FXUS61 KLWX 010902
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
402 AM EST TUE DEC 1 2009

.SYNOPSIS...
HIGH PRESSURE WILL CROSS THE AREA TODAY BEFORE PUSHING OFF THE COAST 
TONIGHT. A DEVELOPING LOW PRESSURE SYSTEM WILL APPROACH THE MID 
ATLANTIC ON WEDNESDAY...AND MOVE THROUGH THE REGION WEDNESDAY NIGHT 
AND INTO THURSDAY. HIGH PRESSURE THEN BUILDS THROUGH FRIDAY. A 
COASTAL DISTURBANCE DEVELOPS OFF THE CAROLINAS AND MOVES OUT TO SEA 
OVER THE WEEKEND.
&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE AT THE SURFACE WILL CONTINUE TO BUILD ACROSS THE 
MIDDLE ATLANTIC TODAY. SKIES ARE MOSTLY CLEAR ACROSS THE CWFA...WITH 
THE EXCEPTION OF THE WESTERN RIDGES. NW FLOW CONTINUES TO BANK 
MOISTURE UP AGAINST THE POTOMAC HIGHLANDS...WHERE A FEW CLOUDS AND 
ISOLATED SNOW SHOWERS CONTINUE EARLY THIS MORNING. THE SNOW SHOWERS 
ARE EXPECTED TO END EARLY THIS MORNING...AS THE SURFACE WINDS SWITCH 
AROUND TO THE W/SW.

TEMPERATURES ARE CURRENTLY RUNNING 15 TO 20 DEGREES COLDER THAN LAST 
NIGHTS READINGS AT THIS TIME...COLDER AIR HAS SETTLED ACROSS THE 
REGION. MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE MAX T VALUES 
FOR TODAY...AND ENDED UP POPULATING WITH THE MAV GUIDANCE. SKIES ARE 
EXPECTED MOSTLY CLEAR ACROSS MOST LOCALES...WITH PARTLY CLOUDY 
ACROSS THE HIGHLANDS.
&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
SURFACE HIGH PRESSURE MOVES OFFSHORE TONIGHT. SOME INCREASING CIRRUS 
CLOUDS ARE POSSIBLE AS LOW PRESSURE MOVES INTO THE GULF STATES 
OVERNIGHT. MIN T VALUES SHOULD BE A COUPLE OF DEGREES WARMER THAN 
THIS MORNINGS READINGS...WITH A FEW MORE CLOUDS AROUND. 
&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
WEDNESDAY INTO THURSDAY...DEVELOPING SOUTHERN STREAM LOW EJECTS 
NORTH FROM THE WESTERN GULF IN THE MORNING...AS UPPER TROUGH DIGS 
INTO THE GREAT PLAINS. 00Z EURO/GFS/CANADIAN MODELS FINALLY IN 
DECENT AGREEMENT WITH 995 MB LOW MOVING ALONG WEST SIDE OF 
APPALACHIANS...WITH STRONG MOISTURE CONVEYOR BRINGING SWATH OF RAIN 
ACROSS THE CWA FROM WEST TO EAST WEDNESDAY AFTERNOON THROUGH THE 
OVERNIGHT. SOME INSTABILITY EXPECTED WITH ISO THUNDER IN FOR THE 
OVERNIGHT HOURS...QPF GENERALLY UP TO AN INCH. STRONG SLY WINDS...25 
TO 30 MPH WITH POSSIBLE WIND ADVISORY WINDS FOR THE RIDGES. 
MOISTURE/TEMPERATURE ADVECTION RESULT IN INCREASING TEMPERATURES 
OVERNIGHT.

THURSDAY...WITH LOW TO OUR NORTH /UPSTATE NY/ BY SUNRISE...WLY 
DOWNSLOPING FLOW BRINGS QUICK END TO PRECIP EAST OF THE ALLEGHENY 
FRONT. UPSLOPE PRECIP CHANGES OVER TO SNOW THURSDAY AS COLD CANADIAN 
AIR BUILDS IN. WARM MORNING NEAR 60F FOR DC AND LOW TO MID 60S FOR 
SRN MARYLAND QUICKLY COOLS INTO THE LOWER 50S FOR MOST OF THE DAY AS 
DRIER AIR BUILDS IN.

FRIDAY...UPSLOPE FLOW CONTINUES...SO ANY DECENT MOISTURE WOULD ALLOW 
SNOW SHOWERS OUT WEST TO PERSIST /THOUGH A GENERAL DECREASE IN 
COVERAGE AND INTENSITY OF SNOW SHOWERS IS EXPECTED DURING THE DAY. 
COOL AIR IN PLACE...MID TO UPPER 40S FOR HIGHS /COLD ENOUGH FOR SNOW 
ALL DAY FOR ALLEGHENY FRONT/.

SATURDAY...UPPER TROUGH FINALLY REACHES THE COAST...TRIGGERING 
COASTAL LOW DEVELOPMENT INVOF CAPE HATTERAS. WITH 
CYCLOGENESIS...BANDED PRECIP /CERTAINLY COLD ENOUGH FOR SNOW/ COULD 
EXPAND INTO OUR CWA. TIMING AND POSITION UNCERTAINTY WITH THIS LOW 
STILL FAIRLY HIGH...CARRIED SCHC FOR SNOW FOR THE BALT-DC METRO 
AREAS AND WEST WITH CHC FOR RAIN/SNOW FOR SOUTHERN MARYLAND FOR 
SATURDAY. TROUGH AXIS OVERHEAD MEANS COLDEST TEMPERATURES FOR THE 
PERIOD...STRUGGLING TO REACH 40F FOR AREAS EAST OF THE BLUE RIDGE.

REST OF WEEKEND INTO NEXT WEEK...LOW WOULD DEVELOP AND PUSH OUT TO 
SEA AS HIGH PRESSURE BUILDS BACK ACROSS THE AREA. TEMPS REMAIN 
SLIGHTLY BELOW NORMAL THOUGH SLOWLY WARM WITH HEIGHT RISES EACH DAY.
&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS ARE EXPECTED THROUGH TONIGHT. WINDS WILL SHIFT FROM 
THE NW EARLY THIS MORNING TO THE W/SW THIS AFTERNOON. SUSTAINED WIND 
SPEEDS AROUND 10 KT ARE LIKELY...SOME GUSTS TO AROUND 15 KT ARE 
POSSIBLE...ESPECIALLY EARLY THIS MORNING.

STRONG LOW MOVES UP WEST SIDE OF APPALACHIANS WED/WED NIGHT BRINGING 
SWATH OF RAIN ACROSS THE TERMINALS WED EVENING/NIGHT. ISO THUNDER 
POSSIBLE IN THE MIDNIGHT TO EARLY MORNING THURSDAY TIMEFRAME. STRONG 
PRESSURE GRADIENT ACROSS THE AREA WEDNESDAY NIGHT AS LOW CENTER 
PASSES TO THE WEST TO BRING STRONG /25 TO 35 KT OR HIGHER/ SLY LOW 
LEVEL WINDS. UNCERTAINTY ABOUT HOW STRONG THE SURFACE GUSTS WILL 
BE...BUT LOW LEVEL WIND SHEAR OF PARTICULAR CONCERN. WINDS SHIFT TO 
THE WEST AND DIMINISH THURSDAY MORNING POST FROPA AS LOW CONTINUES 
TO SPEED NORTH.

HIGH PRESSURE/VFR FOR FRIDAY. WILL CONTINUE TO WATCH FOR A COASTAL 
DISTURBANCE AND POSSIBLE LIGHT SNOW ON SATURDAY.
&&

.MARINE...
WINDS ACROSS THE MARINE AREA CONTINUE GUST TO ABOVE SCA 
CRITERIA...EVEN ACROSS THE UPPER TIDAL POTOMAC. HAVE EXTENDED THE 
SMALL CRAFT FOR THE UPPER TIDAL POTOMAC UNTIL 8 AM. BUFKIT DOES 
INDICATE SOME LESSENING IN THE GUSTS RIGHT AFTER SUNRISE ACROSS THAT 
AREA. FOR THE REMAINDER OF THE MARINE AREA...BUFKIT DOES SHOW A 
DECREASE IN THE GUST POTENTIAL BY EARLY AFTERNOON. THE CURRENT SMALL 
CRAFT RUNS UNTIL 4 PM. SOMETIMES THE MODELS DO UNDERESTIMATE THE 
WIND GUST POTENTIAL...ESPECIALLY WITH N/NW WINDS. HOWEVER...THE 
WINDS SHOULD SHIFT AROUND TO THE W/SW THIS AFTERNOON AS HIGH 
PRESSURE SLIDES TO THE SOUTH...WITH THE GUST POTENTIAL LESSENING. 
WILL HOLD WITH THE CURRENT HEADLINE FOR NOW...DAY SHIFT CAN 
RE-EVALUATE. 

STRONG LOW MOVES UP WEST SIDE OF APPALACHIANS WED/WED NIGHT BRINGING 
SWATH OF RAIN WITH ISO THUNDER POSSIBLE ACROSS THE WATERS WED 
NIGHT. SLY WINDS INCREASE THROUGH WEDNESDAY...RAISED AN SCA FOR THE 
AFTERNOON AND EVENING HOURS. AS LOW PASSES TO THE WEST WEDNESDAY 
NIGHT...STRONG PRESSURE GRADIENT OVER THE WATERS WILL LIKELY RESULT 
IN GALES.

GRADIENT SLACKENS AND WINDS SHIFT TO THE WEST ON THURSDAY AFTER 
EARLY MORNING FROPA. SCA CALIBER WLY WINDS LIKELY THROUGH THURSDAY 
AFTERNOON. WESTERLY FLOW 10 TO 15 KT CONTINUES FOR FRIDAY. WILL 
CONTINUE TO MONITOR COASTAL LOW DEVELOPMENT OFF HATTERAS ON SATURDAY.
&&

.TIDES/COASTAL FLOODING...
STRONG SE WINDS ARE EXPECTED TO DEVELOP WEDNESDAY AND WEDNESDAY 
NIGHT ACROSS THE MIDDLE ATLANTIC. THESE WINDS MAY HELP KEEP ELEVATED 
WATER LEVELS ACROSS THE WESTERN SHORE OF THE CHESAPEAKE BAY AND 
TIDAL POTOMAC FOR THIS TIME PERIOD. 
&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR 
     ANZ530>534-537>543.
     SMALL CRAFT ADVISORY FROM 1 PM WEDNESDAY TO MIDNIGHT EST 
     WEDNESDAY NIGHT FOR ANZ530>543.
     SMALL CRAFT ADVISORY UNTIL 8 AM EST THIS MORNING FOR ANZ535-
     536.

&&

$$
LISTEMAA/BAJ