575
FXUS61 KLWX 090843
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
343 AM EST MON NOV 9 2009
SYNOPSIS
HIGH PRESSURE WILL REMAIN IN CONTROL OF THE MID ATLANTIC WEATHER
TODAY. IDA...PRESENTLY A HURRICANE...WILL AFFECT THE DEEP SOUTH
AS A COASTAL LOW DEVELOPS OFF CAPE HATTERAS. THIS WILL BRING RAINY
AND BREEZY CONDITIONS TO THE MID ATLANTIC THROUGH THE MIDDLE OF
THE WEEK. HIGH PRESSURE WILL BUILD BACK OVER THE AREA FOR THE END
OF THE WEEK...BEFORE ANOTHER FRONT MOVES THROUGH FOR THE WEEKEND.
NEAR TERM /UNTIL 6 PM THIS EVENING/
SFC HIPRES CNTRD OVR CWFA ATTM. CLR SKIES AND LTL WND HAS RSLTD IN
RADL COOLING...AND SUBSEQUENT BCFG FORMATION. THUS FAR...FDK HAS
BEEN DWN TO 1/4SM...THV DWN TO 1 1/2SM...AND MTN DWN TO 1 1/4SM.
CONDS APPR BEST ACRS N-CENT/NERN MD. ALREADY HV NOWCAST OUT. WL ADD
AREAS OF FOG IN THE GRIDS FOR THE ELY MRNG HRS. WON/T DENOTE DENSE
ATTM...AS SHUD BE ISOLTD. WL LET THE NOW HNDL THOSE LCL EFFECTS.
RDG MVS OFFSHR TDA...ALLWG A LGT SLY FLOW TO TAKE OVR. A VAST
EXPANSE OF CI IN THE MISSISSIPPI/OHIO RVR VLYS WL APPROACH AS
WELL...CUTTING INTO THE CLR BLUE SKIES OF SUNDAY. MDL TIME-HGTS
SUGGEST THAT IT/LL BE A FAIRLY THICK LYR...BUT RH W/IN LYR DOES NOT
EXCEED 80 PCT. SO...THINK SOME SUNSHN WL BE ABLE TO MAKE IT THRU...
AND WL BE KEEPING MOSUN /THO NOT BY MUCH/ IN THE E...SLIPPING INTO
THE PTSUN RNG FOR THE W. SINCE THERE WL BE SOME SUN AND H8 TEMPS WL
BE VERY SIMLR...WL FCST MAXT CLOSE TO YDA OBSVD...WHICH WL BE ABV
MET MOS GDNC...AND IN THE BALLPARK OF THE WARMER MAV.
SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/
UPR LVL MSTR GAINS A LTL S/WV SUPPORT...SO WL BE GOING FOR CLDS TO
THICKEN. AS DEWPTS RISE AS WELL...IT/LL BE TUFF FOR TEMPS TO DROP
SGFNTLY. FOR THAT REASON...KEPT MIN-T ON THE WARM SIDE OF MOS...
WHICH HPPND TO PLACE FCST CLSR TO MET.
LONG TERM /TUESDAY THROUGH SUNDAY/
HURRICANE IDA COMPLICATING THE MED RANGE...W/ A WIDE RANGE OF
GUIDANCE SOLUTIONS...ALL HINGING ON THE TIMING/STRENGTH OF A FEW
IMPORTANT SYNOPTIC FEATURES. THE MORE IMPORTANT ONE FOR THE NEAR
FUTURE IS AN UPPER WAVE CURRENTLY MOVING OUT OF THE CANADIAN ROCKIES
INTO THE SRN CANADIAN PLAINS TODAY. THIS FEATURE IS EXPECTED TO
GRADUALLY DEEPEN W/ TIME AS IT MOVES TOWARD THE WRN GREAT LAKES
REGION. MOST GUIDANCE EXPECTS THE WAVE TO DEEPEN DOWN INTO THE OHIO
VLY AND CNTRL APLCNS...BUT THE TIMING OF THIS WILL BE THE KEY TO HOW
FAR NORTH THE REMNANTS OF IDA ARE ALLOWED TO TRAVEL.
THE NAM KEEPS IDA COMPLETELY SQUELCHED DOWN ACROSS THE DEEP SOUTH
AND NEARBY COASTAL AREAS OF FL/GA. INTO THE MIDDLE OF THE
WEEK...BASICALLY AN EFFECT OF HAVING THE UPPER TROF PUSH INTO THE
MID ATLC BEFORE IDA IS ABLE TO DRIFT NEWD. THE GFS USES THE UPPER
TROF TO ACTUALLY STRENGTHEN THE REMNANTS OF IDA INTO A POTENT
COASTAL LOW JUST OFF CAPE HATTERAS...BASED OF IT/S SLIGHTLY SLOWER
TIMING OF ALLOWING IDA TO MOVE ACROSS THE SRN PORTIONS OF THE GA/SC
JUST AHEAD OF THE UPPER TROF...THO IT SEEMS LIKE THE GFS IS THE
OUTLIER IN THE 00Z RUN OF MODEL PACKAGES.
WITH THE GFS SOLUTION...THE EFFECTS OF THIS COASTAL LOW WOULD BE
FELT FOR EVEN LONGER AND STRONGER ACROSS THE I-95 CORRIDOR OF THE
CWA AND SEWD /IN WINDS AND RAIN/. 00Z RUNS OF THE GEM AND EUROPEAN
SEEM A BIT MORE REALISTIC W/ THEIR DEVELOPMENT OF THIS
FEATURE...WHICH THEY DO BUT FURTHER OFFSHORE AND THEREFORE MUCH LESS
IMPACT ON THE ERN SEABOARD. THE GEM IS VERY SLOW W/ THE NEAR-TERM
PROGRESS OF IDA...AND NO LANDFALL /SO DISCOUNTING THE 00Z RUN/. THE
ECMWF IS SLOWER THAN THE GFS W/ THE UPPER WAVE...BUT IT DOESN/T
DEVELOP THE COASTAL NEARLY AS STRONG OR CLOSE TO THE COAST.
FAIRLY CONFIDENT TO SEE PRECIP STREAMING UP THE SRN APLCNS ON TUE
AFTN AND BEGINNING TO PUSH INTO SRN SECTIONS OF THE CWA BY MID-LATE
AFTN AND IN A BIT MORE EARNEST THRU THE LATE NIGHT-OVERNIGHT HRS.
FROM THERE...IT ALL DEPENDS ON THE DEVELOPMENT OF THE BAROCLINIC
ZONE AND COASTAL LOW. WITH THE GEM/EURO SOLUTIONS...THE SYSTEM WILL
PIVOT OVER DEEP SOUTH TAKE MUCH OF THE ACTIVITY ACROSS THE SERN-MOST
PORTIONS OF THE AREA AND THEN OUT TO SEA BY LATE WED.
RAISED POPS JUST A BIT FROM PREV PACKAGE...KEEPING W/ THE IDEA THAT
A BULK OF THE ACTIVITY WILL BE STREWN ACROSS THE SRN-SERN PORTIONS
OF THE CWA. REGARDLESS OF THE EXACT POSITION OF THE COASTAL
LOW...BREEZY CONDITIONS ARE STILL EXPECTED BOTH WED AND
THU...ESPECIALLY CLOSER TO THE BAY BUT ALSO FAIRLY BREEZY TO THE VA
BLUE RIDGE. AS THIS ACTIVITY DRIFTS SLOWLY OFF THE MID/SRN ATLC
COAST TOWARD THE END OF THE WEEK...A WEAK COLD FRONT WILL BE SLIDING
ACROSS THE MIDWEST...BUT STALL-OUT JUST ACROSS THE GREAT LAKES
REGION BY THIS WEEKEND.
AVIATION /09Z MONDAY THROUGH FRIDAY/
MOST CHALLENGING PART OF FCST COMES BTWN NOW AND SUNRISE...AS CLR
SKIES AND LTL/NO WND HV LED TO RADL COOLING AND SUBSEQUENT BCFG...
SPCLY ACRS NRN MD. HV TEMPO MVFR FOR IAD/BWI AND PREVAILING MVFR
AT MRB FOR A STARTING PT. ISSUE MOST PREVALENT ACRS N-CENT/NE MD.
XPCT TAFS TO BE AMD AS REQD THRU ELY THIS MRNG.
DURING THE DAYLIGHT HRS...VFR CONDS WL PREVAIL IN LGT SLY FLOW. HIGH
CLDS WL OVRSPRD TERMINALS...BUT HV NO OPERATIONAL CONSEQUENCE.
THE NRN EXTENT OF THE RAIN SHIELD FROM /WHAT IS NOW/ HURRICANE IDA
WILL BE PUSHING INTO THE MID ATLC BY LATE TUE. THE REMNANTS OF IDA
EXPECTED TO STAY WELL S OF THE MID ATLC...THO A SUBSEQUENT COASTAL
LOW IS EXPECTED TO DEVELOP OFF THE CAROLINAS INTO WED...WHICH WILL
STRENGTH LOW LEVEL WINDS AND CREATE BREEZY CONDITIONS AT THE SFC
/LIKELY INTO LATE THU/. THEN THE LOW IS EXPECTED TO PUSH OFF E OF
MID ATLC COAST INTO LATE THIS WEEK...W/ HIGH PRESSURE BUILDING IN
FOR THE WEEKEND.
MARINE
ALL QUIET ON THE WATERS TDA-TNGT...AS L/V WNDS INCR AFTR DAYBRK BUT
REMAIN BLO 10 KT FM THE S.
CONCERNS FOR IDA/S EFFECTS ON THE MID ATLC LIE MAINLY W/ THE
DEVELOPMENT OF A SUBSEQUENT COASTAL LOW AFTER THE TROPICAL SYSTEM
HAS DISSIPATED OVER THE DEEP SOUTH. STILL MUCH UNCERTAINTY IN WHERE
THE LOW WILL DEVELOP/MOVE...THO TRENDS POINT TOWARD JUST OFF CAPE
HATTERAS AND THEN OFF THE MID ATLC COAST. WINDS WILL STRENGTHEN
ACROSS THE CAROLINAS AND UP THE MID ATLC COAST ON WED...AND STAY
BREEZY INTO LATE THU. NEAR GALE CONDITIONS EXPECTED AT TIMES
ESPECIALLY ACROSS MIDDLE/LOWER PORTIONS OF THE BAY THRU THIS TIME
PERIOD. THE SYSTEM WILL LIKELY MOVE WELL OFF THE COAST BY EARLY
FRI...W/ MUCH MORE QUIET WX CONDITIONS GOING INTO NEXT WEEKEND.
TIDES/COASTAL FLOODING
TIDES MAY INCR TWD MIDWK DUE TO CSTL LOPRES DVLPMNT. EXACT
PLACEMENT/TIMING IN DOUBT...WHICH WL BE DETERMINING FACTOR ON HOW
THINGS UNFOLD. INTERESTS ALNG THE BAY/PTMC SHUD MONITOR LATER
FCSTS.
CLIMATE
MAXT WL APPROACH RECORDS SET IN 1994...AND WL BE 10-15 DEGF ABV
NRML. BELOW ARE THE RECORD MAXIMUM TEMPERATURES FOR MONDAY AT
SELECTED AREA CLIMATE SITES...
SITE 09/11 YEAR
BWI......78......1994
DCA......79......1994
IAD......78......1994
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
SYNOPSIS...HTS/GMS
NEAR TERM...HTS
SHORT TERM...HTS
LONG TERM...GMS
AVIATION...HTS/GMS
MARINE...HTS/GMS
TIDES/COASTAL FLOODING...HTS
CLIMATE...BAJ/HTS
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