FXUS61 KLWX 152017
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
317 PM EST TUE DEC 15 2009

.SYNOPSIS...
A COLDER AIR MASS WILL BE USHERED IN TONIGHT THROUGH WEDNESDAY AS
HIGH PRESSURE BUILDS INTO THE REGION. HIGH PRESSURE PERSISTS OVER
THE MID ATLANTIC REGION THROUGH THE END OF THE WEEK AND INTO THE
WEEKEND. A STORM SYSTEM MAY IMPACT THE AREA LATE IN THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
CDFNT MAKING PROGRESS ACRS NRN PORTIONS OF FCST AREA AS NOTED BY
GUSTY WNWLY WINDS. CLD CVR XPCD TO DECR IN CVRG THRU NEXT SVRL
HOURS WITH XCPTN OF WRN SLOPES OF ALLEGHENY FRONT...WHERE UPSLP
FLOW AND COLD AIR ADVCTN WILL SUSTAIN INSTBY. RAIN AND SNOW
SHOWERS SHUD INCR IN CVRG LATE THIS AFTN ACRS FAR WRN ZONES. ANY
SNOW ACCUMULATIONS SHUD RMN BLW ONE INCH.

DRY AIR INVADES AMID CLRG SKIES TNGT. DIURNAL COOLING TRENDS WILL
BE PARTIALLY OFFSET BY WINDS TNGT XCPT ACRS FAR SRN ZONES. MINIMA
UPR TEENS W TO LWR 30S E.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
DEEP WNWLY FLOW AND COLD ADVCTN CONT THRU WED. H9 TEMPS OF -4 TO
-7 DEG C SUGGEST MAXIMA IN LWR 30S F TMW...WHICH WOULD BE SVRL DEG
F BLW GUIDANCE. WILL FCST MAXIMA 2-4 DEG F BLW GUIDANCE...NOT
QUITE AS AGGRESSIVE AS MODEL OUTPUT SUGGESTS BUT IN THE SAME
DIRECTION. DRY FCST AS SUBSIDENCE DOMINATES IN WAKE OF UPR WAVE
PASSAGE.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
LOPRES STALLING NEAR SERN CANADA WILL PUT THE REGION INTO A CAA/NW 
FLOW REGIME WITH HIPRES BUILDING OVER THE AREA. THIS WX PATTERN WILL 
RESULT IN DRY AND SEASONABLY COOL TEMPS THRU THE END OF THE WEEK.

NEXT WAVE OF LOPRES FORMS OVER THE GULF OF MEXICO LATE THIS WEEK AND 
TRACKS OFF THE SE COAST BY SAT. THIS FAR OUT...PLENTY OF UNCERTAINTY 
WITH THE EVOLUTION/TRACK OF THIS SYSTEM AFTER IT MOVES OFF THE SE 
COAST AS EVIDENT IN THE LARGE MODEL SPREAD AMONG BOTH OPERATIONAL
MEDIUM RANGE MODELS AND GEFS ENSEMBLES. ECMWF PROG SYSTEM TO PHASE
WITH AMPLIFYING NRN STREAM UPPER TROUGH OVER CNTRL CONUS...RESULTING
IN A DEEPENING NOREASTER THAT TRACKS UP THE ERN SEABOARD SAT AND
SUN WHILE THE MORE PROGRESSIVE SOLUTIONS FROM THE GFS/GEM PROVIDES
NO SUCH PHASING.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
GUSTY WNWLY WINDS WILL SPREAD ACRS TERMINALS LATE THIS AFTN AND
EVE. HIPRES BUILDS TNGT...BUT WINDS NOT XPCD TO SUBSIDE XCPT VCTY
KCHO. OTHERWISE...DECRG CLDS XPCD THRU WED AS GUSTY WNWLY WINDS
CONT.

VFR CONDITIONS EXPECTED THRU THE END OF THE WEEK. BREEZY NW WINDS 
WED NGT AND THU WILL RELAX AS HIPRES SETTLES OVER THE REGION. A STORM 
SYSTEM MIGHT AFFECT THE AREA THIS WEEKEND.

&&

.MARINE...
SMALL CRAFT ADZY WILL STAY AS DEPICTED IN PREV UPDATE...WITH GUSTS TO
20 KT SPREADING SWD ACRS RMNDR OF CHSPK BAY AND TIDAL POTOMAC. AS
HIPRES BUILDS TMW...HAVE CANCELLED ADZY FOR NRN AND MIDDLE PORTION
OF TIDAL POTOMAC.

SCA HAS BEEN EXTENDED INTO WED NGT. SCA CONDITIONS MAY CONT INTO THU 
BEFORE THE FLOW WEAKENS AS HIPRES BUILDS OVRHD.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ530>532-
     538>540.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ533-534-
     537-541>543.
     SMALL CRAFT ADVISORY UNTIL 1 PM EST WEDNESDAY FOR ANZ535.
     SMALL CRAFT ADVISORY UNTIL 1 PM EST WEDNESDAY FOR ANZ536.

&&

$$

KRAMAR/KLEIN