FXUS61 KLWX 300825
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
325 AM EST MON NOV 30 2009

.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE REGION TODAY BRINGING SHOWERS. 
HIGH PRESSURE RETURNS TUESDAY AND TUESDAY NIGHT...THOUGH A LOW 
PRESSURE SYSTEM WILL IMPACT THE REGION WEDNESDAY INTO THURSDAY. 
CANADIAN HIGH PRESSURE TO BUILD OVERHEAD LATE IN THE WEEK.
&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
COLD FRONT CURRENTLY STRETCHES FROM WESTERN NY BACK THROUGH THE OHIO 
VALLEY AND DOWN THROUGH THE LOWER MISSISSIPPI RIVER VALLEY. REGIONAL 
RADAR SHOWS A LONG LINE OF SHOWERS AND SOME THUNDERSTORMS ASSOCIATED 
WITH THE BOUNDARY. THE THUNDER SHOULD STAY CONFINED WELL SOUTH OF 
THE CWFA TODAY...MOSTLY ALONG THE GULF COAST. HOWEVER...THE SHOWERS 
ALONG AND BEHIND THE FRONT WILL MOVE THROUGH THE AREA THIS MORNING 
AND AFTERNOON. SKIES WILL BECOME INCREASINGLY CLOUDY EARLY THIS 
MORNING AS THE FRONT APPROACHES.

BOTH THE GFS AND THE NAM HAVE THE COLD AIR ALOFT MOVING INTO THE FAR 
WESTERN PORTIONS OF THE CWFA LATE THIS AFTERNOON/EARLY EVENING. IT 
MAY BE COLD ENOUGH JUST BEFORE SUNSET TO GET A FEW RAIN/SNOW SHOWERS 
ALONG THE WESTERN SLOPES OF THE HIGHER TERRAIN. TEMPS ARE NOT REALLY 
EXPECTED TO DROP TO NEAR FREEZING UNTIL WELL AFTER SUNSET...SO VERY 
LITTLE ACCUMULATION OF SNOW IS EXPECTED. 

HIGH TEMP FORECAST WILL BE A LITTLE TRICKY TODAY. TEMPS ARE STILL 
VERY MILD ACROSS THE CWFA RANGING FROM THE UPPER 40S IN THE HIGHEST 
ELEVATIONS TO NEAR 60 ACROSS MUCH OF THE METROPOLITAN AREAS. HAVE 
NOT DONE A DIURNAL CURVE FOR TODAY. BELIEVE TEMPS EAST OF THE BLUE 
RIDGE WILL RISE A FEW DEGREES BEFORE THE CLOUDS/FRONT/PRECIP MOVE 
INTO THE AREA. AREAS WEST OF THE BLUE RIDGE SHOULD SEE EARLY HIGHS 
THIS MORNING BEFORE THE CLOUDS/PRECIP/FRONT MOVE THROUGH LATER THIS 
MORNING.
&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
FRONT WILL MOVE THROUGH THE REMAINDER OF THE CWFA EARLY THIS 
EVENING...WITH SKIES CLEARING ALONG AND EAST OF THE SHENANDOAH 
VALLEY. CLOUDS WILL HANG TOUGH ALONG THE WESTERN RIDGES 
OVERNIGHT...AS UPSLOPE SNOW SHOWERS WILL BE POSSIBLE. COLD AIR WILL 
SETTLE OVER THE CWFA...WITH OVERNIGHT MINS SOME 20 TO 25 DEGREES 
COLDER THAN READINGS THIS MORNING.
&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
TUESDAY...WESTERLY/DOWNSLOPING FLOW BUILDS WITH HIGH PRESSURE 
ENTERING THE AREA. ANTICIPATE ANY UPSLOPE SNOW SHOWERS OUT WEST TO 
END TUESDAY MORNING AS DRIER AIR MOVES IN. LINGERING COOL AIR 
MODIFIED ONLY SOMEWHAT BY DOWNSLOPING AND PARTLY TO MOSTLY SUNNY 
SKIES...LOW TO MID 50S EAST OF THE BLUE RIDGE/SHENANDOAH VALLEY.

TUESDAY NIGHT...HIGH PRESSURE SLIDES OFF THE COAST IN ADVANCE OF THE 
CUTOFF LOW APPROACHING FROM THE GULF COAST. TIMING OF OVERRUNNING 
HIGH CLOUDS LATE IN THE NIGHT TO DETERMINE MIN-T WITH AN INVERSION 
SETTING UP AFTER NIGHTFALL. LOW TO MID 30S.

WEDNESDAY AND THURSDAY...CONSIDERED THE 00Z GFS TOO QUICK WITH LOW 
MOVING UP APPALACHIAN SPINE...DELAYED LIKELY/CHANCE POPS UNTIL WED 
AFTERNOON. BEST CHANCES FOR PRECIP /AREAS OF RAIN WITH SOME EMBEDDED 
SHOWER ACTIVITY POSSIBLE IN WARM SECTOR/ AS LOW CENTER CROSSES ALONG 
WESTERN PERIPHERY OF THE CWA WEDNESDAY EVENING AND OVERNIGHT. WILL 
HAVE TO WATCH FOR DRY SLOT SLIDING UP THE BLUE RIDGE/PIEDMONT FROM 
NC AND LIMITING RAINFALL ACROSS THE CENTRAL CWA LATER WEDNESDAY 
NIGHT. AN INCH OR MORE OF RAIN IS POSSIBLE WITH THIS SYSTEM. MILD 
AIR IN THE WARM SECTOR RESULTS IN TEMPERATURES AROUND FIVE DEGREES 
/MID 50S/ ABOVE NORMAL FOR EARLY DECEMBER.

FRIDAY AND INTO THE WEEKEND...UPPER TROUGH FROM NRN STREAM DIGS 
SOUTH ACROSS ERN CONUS IN WAKE OF LOW SYSTEM. UPSLOPE SNOW POSSIBLE 
LATE THURSDAY NIGHT INTO SATURDAY...THOUGH MOISTURE AVAILABILITY 
COULD BE AN ISSUE. DRY EAST OF THE BLUE RIDGE.
&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
COLD FRONT WILL MOVE THROUGH THE AREA TODAY. WINDS WILL SHIFT FROM 
THE S/SW TO W/NW LATER THIS AFTERNOON...BEHIND THE BOUNDARY. WINDS 
MAY BRIEFLY GUST TO BETWEEN 15 AND 20KT THIS EVENING. WIDESPREAD 
SHOWERS WILL ALSO ACCOMPANY THE FRONTAL PASSAGE...WITH MVFR 
CIGS/VSBYS ANTICIPATED FROM LATE MORNING THROUGH THE LATE AFTERNOON. 
SKIES ARE EXPECTED TO CLEAR OUT BETWEEN 00Z AND 03Z.

VFR TUESDAY WITH GUSTY MORNING WINDS DECREASING THROUGH THE DAY AS 
HIGH PRESSURE BUILDS IN. MOSTLY CLEAR SKIES TO AID FOG DEVELOPMENT 
TUESDAY NIGHT. RAIN CHANCES INCREASE WEDNESDAY WITH IFR CONDITIONS 
AND GUSTY SELY/ELY WINDS DURING PRECIP WEDNESDAY EVENING/NIGHT. 
FROPA BY THURSDAY MORNING WITH WINDS VEERING TO WLY.
&&

.MARINE...
A COLD FRONT WILL MOVE THROUGH THE WATERS LATER THIS AFTERNOON. 
UNTIL THEN...S/SW WINDS WILL REMAIN NEAR SCA CRITERIA ACROSS THE 
LOWER TIDAL POTOMAC AND THE MIDDLE CHESAPEAKE BAY. AFTER THE FRONTAL 
PASSAGE...WINDS WILL SHIFT TO THE NW...AND GUSTS WILL INCREASE TO 
SCA CRITERIA. A SMALL CRAFT CRITERIA IS IN EFFECT FOR THE ENTIRE 
MARYLAND CHESAPEAKE BAY AND TIDAL POTOMAC OVERNIGHT. 

CONTINUED SMALL CRAFT FOR THE WATERS /EXCEPT UPPER TIDAL POTOMAC/ 
FOR ALL DAY TUESDAY...THOUGH AN EARLIER CANCELLATION IS POSSIBLE AS 
THE PRESSURE GRADIENT SLACKENS THROUGH THE DAY. SELY FLOW INCREASES 
WEDNESDAY AHEAD OF A LOW PRESSURE SYSTEM MOVING UP THE APPALACHIANS. 
GUSTY RAIN WEDNESDAY NIGHT WITH FROPA THURSDAY MORNING...A SMALL 
CRAFT ADVISORY IS LIKELY TO BE NEEDED LATER WEDNESDAY THROUGH 
THURSDAY.
&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST 
     TUESDAY FOR ANZ530>533-536-538>542.
     SMALL CRAFT ADVISORY UNTIL 6 PM EST TUESDAY FOR ANZ534-537-543.
     SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EST 
     TUESDAY FOR ANZ535.

&&

$$
LISTEMAA/BAJ