIN CONCERN ON FRIDAY AND POTENTIAL FOR SOME STRONG NORTHWEST
GUSTS BEHIND A COLD FRONT. A TROUGH OF LOW PRESSURE ACROSS
CENTRAL/NORTHERN SECTIONS OF LAKE MICHIGAN WILL TRACK SOUTHWARD
TONIGHT MAINTAINING NORTH WINDS. WINDS WILL BACK TO THE WEST
TUESDAY AFTERNOON INTO TUESDAY EVENING AS A SFC RIDGE AXIS BUILDS
ACROSS THE LOWER/MID MISSISSIPPI RIVER VALLEY. THIS RIDGE WILL
MOVE OFF TO THE EAST EARLY WEDNESDAY AS AN AREA OF LOW PRESSURE
TRACKS ACROSS HUDSON BAY. THIS COMBINATION WILL PRODUCE WEST
SOUTHWEST WINDS ON WEDNESDAY WITH GUSTS AROUND 20 KNOTS. WEST
WINDS WILL CONTINUE INTO THURSDAY AND THEN FOCUS WILL BE ON POTENTIAL
OF STRONGER NORTHWEST WINDS FOR FRIDAY AS A FAIRLY STRONG COLD
FRONT TRACKS SOUTHWARD ACROSS THE LAKE. GUSTS TO 30 KNOTS SEEM
REASONABLE AT THIS TIME...ALTHOUGH WOULD SUSPECT GUSTS TO GALES
NOT OUT OF THE QUESTION BASED ON EXPECTED STRENGTH OF COLD
ADVECTION. WINDS WILL SUBSIDE THIS WEEKEND AS A STRONG RIDGE OF
HIGH PRESSURE OUT OF SOUTHWEST CANADA BUILDS ACROSS THE WESTERN
GREAT LAKES.
MARSILI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 6 PM TUESDAY.
LAKE EFFECT SNOW ADVISORY...INZ001...MIDNIGHT TUESDAY TO 6 PM
TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 191806
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1206 PM CST MON JAN 19 2009
.DISCUSSION...
925 AM CST
HAVE UPGRADED THE LAKE EFFECT SNOW ADVISORY FOR PORTER COUNTY TO A
WARNING. SPOTTER REPORTS INDICATE SNOW ACCUMULATIONS OF 3 TO 6
INCHES ACROSS NORTHERN PORTER COUNTY WITH INTEGRITY OF BANDING
CONTINUING TO BE MAINTAINED PER RADAR IMAGERY/SATELLITE. RADAR
ALSO SUGGEST POSSIBLE DEVELOPMENT OF MESOVORTICES OVER SOUTHERN
LAKE MICHIGAN THAT WILL LIKELY ENHANCE SNOWFALL AMOUNTS ACROSS
PORTER COUNTY. HAVE MENTIONED ACCUMS OF 2 TO 4 INCHES FOR REST OF
TODAY...ALTHOUGH SOME LOCALLY HIGHER AMOUNTS ARE POSSIBLE. MAIN
LAKE EFFECT BAND IS EXPECTED TO SHIFT EAST THIS AFTERNOON...BUT
THEN RETURN BACK WEST LATER TONIGHT AS UPPER LEVEL SHORT WAVE
DROPS INTO THE MID MS RVR VALLEY ALLOWING WINDS TO BACK. HAVE
ALSO INCLUDED LAKE COUNTY INDIANA IN LAKE EFFECT SNOW ADVISORY
WITH 3 TO 5 INCHES OF SNOW EXPECTED FROM LATE TONIGHT INTO TUESDAY
AFTERNOON. SOME CONCERN FOR FAR SOUTHERN COOK COUNTY BUT WILL
MAINTAIN ACCUMS BELOW ADVISORY LEVEL AT THIS TIME.
&&
.AVIATION...
1205 PM CST
1800 UTC TAFS...MAIN AVIATION FORECAST CONCERNS WILL CONTINUE TO
BE LAKE EFFECT SNOW ACROSS NORTHERN INDIANA...AND THEN INCREASING
LIGHT SNOW CHANCES TOWARD EVENING WITH A DISTURBANCE APPROACHING
IN NORTHWEST FLOW.
RADAR/SATELLITE IMAGERY CONTINUES TO SUGGEST MAIN LAKE EFFECT SNOW
BAND TO AFFECT AREAS EAST OF GYY INTO THIS AFTERNOON. DID CONFINE
MENTION OF SNOW AT GYY TO THE 18Z-19Z TIME PERIOD WHEN SOME LIGHT
SNOW SHOWERS WILL STILL BE POSSIBLE WITH SOME MVFR CIGS AROUND
1500 FT. OTHERWISE...REMAINDER OF TERMINALS SHOULD BE DRY THROUGH
THE AFTERNOON HOURS. FOCUS FOR LATE AFTERNOON INTO EARLY THIS
EVENING WILL TURN TO UPPER LEVEL VORT MAX DIGGING SOUTHWARD ACROSS
EAST CENTRAL MINNESOTA. THE STRONGEST UPPER FORCING WITH THIS WAVE
SHOULD AFFECT MAINLY NORTHWEST ILLINOIS BASED ON STRAIGHT
SOUTHWARD TRACK...BUT EXPECTING SOME SCATTERED SNOW SHOWERS TO
AFFECT MOST OF THE AREA THIS EVENING. HAVE MAINTAINED IDEA OF MVFR
VSBYS WITH THE SNOW SHOWERS THIS EVENING...AND ONLY INCLUSION OF
IFR VSBYS AT THIS TIME FOR THE RFD AREA IN CLOSER PROXIMITY TO THE
MAIN VORT MAX. MID LEVEL CLOUDS AHEAD OF THIS VORT WILL OVERSPREAD
TERMINALS THIS AFTERNOON...WITH MVFR CIGS LIKELY BY EARLY THIS
EVENING. WINDS WILL REMAIN NORTHWEST AROUND 10 KNOTS THROUGH THE
EVENING HOURS.
SNOW CHANCES SHOULD DIMINISH AFTER MIDNIGHT AS THIS VORT MAX
SLIDES SOUTHWARD...BUT LOW LEVEL WINDS WILL LIKELY BACK SLIGHTLY
LATE EVENING WHICH SHOULD ALLOW LAKE EFFECT SNOW BAND TO SHIFT
BACK WESTWARD ACROSS NORTHWEST INDIANA AND EVENTUALLY INTO FAR
NORTHEAST ILLINOIS. HAVE CONTINUED SNOW SHOWER MENTION THROUGH THE
REMAINDER OF THE FORECAST PERIOD AT GYY. CONFIDENCE IN LAKE EFFECT
SNOW POTENTIAL AS FAR WEST AS MDW IS SOMEWHAT LOWER AND CURRENT
TAF REFLECTS SNOW MORE WITH THE SYNOPTIC WAVE AS OPPOSED TO LAKE
EFFECT...BUT FUTURE FORECASTS WILL LIKELY NEED TO EXAMINE
POTENTIAL FOR LAKE EFFECT SNOW SHOWERS AFFECTING MDW EARLY TUESDAY
MORNING.
MARSILI
&&
.PREV DISCUSSION...
302 AM CST
POST TROF VEERING OF WINDS ON SCHEDULE WITH PUSHING LAKE PLUMES SWD
INTO NW INDIANA. BELIEVE A FEW INCHES IN LAKE COUNTY WILL SUFFICE
BEFORE WINDS BACK AGAIN TO THE NW. ALREADY PLUME APPEARS TO BE
SHIFTING EAST MID LAKE OFF OF MKE. WILL PROBLY GO AHEAD AND KEEP
ADVISORY FOR 3-5 INCHES GOING FOR PORTER COUNTY TODAY...ESP FOR THAT
NORTHEAST CORNER NEAR CHESTERTON. WINDS BACK THIS AFTN TO A POINT
WHERE LAKE EFFECT SNOWS SHIFT EAST OF PORTER COUNTY.
WINDS HAVE ALSO VEERED BEHIND A TROF SWINGING AROUND AN UPPER
VORTEX LOCATED NEAR HUDSON BAY. ANOTHER JET VISUALIZED ON WATER
VAPOR IMAGERY DIVING SOUTH THRU WESTERN ONTARIO THIS MRNG. THIS
JET DEEPENS ANOTHER WAVE AROUND THIS VORTEX THIS AFTN AND SWINGS
ANOTHER UPR TROF DOWN THE LAKE BY EVENING. THE SHORT OF IT IS THAT
WE ARE LIKELY IN FOR A REPEAT PERFORMANCE OF LAKE EFFECT TONIGHT
AS WINDS VEER AGAIN MORE NORTHEASTERLY DOWN THE LAKE. LIFT AROUND
THE LFQ OF THIS JET WILL DEVELOP SNOW SHOWERS IN NW ILLINOIS...WITH
PSBL FLURRIES THE REST OF NRN IL TONIGHT. BUT THE MAIN FOCUS WILL
BE THE CONVECTIVE PLUMES SHIFTING WEST INTO SRN COOK COUNTY AND NW
INDIANA AGAIN. MODEL SOUNDINGS STILL INDICATE THAT THE HEIGHT OF
THE INVERSION BEGINS AROUND 800 MB WHICH LIMITS THE DEEPENING OF
MSTR AND IN EFFECT LESSENS THE IMPACT OF THESE LAKE EFFECT
PLUMES. SO AT BEST LOOKING ONLY AT ANOTHER ADVISORY ISSUANCE
MONDAY NIGHT INTO TUESDAY FOR 3 TO 5 INCHES FOR LAKE AND PORTER
COUNTIES WITH PSBLY 2-3 INCHES FOR SERN COOK COUNTY. WILL LET DAY
SHIFT MAKE THIS CALL SINCE ALREADY HAVE A LAKE EFFECT SNOW
ADVISORY IN EFFECT FOR THE SAME AREA. THIS CURRENT ADVISORY MAY
NEED TO BE CANCELLED EARLY TODAY.
WINDS BACK AGAIN TO THE NW TUESDAY MRNG WHILE THE MAIN POLAR VORTEX
NEAR HUDSON BAY KICKS OUT TO THE EAST. UPR FLOW FLATTENS A LITTLE
MORE TO NW FLOW ON WED AND THURS TO ALMOST STRAIGHT EAST WEST OR
ZONAL FLOW ON FRIDAY. THIS DRY PERIOD FROM TUES NIGHT THRU FRIDAY
WITH TEMPS WARMING DURING THE DAY INTO THE MID 20S TO LOWER 30S WILL
HELP GET RID OF SOME OF THIS ACCUMULATED SNOW. WEAK TROFFING SLIPS
ACROSS THE REGION FRI NGT INTO SATURDAY AND LOWERS HIGH AND LOW
TEMPS INTO THE TEENS AND SINGLE DIGITS THRU THE WEEKEND. SOME LIGHT
OVERRUNNING SNOWS MAY BE PSBL OVER THE WEEKEND AS WELL BUT WILL LEAVE
DRY IN GOING ALONG WITH CURRENT FCST PACKAGE.
RLB
&&
.MARINE...
1255 AM CST
A RATHER QUIET PERIOD SETTING UP ON LAKE MICHIGAN. WEAK LOW
PRESSURE OVER THE EASTERN GREAT LAKES WILL MOVE EAST INTO NEW
ENGLAND TODAY. A LARGE AREA OF STRONG HIGH PRESSURE OVER THE
ROCKIES WILL BUILD SOUTHEAST TO THE GULF COAST TUESDAY AND
WEDNESDAY WHILE WEAKENING. A TROUGH OF LOW PRESSURE IS FORECAST
TO DROP OUT OF CENTRAL CANADA AND INTO THE NORTHERN PLAINS
TUESDAY. THIS TROUGH WILL THEN MOVE ACROSS THE UPPER MISSISSIPPI
VALLEY AND WESTERN GREAT LAKES WEDNESDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 6 PM TUESDAY.
LAKE EFFECT SNOW ADVISORY...INZ001...MIDNIGHT TUESDAY TO 6 PM
TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 190908
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
308 AM CST MON JAN 19 2009
.DISCUSSION...
302 AM CST
POST TROF VEERING OF WINDS ON SCHEDULE WITH PUSHING LAKE PLUMES SWD
INTO NW INDIANA. BELIEVE A FEW INCHES IN LAKE COUNTY WILL SUFFICE
BEFORE WINDS BACK AGAIN TO THE NW. ALREADY PLUME APPEARS TO BE
SHIFTING EAST MID LAKE OFF OF MKE. WILL PROBLY GO AHEAD AND KEEP
ADVISORY FOR 3-5 INCHES GOING FOR PORTER COUNTY TODAY...ESP FOR THAT
NORTHEAST CORNER NEAR CHESTERTON. WINDS BACK THIS AFTN TO A POINT
WHERE LAKE EFFECT SNOWS SHIFT EAST OF PORTER COUNTY.
WINDS HAVE ALSO VEERED BEHIND A TROF SWINGING AROUND AN UPPER
VORTEX LOCATED NEAR HUDSON BAY. ANOTHER JET VISUALIZED ON WATER
VAPOR IMAGERY DIVING SOUTH THRU WESTERN ONTARIO THIS MRNG. THIS
JET DEEPENS ANOTHER WAVE AROUND THIS VORTEX THIS AFTN AND SWINGS
ANOTHER UPR TROF DOWN THE LAKE BY EVENING. THE SHORT OF IT IS THAT
WE ARE LIKELY IN FOR A REPEAT PERFORMANCE OF LAKE EFFECT TONIGHT
AS WINDS VEER AGAIN MORE NORTHEASTERLY DOWN THE LAKE. LIFT AROUND
THE LFQ OF THIS JET WILL DEVELOP SNOW SHOWERS IN NW ILLINOIS...WITH
PSBL FLURRIES THE REST OF NRN IL TONIGHT. BUT THE MAIN FOCUS WILL
BE THE CONVECTIVE PLUMES SHIFTING WEST INTO SRN COOK COUNTY AND NW
INDIANA AGAIN. MODEL SOUNDINGS STILL INDICATE THAT THE HEIGHT OF
THE INVERSION BEGINS AROUND 800 MB WHICH LIMITS THE DEEPENING OF
MSTR AND IN EFFECT LESSENS THE IMPACT OF THESE LAKE EFFECT
PLUMES. SO AT BEST LOOKING ONLY AT ANOTHER ADVISORY ISSUANCE
MONDAY NIGHT INTO TUESDAY FOR 3 TO 5 INCHES FOR LAKE AND PORTER
COUNTIES WITH PSBLY 2-3 INCHES FOR SERN COOK COUNTY. WILL LET DAY
SHIFT MAKE THIS CALL SINCE ALREADY HAVE A LAKE EFFECT SNOW
ADVISORY IN EFFECT FOR THE SAME AREA. THIS CURRENT ADVISORY MAY
NEED TO BE CANCELLED EARLY TODAY.
WINDS BACK AGAIN TO THE NW TUESDAY MRNG WHILE THE MAIN POLAR VORTEX
NEAR HUDSON BAY KICKS OUT TO THE EAST. UPR FLOW FLATTENS A LITTLE
MORE TO NW FLOW ON WED AND THURS TO ALMOST STRAIGHT EAST WEST OR
ZONAL FLOW ON FRIDAY. THIS DRY PERIOD FROM TUES NIGHT THRU FRIDAY
WITH TEMPS WARMING DURING THE DAY INTO THE MID 20S TO LOWER 30S WILL
HELP GET RID OF SOME OF THIS ACCUMULATED SNOW. WEAK TROFFING SLIPS
ACROSS THE REGION FRI NGT INTO SATURDAY AND LOWERS HIGH AND LOW
TEMPS INTO THE TEENS AND SINGLE DIGITS THRU THE WEEKEND. SOME LIGHT
OVERRUNNING SNOWS MAY BE PSBL OVER THE WEEKEND AS WELL BUT WILL LEAVE
DRY IN GOING ALONG WITH CURRENT FCST PACKAGE.
RLB
&&
.AVIATION...
0000 UTC TAFS...ANOTHER SHORTWAVE IS PIVOTING AROUND THE LARGE
TROUGH OVER THE GREAT LAKES AND SHOULD BRING SOME LIGHT SNOW TO
THE TERMINALS THIS EVENING. THIS EVENING`S VORT IS TRACKING A BIT
FARTHER WEST THAN LAST NIGHTS AND WOULD ANTICIPATE THE HEAVIER
(THOUGH STILL LIGHT) SNOWFALL TO BE WEST OF THE TERMINALS...STILL
WOULD ANTICIPATE EVEN CHGO METRO TAF SITES TO DROP TO MVFR VSBY IN
-SN THIS EVENING AS COLUMN SATURATES FROM TOP DOWN. VSBYS WILL
PROBABLY DROP DOWN TO IFR AT TIMES IN THE HEAVIER SNOW SHOWERS
THIS EVENING AREA WIDE...THOUGH HIGHER CHANCES/LONGER DURATIONS OF
IFR PROBABLY WILL REMAIN WEST OF ORD/MDW SO ONLY INCLUDED TEMPO
IFR CONDITIONS AT DPA AND RFD FOR NOW. CIGS SHOULD SCATTER OUT
LATE TONIGHT AS SHORTWAVE PASSES SOUTH OF THE AREA. ANOTHER
SHORTWAVE PROGGED TO ROTATE AROUND THE TROUGH MONDAY AFTERNOON AND
EVENING...THOUGH CURRENTLY APPEARS AS THOUGH THE BETTER FORCING
WITH THIS DISTURBANCE WILL REMAIN FAR ENOUGH WEST TO HAVE LITTLE
IMPACT ON THE TERMINALS.
LAKE EFFECT SNOW PLUME WILL LIKELY DEVELOP LATER TONIGHT...THOUGH
ALL INDICATIONS ARE THAT IT WILL STAY EAST OF GYY TONIGHT INTO
MONDAY. IN THE WAKE OF MONDAY EVENINGS TROUGH THE WINDS COULD VEER
ENOUGH SO THAT THE LAKE EFFECT MAY MAKE A RUN AT GYY MONDAY
EVENING...BUT THATS BEYOND THE SCOPE OF THIS SET OF TAFS.
IZZI
&&
.MARINE...
1255 AM CST
A RATHER QUIET PERIOD SETTING UP ON LAKE MICHIGAN. WEAK LOW
PRESSURE OVER THE EASTERN GREAT LAKES WILL MOVE EAST INTO NEW
ENGLAND TODAY. A LARGE AREA OF STRONG HIGH PRESSURE OVER THE
ROCKIES WILL BUILD SOUTHEAST TO THE GULF COAST TUESDAY AND
WEDNESDAY WHILE WEAKENING. A TROUGH OF LOW PRESSURE IS FORECAST
TO DROP OUT OF CENTRAL CANADA AND INTO THE NORTHERN PLAINS
TUESDAY. THIS TROUGH WILL THEN MOVE ACROSS THE UPPER MISSISSIPPI
VALLEY AND WESTERN GREAT LAKES WEDNESDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW ADVISORY...INZ002 UNTIL 6 PM MONDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 190854
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
254 AM CST MON JAN 19 2009
.DISCUSSION...
749 PM CST
LAKE EFFECT WATCH FOR LAKE AND PORTER HAS BEEN REPLACED BY AN
ADVISORY FOR JUST PORTER CO. LES BAND CONTINUES TO DEVELOP OFF OF
PT. BETSIE SOUTHWARD AS FLOW VEERS TO NORTHWARD BEHIND LATEST SHORT
WAVE DROPPING OVER SOUTHERN LAKE MI. THE VEERING CONTINUES TO SHIFT
DOWN THE LAKE FOLLOWING THE SHORT WAVE SHIFTING THE TAIL OF THE
PLUME INTO NORTHWEST IN AND TO PORTER CO. BETWEEN 06Z AND 09Z. BASED
ON FORECAST SOUNDINGS OVER THE S END OF THE LAKE CLOUDS TOP OUT
AROUND 750MB. THIS IS ENOUGH DEPTH FOR DECENT SHSN BUT NOT OF THE
2-3IN/HR VARIETY. DURING THE DAY MON SFC RIDGING PROGGED BY MODELS
FROM NORTHERN IA ACROSS NORTHERN IL INTO CENTRAL IN WITH THE LOW
LEVEL FLOW ACROSS THE S END OF THE LAKE BACKING IN RESPONSE. THE BIT
OF WESTERLY COMPONENT TO THE LOW LEVEL FLOW IS EXPECTED TO SHIFT THE
TAIL END OF THE LES EASTWARD. EXPECT TO MOVE OUT OF PORTER BY 21Z
BUT WILL LEAVE A FEW HR BUFFER BEYOND THEN FOR THE ADVISORY.
EXPECTED RANGE OF SF 1 INCH ALONG I-65 TO 5 INCHES IN NE PORTER CO.
ELSEWHERE...SHORT WAVE TROF TO ROTATE TO CENTRAL IL BY 06Z ENDING
-SN. SOME CLEARING IN WAKE OF THE SHORT WAVE ALREADY DOWN TO THE TO
THE WI BORDER AT 01Z.
TRS
PREVIOUS DISCUSSION
313 PM CST
A LAKE EFFECT SNOW WATCH IS IS POSTED FOR TONIGHT THROUGH TUESDAY
MORNING.
TONIGHT AND MONDAY...THE LAKE EFFECT SNOW WATCH IS IN EFFECT FOR
NORTHWEST INDIANA TONIGHT. WE ARE STILL UNCERTAIN ABOUT SNOW
ACCUMULATION BY MONDAY EVENING. SO WE DECIDED ON A LAKE SNOW WATCH
INSTEAD OF AN ADVISORY AT THIS TIME. THE HEAVIEST SNOWFALL WILL
OCCUR DURING THE DAY MONDAY. WE USED OUR LOCAL WRF AND NAM MODELS
FOR THE SNOW FORECAST.
SNOW WILL OCCUR OVER NORTHEAST AND NORTH CENTRAL ILLINOIS TONIGHT.
THIS SNOW WILL MOVE INTO THE REGION AFTER 6 PM CDT. SNOWFALL WILL BE
LIGHT AND WE EXPECT LITTLE ACCUMULATION. MOST OF THE SNOW WILL BE
EAST OF THE OUR FORECAST REGION AFTER MIDNIGHT.
TUESDAY THROUGH SUNDAY...MOST OF THE LAKE EFFECT SNOW WILL BE EAST
OF PORTER COUNTY INDIANA BY TUESDAY MORNING. WE EXPECT NO
PRECIPITATION
AND THE HIGH TEMPERATURES WILL THE UPPER 20S AND THE LOW TEMPERATURES
WILL BE IN THE LOWER TEENS AND UPPER SINGLE DIGITS THROUGH
WEDNESDAY MORNING. A LARGE HIGH PRESSURE RIDGE WILL LIE FROM
OKLAHOMA TO ONTARIO ON TUESDAY. TUESDAY NIGHT WILL BE THE COLDEST
NIGHT. A RAPID WARM UP IS EXPECTED WEDNESDAY...AS A LOW MOVES INTO
EASTERN IOWA. THE HIGH TEMPERATURES COULD REACH THE MIDDLE 30S BY
THURSDAY. BY NEXT SATURDAY ANOTHER STRONG HIGH OVER ALBERTA WILL
EXTEND INTO THE MIDWEST UNITED STATES. THIS HIGH WILL BRING VERY
COLD AIR INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA. THE HIGH
TEMPERATURES WILL BE IN THE TEENS AND THE LOW TEMPERATURES WILL BE
IN THE SINGLE DIGITS TO AROUND ZERO SATURDAY. WE USED THE ECMWF
AND GFS MODELS AND GUIDANCE FROM THE NATIONAL METEOROLOGICAL
CENTER FOR THE EXTENDED FORECASTS.
&&
.AVIATION...
0000 UTC TAFS...ANOTHER SHORTWAVE IS PIVOTING AROUND THE LARGE
TROUGH OVER THE GREAT LAKES AND SHOULD BRING SOME LIGHT SNOW TO
THE TERMINALS THIS EVENING. THIS EVENING`S VORT IS TRACKING A BIT
FARTHER WEST THAN LAST NIGHTS AND WOULD ANTICIPATE THE HEAVIER
(THOUGH STILL LIGHT) SNOWFALL TO BE WEST OF THE TERMINALS...STILL
WOULD ANTICIPATE EVEN CHGO METRO TAF SITES TO DROP TO MVFR VSBY IN
-SN THIS EVENING AS COLUMN SATURATES FROM TOP DOWN. VSBYS WILL
PROBABLY DROP DOWN TO IFR AT TIMES IN THE HEAVIER SNOW SHOWERS
THIS EVENING AREA WIDE...THOUGH HIGHER CHANCES/LONGER DURATIONS OF
IFR PROBABLY WILL REMAIN WEST OF ORD/MDW SO ONLY INCLUDED TEMPO
IFR CONDITIONS AT DPA AND RFD FOR NOW. CIGS SHOULD SCATTER OUT
LATE TONIGHT AS SHORTWAVE PASSES SOUTH OF THE AREA. ANOTHER
SHORTWAVE PROGGED TO ROTATE AROUND THE TROUGH MONDAY AFTERNOON AND
EVENING...THOUGH CURRENTLY APPEARS AS THOUGH THE BETTER FORCING
WITH THIS DISTURBANCE WILL REMAIN FAR ENOUGH WEST TO HAVE LITTLE
IMPACT ON THE TERMINALS.
LAKE EFFECT SNOW PLUME WILL LIKELY DEVELOP LATER TONIGHT...THOUGH
ALL INDICATIONS ARE THAT IT WILL STAY EAST OF GYY TONIGHT INTO
MONDAY. IN THE WAKE OF MONDAY EVENINGS TROUGH THE WINDS COULD VEER
ENOUGH SO THAT THE LAKE EFFECT MAY MAKE A RUN AT GYY MONDAY
EVENING...BUT THATS BEYOND THE SCOPE OF THIS SET OF TAFS.
IZZI
&&
.MARINE...
1255 AM CST
A RATHER QUIET PERIOD SETTING UP ON LAKE MICHIGAN. WEAK LOW
PRESSURE OVER THE EASTERN GREAT LAKES WILL MOVE EAST INTO NEW
ENGLAND TODAY. A LARGE AREA OF STRONG HIGH PRESSURE OVER THE
ROCKIES WILL BUILD SOUTHEAST TO THE GULF COAST TUESDAY AND
WEDNESDAY WHILE WEAKENING. A TROUGH OF LOW PRESSURE IS FORECAST
TO DROP OUT OF CENTRAL CANADA AND INTO THE NORTHERN PLAINS
TUESDAY. THIS TROUGH WILL THEN MOVE ACROSS THE UPPER MISSISSIPPI
VALLEY AND WESTERN GREAT LAKES WEDNESDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW ADVISORY...INZ002 UNTIL 6 PM MONDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 190152
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
752 PM CST SUN JAN 18 2009
.DISCUSSION...UPDATE
749 PM CST
LAKE EFFECT WATCH FOR LAKE AND PORTER HAS BEEN REPLACED BY AN
ADVISORY FOR JUST PORTER CO. LES BAND CONTINUES TO DEVELOP OFF OF
PT. BETSIE SOUTHWARD AS FLOW VEERS TO NORTHWARD BEHIND LATEST SHORT
WAVE DROPPING OVER SOUTHERN LAKE MI. THE VEERING CONTINUES TO SHIFT
DOWN THE LAKE FOLLOWING THE SHORT WAVE SHIFTING THE TAIL OF THE
PLUME INTO NORTHWEST IN AND TO PORTER CO. BETWEEN 06Z AND 09Z. BASED
ON FORECAST SOUNDINGS OVER THE S END OF THE LAKE CLOUDS TOP OUT
AROUND 750MB. THIS IS ENOUGH DEPTH FOR DECENT SHSN BUT NOT OF THE
2-3IN/HR VARIETY. DURING THE DAY MON SFC RIDGING PROGGED BY MODELS
FROM NORTHERN IA ACROSS NORTHERN IL INTO CENTRAL IN WITH THE LOW
LEVEL FLOW ACROSS THE S END OF THE LAKE BACKING IN RESPONSE. THE BIT
OF WESTERLY COMPONENT TO THE LOW LEVEL FLOW IS EXPECTED TO SHIFT THE
TAIL END OF THE LES EASTWARD. EXPECT TO MOVE OUT OF PORTER BY 21Z
BUT WILL LEAVE A FEW HR BUFFER BEYOND THEN FOR THE ADVISORY.
EXPECTED RANGE OF SF 1 INCH ALONG I-65 TO 5 INCHES IN NE PORTER CO.
ELSEWHERE...SHORT WAVE TROF TO ROTATE TO CENTRAL IL BY 06Z ENDING
-SN. SOME CLEARING IN WAKE OF THE SHORT WAVE ALREADY DOWN TO THE TO
THE WI BORDER AT 01Z.
TRS
PREVIOUS DISCUSSION
313 PM CST
A LAKE EFFECT SNOW WATCH IS IS POSTED FOR TONIGHT THROUGH TUESDAY
MORNING.
TONIGHT AND MONDAY...THE LAKE EFFECT SNOW WATCH IS IN EFFECT FOR
NORTHWEST INDIANA TONIGHT. WE ARE STILL UNCERTAIN ABOUT SNOW
ACCUMULATION BY MONDAY EVENING. SO WE DECIDED ON A LAKE SNOW WATCH
INSTEAD OF AN ADVISORY AT THIS TIME. THE HEAVIEST SNOWFALL WILL
OCCUR DURING THE DAY MONDAY. WE USED OUR LOCAL WRF AND NAM MODELS
FOR THE SNOW FORECAST.
SNOW WILL OCCUR OVER NORTHEAST AND NORTH CENTRAL ILLINOIS TONIGHT.
THIS SNOW WILL MOVE INTO THE REGION AFTER 6 PM CDT. SNOWFALL WILL BE
LIGHT AND WE EXPECT LITTLE ACCUMULATION. MOST OF THE SNOW WILL BE
EAST OF THE OUR FORECAST REGION AFTER MIDNIGHT.
TUESDAY THROUGH SUNDAY...MOST OF THE LAKE EFFECT SNOW WILL BE EAST
OF PORTER COUNTY INDIANA BY TUESDAY MORNING. WE EXPECT NO
PRECIPITATION
AND THE HIGH TEMPERATURES WILL THE UPPER 20S AND THE LOW TEMPERATURES
WILL BE IN THE LOWER TEENS AND UPPER SINGLE DIGITS THROUGH
WEDNESDAY MORNING. A LARGE HIGH PRESSURE RIDGE WILL LIE FROM
OKLAHOMA TO ONTARIO ON TUESDAY. TUESDAY NIGHT WILL BE THE COLDEST
NIGHT. A RAPID WARM UP IS EXPECTED WEDNESDAY...AS A LOW MOVES INTO
EASTERN IOWA. THE HIGH TEMPERATURES COULD REACH THE MIDDLE 30S BY
THURSDAY. BY NEXT SATURDAY ANOTHER STRONG HIGH OVER ALBERTA WILL
EXTEND INTO THE MIDWEST UNITED STATES. THIS HIGH WILL BRING VERY
COLD AIR INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA. THE HIGH
TEMPERATURES WILL BE IN THE TEENS AND THE LOW TEMPERATURES WILL BE
IN THE SINGLE DIGITS TO AROUND ZERO SATURDAY. WE USED THE ECMWF
AND GFS MODELS AND GUIDANCE FROM THE NATIONAL METEOROLOGICAL
CENTER FOR THE EXTENDED FORECASTS.
&&
.AVIATION...
0000 UTC TAFS...ANOTHER SHORTWAVE IS PIVOTING AROUND THE LARGE
TROUGH OVER THE GREAT LAKES AND SHOULD BRING SOME LIGHT SNOW TO
THE TERMINALS THIS EVENING. THIS EVENING`S VORT IS TRACKING A BIT
FARTHER WEST THAN LAST NIGHTS AND WOULD ANTICIPATE THE HEAVIER
(THOUGH STILL LIGHT) SNOWFALL TO BE WEST OF THE TERMINALS...STILL
WOULD ANTICIPATE EVEN CHGO METRO TAF SITES TO DROP TO MVFR VSBY IN
-SN THIS EVENING AS COLUMN SATURATES FROM TOP DOWN. VSBYS WILL
PROBABLY DROP DOWN TO IFR AT TIMES IN THE HEAVIER SNOW SHOWERS
THIS EVENING AREA WIDE...THOUGH HIGHER CHANCES/LONGER DURATIONS OF
IFR PROBABLY WILL REMAIN WEST OF ORD/MDW SO ONLY INCLUDED TEMPO
IFR CONDITIONS AT DPA AND RFD FOR NOW. CIGS SHOULD SCATTER OUT
LATE TONIGHT AS SHORTWAVE PASSES SOUTH OF THE AREA. ANOTHER
SHORTWAVE PROGGED TO ROTATE AROUND THE TROUGH MONDAY AFTERNOON AND
EVENING...THOUGH CURRENTLY APPEARS AS THOUGH THE BETTER FORCING
WITH THIS DISTURBANCE WILL REMAIN FAR ENOUGH WEST TO HAVE LITTLE
IMPACT ON THE TERMINALS.
LAKE EFFECT SNOW PLUME WILL LIKELY DEVELOP LATER TONIGHT...THOUGH
ALL INDICATIONS ARE THAT IT WILL STAY EAST OF GYY TONIGHT INTO
MONDAY. IN THE WAKE OF MONDAY EVENINGS TROUGH THE WINDS COULD VEER
ENOUGH SO THAT THE LAKE EFFECT MAY MAKE A RUN AT GYY MONDAY
EVENING...BUT THATS BEYOND THE SCOPE OF THIS SET OF TAFS.
IZZI
&&
.MARINE...
123 PM CST
WINDS WILL BE SHIFTING AROUND FROM THE NORTHWEST TO THE NORTH
TONIGHT AS A TROF OF LOW PRESSURE MOVES SOUTH ALONG THE LAKE.
WINDS ARE EXPECTED TO BRIEFLY GUST UP BEHIND IT...BUT SHOULD
REMAIN NO STRONGER THAN 25KTS. WILL PROBABLY BE GOING WITH A SMALL
CRAFT ADVISORY FOR 6Z TO 18Z MONDAY.
A BROAD RIDGE OF HIGH PRESSURE WILL THEN BE MOVING SOUTHEAST OUT
OF THE ROCKIES DOWN TOWARD THE GULF COAST TUESDAY INTO WEDNESDAY
AS THE NEXT LOW PRESSURE SYSTEM DEVELOPS UP IN CANADA. THIS LOW IS
EXPECTED TO DIVE DOWN FROM THE WESTERN COAST OF THE HUDSON BAY
TOWARD THE EASTERN GREAT LAKES ON WEDNESDAY...WHICH COULD LEAD TO
SOME MARGINAL GALES ACROSS THE LAKE...MORE SO ACROSS THE SOUTH
HALF.
ANOTHER RIDGE OF HIGH PRESSURE THEN SPILLS EASTWARD OUT INTO THE
PLAINS FROM SOUTHWEST CANADA TOWARD THE END OF THE WEEK.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WATCH...INZ001-INZ002...MIDNIGHT MONDAY TO 6
AM
TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 182329
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
529 PM CST SUN JAN 18 2009
.DISCUSSION...
313 PM CST
A LAKE EFFECT SNOW WATCH IS IS POSTED FOR TONIGHT THROUGH TUESDAY
MORNING.
TONIGHT AND MONDAY...THE LAKE EFFECT SNOW WATCH IS IN EFFECT FOR
NORTHWEST INDIANA TONIGHT. WE ARE STILL UNCERTAIN ABOUT SNOW
ACCUMULATION BY MONDAY EVENING. SO WE DECIDED ON A LAKE SNOW WATCH
INSTEAD OF AN ADVISORY AT THIS TIME. THE HEAVIEST SNOWFALL WILL
OCCUR DURING THE DAY MONDAY. WE USED OUR LOCAL WRF AND NAM MODELS
FOR THE SNOW FORECAST.
SNOW WILL OCCUR OVER NORTHEAST AND NORTH CENTRAL ILLINOIS TONIGHT.
THIS SNOW WILL MOVE INTO THE REGION AFTER 6 PM CDT. SNOWFALL WILL BE
LIGHT AND WE EXPECT LITTLE ACCUMULATION. MOST OF THE SNOW WILL BE
EAST OF THE OUR FORECAST REGION AFTER MIDNIGHT.
TUESDAY THROUGH SUNDAY...MOST OF THE LAKE EFFECT SNOW WILL BE EAST
OF PORTER COUNTY INDIANA BY TUESDAY MORNING. WE EXPECT NO PRECIPITATION
AND THE HIGH TEMPERATURES WILL THE UPPER 20S AND THE LOW TEMPERATURES
WILL BE IN THE LOWER TEENS AND UPPER SINGLE DIGITS THROUGH
WEDNESDAY MORNING. A LARGE HIGH PRESSURE RIDGE WILL LIE FROM
OKLAHOMA TO ONTARIO ON TUESDAY. TUESDAY NIGHT WILL BE THE COLDEST
NIGHT. A RAPID WARM UP IS EXPECTED WEDNESDAY...AS A LOW MOVES INTO
EASTERN IOWA. THE HIGH TEMPERATURES COULD REACH THE MIDDLE 30S BY
THURSDAY. BY NEXT SATURDAY ANOTHER STRONG HIGH OVER ALBERTA WILL
EXTEND INTO THE MIDWEST UNITED STATES. THIS HIGH WILL BRING VERY
COLD AIR INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA. THE HIGH
TEMPERATURES WILL BE IN THE TEENS AND THE LOW TEMPERATURES WILL BE
IN THE SINGLE DIGITS TO AROUND ZERO SATURDAY. WE USED THE ECMWF
AND GFS MODELS AND GUIDANCE FROM THE NATIONAL METEOROLOGICAL
CENTER FOR THE EXTENDED FORECASTS.
&&
.AVIATION...
0000 UTC TAFS...ANOTHER SHORTWAVE IS PIVOTING AROUND THE LARGE
TROUGH OVER THE GREAT LAKES AND SHOULD BRING SOME LIGHT SNOW TO
THE TERMINALS THIS EVENING. THIS EVENING`S VORT IS TRACKING A BIT
FARTHER WEST THAN LAST NIGHTS AND WOULD ANTICIPATE THE HEAVIER
(THOUGH STILL LIGHT) SNOWFALL TO BE WEST OF THE TERMINALS...STILL
WOULD ANTICIPATE EVEN CHGO METRO TAF SITES TO DROP TO MVFR VSBY IN
-SN THIS EVENING AS COLUMN SATURATES FROM TOP DOWN. VSBYS WILL
PROBABLY DROP DOWN TO IFR AT TIMES IN THE HEAVIER SNOW SHOWERS
THIS EVENING AREA WIDE...THOUGH HIGHER CHANCES/LONGER DURATIONS OF
IFR PROBABLY WILL REMAIN WEST OF ORD/MDW SO ONLY INCLUDED TEMPO
IFR CONDITIONS AT DPA AND RFD FOR NOW. CIGS SHOULD SCATTER OUT
LATE TONIGHT AS SHORTWAVE PASSES SOUTH OF THE AREA. ANOTHER
SHORTWAVE PROGGED TO ROTATE AROUND THE TROUGH MONDAY AFTERNOON AND
EVENING...THOUGH CURRENTLY APPEARS AS THOUGH THE BETTER FORCING
WITH THIS DISTURBANCE WILL REMAIN FAR ENOUGH WEST TO HAVE LITTLE
IMPACT ON THE TERMINALS.
LAKE EFFECT SNOW PLUME WILL LIKELY DEVELOP LATER TONIGHT...THOUGH
ALL INDICATIONS ARE THAT IT WILL STAY EAST OF GYY TONIGHT INTO
MONDAY. IN THE WAKE OF MONDAY EVENINGS TROUGH THE WINDS COULD VEER
ENOUGH SO THAT THE LAKE EFFECT MAY MAKE A RUN AT GYY MONDAY
EVENING...BUT THATS BEYOND THE SCOPE OF THIS SET OF TAFS.
IZZI
&&
.MARINE...
123 PM CST
WINDS WILL BE SHIFTING AROUND FROM THE NORTHWEST TO THE NORTH
TONIGHT AS A TROF OF LOW PRESSURE MOVES SOUTH ALONG THE LAKE.
WINDS ARE EXPECTED TO BRIEFLY GUST UP BEHIND IT...BUT SHOULD
REMAIN NO STRONGER THAN 25KTS. WILL PROBABLY BE GOING WITH A SMALL
CRAFT ADVISORY FOR 6Z TO 18Z MONDAY.
A BROAD RIDGE OF HIGH PRESSURE WILL THEN BE MOVING SOUTHEAST OUT
OF THE ROCKIES DOWN TOWARD THE GULF COAST TUESDAY INTO WEDNESDAY
AS THE NEXT LOW PRESSURE SYSTEM DEVELOPS UP IN CANADA. THIS LOW IS
EXPECTED TO DIVE DOWN FROM THE WESTERN COAST OF THE HUDSON BAY
TOWARD THE EASTERN GREAT LAKES ON WEDNESDAY...WHICH COULD LEAD TO
SOME MARGINAL GALES ACROSS THE LAKE...MORE SO ACROSS THE SOUTH
HALF.
ANOTHER RIDGE OF HIGH PRESSURE THEN SPILLS EASTWARD OUT INTO THE
PLAINS FROM SOUTHWEST CANADA TOWARD THE END OF THE WEEK.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WATCH...INZ001-INZ002...MIDNIGHT MONDAY TO 6 AM
TUESDAY.
LM...NONE.
&&
$$
000
FXUS63 KLOT 182157
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
357 PM CST SUN JAN 18 2009
.DISCUSSION...
313 PM CST
A LAKE EFFECT SNOW WATCH IS IS POSTED FOR TONIGHT THROUGH TUESDAY
MORNING.
TONIGHT AND MONDAY...THE LAKE EFFECT SNOW WATCH IS IN EFFECT FOR
NORTHWEST INDIANA TONIGHT. WE ARE STILL UNCERTAIN ABOUT SNOW
ACCUMULATION BY MONDAY EVENING. SO WE DECIDED ON A LAKE SNOW WATCH
INSTEAD OF AN ADVISORY AT THIS TIME. THE HEAVIEST SNOWFALL WILL
OCCUR DURING THE DAY MONDAY. WE USED OUR LOCAL WRF AND NAM MODELS
FOR THE SNOW FORECAST.
SNOW WILL OCCUR OVER NORTHEAST AND NORTH CENTRAL ILLINOIS TONIGHT.
THIS SNOW WILL MOVE INTO THE REGION AFTER 6 PM CDT. SNOWFALL WILL BE
LIGHT AND WE EXPECT LITTLE ACCUMULATION. MOST OF THE SNOW WILL BE
EAST OF THE OUR FORECAST REGION AFTER MIDNIGHT.
TUESDAY THROUGH SUNDAY...MOST OF THE LAKE EFFECT SNOW WILL BE EAST
OF PORTER COUNTY INDIANA BY TUESDAY MORNING. WE EXPECT NO PRECIPITATION
AND THE HIGH TEMPERATURES WILL THE UPPER 20S AND THE LOW TEMPERATURES
WILL BE IN THE LOWER TEENS AND UPPER SINGLE DIGITS THROUGH
WEDNESDAY MORNING. A LARGE HIGH PRESSURE RIDGE WILL LIE FROM
OKLAHOMA TO ONTARIO ON TUESDAY. TUESDAY NIGHT WILL BE THE COLDEST
NIGHT. A RAPID WARM UP IS EXPECTED WEDNESDAY...AS A LOW MOVES INTO
EASTERN IOWA. THE HIGH TEMPERATURES COULD REACH THE MIDDLE 30S BY
THURSDAY. BY NEXT SATURDAY ANOTHER STRONG HIGH OVER ALBERTA WILL
EXTEND INTO THE MIDWEST UNITED STATES. THIS HIGH WILL BRING VERY
COLD AIR INTO NORTHERN ILLINOIS AND NORTHWEST INDIANA. THE HIGH
TEMPERATURES WILL BE IN THE TEENS AND THE LOW TEMPERATURES WILL BE
IN THE SINGLE DIGITS TO AROUND ZERO SATURDAY. WE USED THE ECMWF
AND GFS MODELS AND GUIDANCE FROM THE NATIONAL METEOROLOGICAL
CENTER FOR THE EXTENDED FORECASTS.
&&
.AVIATION...
1148 AM CST
1800 UTC TAFS...MAIN FORECAST CONCERN OVER THIS SET OF TAFS IS ON
THE CHANCES FOR SNOW SHOWERS AND DROPPING VIS/CIGS THIS EVENING.
VIGOROUS UPPER LEVEL DISTURBANCE OVER LAKE SUPERIOR WILL DROP
DOWN INTO THE REGION LATE THIS AFTERNOON INTO TONIGHT WHILE AT THE
SFC AN INVERTED TROF WILL DIVE DOWN INTO NORTHERN
ILLINOIS/INDIANA. WHILE SKIES WILL REMAIN CLEAR THROUGH THE EARLY
PORTION OF THE AFTERNOON...LOW TO MID LEVEL CLOUDS WILL MOVE IN
AROUND MID AFTERNOON AND SHOULD DROP TO MVFR BY EVENING. BEST
CHANCE FOR ANY SNOW SHOWERS WILL COME IN THE EVENING WITH VIS/CIGS
MAINLY EXPECTED TO MVFR WITH SOME BRIEF IFR VIS POSSIBLE. SNOW
SHOULD TAPER OFF LATER THIS EVENING AS THE DISTURBANCE PASSES TO
THE SOUTH. WINDS WILL SHIFT FROM THE WEST-NORTHWEST TO THE NORTH
AS THE SFC TROF PASSES AND SHOULD BRING SOME GUSTS UP TO 20KTS AT
TIMES FOR A BRIEF PERIOD THIS EVENING.
SKIES SHOULD CLEAR OUT TOWARD MORNING WITH SOME UPPER LEVEL CLOUDS
COMING IN AHEAD OF THE NEXT DISTURBANCE. WILL HAVE TO KEEP AN EYE
ON THE LAKE EFFECT BAND FOR THE GYY TAF...BUT AT THIS POINT IT
APPEARS THAT IT SHOULD STAY EAST INTO PORTER COUNTY.
EXPECT VFR CONDITIONS THROUGH MID AFTERNOON WITH MVFR VIS/CIGS
LATE THIS AFTERNOON INTO THE EVENING...THEN GOING BACK TO VFR
OVERNIGHT INTO MONDAY.
HALBACH
&&
.MARINE...
123 PM CST
WINDS WILL BE SHIFTING AROUND FROM THE NORTHWEST TO THE NORTH
TONIGHT AS A TROF OF LOW PRESSURE MOVES SOUTH ALONG THE LAKE.
WINDS ARE EXPECTED TO BRIEFLY GUST UP BEHIND IT...BUT SHOULD
REMAIN NO STRONGER THAN 25KTS. WILL PROBABLY BE GOING WITH A SMALL
CRAFT ADVISORY FOR 6Z TO 18Z MONDAY.
A BROAD RIDGE OF HIGH PRESSURE WILL THEN BE MOVING SOUTHEAST OUT
OF THE ROCKIES DOWN TOWARD THE GULF COAST TUESDAY INTO WEDNESDAY
AS THE NEXT LOW PRESSURE SYSTEM DEVELOPS UP IN CANADA. THIS LOW IS
EXPECTED TO DIVE DOWN FROM THE WESTERN COAST OF THE HUDSON BAY
TOWARD THE EASTERN GREAT LAKES ON WEDNESDAY...WHICH COULD LEAD TO
SOME MARGINAL GALES ACROSS THE LAKE...MORESO ACROSS THE SOUTH
HALF.
ANOTHER RIDGE OF HIGH PRESSURE THEN SPILLS EASTWARD OUT INTO THE
PLAINS FROM SOUTHWEST CANADA TOWARD THE END OF THE WEEK.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW WATCH...INZ001-INZ002...MIDNIGHT MONDAY TO 6 AM
TUESDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...MIDNIGHT MONDAY TO NOON MONDAY.
&&
$$
000
FXUS63 KLOT 181923
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
123 PM CST SUN JAN 18 2009
.DISCUSSION...
251 AM CST
THE MAIN SFC COLD FRONT HAS MADE IT THRU NW INDY BY NOW WITH REMNANT
SNOW SHOWERS IN THE LEADING CAA FIELD STILL GENERATING IN NE IL.
DETECTING SOME BACKING SFC WINDS IN CNTL WI AND PROBABLY A SFC
REFLECTION OF AN UPR TROF SWINGING DOWN THRU NRN IL AFTER
SUNUP. MEANWHILE A STRONG POLAR JET MAKES A DIVE DOWN THRU THE MS
VLY THIS MRNG. RADAR MOSAIC AND WATER VAPOR INDICATING PATCHY SNOW
SHOWERS IN MO AND IA ON THE LFQ OF THIS JET. ANOTHER AREA OF SNOW
SHOWERS LIKELY TO SWING DOWN THE MS RVR VALLEY AND INTO NW IL THIS
AFTN ON THE RRQ OF THIS SAME JET. THIS IS COINCIDENT ON MODELS
WITH ANOTHER UPR TROF SWINGING DOWN THRU NRN IL THIS EVENING
AROUND A POLAR VORTEX WORKING ACROSS LAKE HURON BY THEN. WILL
LIKELY BE SOME SCATTERED SNOW SHOWERS DEPOSITING A DUSTING HERE
AND THERE BUT MAINLY JUST FLURRIES WRINGING OUT OF CAA SC IN
CYCLONIC FLOW.
WHILE RIDGING WORKS INTO NRN IL LATE TONIGHT...THE PASSING UPR
TROF THIS EVENING WORKS TO ALTER FLOW OVER THE LAKE. TEMP
DIFFERENTIAL TO 850 MB SUFFICIENT TO PRODUCE CONVECTION OVERNIGHT
OVER THE LAKE. LAKE PLUMES MAINLY AFFECTING MICHIGAN EARLY
TONIGHT...BUT POST TROF VEERING WINDS SHIFT PLUMES WESTWARD INTO
NW INDIANA. THE LIMITING FACTOR FOR A GOOD SNOW MACHINE IS HEIGHT
OF THE INVERSION ONLY TO 800MB. CONSIDERING QPF VALUES AND LENGTH
OF TIME OVER NW INDY...AM CONSIDERING AROUND 4 INCHES AVERAGE
PROBABLY IN NRN PORTER COUNTY LATE TNGT THRU MID MRNG MONDAY WITH
A COUPLE INCHES IN LAKE COUNTY INDIANA IN THE SAME TIME FRAME. IS
PSBL FOR SRN COOK CNTY TO GET HIT WITH A WIDE SWINGING PLUME IN
THE PREDAWN BUT FIGURING NOT MORE THAN AN INCH ACCUMULATION THERE.
PSBL FOR PORTER COUNTY TO SEE A LAKE SNOW ADVISORY LATER TODAY IF
MODEL PREDICTIONS OF INVERSION HEIGHTS BECOME HIER. HIGHEST QPF
VALUES INDICATED ON NAM WHILE GFS AND ECMWF MORE STINGY.
AS RIDGING WORKS EAST DURING THE DAY MONDAY...WINDS BACK MORE
WESTERLY AND SENDING PLUMES BACK TOWARD MICHIGAN. HOWEVER THE MAIN
POLAR VORTEX REMAINS IN PLACE NEAR HUDSON BAY AND SWINGS ANOTHER
TROF DOWN FROM CANADA MONDAY NIGHT INTO TUESDAY...COINCIDENT WITH
ANOTHER LFQ OF AN UPR JET DIVING DOWN THE MS VLY. WINDS AGAIN VEER
DOWN THE LAKE FORMING GOOD CONVERGENCE PLUMES OVER THE LAKE AND
REPEAT THE SUNDAY NIGHT RISK OF SNOW OVER NW INDY. MODELS STILL
SHOWING A SHALLOW INVERSION HEIGHT TO 800 MB AT THAT TIME. AT THE
END OF THE DAY TUESDAY...GOOD UPR RIDGING WORKS ACROSS THE MS VLY
AND BACKS WINDS WEST TO SOUTHWEST. H8 TEMPS WARM ABOVE -10C AND
SHUT OFF LAKE CONVECTION TUES NGT.
CONTINUED WARMING AND FLATTENING OF UPR FLOW IS LIKELY TO YIELD
MELTING OR NEAR MELTING CONDITIONS FOR WEDNESDAY AND THURSDAY.
HOWEVER A PASSING SYSTEM TO OUR SOUTH NEAR THE WEEKEND IS LIKELY TO
RETURN COOLER CONDITIONS FOR FRIDAY AND SATURDAY. WHETHER WE SEE ANY
MORE SNOW WITH THIS PASSING FEATURE IS QUESTIONABLE. FOR NOW WILL
KEEP PROSPECTS DRY.
RLB
&&
.AVIATION...
1148 AM CST
1800 UTC TAFS...MAIN FORECAST CONCERN OVER THIS SET OF TAFS IS ON
THE CHANCES FOR SNOW SHOWERS AND DROPPING VIS/CIGS THIS EVENING.
VIGOROUS UPPER LEVEL DISTURBANCE OVER LAKE SUPERIOR WILL DROP
DOWN INTO THE REGION LATE THIS AFTERNOON INTO TONIGHT WHILE AT THE
SFC AN INVERTED TROF WILL DIVE DOWN INTO NORTHERN
ILLINOIS/INDIANA. WHILE SKIES WILL REMAIN CLEAR THROUGH THE EARLY
PORTION OF THE AFTERNOON...LOW TO MID LEVEL CLOUDS WILL MOVE IN
AROUND MID AFTERNOON AND SHOULD DROP TO MVFR BY EVENING. BEST
CHANCE FOR ANY SNOW SHOWERS WILL COME IN THE EVENING WITH VIS/CIGS
MAINLY EXPECTED TO MVFR WITH SOME BRIEF IFR VIS POSSIBLE. SNOW
SHOULD TAPER OFF LATER THIS EVENING AS THE DISTURBANCE PASSES TO
THE SOUTH. WINDS WILL SHIFT FROM THE WEST-NORTHWEST TO THE NORTH
AS THE SFC TROF PASSES AND SHOULD BRING SOME GUSTS UP TO 20KTS AT
TIMES FOR A BRIEF PERIOD THIS EVENING.
SKIES SHOULD CLEAR OUT TOWARD MORNING WITH SOME UPPER LEVEL CLOUDS
COMING IN AHEAD OF THE NEXT DISTURBANCE. WILL HAVE TO KEEP AN EYE
ON THE LAKE EFFECT BAND FOR THE GYY TAF...BUT AT THIS POINT IT
APPEARS THAT IT SHOULD STAY EAST INTO PORTER COUNTY.
EXPECT VFR CONDITIONS THROUGH MID AFTERNOON WITH MVFR VIS/CIGS
LATE THIS AFTERNOON INTO THE EVENING...THEN GOING BACK TO VFR
OVERNIGHT INTO MONDAY.
HALBACH
&&
.MARINE...
123 PM CST
WINDS WILL BE SHIFTING AROUND FROM THE NORTHWEST TO THE NORTH
TONIGHT AS A TROF OF LOW PRESSURE MOVES SOUTH ALONG THE LAKE.
WINDS ARE EXPECTED TO BRIEFLY GUST UP BEHIND IT...BUT SHOULD
REMAIN NO STRONGER THAN 25KTS. WILL PROBABLY BE GOING WITH A SMALL
CRAFT ADVISORY FOR 6Z TO 18Z MONDAY.
A BROAD RIDGE OF HIGH PRESSURE WILL THEN BE MOVING SOUTHEAST OUT
OF THE ROCKIES DOWN TOWARD THE GULF COAST TUESDAY INTO WEDNESDAY
AS THE NEXT LOW PRESSURE SYSTEM DEVELOPS UP IN CANADA. THIS LOW IS
EXPECTED TO DIVE DOWN FROM THE WESTERN COAST OF THE HUDSON BAY
TOWARD THE EASTERN GREAT LAKES ON WEDNESDAY...WHICH COULD LEAD TO
SOME MARGINAL GALES ACROSS THE LAKE...MORESO ACROSS THE SOUTH
HALF.
ANOTHER RIDGE OF HIGH PRESSURE THEN SPILLS EASTWARD OUT INTO THE
PLAINS FROM SOUTHWEST CANADA TOWARD THE END OF THE WEEK.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KLOT 181748
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1148 AM CST SUN JAN 18 2009
.DISCUSSION...
251 AM CST
THE MAIN SFC COLD FRONT HAS MADE IT THRU NW INDY BY NOW WITH REMNANT
SNOW SHOWERS IN THE LEADING CAA FIELD STILL GENERATING IN NE IL.
DETECTING SOME BACKING SFC WINDS IN CNTL WI AND PROBABLY A SFC
REFLECTION OF AN UPR TROF SWINGING DOWN THRU NRN IL AFTER
SUNUP. MEANWHILE A STRONG POLAR JET MAKES A DIVE DOWN THRU THE MS
VLY THIS MRNG. RADAR MOSAIC AND WATER VAPOR INDICATING PATCHY SNOW
SHOWERS IN MO AND IA ON THE LFQ OF THIS JET. ANOTHER AREA OF SNOW
SHOWERS LIKELY TO SWING DOWN THE MS RVR VALLEY AND INTO NW IL THIS
AFTN ON THE RRQ OF THIS SAME JET. THIS IS COINCIDENT ON MODELS
WITH ANOTHER UPR TROF SWINGING DOWN THRU NRN IL THIS EVENING
AROUND A POLAR VORTEX WORKING ACROSS LAKE HURON BY THEN. WILL
LIKELY BE SOME SCATTERED SNOW SHOWERS DEPOSITING A DUSTING HERE
AND THERE BUT MAINLY JUST FLURRIES WRINGING OUT OF CAA SC IN
CYCLONIC FLOW.
WHILE RIDGING WORKS INTO NRN IL LATE TONIGHT...THE PASSING UPR
TROF THIS EVENING WORKS TO ALTER FLOW OVER THE LAKE. TEMP
DIFFERENTIAL TO 850 MB SUFFICIENT TO PRODUCE CONVECTION OVERNIGHT
OVER THE LAKE. LAKE PLUMES MAINLY AFFECTING MICHIGAN EARLY
TONIGHT...BUT POST TROF VEERING WINDS SHIFT PLUMES WESTWARD INTO
NW INDIANA. THE LIMITING FACTOR FOR A GOOD SNOW MACHINE IS HEIGHT
OF THE INVERSION ONLY TO 800MB. CONSIDERING QPF VALUES AND LENGTH
OF TIME OVER NW INDY...AM CONSIDERING AROUND 4 INCHES AVERAGE
PROBABLY IN NRN PORTER COUNTY LATE TNGT THRU MID MRNG MONDAY WITH
A COUPLE INCHES IN LAKE COUNTY INDIANA IN THE SAME TIME FRAME. IS
PSBL FOR SRN COOK CNTY TO GET HIT WITH A WIDE SWINGING PLUME IN
THE PREDAWN BUT FIGURING NOT MORE THAN AN INCH ACCUMULATION THERE.
PSBL FOR PORTER COUNTY TO SEE A LAKE SNOW ADVISORY LATER TODAY IF
MODEL PREDICTIONS OF INVERSION HEIGHTS BECOME HIER. HIGHEST QPF
VALUES INDICATED ON NAM WHILE GFS AND ECMWF MORE STINGY.
AS RIDGING WORKS EAST DURING THE DAY MONDAY...WINDS BACK MORE
WESTERLY AND SENDING PLUMES BACK TOWARD MICHIGAN. HOWEVER THE MAIN
POLAR VORTEX REMAINS IN PLACE NEAR HUDSON BAY AND SWINGS ANOTHER
TROF DOWN FROM CANADA MONDAY NIGHT INTO TUESDAY...COINCIDENT WITH
ANOTHER LFQ OF AN UPR JET DIVING DOWN THE MS VLY. WINDS AGAIN VEER
DOWN THE LAKE FORMING GOOD CONVERGENCE PLUMES OVER THE LAKE AND
REPEAT THE SUNDAY NIGHT RISK OF SNOW OVER NW INDY. MODELS STILL
SHOWING A SHALLOW INVERSION HEIGHT TO 800 MB AT THAT TIME. AT THE
END OF THE DAY TUESDAY...GOOD UPR RIDGING WORKS ACROSS THE MS VLY
AND BACKS WINDS WEST TO SOUTHWEST. H8 TEMPS WARM ABOVE -10C AND
SHUT OFF LAKE CONVECTION TUES NGT.
CONTINUED WARMING AND FLATTENING OF UPR FLOW IS LIKELY TO YIELD
MELTING OR NEAR MELTING CONDITIONS FOR WEDNESDAY AND THURSDAY.
HOWEVER A PASSING SYSTEM TO OUR SOUTH NEAR THE WEEKEND IS LIKELY TO
RETURN COOLER CONDITIONS FOR FRIDAY AND SATURDAY. WHETHER WE SEE ANY
MORE SNOW WITH THIS PASSING FEATURE IS QUESTIONABLE. FOR NOW WILL
KEEP PROSPECTS DRY.
RLB
&&
.AVIATION...
1148 AM CST
1800 UTC TAFS...MAIN FORECAST CONCERN OVER THIS SET OF TAFS IS ON
THE CHANCES FOR SNOW SHOWERS AND DROPPING VIS/CIGS THIS EVENING.
VIGOROUS UPPER LEVEL DISTURBANCE OVER LAKE SUPERIOR WILL DROP
DOWN INTO THE REGION LATE THIS AFTERNOON INTO TONIGHT WHILE AT THE
SFC AN INVERTED TROF WILL DIVE DOWN INTO NORTHERN
ILLINOIS/INDIANA. WHILE SKIES WILL REMAIN CLEAR THROUGH THE EARLY
PORTION OF THE AFTERNOON...LOW TO MID LEVEL CLOUDS WILL MOVE IN
AROUND MID AFTERNOON AND SHOULD DROP TO MVFR BY EVENING. BEST
CHANCE FOR ANY SNOW SHOWERS WILL COME IN THE EVENING WITH VIS/CIGS
MAINLY EXPECTED TO MVFR WITH SOME BRIEF IFR VIS POSSIBLE. SNOW
SHOULD TAPER OFF LATER THIS EVENING AS THE DISTURBANCE PASSES TO
THE SOUTH. WINDS WILL SHIFT FROM THE WEST-NORTHWEST TO THE NORTH
AS THE SFC TROF PASSES AND SHOULD BRING SOME GUSTS UP TO 20KTS AT
TIMES FOR A BRIEF PERIOD THIS EVENING.
SKIES SHOULD CLEAR OUT TOWARD MORNING WITH SOME UPPER LEVEL CLOUDS
COMING IN AHEAD OF THE NEXT DISTURBANCE. WILL HAVE TO KEEP AN EYE
ON THE LAKE EFFECT BAND FOR THE GYY TAF...BUT AT THIS POINT IT
APPEARS THAT IT SHOULD STAY EAST INTO PORTER COUNTY.
EXPECT VFR CONDITIONS THROUGH MID AFTERNOON WITH MVFR VIS/CIGS
LATE THIS AFTERNOON INTO THE EVENING...THEN GOING BACK TO VFR
OVERNIGHT INTO MONDAY.
HALBACH
&&
.MARINE...
200 PM CST
WINDS PICKED UP TO GALE FORCE ACROSS THE SOUTHERN HALF OF THE LAKE
THIS MORNING...BUT SHOULD CONTINUE A GRADUAL DECLINE IN SPEEDS
THROUGH TONIGHT AS A LOW PRESSURE SYSTEM NEARS THE MID PORTION OF
THE LAKE. WINDS WILL AROUND TO THE NORTHWEST TONIGHT AS THE LOW
MOVES INTO MICHIGAN AND TRACKS EASTWARD ACROSS THE GREAT LAKES ON
SUNDAY. WILL LET THE GALE WARNING EXPIRE AT 21Z THIS AFTERNOON
WITH A SMALL CRAFT ADVISORY TAKING OVER IN THE NEARSHORE ZONES
THEREAFTER. WINDS SHOULD STAY OUT OF THE NORTH TO NORTHWEST
THROUGHOUT MOST OF THE FORECAST PERIOD WITH NO STRONG CASES FOR
GALES THROUGHOUT AS WE STAY STUCK IN THE SAME WEATHER PATTERN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KLOT 181155
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
555 AM CST SUN JAN 18 2009
.DISCUSSION...
251 AM CST
THE MAIN SFC COLD FRONT HAS MADE IT THRU NW INDY BY NOW WITH REMNANT
SNOW SHOWERS IN THE LEADING CAA FIELD STILL GENERATING IN NE IL.
DETECTING SOME BACKING SFC WINDS IN CNTL WI AND PROBABLY A SFC
REFLECTION OF AN UPR TROF SWINGING DOWN THRU NRN IL AFTER
SUNUP. MEANWHILE A STRONG POLAR JET MAKES A DIVE DOWN THRU THE MS
VLY THIS MRNG. RADAR MOSAIC AND WATER VAPOR INDICATING PATCHY SNOW
SHOWERS IN MO AND IA ON THE LFQ OF THIS JET. ANOTHER AREA OF SNOW
SHOWERS LIKELY TO SWING DOWN THE MS RVR VALLEY AND INTO NW IL THIS
AFTN ON THE RRQ OF THIS SAME JET. THIS IS COINCIDENT ON MODELS
WITH ANOTHER UPR TROF SWINGING DOWN THRU NRN IL THIS EVENING
AROUND A POLAR VORTEX WORKING ACROSS LAKE HURON BY THEN. WILL
LIKELY BE SOME SCATTERED SNOW SHOWERS DEPOSITING A DUSTING HERE
AND THERE BUT MAINLY JUST FLURRIES WRINGING OUT OF CAA SC IN
CYCLONIC FLOW.
WHILE RIDGING WORKS INTO NRN IL LATE TONIGHT...THE PASSING UPR
TROF THIS EVENING WORKS TO ALTER FLOW OVER THE LAKE. TEMP
DIFFERENTIAL TO 850 MB SUFFICIENT TO PRODUCE CONVECTION OVERNIGHT
OVER THE LAKE. LAKE PLUMES MAINLY AFFECTING MICHIGAN EARLY
TONIGHT...BUT POST TROF VEERING WINDS SHIFT PLUMES WESTWARD INTO
NW INDIANA. THE LIMITING FACTOR FOR A GOOD SNOW MACHINE IS HEIGHT
OF THE INVERSION ONLY TO 800MB. CONSIDERING QPF VALUES AND LENGTH
OF TIME OVER NW INDY...AM CONSIDERING AROUND 4 INCHES AVERAGE
PROBABLY IN NRN PORTER COUNTY LATE TNGT THRU MID MRNG MONDAY WITH
A COUPLE INCHES IN LAKE COUNTY INDIANA IN THE SAME TIME FRAME. IS
PSBL FOR SRN COOK CNTY TO GET HIT WITH A WIDE SWINGING PLUME IN
THE PREDAWN BUT FIGURING NOT MORE THAN AN INCH ACCUMULATION THERE.
PSBL FOR PORTER COUNTY TO SEE A LAKE SNOW ADVISORY LATER TODAY IF
MODEL PREDICTIONS OF INVERSION HEIGHTS BECOME HIER. HIGHEST QPF
VALUES INDICATED ON NAM WHILE GFS AND ECMWF MORE STINGY.
AS RIDGING WORKS EAST DURING THE DAY MONDAY...WINDS BACK MORE
WESTERLY AND SENDING PLUMES BACK TOWARD MICHIGAN. HOWEVER THE MAIN
POLAR VORTEX REMAINS IN PLACE NEAR HUDSON BAY AND SWINGS ANOTHER
TROF DOWN FROM CANADA MONDAY NIGHT INTO TUESDAY...COINCIDENT WITH
ANOTHER LFQ OF AN UPR JET DIVING DOWN THE MS VLY. WINDS AGAIN VEER
DOWN THE LAKE FORMING GOOD CONVERGENCE PLUMES OVER THE LAKE AND
REPEAT THE SUNDAY NIGHT RISK OF SNOW OVER NW INDY. MODELS STILL
SHOWING A SHALLOW INVERSION HEIGHT TO 800 MB AT THAT TIME. AT THE
END OF THE DAY TUESDAY...GOOD UPR RIDGING WORKS ACROSS THE MS VLY
AND BACKS WINDS WEST TO SOUTHWEST. H8 TEMPS WARM ABOVE -10C AND
SHUT OFF LAKE CONVECTION TUES NGT.
CONTINUED WARMING AND FLATTENING OF UPR FLOW IS LIKELY TO YIELD
MELTING OR NEAR MELTING CONDITIONS FOR WEDNESDAY AND THURSDAY.
HOWEVER A PASSING SYSTEM TO OUR SOUTH NEAR THE WEEKEND IS LIKELY TO
RETURN COOLER CONDITIONS FOR FRIDAY AND SATURDAY. WHETHER WE SEE ANY
MORE SNOW WITH THIS PASSING FEATURE IS QUESTIONABLE. FOR NOW WILL
KEEP PROSPECTS DRY.
RLB
&&
.AVIATION...
1200 UTC TAFS...A GENERALLY QUIET DAY ON TAP FOR AVIATION WEATHER
CONCERNS. THE UPPER LOW REMAINS NEARLY STATIONARY OVER THE GREAT
LAKES. LATEST SATELLITE IMAGERY SHOWS PATCHY STRATUS OVER THE
UPPER MIDWEST WITH THE BULK OF THE MVFR CLOUD COVER OVER
MINNESOTA AND IOWA...WITH JUST PATCHY CLOUD OVER NRN IL AND
WISCONSIN. HOWEVER...EXPECT SOME INCREASE IN THE STRATUS/STRATOCU
WITH DAYTIME WARMING UNDER PERSISTENT CYCLONIC FLOW ALOFT. HAVE
INTRODUCED A PROB30 GROUP FOR 4SM -SN FOR THE LATE AFTERNOON/EARLY
EVENING HOURS TO COINCIDE WITH THE PASSAGE OF A WEAK IMPULSE
ROTATING AROUND THE WRN PERIPHERY OF THE UPPER LOW...WHICH WILL
BRING SOME WEAK MID LEVEL FORCING AND INCREASED LOW LEVEL MOISTURE
AS IS EVIDENT IN THE MODEL FORECAST RH TIME SECTIONS. WINDS WILL
REMAIN GENERALLY NWLY THRU THE PERIOD AND DECREASE IN STRENGTH
WITH TIME AS THE SFC PRESSURE GRADIENT WEAKENS.
KREIN
&&
.MARINE...
200 PM CST
WINDS PICKED UP TO GALE FORCE ACROSS THE SOUTHERN HALF OF THE LAKE
THIS MORNING...BUT SHOULD CONTINUE A GRADUAL DECLINE IN SPEEDS
THROUGH TONIGHT AS A LOW PRESSURE SYSTEM NEARS THE MID PORTION OF
THE LAKE. WINDS WILL AROUND TO THE NORTHWEST TONIGHT AS THE LOW
MOVES INTO MICHIGAN AND TRACKS EASTWARD ACROSS THE GREAT LAKES ON
SUNDAY. WILL LET THE GALE WARNING EXPIRE AT 21Z THIS AFTERNOON
WITH A SMALL CRAFT ADVISORY TAKING OVER IN THE NEARSHORE ZONES
THEREAFTER. WINDS SHOULD STAY OUT OF THE NORTH TO NORTHWEST
THROUGHOUT MOST OF THE FORECAST PERIOD WITH NO STRONG CASES FOR
GALES THROUGHOUT AS WE STAY STUCK IN THE SAME WEATHER PATTERN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KLOT 180851
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
251 AM CST SUN JAN 18 2009
.DISCUSSION...
251 AM CST
THE MAIN SFC COLD FRONT HAS MADE IT THRU NW INDY BY NOW WITH REMNANT
SNOW SHOWERS IN THE LEADING CAA FIELD STILL GENERATING IN NE IL.
DETECTING SOME BACKING SFC WINDS IN CNTL WI AND PROBABLY A SFC
REFLECTION OF AN UPR TROF SWINGING DOWN THRU NRN IL AFTER
SUNUP. MEANWHILE A STRONG POLAR JET MAKES A DIVE DOWN THRU THE MS
VLY THIS MRNG. RADAR MOSAIC AND WATER VAPOR INDICATING PATCHY SNOW
SHOWERS IN MO AND IA ON THE LFQ OF THIS JET. ANOTHER AREA OF SNOW
SHOWERS LIKELY TO SWING DOWN THE MS RVR VALLEY AND INTO NW IL THIS
AFTN ON THE RRQ OF THIS SAME JET. THIS IS COINCIDENT ON MODELS
WITH ANOTHER UPR TROF SWINGING DOWN THRU NRN IL THIS EVENING
AROUND A POLAR VORTEX WORKING ACROSS LAKE HURON BY THEN. WILL
LIKELY BE SOME SCATTERED SNOW SHOWERS DEPOSITING A DUSTING HERE
AND THERE BUT MAINLY JUST FLURRIES WRINGING OUT OF CAA SC IN
CYCLONIC FLOW.
WHILE RIDGING WORKS INTO NRN IL LATE TONIGHT...THE PASSING UPR
TROF THIS EVENING WORKS TO ALTER FLOW OVER THE LAKE. TEMP
DIFFERENTIAL TO 850 MB SUFFICIENT TO PRODUCE CONVECTION OVERNIGHT
OVER THE LAKE. LAKE PLUMES MAINLY AFFECTING MICHIGAN EARLY
TONIGHT...BUT POST TROF VEERING WINDS SHIFT PLUMES WESTWARD INTO
NW INDIANA. THE LIMITING FACTOR FOR A GOOD SNOW MACHINE IS HEIGHT
OF THE INVERSION ONLY TO 800MB. CONSIDERING QPF VALUES AND LENGTH
OF TIME OVER NW INDY...AM CONSIDERING AROUND 4 INCHES AVERAGE
PROBABLY IN NRN PORTER COUNTY LATE TNGT THRU MID MRNG MONDAY WITH
A COUPLE INCHES IN LAKE COUNTY INDIANA IN THE SAME TIME FRAME. IS
PSBL FOR SRN COOK CNTY TO GET HIT WITH A WIDE SWINGING PLUME IN
THE PREDAWN BUT FIGURING NOT MORE THAN AN INCH ACCUMULATION THERE.
PSBL FOR PORTER COUNTY TO SEE A LAKE SNOW ADVISORY LATER TODAY IF
MODEL PREDICTIONS OF INVERSION HEIGHTS BECOME HIER. HIGHEST QPF
VALUES INDICATED ON NAM WHILE GFS AND ECMWF MORE STINGY.
AS RIDGING WORKS EAST DURING THE DAY MONDAY...WINDS BACK MORE
WESTERLY AND SENDING PLUMES BACK TOWARD MICHIGAN. HOWEVER THE MAIN
POLAR VORTEX REMAINS IN PLACE NEAR HUDSON BAY AND SWINGS ANOTHER
TROF DOWN FROM CANADA MONDAY NIGHT INTO TUESDAY...COINCIDENT WITH
ANOTHER LFQ OF AN UPR JET DIVING DOWN THE MS VLY. WINDS AGAIN VEER
DOWN THE LAKE FORMING GOOD CONVERGENCE PLUMES OVER THE LAKE AND
REPEAT THE SUNDAY NIGHT RISK OF SNOW OVER NW INDY. MODELS STILL
SHOWING A SHALLOW INVERSION HEIGHT TO 800 MB AT THAT TIME. AT THE
END OF THE DAY TUESDAY...GOOD UPR RIDGING WORKS ACROSS THE MS VLY
AND BACKS WINDS WEST TO SOUTHWEST. H8 TEMPS WARM ABOVE -10C AND
SHUT OFF LAKE CONVECTION TUES NGT.
CONTINUED WARMING AND FLATTENING OF UPR FLOW IS LIKELY TO YIELD
MELTING OR NEAR MELTING CONDITIONS FOR WEDNESDAY AND THURSDAY.
HOWEVER A PASSING SYSTEM TO OUR SOUTH NEAR THE WEEKEND IS LIKELY TO
RETURN COOLER CONDITIONS FOR FRIDAY AND SATURDAY. WHETHER WE SEE ANY
MORE SNOW WITH THIS PASSING FEATURE IS QUESTIONABLE. FOR NOW WILL
KEEP PROSPECTS DRY.
RLB
&&
.AVIATION...
0600 UTC TAFS...WEAK SHORTWAVE RESPONSIBLE FOR THE SNOW SHOWERS
SAT EVENING IS QUICKLY EXITING THE AREA. A COUPLE TAILS OF STRATUS
LINGER BACK INTO WISCONSIN AND THESE STREAKS OF STRATUS HAVE BEEN
LEAKING OUT SOME SHSN AT TIMES...BUT ANY LINGERING SNOW SHOWERS
WOULD LIKELY BE THE EXCEPTION RATHER THAN THE RULE SO KEPT TAFS
DRY EXCEPT FOR RFD WHICH APPEARS TO BE IN LINE TO GET AFFECTED BY
ONE OF THESE LEAKY BANDS OF STRATUS. SATELLITE AND UPSTREAM OBS
INDICATE THAT A TREND TOWARD SCATTERING OUT OF THE CLOUDINESS
SHOULD OCCUR OVERNIGHT. HOLES IN THE CLOUDINESS MAY TEND TO FILL
IN WITH STRATOCUMULUS BY MIDDAY SUNDAY...THOUGH GENERALLY EXPECT
ANY BKN CIGS THAT DO DEVELOP TO REMAIN VFR TO POSSIBLY HIGH END
MVFR. BEST FORCING FOR -SN/-SHSN SHOULD GENERALLY REMAIN WEST OF
THE TERMINALS SUNDAY THOUGH A COUPLE FLURRIES CANNOT BE RULED OUT.
IZZI
&&
.MARINE...
200 PM CST
WINDS PICKED UP TO GALE FORCE ACROSS THE SOUTHERN HALF OF THE LAKE
THIS MORNING...BUT SHOULD CONTINUE A GRADUAL DECLINE IN SPEEDS
THROUGH TONIGHT AS A LOW PRESSURE SYSTEM NEARS THE MID PORTION OF
THE LAKE. WINDS WILL AROUND TO THE NORTHWEST TONIGHT AS THE LOW
MOVES INTO MICHIGAN AND TRACKS EASTWARD ACROSS THE GREAT LAKES ON
SUNDAY. WILL LET THE GALE WARNING EXPIRE AT 21Z THIS AFTERNOON
WITH A SMALL CRAFT ADVISORY TAKING OVER IN THE NEARSHORE ZONES
THEREAFTER. WINDS SHOULD STAY OUT OF THE NORTH TO NORTHWEST
THROUGHOUT MOST OF THE FORECAST PERIOD WITH NO STRONG CASES FOR
GALES THROUGHOUT AS WE STAY STUCK IN THE SAME WEATHER PATTERN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 6 AM SUNDAY.
&&
$$
000
FXUS63 KLOT 180441
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1041 PM CST SAT JAN 17 2009
.DISCUSSION...
931 PM CST
EVENING UPDATE...REGIONAL RADAR COMPOSITE LOOP SHOWS THAT THE SNOW
AREA HAS SLOWLY DROPPED SOUTH TO APPROXIMATELY ALONG THE I-80
CORRIDOR DURING THE FIRST HALF OF THE EVENING AS A MINOR SHORT WAVE
TROUGH MOVES ACROSS FAR SOUTHEAST WI AND NORTHWEST IL. PROFILER
WINDS FROM BLUE RIVER WI SITE SHOW VEERING WITH MID LEVEL TROF
PASSAGE THAT OCCURRED AT 23Z. ACROSS FAR SOUTHERN PORTIONS OF THE
FORECAST AREA CLOUD TOPS MARGINAL FOR ICE CRYSTAL FORMATION SO
SOME FREEZING DRIZZLE LIKELY MIXED IN WITH THE SNOW.
AS THE SHORT WAVE CONTINUES TO ROTATE ACROSS THE AREA THE SNOW
WILL CONTINUE TO MOVE OFF TO THE SOUTHEAST AND EAST TONIGHT.
ANOTHER MINOR WAVE DIVING SOUTH ACROSS THE EASTERN DAKOTAS AND
WESTERN MN WITH SNOW SPREADING INTO NORTHWEST IA. THIS IMPULSE WILL
MOVE OVER THE MID MS VALLEY OVERNIGHT WITH ASSOCIATED PRECIP
PASSING TO THE WEST AND SOUTHWEST OF THE LOCAL FORECAST AREA.
LATEST NAM12 OUTPUT SHOWS SOME UVV IN THE LOWER TO MID LEVELS
ACROSS NORTHEAST IL 06Z-09Z BUT HAVE YET TO DETECT ANY
DISTURBANCES UPSTREAM TO ASSOCIATE WITH. MODEL DOES NOT SPIT OUT
ANT QPF IN NORTHERN IL DURING THE OVERNIGHT SO WILL KEEP ONLY
MENTION OF FLURRIES FOR THE LATE NIGHT.
TRS
PREVIOUS DISCUSSION
241 PM CST
OCCASIONAL LIGHT SNOW WILL OCCUR TONIGHT OVER NORTH CENTRAL ILLINOIS
...NORTHEAST ILLINOIS AND NORTHWEST INDIANA. SOME LAKE EFFECT SNOW
IS EXPECTED MONDAY IN NORTHWEST INDIANA.
TONIGHT...THE FRONT WILL MOVE THROUGH THIS EVENING. WE USED A LOCALLY
RUN WRF MODEL FOR THE FORECAST EASTWARD MOVEMENT OF THE FRONT.
SOME COLDER AIR MAY REACH NORTHERN ILLINOIS AND NORTHWEST INDIANA.
BUT THE AIR WILL NOT BE AS COLD AS THE PAST FEW DAYS. THE FRONT
WILL PROVIDE ENOUGH LIFT FOR SCATTERED LIGHT SNOW SHOWERS. WE WILL
KEEP THESE SNOW SHOWERS IN THE FORECAST GRIDS TONIGHT.
SUNDAY THROUGH MONDAY...A LARGE 500 MB WAVE TROUGH WILL BE OVER
THE GREAT LAKES THROUGH 00 UTC TUESDAY. THERE WILL BE SCATTERED
LIGHT SNOW SHOWERS SUNDAY AND SUNDAY NIGHT. THERE WILL BE A
NORTHWEST WIND OVER LAKE MICHIGAN AND IT WILL HAVE A FETCH ALONG
THE NORTH TO SOUTH AXIS OF THE LAKE. THE GFS MODELS SHOWS A BAND
OF CONVERGENCE FROM THE NORTH PART LAKE MICHIGAN TO NORTHWEST
INDIANA ON MONDAY. WE WILL FORECAST SOME LAKE EFFECT SNOW FOR
MONDAY FOR NORTHWEST INDIANA.
TUESDAY THROUGH SATURDAY...A SURFACE HIGH PRESSURE RIDGE WILL
MOVE INTO ILLINOIS MONDAY NIGHT. THIS RIDGE WILL BE ABSORBED INTO
A LARGER HIGH PRESSURE AREA OVER OKLAHOMA TUESDAY MORNING. THIS
HIGH WILL MOVE INTO TEXAS AND WILL SPREAD FROM TEXAS TO QUEBEC. A
WEAK SURFACE TROUGH WILL MOVE INTO THE GREAT LAKES WEDNESDAY
MORNING. WE ARE NOT SURE OF ANY PRECIPITATION WITH THIS TROUGH. BY
WEDNESDAY NIGHT...A HIGH WILL BE OVER MISSOURI. THE HIGH
TEMPERATURES WILL BE IN THE 20S AND THE LOW TEMPERATURES WILL BE
IN THE TEENS THROUGH THURSDAY. A LOW WILL MOVE INTO NORTHERN
WISCONSIN BY THURSDAY EVENING. WE HAVE A CHANCE OF PRECIPITATION
FOR NORTHEAST ILLINOIS AND NORTHWEST INDIANA FRIDAY. A LARGE HIGH
WILL SPREAD FROM THE CANADIAN ROCKY MOUNTAINS TO ILLINOIS BY
SATURDAY. THIS WILL LOWER THE HIGH AND LOW TEMPERATURES ON
SATURDAY. WE USED THE ECMWF MODEL FOR OUR FORECAST.
&&
.AVIATION...
0600 UTC TAFS...WEAK SHORTWAVE RESPONSIBLE FOR THE SNOW SHOWERS
SAT EVENING IS QUICKLY EXITING THE AREA. A COUPLE TAILS OF STRATUS
LINGER BACK INTO WISCONSIN AND THESE STREAKS OF STRATUS HAVE BEEN
LEAKING OUT SOME SHSN AT TIMES...BUT ANY LINGERING SNOW SHOWERS
WOULD LIKELY BE THE EXCEPTION RATHER THAN THE RULE SO KEPT TAFS
DRY EXCEPT FOR RFD WHICH APPEARS TO BE IN LINE TO GET AFFECTED BY
ONE OF THESE LEAKY BANDS OF STRATUS. SATELLITE AND UPSTREAM OBS
INDICATE THAT A TREND TOWARD SCATTERING OUT OF THE CLOUDINESS
SHOULD OCCUR OVERNIGHT. HOLES IN THE CLOUDINESS MAY TEND TO FILL
IN WITH STRATOCUMULUS BY MIDDAY SUNDAY...THOUGH GENERALLY EXPECT
ANY BKN CIGS THAT DO DEVELOP TO REMAIN VFR TO POSSIBLY HIGH END
MVFR. BEST FORCING FOR -SN/-SHSN SHOULD GENERALLY REMAIN WEST OF
THE TERMINALS SUNDAY THOUGH A COUPLE FLURRIES CANNOT BE RULED OUT.
IZZI
&&
.MARINE...
200 PM CST
WINDS PICKED UP TO GALE FORCE ACROSS THE SOUTHERN HALF OF THE LAKE
THIS MORNING...BUT SHOULD CONTINUE A GRADUAL DECLINE IN SPEEDS
THROUGH TONIGHT AS A LOW PRESSURE SYSTEM NEARS THE MID PORTION OF
THE LAKE. WINDS WILL AROUND TO THE NORTHWEST TONIGHT AS THE LOW
MOVES INTO MICHIGAN AND TRACKS EASTWARD ACROSS THE GREAT LAKES ON
SUNDAY. WILL LET THE GALE WARNING EXPIRE AT 21Z THIS AFTERNOON
WITH A SMALL CRAFT ADVISORY TAKING OVER IN THE NEARSHORE ZONES
THEREAFTER. WINDS SHOULD STAY OUT OF THE NORTH TO NORTHWEST
THROUGHOUT MOST OF THE FORECAST PERIOD WITH NO STRONG CASES FOR
GALES THROUGHOUT AS WE STAY STUCK IN THE SAME WEATHER PATTERN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 6 AM SUNDAY.
&&
$$
000
FXUS63 KLOT 180332
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
932 PM CST SAT JAN 17 2009
.DISCUSSION...
931 PM CST
EVENING UPDATE...REGIONAL RADAR COMPOSITE LOOP SHOWS THAT THE SNOW
AREA HAS SLOWLY DROPPED SOUTH TO APPROXIMATELY ALONG THE I-80
CORRIDOR DURING THE FIRST HALF OF THE EVENING AS A MINOR SHORT WAVE
TROUGH MOVES ACROSS FAR SOUTHEAST WI AND NORTHWEST IL. PROFILER
WINDS FROM BLUE RIVER WI SITE SHOW VEERING WITH MID LEVEL TROF
PASSAGE THAT OCCURRED AT 23Z. ACROSS FAR SOUTHERN PORTIONS OF THE
FORECAST AREA CLOUD TOPS MARGINAL FOR ICE CRYSTAL FORMATION SO
SOME FREEZING DRIZZLE LIKELY MIXED IN WITH THE SNOW.
AS THE SHORT WAVE CONTINUES TO ROTATE ACROSS THE AREA THE SNOW
WILL CONTINUE TO MOVE OFF TO THE SOUTHEAST AND EAST TONIGHT.
ANOTHER MINOR WAVE DIVING SOUTH ACROSS THE EASTERN DAKOTAS AND
WESTERN MN WITH SNOW SPREADING INTO NORTHWEST IA. THIS IMPULSE WILL
MOVE OVER THE MID MS VALLEY OVERNIGHT WITH ASSOCIATED PRECIP
PASSING TO THE WEST AND SOUTHWEST OF THE LOCAL FORECAST AREA.
LATEST NAM12 OUTPUT SHOWS SOME UVV IN THE LOWER TO MID LEVELS
ACROSS NORTHEAST IL 06Z-09Z BUT HAVE YET TO DETECT ANY
DISTURBANCES UPSTREAM TO ASSOCIATE WITH. MODEL DOES NOT SPIT OUT
ANT QPF IN NORTHERN IL DURING THE OVERNIGHT SO WILL KEEP ONLY
MENTION OF FLURRIES FOR THE LATE NIGHT.
TRS
PREVIOUS DISCUSSION
241 PM CST
OCCASIONAL LIGHT SNOW WILL OCCUR TONIGHT OVER NORTH CENTRAL ILLINOIS
...NORTHEAST ILLINOIS AND NORTHWEST INDIANA. SOME LAKE EFFECT SNOW
IS EXPECTED MONDAY IN NORTHWEST INDIANA.
TONIGHT...THE FRONT WILL MOVE THROUGH THIS EVENING. WE USED A LOCALLY
RUN WRF MODEL FOR THE FORECAST EASTWARD MOVEMENT OF THE FRONT.
SOME COLDER AIR MAY REACH NORTHERN ILLINOIS AND NORTHWEST INDIANA.
BUT THE AIR WILL NOT BE AS COLD AS THE PAST FEW DAYS. THE FRONT
WILL PROVIDE ENOUGH LIFT FOR SCATTERED LIGHT SNOW SHOWERS. WE WILL
KEEP THESE SNOW SHOWERS IN THE FORECAST GRIDS TONIGHT.
SUNDAY THROUGH MONDAY...A LARGE 500 MB WAVE TROUGH WILL BE OVER
THE GREAT LAKES THROUGH 00 UTC TUESDAY. THERE WILL BE SCATTERED
LIGHT SNOW SHOWERS SUNDAY AND SUNDAY NIGHT. THERE WILL BE A
NORTHWEST WIND OVER LAKE MICHIGAN AND IT WILL HAVE A FETCH ALONG
THE NORTH TO SOUTH AXIS OF THE LAKE. THE GFS MODELS SHOWS A BAND
OF CONVERGENCE FROM THE NORTH PART LAKE MICHIGAN TO NORTHWEST
INDIANA ON MONDAY. WE WILL FORECAST SOME LAKE EFFECT SNOW FOR
MONDAY FOR NORTHWEST INDIANA.
TUESDAY THROUGH SATURDAY...A SURFACE HIGH PRESSURE RIDGE WILL
MOVE INTO ILLINOIS MONDAY NIGHT. THIS RIDGE WILL BE ABSORBED INTO
A LARGER HIGH PRESSURE AREA OVER OKLAHOMA TUESDAY MORNING. THIS
HIGH WILL MOVE INTO TEXAS AND WILL SPREAD FROM TEXAS TO QUEBEC. A
WEAK SURFACE TROUGH WILL MOVE INTO THE GREAT LAKES WEDNESDAY
MORNING. WE ARE NOT SURE OF ANY PRECIPITATION WITH THIS TROUGH. BY
WEDNESDAY NIGHT...A HIGH WILL BE OVER MISSOURI. THE HIGH
TEMPERATURES WILL BE IN THE 20S AND THE LOW TEMPERATURES WILL BE
IN THE TEENS THROUGH THURSDAY. A LOW WILL MOVE INTO NORTHERN
WISCONSIN BY THURSDAY EVENING. WE HAVE A CHANCE OF PRECIPITATION
FOR NORTHEAST ILLINOIS AND NORTHWEST INDIANA FRIDAY. A LARGE HIGH
WILL SPREAD FROM THE CANADIAN ROCKY MOUNTAINS TO ILLINOIS BY
SATURDAY. THIS WILL LOWER THE HIGH AND LOW TEMPERATURES ON
SATURDAY. WE USED THE ECMWF MODEL FOR OUR FORECAST.
&&
.AVIATION...
0000 UTC TAFS...MVFR CONDITIONS EXPECTED TO PREVAIL THIS EVENING
WITH LIGHT SNOW LIKELY RESULTING IN VSBYS 3-5SM...THOUGH SOME
BRIEF REDUCTIONS TO IFR VSBYS POSSIBLE IN THE SLIGHTLY HEAVIER
SNOW SHOWERS. WEST WINDS WILL TEND MORE NW WITH TIME THIS EVENING
WITH SOME GUSTS IN THE 20-25KT RANGE EXPECTED WITH THE
STRENGTHENING COLD AIR ADVECTION. WHILE THE LIGHT SNOW REALLY NOT
LIKELY TO ACCUMULATE...THE GUSTY WINDS COULD BLOW SOME SNOW
AROUND A BIT AND MAYBE DRIFT SOME OF THE OLDER SNOW BACK ONTO
RUNWAYS MAKING FOR A FEW CLICK SPOTS. COULD SEE A TOUCH OF LIGHT
SNOW/FLURRY ACTIVITY THROUGH THE NIGHT...THE GREATER CHANCES ARE
EARLY IN THE TAF CYCLE AND KEPT CONDITIONS VFR FOLLOWING THIS
FIRST WAVE OF SNOW. MVFR CIGS LIKELY TO HOLD THROUGH MUCH OF
TONIGHT...THOUGH COULD SEE CIGS RISE SOME TO LOW END VFR LATE
TONIGHT INTO SUNDAY. OVERALL WEATHER SHOULD HAVE RELATIVELY LOW
IMPACTS ON AVIATION THROUGH THIS TAF CYCLE.
IZZI
&&
.MARINE...
200 PM CST
WINDS PICKED UP TO GALE FORCE ACROSS THE SOUTHERN HALF OF THE LAKE
THIS MORNING...BUT SHOULD CONTINUE A GRADUAL DECLINE IN SPEEDS
THROUGH TONIGHT AS A LOW PRESSURE SYSTEM NEARS THE MID PORTION OF
THE LAKE. WINDS WILL AROUND TO THE NORTHWEST TONIGHT AS THE LOW
MOVES INTO MICHIGAN AND TRACKS EASTWARD ACROSS THE GREAT LAKES ON
SUNDAY. WILL LET THE GALE WARNING EXPIRE AT 21Z THIS AFTERNOON
WITH A SMALL CRAFT ADVISORY TAKING OVER IN THE NEARSHORE ZONES
THEREAFTER. WINDS SHOULD STAY OUT OF THE NORTH TO NORTHWEST
THROUGHOUT MOST OF THE FORECAST PERIOD WITH NO STRONG CASES FOR
GALES THROUGHOUT AS WE STAY STUCK IN THE SAME WEATHER PATTERN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 6 AM SUNDAY.
&&
$$
000
FXUS63 KLOT 172315
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
515 PM CST SAT JAN 17 2009
.DISCUSSION...
241 PM CST
OCCASIONAL LIGHT SNOW WILL OCCUR TONIGHT OVER NORTH CENTRAL ILLINOIS
...NORTHEAST ILLINOIS AND NORTHWEST INDIANA. SOME LAKE EFFECT SNOW
IS EXPECTED MONDAY IN NORTHWEST INDIANA.
TONIGHT...THE FRONT WILL MOVE THROUGH THIS EVENING. WE USED A LOCALLY
RUN WRF MODEL FOR THE FORECAST EASTWARD MOVEMENT OF THE FRONT.
SOME COLDER AIR MAY REACH NORTHERN ILLINOIS AND NORTHWEST INDIANA.
BUT THE AIR WILL NOT BE AS COLD AS THE PAST FEW DAYS. THE FRONT
WILL PROVIDE ENOUGH LIFT FOR SCATTERED LIGHT SNOW SHOWERS. WE WILL
KEEP THESE SNOW SHOWERS IN THE FORECAST GRIDS TONIGHT.
SUNDAY THROUGH MONDAY...A LARGE 500 MB WAVE TROUGH WILL BE OVER
THE GREAT LAKES THROUGH 00 UTC TUESDAY. THERE WILL BE SCATTERED
LIGHT SNOW SHOWERS SUNDAY AND SUNDAY NIGHT. THERE WILL BE A
NORTHWEST WIND OVER LAKE MICHIGAN AND IT WILL HAVE A FETCH ALONG
THE NORTH TO SOUTH AXIS OF THE LAKE. THE GFS MODELS SHOWS A BAND
OF CONVERGENCE FROM THE NORTH PART LAKE MICHIGAN TO NORTHWEST
INDIANA ON MONDAY. WE WILL FORECAST SOME LAKE EFFECT SNOW FOR
MONDAY FOR NORTHWEST INDIANA.
TUESDAY THROUGH SATURDAY...A SURFACE HIGH PRESSURE RIDGE WILL
MOVE INTO ILLINOIS MONDAY NIGHT. THIS RIDGE WILL BE ABSORBED INTO
A LARGER HIGH PRESSURE AREA OVER OKLAHOMA TUESDAY MORNING. THIS
HIGH WILL MOVE INTO TEXAS AND WILL SPREAD FROM TEXAS TO QUEBEC. A
WEAK SURFACE TROUGH WILL MOVE INTO THE GREAT LAKES WEDNESDAY
MORNING. WE ARE NOT SURE OF ANY PRECIPITATION WITH THIS TROUGH. BY
WEDNESDAY NIGHT...A HIGH WILL BE OVER MISSOURI. THE HIGH
TEMPERATURES WILL BE IN THE 20S AND THE LOW TEMPERATURES WILL BE
IN THE TEENS THROUGH THURSDAY. A LOW WILL MOVE INTO NORTHERN
WISCONSIN BY THURSDAY EVENING. WE HAVE A CHANCE OF PRECIPITATION
FOR NORTHEAST ILLINOIS AND NORTHWEST INDIANA FRIDAY. A LARGE HIGH
WILL SPREAD FROM THE CANADIAN ROCKY MOUNTAINS TO ILLINOIS BY
SATURDAY. THIS WILL LOWER THE HIGH AND LOW TEMPERATURES ON
SATURDAY. WE USED THE ECMWF MODEL FOR OUR FORECAST.
&&
.AVIATION...
0000 UTC TAFS...MVFR CONDITIONS EXPECTED TO PREVAIL THIS EVENING
WITH LIGHT SNOW LIKELY RESULTING IN VSBYS 3-5SM...THOUGH SOME
BRIEF REDUCTIONS TO IFR VSBYS POSSIBLE IN THE SLIGHTLY HEAVIER
SNOW SHOWERS. WEST WINDS WILL TEND MORE NW WITH TIME THIS EVENING
WITH SOME GUSTS IN THE 20-25KT RANGE EXPECTED WITH THE
STRENGTHENING COLD AIR ADVECTION. WHILE THE LIGHT SNOW REALLY NOT
LIKELY TO ACCUMULATE...THE GUSTY WINDS COULD BLOW SOME SNOW
AROUND A BIT AND MAYBE DRIFT SOME OF THE OLDER SNOW BACK ONTO
RUNWAYS MAKING FOR A FEW CLICK SPOTS. COULD SEE A TOUCH OF LIGHT
SNOW/FLURRY ACTIVITY THROUGH THE NIGHT...THE GREATER CHANCES ARE
EARLY IN THE TAF CYCLE AND KEPT CONDITIONS VFR FOLLOWING THIS
FIRST WAVE OF SNOW. MVFR CIGS LIKELY TO HOLD THROUGH MUCH OF
TONIGHT...THOUGH COULD SEE CIGS RISE SOME TO LOW END VFR LATE
TONIGHT INTO SUNDAY. OVERALL WEATHER SHOULD HAVE RELATIVELY LOW
IMPACTS ON AVIATION THROUGH THIS TAF CYCLE.
IZZI
&&
.MARINE...
200 PM CST
WINDS PICKED UP TO GALE FORCE ACROSS THE SOUTHERN HALF OF THE LAKE
THIS MORNING...BUT SHOULD CONTINUE A GRADUAL DECLINE IN SPEEDS
THROUGH TONIGHT AS A LOW PRESSURE SYSTEM NEARS THE MID PORTION OF
THE LAKE. WINDS WILL AROUND TO THE NORTHWEST TONIGHT AS THE LOW
MOVES INTO MICHIGAN AND TRACKS EASTWARD ACROSS THE GREAT LAKES ON
SUNDAY. WILL LET THE GALE WARNING EXPIRE AT 21Z THIS AFTERNOON
WITH A SMALL CRAFT ADVISORY TAKING OVER IN THE NEARSHORE ZONES
THEREAFTER. WINDS SHOULD STAY OUT OF THE NORTH TO NORTHWEST
THROUGHOUT MOST OF THE FORECAST PERIOD WITH NO STRONG CASES FOR
GALES THROUGHOUT AS WE STAY STUCK IN THE SAME WEATHER PATTERN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 6 AM SUNDAY.
&&
$$
000
FXUS63 KLOT 172130
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
330 PM CST SAT JAN 17 2009
.DISCUSSION...
241 PM CST
OCCASIONAL LIGHT SNOW WILL OCCUR TONIGHT OVER NORTH CENTRAL ILLINOIS
...NORTHEAST ILLINOIS AND NORTHWEST INDIANA. SOME LAKE EFFECT SNOW
IS EXPECTED MONDAY IN NORTHWEST INDIANA.
TONIGHT...THE FRONT WILL MOVE THROUGH THIS EVENING. WE USED A LOCALLY
RUN WRF MODEL FOR THE FORECAST EASTWARD MOVEMENT OF THE FRONT.
SOME COLDER AIR MAY REACH NORTHERN ILLINOIS AND NORTHWEST INDIANA.
BUT THE AIR WILL NOT BE AS COLD AS THE PAST FEW DAYS. THE FRONT
WILL PROVIDE ENOUGH LIFT FOR SCATTERED LIGHT SNOW SHOWERS. WE WILL
KEEP THESE SNOW SHOWERS IN THE FORECAST GRIDS TONIGHT.
SUNDAY THROUGH MONDAY...A LARGE 500 MB WAVE TROUGH WILL BE OVER
THE GREAT LAKES THROUGH 00 UTC TUESDAY. THERE WILL BE SCATTERED
LIGHT SNOW SHOWERS SUNDAY AND SUNDAY NIGHT. THERE WILL BE A
NORTHWEST WIND OVER LAKE MICHIGAN AND IT WILL HAVE A FETCH ALONG
THE NORTH TO SOUTH AXIS OF THE LAKE. THE GFS MODELS SHOWS A BAND
OF CONVERGENCE FROM THE NORTH PART LAKE MICHIGAN TO NORTHWEST
INDIANA ON MONDAY. WE WILL FORECAST SOME LAKE EFFECT SNOW FOR
MONDAY FOR NORTHWEST INDIANA.
TUESDAY THROUGH SATURDAY...A SURFACE HIGH PRESSURE RIDGE WILL
MOVE INTO ILLINOIS MONDAY NIGHT. THIS RIDGE WILL BE ABSORBED INTO
A LARGER HIGH PRESSURE AREA OVER OKLAHOMA TUESDAY MORNING. THIS
HIGH WILL MOVE INTO TEXAS AND WILL SPREAD FROM TEXAS TO QUEBEC. A
WEAK SURFACE TROUGH WILL MOVE INTO THE GREAT LAKES WEDNESDAY
MORNING. WE ARE NOT SURE OF ANY PRECIPITATION WITH THIS TROUGH. BY
WEDNESDAY NIGHT...A HIGH WILL BE OVER MISSOURI. THE HIGH
TEMPERATURES WILL BE IN THE 20S AND THE LOW TEMPERATURES WILL BE
IN THE TEENS THROUGH THURSDAY. A LOW WILL MOVE INTO NORTHERN
WISCONSIN BY THURSDAY EVENING. WE HAVE A CHANCE OF PRECIPITATION
FOR NORTHEAST ILLINOIS AND NORTHWEST INDIANA FRIDAY. A LARGE HIGH
WILL SPREAD FROM THE CANADIAN ROCKY MOUNTAINS TO ILLINOIS BY
SATURDAY. THIS WILL LOWER THE HIGH AND LOW TEMPERATURES ON
SATURDAY. WE USED THE ECMWF MODEL FOR OUR FORECAST.
&&
.AVIATION...
1156 AM CST
1800 UTC TAFS...AFTER A BRIEF LULL IN THE ACTION THIS
MORNING...CONDITIONS WILL CONTINUALLY WORSEN THROUGH THE AFTERNOON
AS A WARM FRONT/TROF MOVES THROUGH THE TAF REGION. WINDS HAVE BEEN
STRONGER THAN FORECAST THIS MORNING...BUT SHOULD DIMINISH AS THE
BEST PRESSURE FALLS MOVE OFF TO THE EAST AND THE FRONT/TROF COMES
IN. WHILE A SCAN OF THE MOSAIC RADAR INITIALLY DOESNT LOOK VERY
ACTIVE...TAKING A LOOK AT METARS ACROSS MN/WI SHOWS -SN WITH VIS
RANGING FROM 1 TO 4SM. THIS SNOW IS EXPECTED TO REACH RFD AROUND
20Z AND ORD/MDW BY 22Z WHICH COINCIDES WITH THE FROPA. CIGS WILL
ALSO DROP FROM HIGH END MVFR EARLY THIS AFTERNOON TO LOW END MVFR
BY LATE AFTERNOON AFTER THE FROPA AS WELL. WINDS WILL FOLLOW SUIT
AND SHIFT FROM THE SOUTHWEST TO THE WEST AND EVENTUALLY NORTHWEST
LATER TONIGHT.
HAD SOME CONCERN THAT THERE MAY BE SOME FREEZING DRIZZLE AS
FORECAST SOUNDINGS SUGGEST THAT THERE WOULDNT BE ANY ICE
DEVELOPMENT. FROM LOOKING AT ACARS SOUNDINGS UPSTREAM...IT APPEARS
AS THOUGH THERE IS A SMALL LAYER OF ICE GROWTH IN THE UPPER LEVELS
WHICH HAS BEEN ENOUGH TO FROM THE SNOWFLAKES. WITH NO OBS
REPORTING FREEZING DRIZZLE...HAVE PULLED IT FROM THE TAF.
SNOW WILL BECOME MORE SCATTERED OVERNIGHT AND LIKELY NOT AS
INTENSE...MORE ON THE ORDER OF FLURRIES.
MVFR CONDITIONS WILL PERSIST THROUGH ALL OF THE FORECAST PERIOD
WITH SOME POSSIBLE IFR VIS DUE TO SNOW LATER THIS AFTERNOON.
HALBACH
&&
.MARINE...
200 PM CST
WINDS PICKED UP TO GALE FORCE ACROSS THE SOUTHERN HALF OF THE LAKE
THIS MORNING...BUT SHOULD CONTINUE A GRADUAL DECLINE IN SPEEDS
THROUGH TONIGHT AS A LOW PRESSURE SYSTEM NEARS THE MID PORTION OF
THE LAKE. WINDS WILL AROUND TO THE NORTHWEST TONIGHT AS THE LOW
MOVES INTO MICHIGAN AND TRACKS EASTWARD ACROSS THE GREAT LAKES ON
SUNDAY. WILL LET THE GALE WARNING EXPIRE AT 21Z THIS AFTERNOON
WITH A SMALL CRAFT ADVISORY TAKING OVER IN THE NEARSHORE ZONES
THEREAFTER. WINDS SHOULD STAY OUT OF THE NORTH TO NORTHWEST
THROUGHOUT MOST OF THE FORECAST PERIOD WITH NO STRONG CASES FOR
GALES THROUGHOUT AS WE STAY STUCK IN THE SAME WEATHER PATTERN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 3 PM SATURDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 6 AM SUNDAY.
&&
$$
000
FXUS63 KLOT 172000
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
200 PM CST SAT JAN 17 2009
.DISCUSSION...
1027 AM CST
WE WILL ADD OCCASIONAL LIGHT SNOW THIS AFTERNOON. THE SURFACE MAP
AT 16 UTC SHOWS A FRONT IN MINNESOTA AND IOWA APPROACHING
NORTHERN ILLINOIS. THERE IS SOME LIGHT SNOW WITH THIS FRONT. WE DO
NOT EXPECT ANY SIGNIFICANT ACCUMULATION. THE WIND WILL SLOWLY
DIMINISH AFTER THE FRONT PASSES THROUGH.
&&
.AVIATION...
1156 AM CST
1800 UTC TAFS...AFTER A BRIEF LULL IN THE ACTION THIS
MORNING...CONDITIONS WILL CONTINUALLY WORSEN THROUGH THE AFTERNOON
AS A WARM FRONT/TROF MOVES THROUGH THE TAF REGION. WINDS HAVE BEEN
STRONGER THAN FORECAST THIS MORNING...BUT SHOULD DIMINISH AS THE
BEST PRESSURE FALLS MOVE OFF TO THE EAST AND THE FRONT/TROF COMES
IN. WHILE A SCAN OF THE MOSAIC RADAR INITIALLY DOESNT LOOK VERY
ACTIVE...TAKING A LOOK AT METARS ACROSS MN/WI SHOWS -SN WITH VIS
RANGING FROM 1 TO 4SM. THIS SNOW IS EXPECTED TO REACH RFD AROUND
20Z AND ORD/MDW BY 22Z WHICH COINCIDES WITH THE FROPA. CIGS WILL
ALSO DROP FROM HIGH END MVFR EARLY THIS AFTERNOON TO LOW END MVFR
BY LATE AFTERNOON AFTER THE FROPA AS WELL. WINDS WILL FOLLOW SUIT
AND SHIFT FROM THE SOUTHWEST TO THE WEST AND EVENTUALLY NORTHWEST
LATER TONIGHT.
HAD SOME CONCERN THAT THERE MAY BE SOME FREEZING DRIZZLE AS
FORECAST SOUNDINGS SUGGEST THAT THERE WOULDNT BE ANY ICE
DEVELOPMENT. FROM LOOKING AT ACARS SOUNDINGS UPSTREAM...IT APPEARS
AS THOUGH THERE IS A SMALL LAYER OF ICE GROWTH IN THE UPPER LEVELS
WHICH HAS BEEN ENOUGH TO FROM THE SNOWFLAKES. WITH NO OBS
REPORTING FREEZING DRIZZLE...HAVE PULLED IT FROM THE TAF.
SNOW WILL BECOME MORE SCATTERED OVERNIGHT AND LIKELY NOT AS
INTENSE...MORE ON THE ORDER OF FLURRIES.
MVFR CONDITIONS WILL PERSIST THROUGH ALL OF THE FORECAST PERIOD
WITH SOME POSSIBLE IFR VIS DUE TO SNOW LATER THIS AFTERNOON.
HALBACH
&&
.MARINE...
200 PM CST
WINDS PICKED UP TO GALE FORCE ACROSS THE SOUTHERN HALF OF THE LAKE
THIS MORNING...BUT SHOULD CONTINUE A GRADUAL DECLINE IN SPEEDS
THROUGH TONIGHT AS A LOW PRESSURE SYSTEM NEARS THE MID PORTION OF
THE LAKE. WINDS WILL AROUND TO THE NORTHWEST TONIGHT AS THE LOW
MOVES INTO MICHIGAN AND TRACKS EASTWARD ACROSS THE GREAT LAKES ON
SUNDAY. WILL LET THE GALE WARNING EXPIRE AT 21Z THIS AFTERNOON
WITH A SMALL CRAFT ADVISORY TAKING OVER IN THE NEARSHORE ZONES
THEREAFTER. WINDS SHOULD STAY OUT OF THE NORTH TO NORTHWEST
THROUGHOUT MOST OF THE FORECAST PERIOD WITH NO STRONG CASES FOR
GALES THROUGHOUT AS WE STAY STUCK IN THE SAME WEATHER PATTERN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 3 PM SATURDAY.
&&
$$
000
FXUS63 KLOT 171852
AFDLOT
AREA FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1156 AM CST SAT JAN 17 2009
.DISCUSSION...
1027 AM CST
WE WILL ADD OCCASIONAL LIGHT SNOW THIS AFTERNOON. THE SURFACE MAP
AT 16 UTC SHOWS A FRONT IN MINNESOTA AND IOWA APPROACHING
NORTHERN ILLINOIS. THERE IS SOME LIGHT SNOW WITH THIS FRONT. WE DO
NOT EXPECT ANY SIGNIFICANT ACCUMULATION. THE WIND WILL SLOWLY
DIMINISH AFTER THE FRONT PASSES THROUGH.
&&
.AVIATION...
1156 AM CST
1800 UTC TAFS...AFTER A BRIEF LULL IN THE ACTION THIS
MORNING...CONDITIONS WILL CONTINUALLY WORSEN THROUGH THE AFTERNOON
AS A WARM FRONT/TROF MOVES THROUGH THE TAF REGION. WINDS HAVE BEEN
STRONGER THAN FORECAST THIS MORNING...BUT SHOULD DIMINISH AS THE
BEST PRESSURE FALLS MOVE OFF TO THE EAST AND THE FRONT/TROF COMES
IN. WHILE A SCAN OF THE MOSAIC RADAR INITIALLY DOESNT LOOK VERY
ACTIVE...TAKING A LOOK AT METARS ACROSS MN/WI SHOWS -SN WITH VIS
RANGING FROM 1 TO 4SM. THIS SNOW IS EXPECTED TO REACH RFD AROUND
20Z AND ORD/MDW BY 22Z WHICH COINCIDES WITH THE FROPA. CIGS WILL
ALSO DROP FROM HIGH END MVFR EARLY THIS AFTERNOON TO LOW END MVFR
BY LATE AFTERNOON AFTER THE FROPA AS WELL. WINDS WILL FOLLOW SUIT
AND SHIFT FROM THE SOUTHWEST TO THE WEST AND EVENTUALLY NORTHWEST
LATER TONIGHT.
HAD SOME CONCERN THAT THERE MAY BE SOME FREEZING DRIZZLE AS
FORECAST SOUNDINGS SUGGEST THAT THERE WOULDNT BE ANY ICE
DEVELOPMENT. FROM LOOKING AT ACARS SOUNDINGS UPSTREAM...IT APPEARS
AS THOUGH THERE IS A SMALL LAYER OF ICE GROWTH IN THE UPPER LEVELS
WHICH HAS BEEN ENOUGH TO FROM THE SNOWFLAKES. WITH NO OBS
REPORTING FREEZING DRIZZLE...HAVE PULLED IT FROM THE TAF.
SNOW WILL BECOME MORE SCATTERED OVERNIGHT AND LIKELY NOT AS
INTENSE...MORE ON THE ORDER OF FLURRIES.
MVFR CONDITIONS WILL PERSIST THROUGH ALL OF THE FORECAST PERIOD
WITH SOME POSSIBLE IFR VIS DUE TO SNOW LATER THIS AFTERNOON.
HALBACH
&&
.MARINE...
250 AM CST
HIGH PRESSURE OVER THE MID ATLANTIC REGION WILL MOVE OFF THE THE
VIRGINA COAST THIS AFTERNOON. LOW PRESSURE OVER NORTHERN
MINNESOTA WILL DROP SOUTHEAST AND TRACK ACROSS SOUTHERN LAKE
MICHIGAN THIS EVENING. THE LOW WILL THEN CONTINUE SLOWLY EAST TO
LAKE ERIE BY MONDAY MORNING. HIGH PRESSURE IS FORECAST TO BUILD
OVER THE ROCKIES AND WESTERN HIGH PLAINS SUNDAY AND MONDAY AS A
CANADIAN LOW PRESSURE SYSTEM DROPS SOUTH OUT OF MANITOBA AND OVER
THE UPPER MISSISSIPPI VALLEY.
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 3 PM SATURDAY.
&&
$$
000
FXUS63 KLOT 171756
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1156 AM CST SAT JAN 17 2009
.DISCUSSION...
1027 AM CST
WE WILL ADD OCCASIONAL LIGHT SNOW THIS AFTERNOON. THE SURFACE MAP
AT 16 UTC SHOWS A STRONG COLD FRONT IN MINNESOTA AND IOWA APPROACHING
NORTHERN ILLINOIS. THERE IS SOME LIGHT SNOW WITH THIS FRONT. WE DO
NOT EXPECT ANY SIGNIFICANT ACCUMULATION. THE WIND WILL SLOWLY
DIMINISH AFTER THE FRONT PASSES THROUGH.
&&
.AVIATION...
1156 AM CST
1800 UTC TAFS...AFTER A BRIEF LULL IN THE ACTION THIS
MORNING...CONDITIONS WILL CONTINUALLY WORSEN THROUGH THE AFTERNOON
AS A WARM FRONT/TROF MOVES THROUGH THE TAF REGION. WINDS HAVE BEEN
STRONGER THAN FORECAST THIS MORNING...BUT SHOULD DIMINISH AS THE
BEST PRESSURE FALLS MOVE OFF TO THE EAST AND THE FRONT/TROF COMES
IN. WHILE A SCAN OF THE MOSAIC RADAR INITIALLY DOESNT LOOK VERY
ACTIVE...TAKING A LOOK AT METARS ACROSS MN/WI SHOWS -SN WITH VIS
RANGING FROM 1 TO 4SM. THIS SNOW IS EXPECTED TO REACH RFD AROUND
20Z AND ORD/MDW BY 22Z WHICH COINCIDES WITH THE FROPA. CIGS WILL
ALSO DROP FROM HIGH END MVFR EARLY THIS AFTERNOON TO LOW END MVFR
BY LATE AFTERNOON AFTER THE FROPA AS WELL. WINDS WILL FOLLOW SUIT
AND SHIFT FROM THE SOUTHWEST TO THE WEST AND EVENTUALLY NORTHWEST
LATER TONIGHT.
HAD SOME CONCERN THAT THERE MAY BE SOME FREEZING DRIZZLE AS
FORECAST SOUNDINGS SUGGEST THAT THERE WOULDNT BE ANY ICE
DEVELOPMENT. FROM LOOKING AT ACARS SOUNDINGS UPSTREAM...IT APPEARS
AS THOUGH THERE IS A SMALL LAYER OF ICE GROWTH IN THE UPPER LEVELS
WHICH HAS BEEN ENOUGH TO FROM THE SNOWFLAKES. WITH NO OBS
REPORTING FREEZING DRIZZLE...HAVE PULLED IT FROM THE TAF.
SNOW WILL BECOME MORE SCATTERED OVERNIGHT AND LIKELY NOT AS
INTENSE...MORE ON THE ORDER OF FLURRIES.
MVFR CONDITIONS WILL PERSIST THROUGH ALL OF THE FORECAST PERIOD
WITH SOME POSSIBLE IFR VIS DUE TO SNOW LATER THIS AFTERNOON.
HALBACH
&&
.MARINE...
250 AM CST
HIGH PRESSURE OVER THE MID ATLANTIC REGION WILL MOVE OFF THE THE
VIRGINA COAST THIS AFTERNOON. LOW PRESSURE OVER NORTHERN
MINNESOTA WILL DROP SOUTHEAST AND TRACK ACROSS SOUTHERN LAKE
MICHIGAN THIS EVENING. THE LOW WILL THEN CONTINUE SLOWLY EAST TO
LAKE ERIE BY MONDAY MORNING. HIGH PRESSURE IS FORECAST TO BUILD
OVER THE ROCKIES AND WESTERN HIGH PLAINS SUNDAY AND MONDAY AS A
CANADIAN LOW PRESSURE SYSTEM DROPS SOUTH OUT OF MANITOBA AND OVER
THE UPPER MISSISSIPPI VALLEY.
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 3 PM SATURDAY.
&&
$$
| 
