000
FXUS61 KLWX 201456
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
956 AM EST TUE JAN 20 2009
.SYNOPSIS...
LARGE UPPER TROUGH AXIS OVER THE EASTERN UNITED STATES WILL MOVE
ACROSS THE MID ATLANTIC TODAY. HIGH PRESSURE BUILDS ACROSS THE
AREA FOR THE LATER PART OF THE WORK WEEK WITH MODERATING
TEMPERATURES. A COLD FRONT CROSSES THE REGION SATURDAY. MUCH
COLDER CONDITIONS ARE EXPECTED LATE IN THE WEEKEND.
&&
.NEAR TERM /LATE THIS MRNG AND THIS AFTERNOON/...
AN AMAZING DAY IN DC...CSTL LOW IS WELL E OF HAT...AND IT APPEARS
THAT THE SUBSIDENT RGN IS THE MAIN INFLUENCE OVR THE MID ATLC. WE
CAN`T TOTALLY RULE OUT A STRAY SNOWFLAKE FM DC AND E...AND AM
MAINTAINING THE 20 POP THRU MID AFTN. HV TAKEN A FEW DEGS OFF THE
TEMPS. W/ NW WINDS OF 15 MPH AT NOON BLV WIND CHILLS ON THE MALL
IN THE MU TEENS.
HV TWEAKED THE CLD GRIDS DOWN SLTLY...BUT THERE WL STILL BE HIGH
CLDS SO LEFT THE FCST AS M CLDY.
HV A GREAT DAY!
PRVS DSCN..
UPR AIR PATTERN CHARACTERIZED BY POSITIVELY TILTED LONGWV
TROF OVER ERN CONUS AND AMPLIFIED LONGWV RDG OVER WRN CONUS. SWLY
FLOW FOUND OVER SRN MID-ATLC RGN THIS MRNG...WITH EMBEDDED SHRTWV
TROF MOVG NEWD ACRS CAROLINAS.
CSTL SFC LOPRES OFF CAROLINAS WILL MOVE NEWD WITH SHRTWV TROF AS
LONGWV TROF AXIS MOVES ACRS MID ATLC TDA. LGT SNOW BANDS RADIATING
AWAY FROM SYSTEM WILL MOVE NWD THIS MRNG...AND MAY IMPACT SRN
PORTION OF FCST AREA THIS MRNG BFR SYSTEM DVLPS INTO ATLC.
CDFNT TO MOVE ACRS MID DAY AS UPR TROF AXIS TRANSLATES EWD. RESULT
WILL BE INCRG GUSTY NWLY TO NLY WINDS. UPSLP SHSN TO DVLP THIS
MRNG AND INCR IN INTENSITY TDA...SPCLY LATE THIS AFTN.
MOCLDY SKIES THIS MRNG MAY GIVE WAY TO PTLY SUNNY BY LATE THIS
AFTN AS TROF AXIS EXITS AND CDFNT REINFORCES DRIER AIR IN LOW
LVLS.
MAXIMA MID-UPR 20S WRN ZONES TO LOW-MID 30S ERN ZONES...RESULTING
FROM COLD AIR ADVCTN AND CLD CVR.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
UPSLP SHSN CONTS TNGT WRN SLOPES IN DP NWLY FLOW BEHIND UPR TROF
AXIS. ANY PCPN ASSOCIATED WITH ERN SYSTEM FROM THIS MRNG WILL BE
WELL E OF FCST AREA...AND HAVE DECRD POPS FOR TNGT.
PRESSURE GRADIENT WILL BE SUFFICIENT TO GENERATE WIND THIS EVE
BTWN LOPRES IN ATLC AND APRCHG SFC RDG AXIS TO W. WITH DECRG CLD
CVR TNGT AND DRY AIR...XPCG TEMPS TO DROP AFTER MIDNGT ACRS WRN
AND CNTRL ZONES IN PARTICULAR. WIND CHILL ADZY LKLY NEEDED FOR
TNGT AT LEAST ALONG ALLEGHENY FRONT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE UPPER TROUGH THAT HAS BEEN IN PLACE FOR THE PAST WEEK OVER THE
EASTERN US WILL FINALLY BEGIN TO BREAK ON WEDNESDAY. HOWEVER...THE
COLD AIR IN PLACE ABOVE THE REGION WILL NOT BE PUSHED AWAY UNTIL
THURSDAY...SO WEDNESDAY WILL BE ANOTHER DAY WITH TEMPERATURES
STRUGGLING TO REACH 32 FOR MOST OF THE AREA. THE COASTAL LOW
PRESSURE SYSTEM WILL PUSH FURTHER AWAY TUESDAY NIGHT AND ANY
ASSOCIATED PRECIP WILL BE OFF THE MID-ATLANTIC COAST BY WEDNESDAY
MORNING. UPSLOPE SNOW TAPERS OFF DURING THE DAY WEDNESDAY AS LOW
LEVEL WINDS TRANSITION FROM NW TO W AS SURFACE HIGH PRESSURE
BUILDS FROM THE WEST.
MORE ZONAL FLOW ALOFT WITH HIGHER PRESSURE AT THE SURFACE BRINGS
SUNSHINE AND EVEN SLIGHTLY ABOVE NORMAL TEMPERATURES FOR THURSDAY
AND FRIDAY. A LOW TRACKING ACROSS THE EASTERN GREAT LAKES LATE
FRIDAY INTO EARLY SATURDAY DRAGS A COLD FRONT ACROSS THE MID-
ATLANTIC ON SATURDAY BRINGING LOW CHANCES OF SNOW FRIDAY NIGHT AND
RAIN OR SNOW DURING THE DAY SATURDAY /SNOW FOR HIGHER ELEVATIONS/.
UPPER RIDGING ACROSS ALASKA NOW THROUGH THURSDAY SIGNALS AN
AMPLIFYING PATTERN WITH ANOTHER SHOT OF ARCTIC AIR DIVING DOWN
TOWARDS THE EASTERN US BY THE MIDDLE PART OF THE WEEKEND. UNDERCUT
MEX GUIDANCE A COUPLE DEGREES FOR SUNDAY IN ANTICIPATION OF A COLDER
THAN PROGGED AIR MASS.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
GUSTY NWLY WINDS TDA ALL TERMINALS AS CDFNT MOVES ACRS FCST AREA
THIS MRNG.
VFR CONDITIONS WEDNESDAY THROUGH FRIDAY AS HIGH PRESSURE RETURNS TO
THE AREA. A COLD FRONT APPROACHES FRIDAY NIGHT BEFORE CROSSING THE
MID-ATLANTIC SATURDAY MORNING BRINGING SMALL CHANCES OF PRECIP AND
SUBVFR CONDITIONS.
&&
.MARINE...
SMALL CRAFT ADZY CONTS ALL ZONES AS PRESSURE GRADIENT INCRS TDA
WITH PSG OF CDFNT AND ARRIVAL OF GUSTY NWLY WINDS.
SMALL CRAFT CONDITIONS THROUGH MIDDAY WEDNESDAY OVER THE BAY AS
GUSTY NORTHWESTERLY WINDS EASE AND BECOME WESTERLY AS HIGH PRESSURE
BUILDS IN FROM THE WEST. RIVER/BAY ICE TO BEGIN TO MELT THURSDAY
WITH TEMPERATURES REACHING THE LOWER 40S ACROSS THE WATERS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ530>537.
&&
$$
UPDATE...WOODY!
PRVS...MRK/BAJ
000
FXUS61 KLWX 200856
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
356 AM EST TUE JAN 20 2009
.SYNOPSIS...
LARGE UPPER TROUGH AXIS OVER THE EASTERN UNITED STATES WILL MOVE
ACROSS THE MID ATLANTIC TODAY. HIGH PRESSURE BUILDS ACROSS THE
AREA FOR THE LATER PART OF THE WORK WEEK WITH MODERATING
TEMPERATURES. A COLD FRONT CROSSES THE REGION SATURDAY. MUCH
COLDER CONDITIONS ARE EXPECTED LATE IN THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPR AIR PATTERN CHARACTERIZED BY POSITIVELY TILTED LONGWV TROF
OVER ERN CONUS AND AMPLIFIED LONGWV RDG OVER WRN CONUS. SWLY FLOW
FOUND OVER SRN MID-ATLC RGN THIS MRNG...WITH EMBEDDED SHRTWV TROF
MOVG NEWD ACRS CAROLINAS.
CSTL SFC LOPRES OFF CAROLINAS WILL MOVE NEWD WITH SHRTWV TROF AS
LONGWV TROF AXIS MOVES ACRS MID ATLC TDA. LGT SNOW BANDS RADIATING
AWAY FROM SYSTEM WILL MOVE NWD THIS MRNG...AND MAY IMPACT SRN
PORTION OF FCST AREA THIS MRNG BFR SYSTEM DVLPS INTO ATLC.
CDFNT TO MOVE ACRS MID DAY AS UPR TROF AXIS TRANSLATES EWD. RESULT
WILL BE INCRG GUSTY NWLY TO NLY WINDS. UPSLP SHSN TO DVLP THIS
MRNG AND INCR IN INTENSITY TDA...SPCLY LATE THIS AFTN.
MOCLDY SKIES THIS MRNG MAY GIVE WAY TO PTLY SUNNY BY LATE THIS
AFTN AS TROF AXIS EXITS AND CDFNT REINFORCES DRIER AIR IN LOW
LVLS.
MAXIMA MID-UPR 20S WRN ZONES TO LOW-MID 30S ERN ZONES...RESULTING
FROM COLD AIR ADVCTN AND CLD CVR.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
UPSLP SHSN CONTS TNGT WRN SLOPES IN DP NWLY FLOW BEHIND UPR TROF
AXIS. ANY PCPN ASSOCIATED WITH ERN SYSTEM FROM THIS MRNG WILL BE
WELL E OF FCST AREA...AND HAVE DECRD POPS FOR TNGT.
PRESSURE GRADIENT WILL BE SUFFICIENT TO GENERATE WIND THIS EVE
BTWN LOPRES IN ATLC AND APRCHG SFC RDG AXIS TO W. WITH DECRG CLD
CVR TNGT AND DRY AIR...XPCG TEMPS TO DROP AFTER MIDNGT ACRS WRN
AND CNTRL ZONES IN PARTICULAR. WIND CHILL ADZY LKLY NEEDED FOR
TNGT AT LEAST ALONG ALLEGHENY FRONT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE UPPER TROUGH THAT HAS BEEN IN PLACE FOR THE PAST WEEK OVER THE
EASTERN US WILL FINALLY BEGIN TO BREAK ON WEDNESDAY. HOWEVER...THE
COLD AIR IN PLACE ABOVE THE REGION WILL NOT BE PUSHED AWAY UNTIL
THURSDAY...SO WEDNESDAY WILL BE ANOTHER DAY WITH TEMPERATURES
STRUGGLING TO REACH 32 FOR MOST OF THE AREA. THE COASTAL LOW
PRESSURE SYSTEM WILL PUSH FURTHER AWAY TUESDAY NIGHT AND ANY
ASSOCIATED PRECIP WILL BE OFF THE MID-ATLANTIC COAST BY WEDNESDAY
MORNING. UPSLOPE SNOW TAPERS OFF DURING THE DAY WEDNESDAY AS LOW
LEVEL WINDS TRANSITION FROM NW TO W AS SURFACE HIGH PRESSURE
BUILDS FROM THE WEST.
MORE ZONAL FLOW ALOFT WITH HIGHER PRESSURE AT THE SURFACE BRINGS
SUNSHINE AND EVEN SLIGHTLY ABOVE NORMAL TEMPERATURES FOR THURSDAY
AND FRIDAY. A LOW TRACKING ACROSS THE EASTERN GREAT LAKES LATE
FRIDAY INTO EARLY SATURDAY DRAGS A COLD FRONT ACROSS THE MID-
ATLANTIC ON SATURDAY BRINGING LOW CHANCES OF SNOW FRIDAY NIGHT AND
RAIN OR SNOW DURING THE DAY SATURDAY /SNOW FOR HIGHER ELEVATIONS/.
UPPER RIDGING ACROSS ALASKA NOW THROUGH THURSDAY SIGNALS AN
AMPLIFYING PATTERN WITH ANOTHER SHOT OF ARCTIC AIR DIVING DOWN
TOWARDS THE EASTERN US BY THE MIDDLE PART OF THE WEEKEND. UNDERCUT
MEX GUIDANCE A COUPLE DEGREES FOR SUNDAY IN ANTICIPATION OF A COLDER
THAN PROGGED AIR MASS.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
GUSTY NWLY WINDS TDA ALL TERMINALS AS CDFNT MOVES ACRS FCST AREA
THIS MRNG. CIGS AOA 4KFT. AFTER ISSUANCE OF PCKG...WILL EXAMINE
PSBLTY OF LGT SNOW AT KDCA AND KCHO THIS MRNG. AMENDMENTS PSBL.
VFR CONDITIONS WEDNESDAY THROUGH FRIDAY AS HIGH PRESSURE RETURNS TO
THE AREA. A COLD FRONT APPROACHES FRIDAY NIGHT BEFORE CROSSING THE
MID-ATLANTIC SATURDAY MORNING BRINGING SMALL CHANCES OF PRECIP AND
SUBVFR CONDITIONS.
&&
.MARINE...
SMALL CRAFT ADZY CONTS ALL ZONES AS PRESSURE GRADIENT INCRS TDA
WITH PSG OF CDFNT AND ARRIVAL OF GUSTY NWLY WINDS. HAVE SOME
SKEPTICISM THAT SMALL CRAFT ADZY CONDITIONS LKLY ON FROZEN
PORTIONS OF CHSPK BAY AND POTOMAC OWING TO LACK OF INSTBY-RELATED
MIXING /OBS SHOW GUSTS TO NEAR 20 KT ALL SITES BUT FROZEN ZONES/...
BUT WILL CONT INHERITED ADZY FOR NOW.
SMALL CRAFT CONDITIONS THROUGH MIDDAY WEDNESDAY OVER THE BAY AS
GUSTY NORTHWESTERLY WINDS EASE AND BECOME WESTERLY AS HIGH PRESSURE
BUILDS IN FROM THE WEST. RIVER/BAY ICE TO BEGIN TO MELT THURSDAY
WITH TEMPERATURES REACHING THE LOWER 40S ACROSS THE WATERS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ530>537.
&&
$$
KRAMAR/BAJ
000
FXUS61 KLWX 200043
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
743 PM EST MON JAN 19 2009
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL REMAIN ACROSS THE REGION THROUGH
TUESDAY. HIGH PRESSURE BUILDS ACROSS THE AREA DURING THE MID TO
LATE WEEK. TEMPERATURES WILL MODERATE TOWARD THE END OF THE WEEK.
UNSETTLED CONDITIONS MAY RETURN OVER THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
S/WV HAS FINALLY KICKED OUT OF N-CNTRL CWFA...PERMITTING CDFNT TO
FINALLY SNEAK EWD. HV CONSEQUENTLY NOTICED PCPN DRYING UP. KTHV
DROPPED FM TEMP 18/TD 16 TO TEMP 11/TD 8 IN PAST HR. THINK PCPN
JUST ABT BE DONE FOR NGT...AND FEEL LIKE ITS TIME TO CANX WSW.
SKIES ACRS MUCH OF VA HV PARTIALLY CLRD...PERMITTING A QUICK FRZ.
WL NEED TO WATCH MD CNTYS FOR ICY CONDS OVNGT. TEMP/DEWPT FCSTS
OVNGT WL BE A CHALLENGE...AS ANTICIPATE A QUICK FALL AT MANY
STATIONS LIKE WHAT THV EXPERIENCED. PRVS FCST APPEARS REASONABLE
IN THAT ASPECT...COOLER THAN LAMP...AND HV MADE ONLY MINOR TWEAKS
ATTM. MAY NEED FUTURE REVISIONS
ALSO XPCT UPSLP SHSN TO COMMENCE SHORTLY...AND COND THRU THE NGT.
POPS CONT IN THE W. WL ASSESS NEED FOR ADVY INT HE HRS TO COME.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
A MODEL CONSENSUS FOR THE COASTAL LOW WAS REACHED W/ THE 12Z
RUNS...AS THE SOLUTION LOOKS LIKE A COUPLE OF LOWS WILL DEVELOP
OFF THE CAROLINAS THRU THE NEXT DAY. A SFC LOW MOVING OFF THE NC/SC
COAST FROM THE COASTAL AREAS WILL DEEPEN THRU THE OVERNIGHT HRS AND
SLIDE QUICKLY OFF TO THE NE. THIS LOW WILL BE NO CONSEQUENCE TO THE
MID ATLC...BUT THE SECOND LOW THAT DIRECTLY OFF THE COAST OF CAPE
HATTERAS THRU THE MRNG/EARLY AFTN HRS TUE.
A LOW PROBABILITY THAT A PRECIP BAND OR TWO MAY DEVELOP ACROSS THE
I-95 CORRIDOR OF NRN VA...AFFECTING MAINLY SRN MD. A BRIEF PERIOD OF
THIS ACTIVITY MAY BE SLIDE ACROSS THE DISTRICT DURING THE EARLY AFTN
HRS...THO THIS WILL MOST LIKELY BE A IN THE FORM OF FLURRIES AND
LITTLE TO NO ACCUMULATION W/ ANY ACTIVITY...DC OR OTHERWISE. PERIODS
OF MOSTLY CLOUDY SKIES W/ INTERMITTENT BREAKS IN THE CLOUDS DURING
THE LATE MRNG AND EARLY AFTN HRS.
TEMPS WILL BARELY REACH OR FALL A DEGREE OR TWO SHORT OF FREEZING
DURING THE PEAK HEATING OF THE AFTN...SO THE EARLY MRNG HRS WILL
MOSTLY BE RECOVERING FROM OVERNIGHT LOWS IN THE L/M20S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
WILL KEEP SLIGHT CHANCE POPS ACROSS LOWER SOUTHERN MARYLAND EARLY IN
THE EVENING TUESDAY PER 12Z GFS...BUT MOST OF THE CONSENSUS IS FOR
PRECIPITATION ASSOCIATED WITH THE COASTAL SYSTEM TO BE TO OUR EAST.
UPSLOPE SNOW ACROSS THE HIGHLANDS MAY LEAD TO LIGHT ACCUMULATIONS
TUESDAY NIGHT. WIND CHILL VALUES ACROSS THE HIGHLANDS MAY ALSO BE
BELOW ZERO.
A MORE ZONAL FLOW WITH HIGH PRESSURE AT THE SURFACE TAKES HOLD FOR
THE REST OF THE WEEK...WITH MODERATING TEMPERATURES BY THURSDAY.
GIVEN THE EMPHASIS AND FOCUS ON TODAYS SNOW EVENT IN SOME
AREAS...DAYS 4 THROUGH 7 WERE POPULATED USING HPC GUIDANCE WHICH
HIGHLIGHTS LOW CHANCES OF PRECIPITATION OVER THE WEEKEND AND COOLER
TEMPERATURES RELATIVE TO THURSDAY/FRIDAY.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
FCST CONDS TO IMPV TO VFR BY 03Z...AND CONTG THRU THE NGT. 00Z OBS
INDICATE LOW CLDS HV ALREADY SCTD OUT. ANTICIPATE CIGS TO
RTN...BUT ABV 3000 FT. A NWLY FLOW WL PICK UP...AND CONT OVNGT. WL
NEED TO WATCH FOR FZFG IN CASE WNDS DONT PROVIDE ENUF MIXING
BEFORE LWR DEWPTS ARRIVE.
CSTL LOW WL EMERGE OFF KHSE AND TRAVEL NE TMRW. THINK TERMINALS WL
BE FAR ENUF RMVD FM ANY PCPN. KEEPING VFR CIGS /ARND 4K FT/ AND
NLY WNDS 10-20 KT.
HIGH PRESSURE BUILDS IN LATE IN THE WEEK...WITH UNSETTLED CONDITIONS
POSSIBLY RETURNING ON THE WEEKEND.
&&
.MARINE...
WINDS ACROSS THE BAY SHOULD BE LIGHT THRU THE AFTN/EVNG HRS. SCA
CONDITIONS WILL ARISE DURING THE OVERNIGHT HRS ACROSS THE ICE WATER
PORTIONS OF THE TIDAL PTMC AND THE BAY.
SMALL CRAFT ADVISORY CONTINUES TUESDAY NIGHT WITH A GUSTY NORTHWEST
SURGE...AND MAY NEED TO BE EXTENDED INTO AT LEAST PART OF WEDNESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ530>537.
&&
$$
SYNOPSIS...PELOQUIN
NEAR TERM...HTS
SHORT TERM...GMS
LONG TERM...PELOQUIN
AVIATION...HTS/PELOQUIN
MARINE...GMS/PELOQUIN
000
FXUS61 KLWX 192019
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
319 PM EST MON JAN 19 2009
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL REMAIN ACROSS THE REGION THROUGH
TUESDAY. HIGH PRESSURE BUILDS ACROSS THE AREA DURING THE MID TO
LATE WEEK. TEMPERATURES WILL MODERATE TOWARD THE END OF THE WEEK.
UNSETTLED CONDITIONS MAY RETURN OVER THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
THE AREA BETWEEN I-66 AND I-81 AND ESPECIALLY NORTH AND EAST OF THE
POTOMAC RIVER VLY HAS BEEN THE BULLSEYE FOR ACCUMULATING SNOWS
TODAY. MOST AREAS WITHIN THIS QUADRANT HAVE RECEIVED 1-2 INCHES...W/
SURROUNDING AREAS OF A HALF INCH TO A DUSTING. AND IMMEDIATELY
BEHIND THE HEAVIER SNOW BANDS...MOSTLY SUNNY SKIES. ISOLATED
CONVECTIVE-TYPE SNOW SHOWERS WILL CONTINUE TO DEVELOP AND SLIDE ENE
ACROSS THE SAME AREAS STILL UNDER THE WW ADZY THRU LATE EVNG. THE
SLIGHT AMOUNTS OF INSTABILITY STILL LINGERING. AND W/ THE SUDDEN
APPEARANCE OF SUNLIGHT...A BIT MORE INSTABILITY DEVELOPING THRU THE
REMAINDER OF THE AFTN. EXPECT CONTINUED SCATTERED TO ISOLATED SNOW
SHOWERS SLIDING EWD OVER THE NRN SHENANDOAH VLY...AND EVEN ISOLATED
ACTIVITY ACROSS N CNTRL VA /ALONG THE I-64 CORRIDOR.
OVERNIGHT...MUCH OF THE ACTIVITY WILL HAVE DISSIPATED ACROSS THE
PIEDMONT REGION NEAR SUNSET. A FEW ISOLATED UPSLOPE SNOW SHOWERS
STILL EXPECTED ACROSS THE CNTRL APLCNS.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
A MODEL CONSENSUS FOR THE COASTAL LOW WAS REACHED W/ THE 12Z
RUNS...AS THE SOLUTION LOOKS LIKE A COUPLE OF LOWS WILL DEVELOP
OFF THE CAROLINAS THRU THE NEXT DAY. A SFC LOW MOVING OFF THE NC/SC
COAST FROM THE COASTAL AREAS WILL DEEPEN THRU THE OVERNIGHT HRS AND
SLIDE QUICKLY OFF TO THE NE. THIS LOW WILL BE NO CONSEQUENCE TO THE
MID ATLC...BUT THE SECOND LOW THAT DIRECTLY OFF THE COAST OF CAPE
HATTERAS THRU THE MRNG/EARLY AFTN HRS TUE.
A LOW PROBABILITY THAT A PRECIP BAND OR TWO MAY DEVELOP ACROSS THE
I-95 CORRIDOR OF NRN VA...AFFECTING MAINLY SRN MD. A BRIEF PERIOD OF
THIS ACTIVITY MAY BE SLIDE ACROSS THE DISTRICT DURING THE EARLY AFTN
HRS...THO THIS WILL MOST LIKELY BE A IN THE FORM OF FLURRIES AND
LITTLE TO NO ACCUMULATION W/ ANY ACTIVITY...DC OR OTHERWISE. PERIODS
OF MOSTLY CLOUDY SKIES W/ INTERMITTENT BREAKS IN THE CLOUDS DURING
THE LATE MRNG AND EARLY AFTN HRS.
TEMPS WILL BARELY REACH OR FALL A DEGREE OR TWO SHORT OF FREEZING
DURING THE PEAK HEATING OF THE AFTN...SO THE EARLY MRNG HRS WILL
MOSTLY BE RECOVERING FROM OVERNIGHT LOWS IN THE L/M20S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
WILL KEEP SLIGHT CHANCE POPS ACROSS LOWER SOUTHERN MARYLAND EARLY IN
THE EVENING TUESDAY PER 12Z GFS...BUT MOST OF THE CONSENSUS IS FOR
PRECIPITATION ASSOCIATED WITH THE COASTAL SYSTEM TO BE TO OUR EAST.
UPSLOPE SNOW ACROSS THE HIGHLANDS MAY LEAD TO LIGHT ACCUMULATIONS
TUESDAY NIGHT. WIND CHILL VALUES ACROSS THE HIGHLANDS MAY ALSO BE
BELOW ZERO.
A MORE ZONAL FLOW WITH HIGH PRESSURE AT THE SURFACE TAKES HOLD FOR
THE REST OF THE WEEK...WITH MODERATING TEMPERATURES BY THURSDAY.
GIVEN THE EMPHASIS AND FOCUS ON TODAYS SNOW EVENT IN SOME
AREAS...DAYS 4 THROUGH 7 WERE POPULATED USING HPC GUIDANCE WHICH
HIGHLIGHTS LOW CHANCES OF PRECIPITATION OVER THE WEEKEND AND COOLER
TEMPERATURES RELATIVE TO THURSDAY/FRIDAY.
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
OUTSIDE OF THE BALT AREA TAF SITES AND BACK ACROSS I-70 INTO THE NRN
SHENANDOAH VLY...MOST OF THE REGION WILL SEE PLENTY OF SUN THRU THE
NEXT COUPLE OF HRS. MUCH OF BKN-OVC LOW CIGS HAVE BECOME MORE
SCATTERED AND THE DC AREA TAF SITES HAVE SEEN THEIR DUSTING OF SNOW
FOR THE AFTN. OTHER SEVERAL BANDS OF SNOW HAVE BEEN DEVELOPING BACK
ACROSS THE I-81 CORRIDOR AND HAVE THE CHANCE OF SLIDING E OF THE
BLUE RIDGE AND POSSIBLY PUSHING BACK ACROSS THE KIAD AREA FROM
21-00Z. WINDS WILL CONTINUE TO STAY GENERALLY OUT OF THE N AND
INCREASING OVERNIGHT.
HIGH PRESSURE BUILDS IN LATE IN THE WEEK...WITH UNSETTLED CONDITIONS
POSSIBLY RETURNING ON THE WEEKEND.
&&
.MARINE...
WINDS ACROSS THE BAY SHOULD BE LIGHT THRU THE AFTN/EVNG HRS. SCA
CONDITIONS WILL ARISE DURING THE OVERNIGHT HRS ACROSS THE ICE WATER
PORTIONS OF THE TIDAL PTMC AND THE BAY.
SMALL CRAFT ADVISORY CONTINUES TUESDAY NIGHT WITH A GUSTY NORTHWEST
SURGE...AND MAY NEED TO BE EXTENDED INTO AT LEAST PART OF WEDNESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
MDZ003>007-009>011.
VA...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
VAZ028-031-042.
WV...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
WVZ051>053.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM EST
WEDNESDAY FOR ANZ530>537.
&&
$$
SYNOPSIS...PELOQUIN
NEAR TERM...GMS
SHORT TERM...GMS
LONG TERM...PELOQUIN
AVIATION...PELOQUIN/GMS
MARINE...PELOQUIN/GMS
000
FXUS61 KLWX 191101 AAA
AFDLWX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
601 AM EST MON JAN 19 2009
.SYNOPSIS...
UPPER DISTURBANCES WILL ROTATE AROUND A MEAN UPPER TROUGH OVER THE
NORTHEASTERN STATES TODAY...BRINGING A CHANCE OF LIGHT SNOW FOR
MUCH OF THE AREA. AN UPPER LEVEL TROUGH WILL REMAIN IN PLACE ON
TUESDAY. A COASTAL LOW DEVELOPS ALONG THE CAROLINA COAST TUESDAY
AND PUSHES OUT TO SEA BY WEDNESDAY. HIGH PRESSURE GRADUALLY BUILDS
IN TOWARD THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH BROAD SHIELD OF PCPN SPREADING NEWD WITH APRCH OF SHRTWV
TROF...HAVE EXTENDED WINTER WX ADZY FOR NRN THREE ZONES ALONG NRN
PORTION OF ALLEGHENY FRONT. UPSLP FLOW AND LIFT SHUD INCR THIS
AREA AS TROF APRCHS...AND THESE SHUD ENHANCE SNOW GENERATION THIS
MRNG. WILL CONT ADZY TO 17Z. PRVS DSCN FOLLOWS...
MEAN TROF LOCATED OVER NERN CONUS THIS MRNG. SVRL SHRTWV TROFS
MOVG AROUND THE LARGER TROF. ONE SUCH SHRTWV TROF SPARKED LGT SHSN
ACRS NRN MD...ERN WV PNHDL AND EXTREME NRN VA DURG LATE NGT HRS.
THESE SNSH WERE DECRG IN CVRG THIS MRNG.
SFC CDFNT HAVING DIFFICULT TIME MAKING EWD PROGRESS OUT OF WRN
POTOMAC HIGHLANDS. THIS LKLY IS A RESULT OF SECOND SHRTWV TROF
APRCHG OVER CNTRL WV ATTM...AND YIELDING SLGTLY MORE AGGRESSIVE
SHIELD OF PCPN. THIS SECOND TROF WILL MOVE THRU FCST AREA TDA...
AND CDFNT XPCD TO MOVE THRU IN KIND.
PCPN XPCD TO INCR ACRS WRN HIGHLAND AND PENDLETON CNTYS THIS MRNG
AS LIFT SPREADS EWD AND UPSLP FLOW INCRS. HAVE EXTENDED WINTER WX
ADZY THRU TDA...MAINLY FOR WRN SLOPES. LESS CERTAINTY IN TYPICAL
UPSLP AREAS FURTHER N...AND SO WILL RUN WINTER WX ADZY THRU 6 AM
FOR NRN ZONES.
SNOW XPCD TO SPREAD OVER MUCH OF FCST AREA THIS MRNG AND SPCLY
THIS AFTN AS WAVE MOVES THRU. TOTALS GENLY AROUND ONE HALF INCH
XPCD. HOWEVER...MODELS DVLP SMALL AMTS OF INSTBY THIS AFTN OVER
ERN ZONES...VCTY CHSPK BAY AND POTOMAC. NEAR DC AND BALTIMORE
METRO AREAS...MAY SEE ACCUMULATIONS SLGTLY HIGHER THAN ONE HALF
INCH...DURG AFTN COMMUTE. CONFIDENCE IN SNOW IS HIGH...BUT STILL
SOME UNCERTAINTY ON QPF. IF CNVCTV SNOW TREND DVLPS THIS AFTN...
LKLY WILL NEED WINTER WX ADZY FOR PORTIONS OF METRO COMMUTING
AREAS. SHUD BCM MORE CLR BY MRNG UPDATE.
GUIDANCE MAXIMA SEEMED A BIT HIGH GIVEN XPCD CLD CVR...SO HAVE
UNDERCUT MEXMOS SLGTLY TDA. MAY SEE UPWD TREND IN TEMPS ACRS SRN
ZONES LATE THIS AFTN AS CLD CVR ERODES IN WAKE OF SHRTWV TROF.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
SHRTWV TROF EXITS RAPIDLY THIS EVE. MAINTAINED CHC POPS ERN ZONES
EARLY EVE FOR LINGERING PCPN...BUT ALL PCPN SHUD EXIT BY MID EVE...
WITH THE XCPTN OF UPSLP FAVORED AREAS.
COOL MINIMA TNGT...SPCLY IN WRN ZONES OWING TO SNOW CVR. GENLY UPR
TEENS TO LWR 20S...XCPT WRN ZONES...WHERE MINIMA MAY REACH 10-15
DEG F.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
THE UPPER TROUGH PATTERN OF THE PAST WEEK PERSISTS OVER THE AREA FOR
INAUGURATION DAY BEFORE BEGINNING TO BREAK DOWN INTO MORE ZONAL FLOW
ON WEDNESDAY. AN OUTCOME OF THIS TRANSITION IS THE DEVELOPMENT OF A
COASTAL LOW OFF THE CAROLINA COAST ON TUESDAY. THE TRACK OF THIS
SYSTEM IS NE ALONG THE GULF STREAM /AWAY FROM THE MID-ATLANTIC/...
THOUGH DEPENDING ON THE SIZE AND INTENSITY SOUTHERN PORTIONS OF
THE MID-ATLANTIC WILL BE AFFECTED. THE GFS/ECMWF DEVELOP A BROAD
LOW THAT IS STRETCHED SW TO NE OFF THE MID-ATLANTIC COAST BY
TUESDAY NIGHT. THE NAM GREATLY INTENSIFIES THE SYSTEM AND IS SLOW
TO MOVE IT AWAY FROM THE COAST. SNOW BANDS TO EXTEND WEST AND
NORTHWEST FROM THE CENTER OF THE SYSTEM WITH SRN VA AND ERN NC
AFFECTED THE MOST. INTRODUCED SLIGHT CHANCE POPS FOR SNOW FOR
TUESDAY AND TUESDAY NIGHT ACROSS OUR FAR SOUTHERN ZONES /CENTRAL
VA AND FAR SOUTHERN MD...SOUTH OF DC AND BALTIMORE/. UPSLOPE SNOW
FOR WESTERN SLOPES OF THE ALLEGHENY FRONT LIKELY ON TUESDAY BEFORE
TAPERING OFF TUESDAY NIGHT/EARLY WEDNESDAY.
CHILLY AIR PERSISTS FOR TUESDAY AND WEDNESDAY WITH HIGHS IN THE
LOWER 30S /AROUND TEN DEGREES BELOW NORMAL/ UNDER MOSTLY CLOUDY
SKIES. EXPECT BREEZY CONDITIONS ON TUESDAY AND INTO TUESDAY NIGHT
WITH WINDS 10 TO 15 MPH WITH GUSTS TO AROUND 20 MPH...WIND CHILLS
AROUND 20 FOR THE DC AREA DURING THE DAY TUESDAY...SLIPPING INTO
THE TEENS TUESDAY EVENING/NIGHT. THOSE OUT AND ABOUT ON TUESDAY
SHOULD DRESS FOR THESE COLD CONDITIONS.
MORE ZONAL UPPER FLOW THURSDAY AND FRIDAY WILL ALLOW FOR A RETURN OF
NORMAL TEMPERATURES ON THESE DAYS. UPSLOPE SNOW FOR WESTERN SLOPES
ENDS WEDNESDAY MORNING... WITH REST OF WEDNESDAY THROUGH THURSDAY
LOOKING DRY AS A SURFACE HIGH EXPANDS ACROSS THE SOUTHEAST.
UNSETTLED CONDITIONS RETURNING AT THE END OF THE WORK WEEK WITH A
COLD FRONT PASSAGE LATE FRIDAY INTO SATURDAY. PRECIP LOOKS TO BE AT
LEAST WESTERN UPSLOPE SNOW AT THIS TIME...IF/WHEN ANY MAKES IT OVER
THE APPALACHIANS AND WHAT PRECIP TYPE /RAIN OR SNOW/ IS STILL
GREATLY UNCERTAIN.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS SHRTWV TROF APRCHS THIS MRNG...CLD CVR TO INCR ALL TERMINALS.
HAVE INCLUDED LGT SNOW ALL TERMINALS BUT KMRB...MAINLY THIS AFTN.
RAPID EXIT OF PCPN BY TNGT AS WAVE DEPARTS...AND IMPROVEMENT IN
VSBYS AND CIGS XPCD.
GUSTY NORTH WINDS TO AROUND 20 KT TUESDAY...NW WINDS UP TO 20 KT
ON WEDNESDAY WITH VFR CONDITIONS AS ANY PRECIP TUESDAY AND
WEDNESDAY WOULD LIGHT. HIGH PRESSURE RETURNS MID TO LATE WEEK.
&&
.MARINE...
NO WIND CONCERNS TDA AS CLD CVR SHUD INHIBIT DP MIXING. AS FLOW
BCMS NLY BEHIND EXITING SHRTWV TROF THIS EVE...GUSTS TO 20 KT PSBL
ACRS CHSPK BAY AND POTOMAC. THEREFORE WILL CONT SMALL CRAFT ADZY
AS INHERITED...ALTHOUGH HAVE LWR CONFIDENCE THAN PRVS SHIFTS IN
ITS OCCURENCE DURG TNGT PD OVER ENTIRE MARINE AREA.
SMALL CRAFT CONDITIONS INTO WEDNESDAY AS NORTHERLY WINDS WITH GUSTS
UP TO 30 KT OVER THE BAY BECOME NORTHWESTERLY TUESDAY NIGHT BEFORE
EASING. RIVER/BAY ICE TO BEGIN TO MELT THURSDAY WITH TEMPERATURES
REACHING THE LOWER 40S ACROSS THE WATERS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR MDZ501.
VA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR
VAZ021.
WV...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR WVZ501-503.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR
WVZ054.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 5 PM EST
TUESDAY FOR ANZ530>537.
&&
$$
UPDATE...KRAMAR
PRVS DSCN...KRAMAR/BAJ
000
FXUS61 KLWX 190852
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
352 AM EST MON JAN 19 2009
.SYNOPSIS...
UPPER DISTURBANCES WILL ROTATE AROUND A MEAN UPPER TROUGH OVER THE
NORTHEASTERN STATES TODAY...BRINGING A CHANCE OF LIGHT SNOW FOR
MUCH OF THE AREA. AN UPPER LEVEL TROUGH WILL REMAIN IN PLACE ON
TUESDAY. A COASTAL LOW DEVELOPS ALONG THE CAROLINA COAST TUESDAY
AND PUSHES OUT TO SEA BY WEDNESDAY. HIGH PRESSURE GRADUALLY BUILDS
IN TOWARD THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MEAN TROF LOCATED OVER NERN CONUS THIS MRNG. SVRL SHRTWV TROFS
MOVG AROUND THE LARGER TROF. ONE SUCH SHRTWV TROF SPARKED LGT SHSN
ACRS NRN MD...ERN WV PNHDL AND EXTREME NRN VA DURG LATE NGT HRS.
THESE SNSH WERE DECRG IN CVRG THIS MRNG.
SFC CDFNT HAVING DIFFICULT TIME MAKING EWD PROGRESS OUT OF WRN
POTOMAC HIGHLANDS. THIS LKLY IS A RESULT OF SECOND SHRTWV TROF
APRCHG OVER CNTRL WV ATTM...AND YIELDING SLGTLY MORE AGGRESSIVE
SHIELD OF PCPN. THIS SECOND TROF WILL MOVE THRU FCST AREA TDA...
AND CDFNT XPCD TO MOVE THRU IN KIND.
PCPN XPCD TO INCR ACRS WRN HIGHLAND AND PENDLETON CNTYS THIS MRNG
AS LIFT SPREADS EWD AND UPSLP FLOW INCRS. HAVE EXTENDED WINTER WX
ADZY THRU TDA...MAINLY FOR WRN SLOPES. LESS CERTAINTY IN TYPICAL
UPSLP AREAS FURTHER N...AND SO WILL RUN WINTER WX ADZY THRU 6 AM
FOR NRN ZONES.
SNOW XPCD TO SPREAD OVER MUCH OF FCST AREA THIS MRNG AND SPCLY
THIS AFTN AS WAVE MOVES THRU. TOTALS GENLY AROUND ONE HALF INCH
XPCD. HOWEVER...MODELS DVLP SMALL AMTS OF INSTBY THIS AFTN OVER
ERN ZONES...VCTY CHSPK BAY AND POTOMAC. NEAR DC AND BALTIMORE
METRO AREAS...MAY SEE ACCUMULATIONS SLGTLY HIGHER THAN ONE HALF
INCH...DURG AFTN COMMUTE. CONFIDENCE IN SNOW IS HIGH...BUT STILL
SOME UNCERTAINTY ON QPF. IF CNVCTV SNOW TREND DVLPS THIS AFTN...
LKLY WILL NEED WINTER WX ADZY FOR PORTIONS OF METRO COMMUTING
AREAS. SHUD BCM MORE CLR BY MRNG UPDATE.
GUIDANCE MAXIMA SEEMED A BIT HIGH GIVEN XPCD CLD CVR...SO HAVE
UNDERCUT MEXMOS SLGTLY TDA. MAY SEE UPWD TREND IN TEMPS ACRS SRN
ZONES LATE THIS AFTN AS CLD CVR ERODES IN WAKE OF SHRTWV TROF.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
SHRTWV TROF EXITS RAPIDLY THIS EVE. MAINTAINED CHC POPS ERN ZONES
EARLY EVE FOR LINGERING PCPN...BUT ALL PCPN SHUD EXIT BY MID EVE...
WITH THE XCPTN OF UPSLP FAVORED AREAS.
COOL MINIMA TNGT...SPCLY IN WRN ZONES OWING TO SNOW CVR. GENLY UPR
TEENS TO LWR 20S...XCPT WRN ZONES...WHERE MINIMA MAY REACH 10-15
DEG F.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
THE UPPER TROUGH PATTERN OF THE PAST WEEK PERSISTS OVER THE AREA FOR
INAUGURATION DAY BEFORE BEGINNING TO BREAK DOWN INTO MORE ZONAL FLOW
ON WEDNESDAY. AN OUTCOME OF THIS TRANSITION IS THE DEVELOPMENT OF A
COASTAL LOW OFF THE CAROLINA COAST ON TUESDAY. THE TRACK OF THIS
SYSTEM IS NE ALONG THE GULF STREAM /AWAY FROM THE MID-ATLANTIC/...
THOUGH DEPENDING ON THE SIZE AND INTENSITY SOUTHERN PORTIONS OF
THE MID-ATLANTIC WILL BE AFFECTED. THE GFS/ECMWF DEVELOP A BROAD
LOW THAT IS STRETCHED SW TO NE OFF THE MID-ATLANTIC COAST BY
TUESDAY NIGHT. THE NAM GREATLY INTENSIFIES THE SYSTEM AND IS SLOW
TO MOVE IT AWAY FROM THE COAST. SNOW BANDS TO EXTEND WEST AND
NORTHWEST FROM THE CENTER OF THE SYSTEM WITH SRN VA AND ERN NC
AFFECTED THE MOST. INTRODUCED SLIGHT CHANCE POPS FOR SNOW FOR
TUESDAY AND TUESDAY NIGHT ACROSS OUR FAR SOUTHERN ZONES /CENTRAL
VA AND FAR SOUTHERN MD...SOUTH OF DC AND BALTIMORE/. UPSLOPE SNOW
FOR WESTERN SLOPES OF THE ALLEGHENY FRONT LIKELY ON TUESDAY BEFORE
TAPERING OFF TUESDAY NIGHT/EARLY WEDNESDAY.
CHILLY AIR PERSISTS FOR TUESDAY AND WEDNESDAY WITH HIGHS IN THE
LOWER 30S /AROUND TEN DEGREES BELOW NORMAL/ UNDER MOSTLY CLOUDY
SKIES. EXPECT BREEZY CONDITIONS ON TUESDAY AND INTO TUESDAY NIGHT
WITH WINDS 10 TO 15 MPH WITH GUSTS TO AROUND 20 MPH...WIND CHILLS
AROUND 20 FOR THE DC AREA DURING THE DAY TUESDAY...SLIPPING INTO
THE TEENS TUESDAY EVENING/NIGHT. THOSE OUT AND ABOUT ON TUESDAY
SHOULD DRESS FOR THESE COLD CONDITIONS.
MORE ZONAL UPPER FLOW THURSDAY AND FRIDAY WILL ALLOW FOR A RETURN OF
NORMAL TEMPERATURES ON THESE DAYS. UPSLOPE SNOW FOR WESTERN SLOPES
ENDS WEDNESDAY MORNING... WITH REST OF WEDNESDAY THROUGH THURSDAY
LOOKING DRY AS A SURFACE HIGH EXPANDS ACROSS THE SOUTHEAST.
UNSETTLED CONDITIONS RETURNING AT THE END OF THE WORK WEEK WITH A
COLD FRONT PASSAGE LATE FRIDAY INTO SATURDAY. PRECIP LOOKS TO BE AT
LEAST WESTERN UPSLOPE SNOW AT THIS TIME...IF/WHEN ANY MAKES IT OVER
THE APPALACHIANS AND WHAT PRECIP TYPE /RAIN OR SNOW/ IS STILL
GREATLY UNCERTAIN.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
AS SHRTWV TROF APRCHS THIS MRNG...CLD CVR TO INCR ALL TERMINALS.
HAVE INCLUDED LGT SNOW ALL TERMINALS BUT KMRB...MAINLY THIS AFTN.
RAPID EXIT OF PCPN BY TNGT AS WAVE DEPARTS...AND IMPROVEMENT IN
VSBYS AND CIGS XPCD.
GUSTY NORTH WINDS TO AROUND 20 KT TUESDAY...NW WINDS UP TO 20 KT
ON WEDNESDAY WITH VFR CONDITIONS AS ANY PRECIP TUESDAY AND
WEDNESDAY WOULD LIGHT. HIGH PRESSURE RETURNS MID TO LATE WEEK.
&&
.MARINE...
NO WIND CONCERNS TDA AS CLD CVR SHUD INHIBIT DP MIXING. AS FLOW
BCMS NLY BEHIND EXITING SHRTWV TROF THIS EVE...GUSTS TO 20 KT PSBL
ACRS CHSPK BAY AND POTOMAC. THEREFORE WILL CONT SMALL CRAFT ADZY
AS INHERITED...ALTHOUGH HAVE LWR CONFIDENCE THAN PRVS SHIFTS IN
ITS OCCURENCE DURG TNGT PD OVER ENTIRE MARINE AREA.
SMALL CRAFT CONDITIONS INTO WEDNESDAY AS NORTHERLY WINDS WITH GUSTS
UP TO 30 KT OVER THE BAY BECOME NORTHWESTERLY TUESDAY NIGHT BEFORE
EASING. RIVER/BAY ICE TO BEGIN TO MELT THURSDAY WITH TEMPERATURES
REACHING THE LOWER 40S ACROSS THE WATERS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
MDZ501.
VA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR
VAZ021.
WV...WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
WVZ501-503.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR
WVZ054.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 5 PM EST
TUESDAY FOR ANZ530>537.
&&
$$
KRAMAR/BAJ
000
FXUS61 KLWX 190526
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1226 AM EST MON JAN 19 2009
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE ACROSS THE AREA THIS EVENING. A WAVE
OF LOW PRESSURE IS FORECAST TO PASS SOUTH OF THE REGION MONDAY AND
MONDAY EVENING...WHICH COULD BRING A BRIEF PERIOD OF LIGHT SNOW.
AN UPPER LEVEL TROUGH WILL REMAIN IN PLACE ON TUESDAY...THEN HIGH
PRESSURE GRADUALLY BUILDS IN TOWARD THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
HAVE UPDATED FCST LATE TNGT TO INCLUDE SCT SHSN IN NRN MD...ERN WV
PNHDL AND PORTIONS NRN VA...AS LGT SNOW NOTED IN KHGR OB. ANY
ACCUMULATIONS WILL BE LGT...UNDER ONE HALF INCH...AND IN MOST
AREAS ONLY TRACE AMTS. SNOW XPCD TO SPREAD ACRS NRN MD LATE
TNGT...IN ASSOCIATION WITH WEAK SHRTWV TROF. PRVS DSCN FOLLOWS...
WK CDFNT ACRS WRN CWFA ATTM. HWVR...THERE/S NOT MUCH PUSH TO IT AS
WND FLOW LGT. IT SHUD MEANDER ACRS CWFA THIS EVNG...AND BE NEAR
THE BAY BY MIDNGT.
WATER VAPOR LOOP DEPICTS SUBTLE S/WV IN UPR OHVLY. WHILE ITS NOT
MUCH TO LOOK AT...WHEN COMBINED W/ WEAK CAA/UPSLP FLOW...IT/LL
LIKELY BE ENUF TO KICK OFF ANTHR RND OF SHSN. INDEED...RADAR
ECHOES APPARENT ON RNGL RADAR COMPOSITE. SO...HV MADE SOME SMALL
ALTERATIONS TO GOING WSW. HV ONLY FOUND ACCUMS AOB 1 INCH SINCE
DARK IN ADVY AREA. SINCE ANY FUTURE ACCUMS WL BE FOR WRN FACING
SLOPES ONLY...HV CARVED ERN GRANT CNTY OUT OF ADVY AREA. FOR THE
REMAINDER OF THE THREAT AREA...RISK WL LAST FOR NXT 3-6 HRS...
WHICH WL RUN TIL ABT 07Z. SO...HV EXTENDED WSW ACCRDGLY.
GIVEN ONLY WK CAA AND SOLID CLDS...DONT THINK TEMPS ARE GOING TO
DROP TOO FAR...AND HV MADE UPWD ADJUSTMNTS TO MIN-T FCST. FCST IN
LINE W/ 18Z GFS AND LTST LAMP.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
18Z NAM/GFS AND 15Z SREFS IN GNRL AGREEMENT W/ PRVS RUNS WRT S/WV
IN UPR MIDWEST ROUNDING BEND OF DEEP UPR LOW AND TRACKING ACRS SRN
CWFA TMRW. THERMALLY...PROFILE SUPPORTS SNW...BUT LESS THAN A TENTH
INCH LIQ SUGGESTED BY LTST GDNC. THAT WUD GNLY EQUATE TO SNW TTLS
AOB AN INCH...ASSUMING IT DOES INDEED SNW. THINK GOING LIKELY FCST
COVERS THREAT WELL...AND WL MAKE NO CHGS TO THAT ASPECT OF FCST.
/QPF FM PLUMES STILL SHOW A WIDE SPREAD. WUD LIKE TO GIVE OP
SYNOP GDNC SVRL RUNS FOR BETTER CONSISTENCY...AS 12Z WAS A RATHER
BIG SHIFT IN FCST SOLN./ HWVR...WL NARROW TIMING WINDOW...AS VORT
SHUD BE RATHER SWIFT IN TRACKING THRU. FOCUS SHUD BE ON SRN CWFA
DURING THE MIDDAY...AND ERN CWFA IN THE AFTN. HV TRIMMED BACK POPS
IN THE ELY MRNG AND EVNG TIMEFRAMES.
WEAK WAVE WILL MOVE AWAY FROM THE CWA MONDAY EVENING. THERE STILL
MAY BE SOME LINGERING SNOW EARLY IN THE EVENING. BUT AGAIN...THIS
IS DEPENDENT ON THE TRACK AND SPEED OF THIS WEAK WAVE. CHC POPS WL
SUFFICE. THE TREND WILL BE FOR PRECIPITATION TO SHUT OFF
OVERNIGHT EXCEPT FOR SOME UPSLOPE SNOW ACROSS THE HIGHLANDS. ANY
MOISTURE FROM THE SNOW MONDAY/MONDAY EVENING MAY REFREEZE AS
OVERNIGHT LOWS DROPS INTO THE 20S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
INAUGURATION DAY LOOKS DRY ACROSS THE WASHINGTON AREA WITH A MORE
UPSLOPE SNOW OCCURRING OVER THE HIGHLANDS. THE DRY FORECAST FOR
WASHINGTON IS A MODERATE TO REASONABLY HIGH CONFIDENCE FORECAST.
THERE WILL REMAIN PLENTY OF STRATOCU UNDER AN UPPER TROUGH...SO
THE SKY WAS INCREASED TO MOSTLY CLOUDY. TEMPERATURES WILL BE
COLDER...HIGHS ONLY IN THE LOWER 30S...WHICH COMBINED WITH A BRISK
WIND THAT MAY GUST TO 25 MPH AT TIMES MAY PRODUCE WIND CHILL
VALUES IN THE TEENS. THOSE OUT AND ABOUT ON TUESDAY SHOULD DRESS
FOR THESE COLD CONDITIONS.
UPPER FLOW FLATTENS OUT WEDNESDAY THROUGH FRIDAY...ALLOWING FOR
MODERATING TEMPERATURES TOWARD THE END OF THE WEEK. ASIDE FROM
PERIOD UPSLOPE SNOW SHOWERS...WEDNESDAY THROUGH FRIDAY LOOK DRY
WITH UNSETTLED CONDITIONS RETURNING OVER THE WEEKEND. GFS/ECWMF AND
THEIR ENSEMBLES HANDLE DETAILS DIFFERENTLY BUT THE TREND IS FOR
HIGHER CHANCES OF PRECIPITATION. FORECAST REFLECTS THIS...AND AT
LEAST SOME OF THE PRECIPITATION WOULD BE OF THE WINTRY VARIETY.
DETAILS WILL NEED TO BE RESOLVED WITH TIME.
&&
.AVIATION /05Z MONDAY THROUGH FRIDAY/...
VFR CONDS XPCTD OVNGT AS CDFNT SLOWLY TRACKE ACRS CWFA. WNDS
LGT...AND SHIFT FM SLY TO W/NWLY FLOW WL BE SUBTLE.
S/WV FM MIDWEST WL ROUND THE BEND OF DEEP UPR LOW...AND PASS JUST
S OF TERMINALS TMRW. NOT A LOT OF MSTR TO WORK WITH...SO HV BEEN
RATHER OPTIMISTIC ON TAFS. WL TAKE A PD OF MVFR INVOF OF VORT...
WHICH GNLY WL COINCIDE W/ AFTN HRS FOR BALT-DC AIRPORTS.
RESTRICTIONS WL BE TO BOTH CIGS AND VSBYS DUE TO SNW. IF SIGNS
BECOME CLEARER...A PD OF IFR MAY BE INTRODUCED...BUT SUSPECT ANY
SUCH RESTRICTIONS WUD BE LMTD TO TEMPO 1-2 HRS.
GUSTY NORTHWEST WINDS WILL SETTLED IN OVERNIGHT MONDAY INTO
TUESDAY. HIGH PRESSURE RETURNS MID TO LATE WEEK.
&&
.MARINE...
LGT WNDS ON THE WATERS ATTM...AND XPCT IT TO STAY THAT WAY OVNGT.
WK CDFNT WL MAKE IT TO THE WATERS AFTR MIDNGT...BUT LACKING ANY
PUSH...IT/LL ONLY CHG WND TRAJ FM SLY TO W/NWLY. SPDS SHUD REMAIN
AOB 10 KT.
A SFC LOW EXPECTED TO MOVE ACROSS THE WATERS LATE MON AFTN/EVNG.
RAISED A SMALL CRAFT ADVISORY MONDAY NIGHT INTO TUESDAY FOR
INCREASING NORTHWEST WINDS. SMALL CRAFT ADVISORY CONDITIONS MAY
PERSIST INTO TUESDAY NIGHT. HIGH PRESSURE BUILDS IN MID TO LATE
WEEK.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER WEATHER ADVISORY UNTIL 2 AM EST EARLY THIS MORNING FOR
MDZ501.
VA...WINTER WEATHER ADVISORY UNTIL 2 AM EST EARLY THIS MORNING FOR
VAZ021.
WV...WINTER WEATHER ADVISORY UNTIL 2 AM EST EARLY THIS MORNING FOR
WVZ054-501-503.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 5 PM EST
TUESDAY FOR ANZ530>537.
&&
$$
UPDATE...KRAMAR
PRVS DSCN...HTS/PELOQUIN
000
FXUS61 KLWX 190209
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
909 PM EST SUN JAN 18 2009
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE ACROSS THE AREA THIS EVENING. A WAVE
OF LOW PRESSURE IS FORECAST TO PASS SOUTH OF THE REGION MONDAY AND
MONDAY EVENING...WHICH COULD BRING A BRIEF PERIOD OF LIGHT SNOW.
AN UPPER LEVEL TROUGH WILL REMAIN IN PLACE ON TUESDAY...THEN HIGH
PRESSURE GRADUALLY BUILDS IN TOWARD THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
WK CDFNT ACRS WRN CWFA ATTM. HWVR...THERE/S NOT MUCH PUSH TO IT AS
WND FLOW LGT. IT SHUD MEANDER ACRS CWFA THIS EVNG...AND BE NEAR
THE BAY BY MIDNGT.
WATER VAPOR LOOP DEPICTS SUBTLE S/WV IN UPR OHVLY. WHILE ITS NOT
MUCH TO LOOK AT...WHEN COMBINED W/ WEAK CAA/UPSLP FLOW...IT/LL
LIKELY BE ENUF TO KICK OFF ANTHR RND OF SHSN. INDEED...RADAR
ECHOES APPARENT ON RNGL RADAR COMPOSITE. SO...HV MADE SOME SMALL
ALTERATIONS TO GOING WSW. HV ONLY FOUND ACCUMS AOB 1 INCH SINCE
DARK IN ADVY AREA. SINCE ANY FUTURE ACCUMS WL BE FOR WRN FACING
SLOPES ONLY...HV CARVED ERN GRANT CNTY OUT OF ADVY AREA. FOR THE
REMAINDER OF THE THREAT AREA...RISK WL LAST FOR NXT 3-6 HRS...
WHICH WL RUN TIL ABT 07Z. SO...HV EXTENDED WSW ACCRDGLY.
GIVEN ONLY WK CAA AND SOLID CLDS...DONT THINK TEMPS ARE GOING TO
DROP TOO FAR...AND HV MADE UPWD ADJUSTMNTS TO MIN-T FCST. FCST IN
LINE W/ 18Z GFS AND LTST LAMP.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
18Z NAM/GFS AND 15Z SREFS IN GNRL AGREEMENT W/ PRVS RUNS WRT S/WV
IN UPR MIDWEST ROUNDING BEND OF DEEP UPR LOW AND TRACKING ACRS SRN
CWFA TMRW. THERMALLY...PROFILE SUPPORTS SNW...BUT LESS THAN A TENTH
INCH LIQ SUGGESTED BY LTST GDNC. THAT WUD GNLY EQUATE TO SNW TTLS
AOB AN INCH...ASSUMING IT DOES INDEED SNW. THINK GOING LIKELY FCST
COVERS THREAT WELL...AND WL MAKE NO CHGS TO THAT ASPECT OF FCST.
/QPF FM PLUMES STILL SHOW A WIDE SPREAD. WUD LIKE TO GIVE OP
SYNOP GDNC SVRL RUNS FOR BETTER CONSISTENCY...AS 12Z WAS A RATHER
BIG SHIFT IN FCST SOLN./ HWVR...WL NARROW TIMING WINDOW...AS VORT
SHUD BE RATHER SWIFT IN TRACKING THRU. FOCUS SHUD BE ON SRN CWFA
DURING THE MIDDAY...AND ERN CWFA IN THE AFTN. HV TRIMMED BACK POPS
IN THE ELY MRNG AND EVNG TIMEFRAMES.
WEAK WAVE WILL MOVE AWAY FROM THE CWA MONDAY EVENING. THERE STILL
MAY BE SOME LINGERING SNOW EARLY IN THE EVENING. BUT AGAIN...THIS
IS DEPENDENT ON THE TRACK AND SPEED OF THIS WEAK WAVE. CHC POPS WL
SUFFICE. THE TREND WILL BE FOR PRECIPITATION TO SHUT OFF
OVERNIGHT EXCEPT FOR SOME UPSLOPE SNOW ACROSS THE HIGHLANDS. ANY
MOISTURE FROM THE SNOW MONDAY/MONDAY EVENING MAY REFREEZE AS
OVERNIGHT LOWS DROPS INTO THE 20S.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
INAUGURATION DAY LOOKS DRY ACROSS THE WASHINGTON AREA WITH A MORE
UPSLOPE SNOW OCCURRING OVER THE HIGHLANDS. THE DRY FORECAST FOR
WASHINGTON IS A MODERATE TO REASONABLY HIGH CONFIDENCE FORECAST.
THERE WILL REMAIN PLENTY OF STRATOCU UNDER AN UPPER TROUGH...SO
THE SKY WAS INCREASED TO MOSTLY CLOUDY. TEMPERATURES WILL BE
COLDER...HIGHS ONLY IN THE LOWER 30S...WHICH COMBINED WITH A BRISK
WIND THAT MAY GUST TO 25 MPH AT TIMES MAY PRODUCE WIND CHILL
VALUES IN THE TEENS. THOSE OUT AND ABOUT ON TUESDAY SHOULD DRESS
FOR THESE COLD CONDITIONS.
UPPER FLOW FLATTENS OUT WEDNESDAY THROUGH FRIDAY...ALLOWING FOR
MODERATING TEMPERATURES TOWARD THE END OF THE WEEK. ASIDE FROM
PERIOD UPSLOPE SNOW SHOWERS...WEDNESDAY THROUGH FRIDAY LOOK DRY
WITH UNSETTLED CONDITIONS RETURNING OVER THE WEEKEND. GFS/ECWMF AND
THEIR ENSEMBLES HANDLE DETAILS DIFFERENTLY BUT THE TREND IS FOR
HIGHER CHANCES OF PRECIPITATION. FORECAST REFLECTS THIS...AND AT
LEAST SOME OF THE PRECIPITATION WOULD BE OF THE WINTRY VARIETY.
DETAILS WILL NEED TO BE RESOLVED WITH TIME.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
VFR CONDS XPCTD OVNGT AS CDFNT SLOWLY TRACKE ACRS CWFA. WNDS
LGT...AND SHIFT FM SLY TO W/NWLY FLOW WL BE SUBTLE.
S/WV FM MIDWEST WL ROUND THE BEND OF DEEP UPR LOW...AND PASS JUST
S OF TERMINALS TMRW. NOT A LOT OF MSTR TO WORK WITH...SO HV BEEN
RATHER OPTIMISTIC ON TAFS. WL TAKE A PD OF MVFR INVOF OF VORT...
WHICH GNLY WL COINCIDE W/ AFTN HRS FOR BALT-DC AIRPORTS.
RESTRICTIONS WL BE TO BOTH CIGS AND VSBYS DUE TO SNW. IF SIGNS
BECOME CLEARER...A PD OF IFR MAY BE INTRODUCED...BUT SUSPECT ANY
SUCH RESTRICTIONS WUD BE LMTD TO TEMPO 1-2 HRS.
GUSTY NORTHWEST WINDS WILL SETTLED IN OVERNIGHT MONDAY INTO
TUESDAY. HIGH PRESSURE RETURNS MID TO LATE WEEK.
&&
.MARINE...
LGT WNDS ON THE WATERS ATTM...AND XPCT IT TO STAY THAT WAY OVNGT.
WK CDFNT WL MAKE IT TO THE WATERS AFTR MIDNGT...BUT LACKING ANY
PUSH...IT/LL ONLY CHG WND TRAJ FM SLY TO W/NWLY. SPDS SHUD REMAIN
AOB 10 KT.
A SFC LOW EXPECTED TO MOVE ACROSS THE WATERS LATE MON AFTN/EVNG.
RAISED A SMALL CRAFT ADVISORY MONDAY NIGHT INTO TUESDAY FOR
INCREASING NORTHWEST WINDS. SMALL CRAFT ADVISORY CONDITIONS MAY
PERSIST INTO TUESDAY NIGHT. HIGH PRESSURE BUILDS IN MID TO LATE
WEEK.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER WEATHER ADVISORY UNTIL 2 AM EST MONDAY FOR MDZ501.
VA...WINTER WEATHER ADVISORY UNTIL 2 AM EST MONDAY FOR VAZ021.
WV...WINTER WEATHER ADVISORY UNTIL 2 AM EST MONDAY FOR WVZ054-501-
503.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM MONDAY TO 5 PM EST TUESDAY FOR
ANZ530>537.
&&
$$
SYNOPSIS...PELOQUIN
NEAR TERM...HTS
SHORT TERM...HTS/PELOQUIN
LONG TERM...PELOQUIN
AVIATION...HTS/PELOQUIN
MARINE...HTS/PELOQUIN
000
FXUS61 KLWX 182009
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
309 PM EST SUN JAN 18 2009
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE ACROSS THE AREA THIS EVENING. A WAVE
OF LOW PRESSURE IS FORECAST TO PASS SOUTH OF THE REGION MONDAY AND
MONDAY EVENING...WHICH COULD BRING A BRIEF PERIOD OF LIGHT SNOW.
AN UPPER LEVEL TROUGH WILL REMAIN IN PLACE ON TUESDAY...THEN HIGH
PRESSURE GRADUALLY BUILDS IN TOWARD THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 8 AM MONDAY/...
AS MUCH OF THE LOCAL GUIDANCE ALLUDED TO...A LOCALIZED BATCH OF
LIGHT SNOW/FLURRIES FALLING ACROSS EXTREME NERN MD...FROM NEAR KDMW
TO THE NRN BAY REGION. THIS ACTIVITY WILL LIKELY DISSIPATE THRU THE
REMAINDER OF THE AFTN...W/ PORTIONS OF THE BALTIMORE NRN SUBURBS W/
A DUSTING OR TRACE AMOUNTS. OUTSIDE OF THIS AND A COUPLE OF INCHES
ACROSS THE WW ADZY AREA OF THE WRN ZONES...LITTLE MORE THAN OVERCAST
SKIES AND LIGHT SLY WINDS INCREASING LOW LEVEL MOISTURE OUT OF THE
EXTREMELY DRY CATEGORY. THIS FLOW IS A BIT MORE CONTINENTAL...SO NOT
A VERY MOIST FLOW...BUT DWPTS GRADUALLY RISING INTO THE M/U TEENS.
TEMPS SEEMS TO BE TOPPING OUT IN THE M/U30S...AIDED BY THE MOIST SLY
FLOW. WIND CHILL VALUES HOWEVER ARE STILL HOVERING AROUND AND JUST
BELOW FREEZING...AND WILL THEN CONTINUE TO DROP STARTING LATE
AFTN/EARLY EVNG.
STILL A BULK OF THE SNOWFALL OVER THE WRN ZONES WILL FALL THRU THE
NEXT SEVERAL HRS. A GRADUAL DISSIPATION WILL OCCUR THRU THE LATE
AFTN AS MUCH OF THE LOW LEVEL MOISTURE HAS ALREADY BEGUN TO LIFT
NEWD INTO CNTRL PA...AS THE SFC LOW OVER ERN LAKE HURON SLOWLY
MARCHES ACROSS SRN ONTARIO AND EVENTUALLY TOWARD THE NORTHEAST
REGION.
OVERNIGHT LOWS WILL AGAIN DROP INTO THE L/M20S...AS DWPTS WILL STILL
STRUGGLE TO CATCH UP TO AMBIENT TEMPS BEFORE THE COLD FRONT SLIDES
THRU. THIS WILL AIDE IN TEMPS DROPPING AT LEAST 10 DEGREES FROM THE
DAYTIME HIGHS. AFTER THE WEAK SFC COLD FRONT MOVES THROUGH LATE
TONIGHT...WEAK W-NWLY WINDS WILL PUSH IN BEHIND THE FRONT THO MOST
AREAS WILL DROP TO VRB WINDS AND WIND CHILL VALUES CLOSER TO THE
AMBIENT TEMP.
&&
.SHORT TERM /MONDAY/...
AS THE LOW OVER THE ERN GREAT LAKES BEGINS TO SHIFT EWD...A
BACKSIDE UPPER WAVE SLIDES AROUND THE OHIO VLY AND INTO THE APLCNS
OVERNIGHT. EARLIER MODEL RUNS HAD A MOSTLY DRY AND FURTHER SOUTH
DEVELOPMENT OF A LEE SFC LOW ACROSS SRN VA/N CNTRL NC...MOVING ENE
ACROSS SRN VA AND OFF THE TIDEWATER VA REGION MONDAY EVNG. WITH
THE LATEST /12Z/ RUNS OF THE GFS/NAM...COMES A CHANGE. THIS CHANGE
ESPECIALLY AFFECTS THE IMMEDIATE METRO AREAS...ESPECIALLY THE SRN
HALF OF THE CWA. THE LOW EXPECTED TO MOVE SLIGHTLY FURTHER
NORTH...PASSING JUST SOUTH OF THE I-64 CORRIDOR...W/ THE
ASSOCIATED BACKSIDE MOISTURE STREWN ACROSS N CNTRL VA/SRN MD.
THESE MODELS PUSHING NEAR A TENTH INCH OF QPF FOR THE
DURATION...ALL OR MOST OF IT SNOW W/ BOUNDARY LAYER AND CRITICAL
THICKNESSES WELL SUPPORTIVE OF ALL SNOW AROUND THE BACKSIDE OF THE
LOW.
THE ECMWF NOT AS EXCITED ABOUT THIS FEATURE...THO IT DEVELOPS A LOW
IN A SIMILAR PROXIMITY AND GIVES MORE OF A BROAD BRUSHED AREA OF
LIGHT QPF. A TAPERING OF THE GFS/NAM AND A ECM BLEND WERE UTILIZED
TO THE MODIFICATION OF MONDAY/S POPS...W/ A LIKELY BAND ACROSS THE
LOWER HALF OF THE CWA...INCLUDING DC/BALT AND MUCH OF THE I-95
CORRIDOR. SFC TEMPS MAY TOP OUT A DEGREE OR TWO ABOVE FREEZING
MONDAY AFTN...BUT FOR THE MOST PART MUCH OF THE MID ATLC WILL STAY
AT OR BELOW FREEZING FOR MUCH OF THE DAY. THE LEE SFC LOW...UTILIZING
LATEST GUIDANCE...EXPECTED TO DEVELOP THRU THE MRNG HRS AND BEGIN
DEVELOPING PRECIP /ALONG W/ THE WEAK MOIST SLY FLOW AHEAD OF IT/
AND SPREADING IT INTO N CNTRL VA FROM THE LATE MRNG INTO EARLY AFTN.
AS THE LOW TRACKS ACROSS CNTRL VA...WINDS EXPECTED TO BE LIGHTER
/FROM THE WEAK SFC FLOW/ SO WIND CHILL VALUES NOT AS LOW.
SNOW TOTALS FOR THE DAY...FROM LATE MRNG THRU LATE EVNG MONDAY
EXPECTED TO BE LESS THAN AN INCH AREAWIDE /DC METRO AND POINTS SWD/.
THIS BASED OF THE LIGHT MODEL QPFS AND GENERAL UNCERTAINTY IN AND
DISCONTINUITY W/ THIS NEW SOLUTION...BUT CERTAINLY ONE THAT WILL BE
MONITORED CLOSELY. NO ADZY FOR THE METRO AREAS AS OF THIS FORECAST
PACKAGE...BUT STAY TUNED FOR UPDATES.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
WEAK WAVE WILL MOVE AWAY FROM THE CWA MONDAY EVENING. THERE STILL
MAY BE SOME LINGERING SNOW EARLY IN THE EVENING...BUT AGAIN...THIS
IS DEPENDENT ON THE TRACK AND SPEED OF THIS WEAK WAVE WHICH THE
MODELS ARE AT ODDS WITH. WE CONTINUE TO BE A LITTLE SLOWER AND MORE
PESSIMISTIC...BUT THE TREND WILL BE FOR PRECIPITATION TO SHUT OFF
OVERNIGHT EXCEPT FOR SOME UPSLOPE SNOW ACROSS THE HIGHLANDS. ANY
MOISTURE FROM THE SNOW MONDAY/MONDAY EVENING MAY REFREEZE AS
OVERNIGHT LOWS DROPS INTO THE 20S.
TUESDAY...INAUGURATION DAY...LOOKS DRY ACROSS THE WASHINGTON AREA
WITH A MORE UPSLOPE SNOW OCCURRING OVER THE HIGHLANDS. THE DRY
FORECAST FOR WASHINGTON IS A MODERATE TO REASONABLY HIGH CONFIDENCE
FORECAST. THERE WILL REMAIN PLENTY OF STRATOCU UNDER AN UPPER
TROUGH...SO THE SKY WAS INCREASED TO MOSTLY CLOUDY. TEMPERATURES
WILL BE COLDER...HIGHS ONLY IN THE LOWER 30S...WHICH COMBINED WITH A
BRISK WIND THAT MAY GUST TO 25 MPH AT TIMES MAY PRODUCE WIND CHILL
VALUES IN THE TEENS. THOSE OUT AND ABOUT ON TUESDAY SHOULD DRESS FOR
THESE COLD CONDITIONS.
UPPER FLOW FLATTENS OUT WEDNESDAY THROUGH FRIDAY...ALLOWING FOR
MODERATING TEMPERATURES TOWARD THE END OF THE WEEK. ASIDE FROM
PERIOD UPSLOPE SNOW SHOWERS...WEDNESDAY THROUGH FRIDAY LOOK DRY
WITH UNSETTLED CONDITIONS RETURNING OVER THE WEEKEND. GFS/ECWMF AND
THEIR ENSEMBLES HANDLE DETAILS DIFFERENTLY BUT THE TREND IS FOR
HIGHER CHANCES OF PRECIPITATION. FORECAST REFLECTS THIS...AND AT
LEAST SOME OF THE PRECIPITATION WOULD BE OF THE WINTRY VARIETY.
DETAILS WILL NEED TO BE RESOLVED WITH TIME.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
THE MID ATLC IN THE LULL REGION OF A LOW PRESSURE SYSTEM W/ SCTD
SNOW SHRAS OVER THE OHIO VLY AND RAINFALL COVERING MUCH OF THE
SOUTHEAST FROM THE CAROLINAS TO THE GULF COAST. OTHER THAN OVC
4-5KFT CIGS AND A FEW PASSING FLURRIES LATER THIS AFTN...NOT MUCH
CONCERN FOR I-95 TAF SITES. SLY WINDS HAVE DECREASED A BIT AND WILL
LIKELY REMAIN STEADY OUT OF THE SOUTH 5-10KT THRU THE AFTN HRS. A
WEAK COLD FRONT WILL PUSH THRU THE REGION TOWARD LATE EVNG...W/ A
GRADUAL WIND SHIFT AFT MIDNIGHT...BUT REMAINING FAIRLY LIGHT. MOST
SITES WILL LIKELY GO VRB AFTER SUNSET.
A SFC LOW IS EXPECTED TO DEVELOP OVER SRN/CNTRL VA EARLY
MONDAY...MOVING JUST SOUTH OF THE DC METRO AREA DURING THE AFTN HRS.
SCATTERED SNOW BANDS MAY DEVELOP TO THE NORTH OF THE LOW AND MAY BE
IN THE VICINITY OR OVER PORTIONS OF THE I-95 TAF SITES...LESSER
CHANCES ACROSS NRN/WRN MD AND THE WV PANHANDLE EAST OF THE BLUE
RIDGE.
A WEAK WAVE MAY BRING A LITTLE MORE SNOW MONDAY EVENING...THEN GUSTY
NORTHWEST WINDS WILL SETTLED IN OVERNIGHT MONDAY INTO TUESDAY.
HIGH PRESSURE RETURNS MID TO LATE WEEK.
&&
.MARINE...
WINDS THIS AFTN WILL BRIEFLY GUST NEAR SCA CONDITIONS...GRADUALLY
DECREASING INTO THE EVNG HRS AND STAYING LIGHT OVERNIGHT. A SFC LOW
EXPECTED TO MOVE ACROSS THE WATERS LATE WED AFTN/EVNG...SO WINDS
AROUND THE LOW WILL GENERALLY BE LIGHT...THO AN INCREASE TO SCA
CONDITIONS ARE EXPECTED BY LATE TUESDAY NIGHT.
RAISED A SMALL CRAFT ADVISORY MONDAY NIGHT INTO TUESDAY FOR
INCREASING NORTHWEST WINDS. SMALL CRAFT ADVISORY CONDITIONS MAY
PERSIST INTO TUESDAY NIGHT. HIGH PRESSURE BUILDS IN MID TO LATE
WEEK.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MDZ501.
VA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR VAZ021.
WV...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR WVZ054-
501>503.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM MONDAY TO 5 PM EST TUESDAY FOR
ANZ530>537.
&&
$$
SYNOPSIS...PELOQUIN
NEAR TERM...GMS
SHORT TERM...GMS
LONG TERM...PELOQUIN
AVIATION...GMS/PELOQUIN
MARINE...GMS/PELOQUIN
000
FXUS61 KLWX 181600 AAA
AFDLWX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1100 AM EST SUN JAN 18 2009
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE THROUGH THE GREAT LAKES TODAY
INTO TONIGHT. THE COLD FRONT ASSOCIATED WITH THIS LOW WILL PASS
THROUGH THE MID-ATLANTIC LATER TODAY AND TONIGHT. A MID-LEVEL
TROUGH OF LOW PRESSURE WILL REMAIN IN PLACE THROUGH TUESDAY
BRINGING CHILLY CONDITIONS. HIGH PRESSURE WILL BUILD OVER THE
REGION FOR THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LITTLE CHANGE TO PREV FORECAST. SEEING A GRADUAL MOISTURE SURGE
INCREASING ACROSS THE REGION...AHEAD OF THE APPROACHING LOW
PRESSURE SYSTEM. A WEAK COLD FRONT DRAPED ACROSS THE CNTRL OHIO
VLY MOVING TOWARD THE CNTRL APLCNS...ALONG AND SURROUNDING THE
FRONTAL ZONE ARE SCATTERED AREAS OF WEAKLY FORCED PRECIP /MAINLY
SNOW W/ POCKETS OF RA/FZRA. THE WRN ZONES CURRENTLY RECEIVING
LIGHT SNOW AND LIGHT FRZG DZ /MAINLY OVER THE SWRN ZONES/. BUT
AS MODELS HAVE INDICATED FOR THE PAST FEW DAYS...THE MID ATLC
REGION LIES UNDER AN UNFAVORABLE LIFT REGION OF THE UPPER LEVEL
JET MAX. WHILE THESE JET DYNAMICS MAY INHIBIT WIDESPREAD PRECIP
DEVELOPMENT...THERE/S STILL A LOW CHANCE OF LIGHT SNOW OR FLURRIES
ACROSS THE NRN PORTION OF THE CWA...MORE FLURRIES DOWN INTO THE
I-66 CORRIDOR AND INTO THE METRO AREAS. ACROSS THE WRN ZONES...A
WINTER WX ADZY NOW IN EFFECT THROUGH LATE TONIGHT W/ SOME DECENT
SNOW BANDS ALREADY SLIDING INTO THE CNTRL APLCNS...DRAGGING SOME
MODERATE SNOW SHOWERS OVER THE HIGHER ELEVATIONS.
EAST OF THE BLUE RIDGE FOR THIS AFTN...SLY WINDS WILL STAY MAINLY
BELOW 10MPH AHEAD OF THE COLD FRONT. SKIES WILL REMAIN NEARLY
OVERCAST W/ A INTERMITTENT BREAKS AS LOW AND MID DECKS SLIDE OFF
TO THE EAST AHEAD OF THE APPROACHING UPPER TROF. TEMPS W/ THE WEAK
SLY MOISTURE SURGE WILL SLOWLY CONTINUE TO RISE OUT OF THE BELOW
FREEZING REGIME AND INTO THE M/U30S...A FEW LOCALES TOPPING 40.
WIND CHILLS A BIT MORE COMFORTABLE W/ A MOIST SLY WIND THAN A DRY
NWLY WIND...THO WIND CHILL VALUES WILL LIKELY REMAIN NEAR OR JUST
BELOW FREEZING AREAWIDE. A VERY LOW CHANCE OF ISOLATED DISSIPATING
SNOW BANDS FROM THE NW MAY PUSH ACROSS THE AREA...THO LATER THIS
EVNG AS THE COLD FRONT MOVES THRU...BRIEF AREAS OF PRECIP MAY
DEVELOP JUST OUT AHEAD OF THE FRONT AS IT NEARS THE BAY AND
DELMARVA REGION. MOST MODELS RESOLVE THAT LITTLE OR NONE OF THIS
ACTIVITY WILL COME TO FRUITION...AND EVEN W/ THE LOW LEVEL MOISTURE
SURGE...THE BOUNDARY LAYER WILL REMAIN FAIRLY DRY INTO THE LATE
NIGHT HRS.
QUICK UPDATE FOR MONDAY... THE 12Z RUNS OF THE NAM/GFS INDICATING A
BIT STRONGER SFC LOW DEVELOPING ACROSS SRN VA AND CLOSER TO THE DC
METRO AREA. INCREASING POPS FOR TMRW AND THE GRIDS WILL REFLECT
THE CHANGE. MORE ON THIS FOR THE AFTN FORECAST PACKAGE.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM MONDAY/...
THE COLD FRONT WILL CONTINUE TO PASS THROUGH THE REST OF THE CWA
THIS EVENING. WITH SOME INSTABILITY AHEAD OF THE FRONT AND A JET
MAX MOVING THROUGH...WILL CONTINUE WITH SLIGHT CHANCE TO CHANCE
POPS FOR SNOW SHOWERS THIS EVENING FURTHER EAST ACROSS THE
METROPOLITAN AREAS. THIS IS ABOVE WHAT THE LATEST GUIDANCE IS
SUGGESTING. SNOW ACCUMULATION...IF ANY WOULD BE LIGHT AND CONFINED
MAINLY TOWARDS NORTHERN MARYLAND.
THE MID-LEVEL TROUGH OF LOW PRESSURE WILL REMAIN OVER THE REGION
BEHIND THE FRONT OVERNIGHT. LEFT THE SLIGHT CHANCE FOR SNOW SHOWERS
IN THE FORECAST ACROSS THE METROPOLITAN AREAS...BUT NO ACCUMULATION
IS EXPECTED. FURTHER WEST ALONG THE ALLEGHENY FRONT...A PERIOD OF
UPSLOPE SNOW WILL BRING ADDITIONAL SNOW ACCUMULATIONS. A WINTER
WEATHER ADVISORY MAY BE WARRANTED DURING THIS TIME...BUT DID NOT
ISSUE IT WITH THIS PACKAGE. THE INVERSION WILL REMAIN SHALLOW
DESPITE COLDER AIR AND A BETTER UPSLOPE COMPONENT TO THE LOW-LEVEL
FLOW. WILL GO WITH ADDITIONAL ACCUMULATIONS AROUND AN INCH FOR
NOW.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
A COMPLEX UPPER TROUGH PATTERN REMAINS OVER THE AREA THRU THE
EARLY PART OF THE WEEK. THE CENTER OF THE UPPER WAVE MOVES ACROSS
THE EASTERN GREAT LAKES SUNDAY NIGHT THRU MONDAY NIGHT. THE TROUGH
EXTENDING FROM THIS SYSTEM WILL CROSS THE MID-ATLANTIC SUNDAY
NIGHT...THEN DEVELOPS INTO A COASTAL LOW THAT RACES UP THE NE
COAST ON MONDAY. WENT WITH CHC POP FOR SNOW WRN MTNS. SCHC FOR
LIGHT SNOW SHOWERS ON MONDAY EAST OF THE MOUNTAINS...INCLUDING THE
BALTIMORE/WASHINGTON METRO AREA...WHERE SOME LIMITED MOISTURE
EXISTS WITH POSSIBLE INSTABILITY PER NAM/GFS BUFR SOUNDINGS.
GFS/EURO BOTH DEVELOP A COASTAL LOW OFF HATTERAS ON
TUESDAY...WITH MID LEVEL TROUGH AXIS ALONG THE EASTERN
SEABOARD...THE TRACK IS WELL OUT TO SEA WITH ANY ASSOCIATED PRECIP
HELD OFF MID-ATLANTIC COAST TUESDAY AND WEDNESDAY. THEREFORE TUESDAY
APPEARS DRY...EXCEPT FOR UPSLOPE PARTS OF THE MOUNTAINS WITH NW FLOW
ACROSS THE MID-ATLANTIC. TEMPERATURES FIVE TO TEN DEGREES BELOW
NORMAL EARLY AND MID WEEK WITH TUESDAY BEING THE COLDEST DAY.
LATE WEEK...EURO SOLUTION DEVELOPS MORE ZONAL FLOW ON WEDNESDAY WITH
ANY CYCLOGENESIS NORTH OF THE MID-ATLANTIC IN THE LATE PART OF THE
WEEK. THE GFS AMPLIFIES THE FLOW ENOUGH TO BRING A LOW ACROSS THE
SOUTHERN GREAT LAKES WITH FROPA ACROSS THE MID-ATLANTIC FRIDAY
NIGHT. MAINTAINED SLIGHT CHANCE POPS ON FRIDAY AND FRIDAY NIGHT
GIVEN UNCERTAINTY. TEMPERATURES MODERATE TO NEAR OR EVEN SLIGHTLY
ABOVE NORMAL FOR THURSDAY/FRIDAY.
&&
.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
THE MID ATLC IN THE LULL REGION OF A LOW PRESSURE SYSTEM W/ SCTD
SNOW SHRAS OVER THE OHIO VLY AND RAINFALL COVERING MUCH OF THE
SOUTHEAST FROM THE CAROLINAS TO THE GULF COAST. OTHER THAN OVC
4-5KFT CIGS AND A FEW PASSING FLURRIES LATER THIS AFTN...NOT MUCH
CONCERN FOR I-95 TAF SITES. SLY WINDS HAVE DECREASED A BIT AND WILL
LIKELY REMAIN STEADY OUT OF THE SOUTH 5-10KT THRU THE AFTN HRS. A
WEAK COLD FRONT WILL PUSH THRU THE REGION TOWARD LATE EVNG...W/ A
GRADUAL WIND SHIFT AFT MIDNIGHT...BUT REMAINING FAIRLY LIGHT. MOST
SITES WILL LIKELY GO VRB AFTER SUNSET.
MONDAY AND TUESDAY REMAIN UNSETTLED WITH A SLIGHT CHANCE OF SNOW
SHOWERS ON MONDAY. ONLY LIGHT PRECIP IS EXPECTED ON MONDAY AND VFR
CONDITIONS ARE TO PREVAIL MONDAY THROUGH THURSDAY AS HIGH PRESSURE
BUILDS BACK INTO THE AREA ON WEDNESDAY.
&&
.MARINE...
CONTINUING THE MARGINAL SCA ADV FOR THE MIDDLE/LOWER BAY AND THE
ADJACENT TIDAL PTMC ZONE INTO THE LATE AFTN HRS. INTERMITTENT SCA
GUSTS ARE CONTINUING AS SFC PRES GRADIENT SLOWLY WEAKENS OVER THIS
REGION. ACROSS THE REST OF THE NEARBY WATERS...WINDS HAVE SUBSIDED
BELOW 10KTS FOR THE MOST PART...W/ ONLY A BRIEF INCREASE LATER THIS
AFTN W/ A BRIEF PEAK NEAR 15KT.
NW FLOW FOR MONDAY THRU LATE TUESDAY AS AN UPPER TROUGH UNDULATES
OVER THE AREA. STRONGER NW FLOW/COLD AIR SURGE MONDAY NIGHT INTO
TUESDAY MORNING TO APPROACH SMALL CRAFT CONDITIONS. THE PRESSURE
GRADIENT INCREASES AGAIN ON TUESDAY...THE MAGNITUDE OF WHICH DEPENDS
ON HOW DEEP A DEVELOPING LOW OFF HATTERAS GETS ON TUESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
MDZ501.
VA...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
VAZ021.
WV...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
WVZ054-501>503.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
ANZ532>534-537.
&&
$$
UPDATE...GMS
PREV DISCUSSION...LASORSA/BAJ
000
FXUS61 KLWX 180820
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
320 AM EST SUN JAN 18 2009
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE THROUGH THE GREAT LAKES TODAY INTO
TONIGHT. THE COLD FRONT ASSOCIATED WITH THIS LOW WILL PASS THROUGH
THE MID-ATLANTIC LATER TODAY AND TONIGHT. A MID-LEVEL TROUGH OF LOW
PRESSURE WILL REMAIN IN PLACE THROUGH TUESDAY BRINGING CHILLY
CONDITIONS. HIGH PRESSURE WILL BUILD OVER THE REGION FOR THE MIDDLE
OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CURRENT ANALYSIS EARLY THIS MORNING SHOWS LOW PRESSURE OVER THE
GREAT LAKES AND THE COLD FRONT ASSOCIATED WITH THIS LOW MOVING
THROUGH THE OHIO VALLEY. A MID-LEVEL TROUGH OF LOW PRESSURE REMAINS
OVER THE EASTERN PORTION OF THE NATION.
THE LOW PRESSURE SYSTEM OVER THE GREAT LAKES WILL SLOWLY DRIFT EAST
AND THE COLD FRONT ASSOCIATED WITH THIS LOW WILL MOVE INTO THE AREA
THIS AFTERNOON. CURRENT RADAR SHOWS MOST OF THE PRECIPITATION OFF TO
OUR NORTH THIS MORNING AND THAT SHOULD CONTINUE TO BE THE CASE
THROUGHOUT THE DAY. THE BEST LIFT REMAINS TO OUR NORTH CLOSER TO THE
LOW. AS THE COLD FRONT MOVES INTO THE REGION THIS AFTERNOON ANOTHER
UPPER-LEVEL DISTURBANCE ROTATING AROUND THE TROUGH WILL CAUSE A
SURFACE LOW TO DEVELOP ALONG THE FRONT. HOWEVER...WITH THE TROUGH
AXIS REMAINING POSITIVELY TILTED AND FAST WINDS ASSOCIATED WITH THE
SOUTHERN STREAM OF THE JET...THIS AREA OF LOW PRESSURE WILL HAVE
LITTLE INFLUENCE ON OUR WEATHER. NAM/GFS BUFKIT DO SHOW LIMITED
INSTABILITY DEVELOPING AHEAD OF THE FRONT AND WE DO REMAIN IN THE
FAVORABLE REGION OF A MID-LEVEL JET MAX MOVING THROUGH.
THEREFORE...WILL CONTINUE WITH SLIGHT CHANCE TO CHANCE POPS CLOSER
TO THE FRONT THIS AFTERNOON MAINLY ACROSS LOCATIONS WEST OF THE BLUE
RIDGE. HAVE ADDED THE CHANCE FOR FLURRIES THIS AFTERNOON FOR
BALTIMORE AND WASHINGTON DC...BUT THE BEST CHANCE FOR PRECIPITATION
SHOULD HOLD OFF UNTIL THIS EVENING.
ALONG AND WEST OF THE ALLEGHENY FRONT...PLENTY OF LOW-LEVEL MOISTURE
AND A SLIGHT UPSLOPE COMPONENT TO THE LOW-LEVEL FLOW WILL ALLOW FOR
SNOW SHOWERS TODAY. NAM/GFS BUFKIT ALSO INDICATE SOME INSTABILITY
AHEAD OF THE FRONTAL PASSAGE...BUT THE INVERSION REMAINS RATHER
SHALLOW AND WITH A SOUTHWEST FLOW THE UPSLOPE COMPONENT TO THE
LOW-LEVEL FLOW WILL BE WEAK. SO DID NOT ISSUE AND ADVISORY. SNOW
ACCUMULATIONS GENERALLY LESS THAN ONE INCH ARE EXPECTED THROUGH THIS
AFTERNOON.
WITH A SOUTHERLY FLOW AHEAD OF THE FRONT...MAX TEMPS WILL BE
NOTICEABLY MILDER COMPARED TO RECENT DAYS DESPITE THE CLOUD COVER.
MAX TEMPS WILL RANGE FROM THE UPPER 20S IN PORTIONS OF THE POTOMAC
HIGHLANDS TO AROUND 40 IN WASHINGTON DC.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
THE COLD FRONT WILL CONTINUE TO PASS THROUGH THE REST OF THE CWA
THIS EVENING. WITH SOME INSTABILITY AHEAD OF THE FRONT AND A JET
MAX MOVING THROUGH...WILL CONTINUE WITH SLIGHT CHANCE TO CHANCE POPS
FOR SNOW SHOWERS THIS EVENING FURTHER EAST ACROSS THE METROPOLITAN
AREAS. THIS IS ABOVE WHAT THE LATEST GUIDANCE IS SUGGESTING. SNOW
ACCUMULATION...IF ANY WOULD BE LIGHT AND CONFINED MAINLY TOWARDS
NORTHERN MARYLAND.
THE MID-LEVEL TROUGH OF LOW PRESSURE WILL REMAIN OVER THE REGION
BEHIND THE FRONT OVERNIGHT. LEFT THE SLIGHT CHANCE FOR SNOW SHOWERS
IN THE FORECAST ACROSS THE METROPOLITAN AREAS...BUT NO ACCUMULATION
IS EXPECTED. FURTHER WEST ALONG THE ALLEGHENY FRONT...A PERIOD OF
UPSLOPE SNOW WILL BRING ADDITIONAL SNOW ACCUMULATIONS. A WINTER
WEATHER ADVISORY MAY BE WARRANTED DURING THIS TIME...BUT DID NOT
ISSUE IT WITH THIS PACKAGE. THE INVERSION WILL REMAIN SHALLOW
DESPITE COLDER AIR AND A BETTER UPSLOPE COMPONENT TO THE LOW-LEVEL
FLOW. WILL GO WITH ADDITIONAL ACCUMULATIONS AROUND AN INCH FOR
NOW.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
A COMPLEX UPPER TROUGH PATTERN REMAINS OVER THE AREA THRU THE EARLY
PART OF THE WEEK. THE CENTER OF THE UPPER WAVE MOVES ACROSS THE
EASTERN GREAT LAKES SUNDAY NIGHT THRU MONDAY NIGHT. THE TROUGH
EXTENDING FROM THIS SYSTEM WILL CROSS THE MID-ATLANTIC SUNDAY
NIGHT...THEN DEVELOPS INTO A COASTAL LOW THAT RACES UP THE NE COAST
ON MONDAY. WENT WITH CHC POP FOR SNOW WRN MTNS. SCHC FOR LIGHT SNOW
SHOWERS ON MONDAY EAST OF THE MOUNTAINS...INCLUDING THE
BALTIMORE/WASHINGTON METRO AREA...WHERE SOME LIMITED MOISTURE EXISTS
WITH POSSIBLE INSTABILITY PER NAM/GFS BUFR SOUNDINGS.
GFS/EURO BOTH DEVELOP A COASTAL LOW OFF HATTERAS ON
TUESDAY...WITH MID LEVEL TROUGH AXIS ALONG THE EASTERN
SEABOARD...THE TRACK IS WELL OUT TO SEA WITH ANY ASSOCIATED PRECIP
HELD OFF MID-ATLANTIC COAST TUESDAY AND WEDNESDAY. THEREFORE TUESDAY
APPEARS DRY...EXCEPT FOR UPSLOPE PARTS OF THE MOUNTAINS WITH NW FLOW
ACROSS THE MID-ATLANTIC. TEMPERATURES FIVE TO TEN DEGREES BELOW
NORMAL EARLY AND MID WEEK WITH TUESDAY BEING THE COLDEST DAY.
LATE WEEK...EURO SOLUTION DEVELOPS MORE ZONAL FLOW ON WEDNESDAY WITH
ANY CYCLOGENESIS NORTH OF THE MID-ATLANTIC IN THE LATE PART OF THE
WEEK. THE GFS AMPLIFIES THE FLOW ENOUGH TO BRING A LOW ACROSS THE
SOUTHERN GREAT LAKES WITH FROPA ACROSS THE MID-ATLANTIC FRIDAY
NIGHT. MAINTAINED SLIGHT CHANCE POPS ON FRIDAY AND FRIDAY NIGHT
GIVEN UNCERTAINTY. TEMPERATURES MODERATE TO NEAR OR EVEN SLIGHTLY
ABOVE NORMAL FOR THURSDAY/FRIDAY.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS ARE EXPECTED FOR MOST OF TODAY AND TONIGHT ACROSS THE
TERMINALS. THERE WILL BE A PERIOD WHERE MVFR CIGS AND VSBYS ARE
POSSIBLE ALONG WITH SNOW SHOWERS LATER THIS AFTERNOON AND EVENING AS
A COLD FRONT MOVES THROUGH. SOUTHERLY WINDS THIS MORNING INTO THIS
AFTERNOON WILL SHIFT TO THE WEST-NORTHWEST BEHIND THE FRONT THIS
EVENING.
MONDAY AND TUESDAY REMAIN UNSETTLED WITH A SLIGHT CHANCE OF SNOW
SHOWERS ON MONDAY. ONLY LIGHT PRECIP IS EXPECTED ON MONDAY AND VFR
CONDITIONS ARE TO PREVAIL MONDAY THROUGH THURSDAY AS HIGH PRESSURE
BUILDS BACK INTO THE AREA ON WEDNESDAY.
&&
.MARINE...
AN INCREASED PRESSURE GRADIENT HAS CAUSED SOUTHERLY WINDS TO
INCREASE OVERNIGHT. WILL CONTINUE WITH A SMALL CRAFT ADVISORY FOR
TODAY AHEAD OF THE FRONT WITH THE STRONGEST WINDS EXPECTED OVER TH3E
CHESAPEAKE BAY. WINDS SHOULD DIMINISH BELOW SCA CRITERIA BEHIND
THE FRONT THIS EVENING.
NW FLOW FOR MONDAY THRU LATE TUESDAY AS AN UPPER TROUGH UNDULATES
OVER THE AREA. STRONGER NW FLOW/COLD AIR SURGE MONDAY NIGHT INTO
TUESDAY MORNING TO APPROACH SMALL CRAFT CONDITIONS. THE PRESSURE
GRADIENT INCREASES AGAIN ON TUESDAY...THE MAGNITUDE OF WHICH DEPENDS
ON HOW DEEP A DEVELOPING LOW OFF HATTERAS GETS ON TUESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
ANZ530>537.
&&
$$
PRODUCTS...LASORSA/BAJ
000
FXUS61 KLWX 180255 AAB
AFDLWX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
955 PM EST SAT JAN 17 2009
.SYNOPSIS...
ARCTIC HIGH PRESSURE WILL CONTINUE TO MOVE EAST AND AWAY FROM THE
MID ATLANTIC COAST TONIGHT. SEVERAL AREAS OF LOW PRESSURE WILL
AFFECT THE REGION ON SUNDAY. ONE LOW WILL MOVE THROUGH THE GREAT
LAKES TONIGHT INTO SUNDAY. A SECOND AREA OF LOW PRESSURE WILL
DEVELOP IN THE WESTERN ATLANTIC SUNDAY NIGHT WELL EAST OF THE MID
ATLANTIC COAST AND THEN MOVE NORTHEAST TOWARDS THE CANADIAN
MARITIMES ON MONDAY. A COLD FRONT WILL CROSS THE REGION ON EARLY
MONDAY. A TROUGH OF LOW PRESSURE WILL REMAIN OVER THE REGION FOR
INAUGURATION DAY...THEN HIGH PRESSURE WILL BUILD OVER THE AREA FOR
MID WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
SFC HIPRES CONTINUES TO PUSH EASTWARD AND AWAY FROM THE MID ATLANTIC
REGION. A CLIPPER SYSTEM CURRENTLY LOCATED NEAR LAKE MICHIGAN WILL
MOVE EAST TOWARDS LAKE HURON BY SUNDAY MORNING. A COLD FRONT
ASSOCIATED WITH THE LOW WILL TRACK INTO THE OHIO VALLEY BY DAYBREAK.
REGIONAL RADAR HAS CONTINUED TO SHOW LT RETURNS OVER NW SECTIONS...HOWEVER
NO PRECIP HAS BEEN REPORTED YET THIS EVENING. ALTHOUGH THE
ATMOSPHERE STILL REMAINS RATHER DRY...DECIDED TO INCREASE TO
LIKELY POPS IN THE FAVORED UPSLOPE REGIONS OUT WEST AND CHANCE
POPS NEAR THE MASON DIXON LINE BASED ON UPSTREAM OBSERVATIONS.
REGARDLESS CLDY SKIES ARE EXPECTED FOR MOST OF THE AREA TONIGHT.
WITH A 5 TO 10 KT SLY FLOW TONIGHT...TEMPS SHOULD HOLD STEADY
TONIGHT IN THE UPPER TEENS IN THE FAR WESTERN AND NORTHERN ZONES
TO 20S ELSEWHERE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
ALL GUIDANCE NOW POINTS TO A MAINLY DRY FORECAST FOR THE DC/BALT
METRO REGION...ESSENTIALLY EAST OF THE BLUE RIDGE AND SOUTH OF THE
COUNTIES ALONG THE MASON-DIXON LINE. COORDINATION WITH NCEP/HPB
SHORT RANGE EARLIER IS IN AGREEMENT WITH THIS. THEREFORE...HAVE
PULLED BACK ON THE CHANCE OF SNOW ON SUNDAY AFTERNOON FOR THESE
AREAS ON SUNDAY. IN AREAS WEST OF THE BLUE RIDGE AND ALONG THE
MASON DIXON LINE. ANY SNOW ACCUMULATION LIKELY LIMITED TO THE FAR
WESTERN ZONES LATE TONIGHT AND DURING THE DAY ON SUNDAY.
TEMPERATURES ON SUNDAY WILL BE MORE MODERATE THAN THE CHILLY
READINGS FROM SAT. HOWEVER...GUIDANCE SEEMS TO HAVE GONE THE OTHER
DIRECTION AND IS TOO WARM...EXCEPT FOR THE FWC MOS PRODUCTS. FOR
MAX TEMPS ON SUN...LEANED ON THE FWC-MOS WITH A NUDGE UPWARDS.
WINDS ON SUNDAY WILL CONTINUE TO HAVE A SOUTHERLY COMPONENT.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
MODELS HAVE COME INTO BETTER AGREEMENT REGARDING THE SUNDAY
NIGHT/MONDAY TIME PERIOD. 06Z AND 12Z GFS HAVE BACKED OFF ON COASTAL
LOW PRESSURE AFFECTING THE MID ATLANTIC SUNDAY NIGHT INTO EARLY
MONDAY. 03Z AND 09Z SREFS DID THE SAME...WHICH CONVERGES TOWARD
ECMWF AND NAM SOLUTIONS. THIS HAS LEAD TO AN INCREASE IN CERTAINTY
AND CONFIDENCE FOR OUR FORECAST.
A MORE NORTHERN STREAM SHORTWAVE/CLIPPER SYSTEM IS STILL POISED TO
MOVE ACROSS THE AREA SUNDAY NIGHT. THIS SYSTEM WILL PRODUCE SNOW
MAINLY WEST OF THE MTNS...BUT THERE IS A CHANCE THAT A LITTLE BIT OF
LIGHT SNOW WILL BE ABLE TO MAKE IT EAST OF THE MTNS INCLUDING THE
BALTIMORE/WASHINGTON METRO AREA. WITH THE COASTAL SYSTEM NOT
EXPECTED TO AFFECT THE AREA NOW...AND ANY SNOW BEING A FUNCTION OF
THE WEAK CLIPPER SYSTEM...WE HAVE LOWERED OUR CHANCES OF SNOW INTO
THE CHANCE CATEGORY. PRECIPITATION COULD EVEN BEGIN OR MIX WITH RAIN
SOUTHEAST OF WASHINGTON IN THE EVENING. ACCUMULATIONS MAY BE AN INCH
OR TWO ACROSS THE HIGHLANDS...BUT ANY ACCUMULATIONS EAST OF THE MTNS
WOULD MORE THAN LIKELY ONLY BE A TRACE TO A COATING.
THIS LIGHT SNOW WOULD BE DONE BY SUNRISE MONDAY...WITH ANY LEFTOVER
SNOW GENERALLY OCCURRING FROM AN UPSLOPE COMPONENT ACROSS THE
HIGHLANDS. AN UPPER TROUGH WILL REMAIN OVER THE MID ATLANTIC MONDAY
AND TUESDAY. THIS WILL KEEP PLENTY OF CLOUDS AROUND...BUT CHANCES OF
SNOW EAST OF THE MTNS LOOKS SLIM TO NONE. THEREFORE...HAVE REMOVED
MENTION OF SNOW SHOWERS EAST OF THE MTNS ON TUESDAY. WITH NORTHWEST
FLOW...TEMPERATURES WILL BE BELOW CLIMO AND OCCASIONAL UPSLOPE SNOW
WILL OCCUR OVER THE HIGHLANDS.
DURING THE MID TO LATE WEEK...MORE OF A ZONAL FLOW DEVELOPS WHICH
WILL ALLOW FOR MODERATING TEMPERATURES. GFS CONTINUES TO INDICATE A
SYSTEM APPROACHING ON FRIDAY ALTHOUGH THE ECMWF DOES NOT. FOLLOWED
HPC GRIDS WITH MAINLY SLIGHT CHANCE POPS ON FRIDAY AND FRIDAY NIGHT.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS ARE EXPECTED TONIGHT INTO EARLY SUN MORNING. CIGS
WILL GRADUALLY LOWER DURING THE DAY ON SUN...BECOMING MVFR IN THE
MORNING OVER MRB AND CHO...AND MVFR IN THE AFTERNOON ELSEWHERE.
MENTIONED LT SNOW AT MRB TOMORROW AFTERNOON AS CLIPPER SYSTEM
TRACKS NORTH OF THE REGION. A COASTAL LOW COULD BRING LIGHT SNOW
TO THE EASTERN TERMINALS AFTER 00Z MONDAY.
A WEAK CLIPPER WITH BRING A SMALL CHANCE OF SNOW SUNDAY NIGHT. GUSTY
NORTHWEST WINDS WOULD SETTLE IN EARLY NEXT WEEK AS AN UPPER TROUGH
REMAINS OVER THE AREA.
&&
.MARINE...
ISSUED A SCA BASED ON LATEST OBS AND MODEL GUIDANCE. HIPRES HAS
MOVED EAST OF THE WATERS THIS EVENING...LEADING TO SOUTHERLY
CHANNELING ACROSS THE BAY. LOCAL WRF ARW AND NAM/GFS BUFKIT
SOUNDINGS SUPPORT SMALL CRAFT CONDITIONS TO CONTINUE THRU SUN
AFTERNOON.
SMALL CRAFT ADVISORY CONDITIONS MAY RETURN MONDAY INTO TUESDAY WITH
A GUSTY NORTHWEST FLOW IN PLACE.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST SUNDAY FOR ANZ530>537.
&&
$$
UPDATE...JRK
PREV DISC...SMZ/BPP
000
FXUS61 KLWX 180049 AAA
AFDLWX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
749 PM EST SAT JAN 17 2009
.SYNOPSIS...
ARCTIC HIGH PRESSURE WILL CONTINUE TO MOVE EAST AND AWAY FROM THE
COAST THIS EVENING. SEVERAL AREAS OF LOW PRESSURE WILL AFFECT THE
REGION ON SUNDAY. ONE LOW WILL MOVE THROUGH THE GREAT LAKES TONIGHT
INTO SUNDAY. A SECOND AREA OF LOW PRESSURE WILL DEVELOP IN THE WESTERN
ATLANTIC SUNDAY NIGHT WELL EAST OF THE MID ATLANTIC COAST AND THEN
MOVE NORTHEAST TOWARDS THE CANADIAN MARITIMES ON MONDAY. A COLD
FRONT WILL CROSS THE REGION ON EARLY MONDAY. A TROUGH OF LOW
PRESSURE WILL REMAIN OVER THE REGION FOR INAUGURATION DAY...THEN
HIGH PRESSURE WILL BUILD OVER THE AREA FOR MID WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THE CENTER OF THE HIGH PRESSURE SYSTEM THAT BROUGHT THE VERY COLD
CONDITIONS OVER THE LAST FEW DAY IS OVER THE DELMARVA AND
CONTINUES TO SLIDE EAST. WINDS HAVE ON THE BACK SIDE OF THE HIGH
ARE SOUTHERLY ACROSS MOST OF THE CWA AND WILL CONTINUE FROM THIS
DIRECTION OVERNIGHT.
A COUPLE OF LOW PRESSURE SYSTEMS ARE CURRENTLY DROPPING SE ACROSS
THE WESTERN GREAT LAKES. CONSIDERABLE CLOUDINESS RAPIDLY
OVERSPREAD THE REGION THIS AFTERNOON IN ADVANCE OF THE FIRST LOW
PRESSURE SYSTEM. MODELS ARE ALL CONSISTENT IN TRACKING THIS LOW
WELL NORTH OF THE CWA TONIGHT. ANOTHER LOW IS QUICKLY FOLLOWING ON
ITS HEELS.
BOTH THE 12Z AND 18Z NAM SHOW AN ENHANCED AREA OF MID-LEVEL RH
MOVING ACROSS THE AREA THIS AFTERNOON/EVENING BUT SHOWS LITTLE IN
THE WAY OF MEASURABLE QPF. SURFACE OBS SHOW THERE IS NO PRECIP
ACTUALLY MAKING IT TO THE SURFACE ANYWHERE CLOSE TO THE CWA THIS
AFTERNOON. REGNL RADAR IS SHOWING MAINLY VIRGA ACROSS WESTERN
MARYLAND AND THE POTOMAC HIGHLANDS CURRENTLY. NOT EXPECTING ANY
ACCUMULATION FROM THIS FIRST BAND OF MOISTURE. IN THE WESTERN
ZONES AND POTOMAC HIGHLANDS...CANNOT RULE OUT A FEW FLURRIES
OVERNIGHT FROM THIS SYSTEM.
TEMPERATURES OVERNIGHT...GIVING THE MODERATING INFLUENCE OF THE
SOUTHERLY WINDS TONIGHT...WILL NOT MOVE MUCH FROM THE MAX READINGS
ON SAT AFTERNOON.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
ALL GUIDANCE NOW POINTS TO A MAINLY DRY FORECAST FOR THE DC/BALT
METRO REGION...ESSENTIALLY EAST OF THE BLUE RIDGE AND SOUTH OF THE
COUNTIES ALONG THE MASON-DIXON LINE. COORDINATION WITH NCEP/HPB
SHORT RANGE EARLIER IS IN AGREEMENT WITH THIS. THEREFORE...HAVE
PULLED BACK ON THE CHANCE OF SNOW ON SUNDAY AFTERNOON FOR THESE
AREAS ON SUNDAY. IN AREAS WEST OF THE BLUE RIDGE AND ALONG THE
MASON DIXON LINE. ANY SNOW ACCUMULATION LIKELY LIMITED TO THE FAR
WESTERN ZONES LATE TONIGHT AND DURING THE DAY ON SUNDAY.
TEMPERATURES ON SUNDAY WILL BE MORE MODERATE THAN THE CHILLY
READINGS FROM SAT. HOWEVER...GUIDANCE SEEMS TO HAVE GONE THE OTHER
DIRECTION AND IS TOO WARM...EXCEPT FOR THE FWC MOS PRODUCTS. FOR
MAX TEMPS ON SUN...LEANED ON THE FWC-MOS WITH A NUDGE UPWARDS.
WINDS ON SUNDAY WILL CONTINUE TO HAVE A SOUTHERLY COMPONENT.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
MODELS HAVE COME INTO BETTER AGREEMENT REGARDING THE SUNDAY
NIGHT/MONDAY TIME PERIOD. 06Z AND 12Z GFS HAVE BACKED OFF ON COASTAL
LOW PRESSURE AFFECTING THE MID ATLANTIC SUNDAY NIGHT INTO EARLY
MONDAY. 03Z AND 09Z SREFS DID THE SAME...WHICH CONVERGES TOWARD
ECMWF AND NAM SOLUTIONS. THIS HAS LEAD TO AN INCREASE IN CERTAINTY
AND CONFIDENCE FOR OUR FORECAST.
A MORE NORTHERN STREAM SHORTWAVE/CLIPPER SYSTEM IS STILL POISED TO
MOVE ACROSS THE AREA SUNDAY NIGHT. THIS SYSTEM WILL PRODUCE SNOW
MAINLY WEST OF THE MTNS...BUT THERE IS A CHANCE THAT A LITTLE BIT OF
LIGHT SNOW WILL BE ABLE TO MAKE IT EAST OF THE MTNS INCLUDING THE
BALTIMORE/WASHINGTON METRO AREA. WITH THE COASTAL SYSTEM NOT
EXPECTED TO AFFECT THE AREA NOW...AND ANY SNOW BEING A FUNCTION OF
THE WEAK CLIPPER SYSTEM...WE HAVE LOWERED OUR CHANCES OF SNOW INTO
THE CHANCE CATEGORY. PRECIPITATION COULD EVEN BEGIN OR MIX WITH RAIN
SOUTHEAST OF WASHINGTON IN THE EVENING. ACCUMULATIONS MAY BE AN INCH
OR TWO ACROSS THE HIGHLANDS...BUT ANY ACCUMULATIONS EAST OF THE MTNS
WOULD MORE THAN LIKELY ONLY BE A TRACE TO A COATING.
THIS LIGHT SNOW WOULD BE DONE BY SUNRISE MONDAY...WITH ANY LEFTOVER
SNOW GENERALLY OCCURRING FROM AN UPSLOPE COMPONENT ACROSS THE
HIGHLANDS. AN UPPER TROUGH WILL REMAIN OVER THE MID ATLANTIC MONDAY
AND TUESDAY. THIS WILL KEEP PLENTY OF CLOUDS AROUND...BUT CHANCES OF
SNOW EAST OF THE MTNS LOOKS SLIM TO NONE. THEREFORE...HAVE REMOVED
MENTION OF SNOW SHOWERS EAST OF THE MTNS ON TUESDAY. WITH NORTHWEST
FLOW...TEMPERATURES WILL BE BELOW CLIMO AND OCCASIONAL UPSLOPE SNOW
WILL OCCUR OVER THE HIGHLANDS.
DURING THE MID TO LATE WEEK...MORE OF A ZONAL FLOW DEVELOPS WHICH
WILL ALLOW FOR MODERATING TEMPERATURES. GFS CONTINUES TO INDICATE A
SYSTEM APPROACHING ON FRIDAY ALTHOUGH THE ECMWF DOES NOT. FOLLOWED
HPC GRIDS WITH MAINLY SLIGHT CHANCE POPS ON FRIDAY AND FRIDAY NIGHT.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
VFR THROUGH SUNDAY AFTERNOON. MID LEVEL CLOUDS EXPECTED OVERNIGHT
WITH LIGHT SOUTHERLY WINDS.
A WEAK CLIPPER WITH BRING A SMALL CHANCE OF SNOW SUNDAY NIGHT. GUSTY
NORTHWEST WINDS WOULD SETTLE IN EARLY NEXT WEEK AS AN UPPER TROUGH
REMAINS OVER THE AREA.
&&
.MARINE...
ISSUED A SCA BASED ON LATEST OBS AND MODEL GUIDANCE. HIPRES HAS
MOVED EAST OF THE WATERS THIS EVENING...LEADING TO SOUTHERLY
CHANNELING ACROSS THE BAY. LOCAL WRF ARW AND NAM/GFS BUFKIT
SOUNDINGS SUPPORT SMALL CRAFT CONDITIONS TO CONTINUE THRU SUN
AFTERNOON.
SMALL CRAFT ADVISORY CONDITIONS MAY RETURN MONDAY INTO TUESDAY WITH
A GUSTY NORTHWEST FLOW IN PLACE.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST SUNDAY FOR ANZ530>537.
&&
$$
UPDATE...JRK
PREV DISC...SMZ/BPP
000
FXUS61 KLWX 172032
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
332 PM EST SAT JAN 17 2009
.SYNOPSIS...
ARCTIC HIGH PRESSURE WILL CONTINUE TO MOVE EAST AND AWAY FROM THE
COAST THIS EVENING. SEVERAL AREAS OF LOW PRESSURE WILL AFFECT THE
REGION ON SUNDAY. ONE LOW WILL MOVE THROUGH THE GREAT LAKES TONIGHT
INTO SUNDAY. A SECOND AREA OF LOW PRESSURE WILL DEVELOP IN THE WESTERN
ATLANTIC SUNDAY NIGHT WELL EAST OF THE MID ATLANTIC COAST AND THEN
MOVE NORTHEAST TOWARDS THE CANADIAN MARITIMES ON MONDAY. A COLD
FRONT WILL CROSS THE REGION ON EARLY MONDAY. A TROUGH OF LOW
PRESSURE WILL REMAIN OVER THE REGION FOR INAUGURATION DAY...THEN
HIGH PRESSURE WILL BUILD OVER THE AREA FOR MID WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THE CENTER OF THE HIGH PRESSURE SYSTEM THAT BROUGHT THE VERY COLD
CONDITIONS OVER THE LAST FEW DAY IS OVER THE DELMARVA AND
CONTINUES TO SLIDE EAST. WINDS HAVE ON THE BACK SIDE OF THE HIGH
ARE SOUTHERLY ACROSS MOST OF THE CWA AND WILL CONTINUE FROM THIS
DIRECTION OVERNIGHT.
A COUPLE OF LOW PRESSURE SYSTEMS ARE CURRENTLY DROPPING SE ACROSS
THE WESTERN GREAT LAKES. CONSIDERABLE CLOUDINESS RAPIDLY
OVERSPREAD THE REGION THIS AFTERNOON IN ADVANCE OF THE FIRST LOW
PRESSURE SYSTEM. MODELS ARE ALL CONSISTENT IN TRACKING THIS LOW
WELL NORTH OF THE CWA TONIGHT. ANOTHER LOW IS QUICKLY FOLLOWING ON
ITS HEELS.
BOTH THE 12Z AND 18Z NAM SHOW AN ENHANCED AREA OF MID-LEVEL RH
MOVING ACROSS THE AREA THIS AFTERNOON/EVENING BUT SHOWS LITTLE IN
THE WAY OF MEASURABLE QPF. SURFACE OBS SHOW THERE IS NO PRECIP
ACTUALLY MAKING IT TO THE SURFACE ANYWHERE CLOSE TO THE CWA THIS
AFTERNOON. REGNL RADAR IS SHOWING MAINLY VIRGA ACROSS WESTERN
MARYLAND AND THE POTOMAC HIGHLANDS CURRENTLY. NOT EXPECTING ANY
ACCUMULATION FROM THIS FIRST BAND OF MOISTURE. IN THE WESTERN
ZONES AND POTOMAC HIGHLANDS...CANNOT RULE OUT A FEW FLURRIES
OVERNIGHT FROM THIS SYSTEM.
TEMPERATURES OVERNIGHT...GIVING THE MODERATING INFLUENCE OF THE
SOUTHERLY WINDS TONIGHT...WILL NOT MOVE MUCH FROM THE MAX READINGS
ON SAT AFTERNOON.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
ALL GUIDANCE NOW POINTS TO A MAINLY DRY FORECAST FOR THE DC/BALT
METRO REGION...ESSENTIALLY EAST OF THE BLUE RIDGE AND SOUTH OF THE
COUNTIES ALONG THE MASON-DIXON LINE. COORDINATION WITH NCEP/HPB
SHORT RANGE EARLIER IS IN AGREEMENT WITH THIS. THEREFORE...HAVE
PULLED BACK ON THE CHANCE OF SNOW ON SUNDAY AFTERNOON FOR THESE
AREAS ON SUNDAY. IN AREAS WEST OF THE BLUE RIDGE AND ALONG THE
MASON DIXON LINE. ANY SNOW ACCUMULATION LIKELY LIMITED TO THE FAR
WESTERN ZONES LATE TONIGHT AND DURING THE DAY ON SUNDAY.
TEMPERATURES ON SUNDAY WILL BE MORE MODERATE THAN THE CHILLY
READINGS FROM SAT. HOWEVER...GUIDANCE SEEMS TO HAVE GONE THE OTHER
DIRECTION AND IS TOO WARM...EXCEPT FOR THE FWC MOS PRODUCTS. FOR
MAX TEMPS ON SUN...LEANED ON THE FWC-MOS WITH A NUDGE UPWARDS.
WINDS ON SUNDAY WILL CONTINUE TO HAVE A SOUTHERLY COMPONENT.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
MODELS HAVE COME INTO BETTER AGREEMENT REGARDING THE SUNDAY
NIGHT/MONDAY TIME PERIOD. 06Z AND 12Z GFS HAVE BACKED OFF ON COASTAL
LOW PRESSURE AFFECTING THE MID ATLANTIC SUNDAY NIGHT INTO EARLY
MONDAY. 03Z AND 09Z SREFS DID THE SAME...WHICH CONVERGES TOWARD
ECMWF AND NAM SOLUTIONS. THIS HAS LEAD TO AN INCREASE IN CERTAINTY
AND CONFIDENCE FOR OUR FORECAST.
A MORE NORTHERN STREAM SHORTWAVE/CLIPPER SYSTEM IS STILL POISED TO
MOVE ACROSS THE AREA SUNDAY NIGHT. THIS SYSTEM WILL PRODUCE SNOW
MAINLY WEST OF THE MTNS...BUT THERE IS A CHANCE THAT A LITTLE BIT OF
LIGHT SNOW WILL BE ABLE TO MAKE IT EAST OF THE MTNS INCLUDING THE
BALTIMORE/WASHINGTON METRO AREA. WITH THE COASTAL SYSTEM NOT
EXPECTED TO AFFECT THE AREA NOW...AND ANY SNOW BEING A FUNCTION OF
THE WEAK CLIPPER SYSTEM...WE HAVE LOWERED OUR CHANCES OF SNOW INTO
THE CHANCE CATEGORY. PRECIPITATION COULD EVEN BEGIN OR MIX WITH RAIN
SOUTHEAST OF WASHINGTON IN THE EVENING. ACCUMULATIONS MAY BE AN INCH
OR TWO ACROSS THE HIGHLANDS...BUT ANY ACCUMULATIONS EAST OF THE MTNS
WOULD MORE THAN LIKELY ONLY BE A TRACE TO A COATING.
THIS LIGHT SNOW WOULD BE DONE BY SUNRISE MONDAY...WITH ANY LEFTOVER
SNOW GENERALLY OCCURRING FROM AN UPSLOPE COMPONENT ACROSS THE
HIGHLANDS. AN UPPER TROUGH WILL REMAIN OVER THE MID ATLANTIC MONDAY
AND TUESDAY. THIS WILL KEEP PLENTY OF CLOUDS AROUND...BUT CHANCES OF
SNOW EAST OF THE MTNS LOOKS SLIM TO NONE. THEREFORE...HAVE REMOVED
MENTION OF SNOW SHOWERS EAST OF THE MTNS ON TUESDAY. WITH NORTHWEST
FLOW...TEMPERATURES WILL BE BELOW CLIMO AND OCCASIONAL UPSLOPE SNOW
WILL OCCUR OVER THE HIGHLANDS.
DURING THE MID TO LATE WEEK...MORE OF A ZONAL FLOW DEVELOPS WHICH
WILL ALLOW FOR MODERATING TEMPERATURES. GFS CONTINUES TO INDICATE A
SYSTEM APPROACHING ON FRIDAY ALTHOUGH THE ECMWF DOES NOT. FOLLOWED
HPC GRIDS WITH MAINLY SLIGHT CHANCE POPS ON FRIDAY AND FRIDAY NIGHT.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
VFR THROUGH SUNDAY AFTERNOON. MID LEVEL CLOUDS EXPECTED OVERNIGHT
WITH LIGHT SOUTHERLY WINDS.
A WEAK CLIPPER WITH BRING A SMALL CHANCE OF SNOW SUNDAY NIGHT. GUSTY
NORTHWEST WINDS WOULD SETTLE IN EARLY NEXT WEEK AS AN UPPER TROUGH
REMAINS OVER THE AREA.
&&
.MARINE...
HAVE DROPPED THE SCA FOR TONIGHT AND SUNDAY. MODEL GUIDANCE SEEMS
TOO HIGH ON SOUTHERLY CHANNELING UP THE BAY ON SUNDAY. BUT THE
PORTION OF THE BAY SOUTH OF THE CHOPTANK RIVER TO SMITH POINT
STILL COULD EXPERIENCE WIND GUSTS APPROACHING SCA LEVELS ON SUNDAY.
SMALL CRAFT ADVISORY CONDITIONS MAY RETURN MONDAY INTO TUESDAY WITH
A GUSTY NORTHWEST FLOW IN PLACE.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SMZ
NEAR TERM...SMZ
SHORT TERM...SMZ
LONG TERM...BPP
AVIATION...BPP/SMZ
MARINE...BPP/SMZ
| 
