FXUS61 KLWX 301545 AAA
AFDLWX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1045 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 8 PM THIS EVENING/...
A MORE WELL-FORMED LINE OF RAIN SHOWERS STARTED THE DAY BACK
ACROSS THE OHIO RVR VLY. THE QUICK MOVING LINE /ASSOCIATED W/ AN
EMBEDDED SFC COLD FRONT/ HAS MADE A STEADY AND FAIRLY QUICK
TREK ACROSS THE MID ATLC SINCE SUNRISE. AFTER OVERCOMING THE
RELATIVELY DRY BOUNDARY LAYER...RAIN SHOWERS HAVE SPREAD OVER
NEARLY ALL OF THE CWA. THE ERN EDGE OF THE PRECIP NOW MOVING OVER
THE BAY...AND EVENTUALLY OVER DELMARVA AND OFF THE MID ATLC COAST
INTO THE MIDDLE AFTN.
THE COLD FRONT /STRETCHING ALL THE WAY FROM NEN NEW ENGLAND DOWN TO
THE GULF COAST/ WILL CONTINUE TO DRIFT EWD INTO THE AFTN HRS.
BEHIND THE FRONT...CONDITIONS WILL IMPROVE FOR MUCH OF THE REGION.
EVEN W/ A RESIDUAL BACKSIDE-AREA OF PRECIP LINGERING OVER WRN
KY/ERN WV...SKIES WILL BEGIN TO BREAK-UP A BIT AND PRECIP WILL
HAVE ENDED E OF THE APLCNS BY MID AFTN. ACROSS THE WRN SLOPES OF
THE TYPICAL UPSLOPE ALLEGHENIES...SOME OF THIS RESIDUAL PRECIP
WILL CONTINUE TO BANK-UP AGAINST THE HIGHER ELEVATIONS W/ A MIX OF
RAIN-SNOW BY LATER THIS EVENING INTO THE OVERNIGHT HRS.
ALSO BEHIND THE FRONT WILL BE GRADUALLY DROPPING TEMPS AND
INCREASING SFC WINDS FROM THE NW. NOT TOO BREEZY /15-20MPH/ AND
ONLY FOR A BRIEF PERIOD OF A FEW HRS THIS EVENING.
&&
.SHORT TERM /8 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 /16Z MONDAY THROUGH FRIDAY/...
COLD FRONT WILL MOVE THROUGH THE AREA TODAY. RAIN CURRENTLY MOVING
THRU THE METRO AREAS...DOWN TO KCHO WILL BE THE WORST OF IT FOR
TODAY. BY EARLY AFTN...THIS LINE OF SHOWERS WILL BE MOVING ACROSS
E OF THE BAY AND ONLY A FEW RESIDUAL SHOWERS STRETCHING BACK INTO
THE I-95 CORRIDOR.
BEHIND THE FRONT...WINDS WILL SHIFT FROM THE S/SW TO W/NW LATER
THIS AFTERNOON. 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.
&&
$$
UPDATE...GMS
PREV DISCUSSION...LISTEMAA/BAJ
