Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 311431 AAA
AFDLWX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1031 AM EDT TUE MAR 31 2015

.SYNOPSIS...
HIGH PRESSURE WILL SLIDE OFF THE MIDDLE ATLANTIC COAST TODAY. LOW
PRESSURE AND A TRAILING COLD FRONT WILL MOVE THROUGH THE REGION
THIS EVENING. HIGH PRESSURE WILL THEN BUILD THROUGH WEDNESDAY
BEFORE BECOMING A BERMUDA HIGH THURSDAY. ANOTHER COLD FRONT IS
EXPECTED TO CROSS THE AREA FRIDAY INTO SATURDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
MULTIFACETED WEATHER SYSTEM TO IMPACT THE MIDDLE ATLANTIC REGION
THIS AFTERNOON INTO THIS EVENING.

WATER VAPOR IMAGERY SHOWS A VIGOROUS UPPER SHORTWAVE/VORT MAX
SLIDING ACROSS THE GREAT LAKES AND OHIO VALLEY WITH A FORMIDABLE
SURFACE LOW. OUT AHEAD OF THIS FEATURE...ABUNDANT SUNSHINE AND
MILD CONDITIONS ARE IN PLACE WITH TEMPERATURES ALREADY CLIMBING
INTO THE 50S AND EVEN NEAR 60 IN A FEW LOCATIONS. HAVE BUMPED UP
EXPECTED HIGH TEMPERATURES A COUPLE DEGREES EAST OF THE BLUE
RIDGE.

SURFACE LOW WILL SLIDE ACROSS THE NORTHERN PORTION OF THE FORECAST
AREA THIS AFTERNOON...PUSHING A COLD FRONT THROUGH THE REGION.
BUFKIT SOUNDINGS INDICATE AN INVERTED-V SUBCLOUD LAYER WITH SKINNY
CAPE ABOVE. WINDS JUST OFF THE DECK ALSO APPROACH 40KTS. SOME OF
THE SHOWERS THAT DEVELOP COULD CONTAIN GUSTY WINDS ABOVE 40 MPH
ESPECIALLY FOR AREAS EAST OF THE BLUE RIDGE. MAIN THREAT WILL BE
THIS LATER THIS AFTERNOON AND EVENING.

IN ADDITION...GRADIENT WINDS WILL INCREASE BEHIND THE FRONT AND
GUSTS COULD APPROACH WIND ADVISORY CRITERIA MAINLY OVER THE RIDGE
TOPS. CURRENTLY THERE ARE NO HEADLINES UP FOR THIS POTENTIAL. WILL
MONITOR CLOSELY.

FURTHER SOUTH AND WEST...MUCH DRIER DOWNSLOPE FLOW WILL OCCUR
LEADING TO THE THREAT FOR CRITICAL FIRE WEATHER CONDITIONS
ESPECIALLY OVER PORTIONS OF THE CENTRAL VA PIEDMONT AND CENTRAL
SHENANDOAH VALLEY. PLEASE REFER TO THE FIRE WEATHER DISCUSSION
BELOW.

THE COLD FRONT WILL BE TO THE SOUTH OF OUR CWA BY MIDNIGHT. DRIER
AND CHILLIER CONDITIONS ARE EXPECTED BEHIND THE FRONT WITH A
NORTHWEST FLOW OVERNIGHT. MIN TEMPS WILL RANGE FROM THE LOW 30S IN
THE MOUNTAINS TO THE LOWER 40S IN DOWNTOWN WASHINGTON AND
BALTIMORE. WINDS WILL GRADUALLY DIMINISH.

&&

.SHORT TERM /WEDNESDAY/...
HIGH PRESSURE WILL BUILD INTO THE MIDDLE ATLANTIC REGION ON
WEDNESDAY. SUNNY AND COOLER CONDITIONS WITH HIGHS IN THE 50S TO
LOWER 60S CAN BE EXPECTED.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
HIGH PRESSURE SHIFTS OFFSHORE WEDNESDAY EVENING...BECOMING A BERMUDA
HIGH THURSDAY. UPR RIDGE AXIS SHIFTS EAST ACROSS THE MID-ATLANTIC
WEDNESDAY EVENING INTO THURSDAY MORNING. RETURN FLOW WEDNESDAY NIGHT
AND THURSDAY SLOWLY RETURNS MOISTURE TO THE AREA. PVA AHEAD OF THE
NEXT TROUGH ALLOWS CHANCE POPS LATE THURSDAY.

WARMING TREND THURSDAY AND FRIDAY AHEAD OF THE NEXT COLD FRONT. WITH
DRY AND SUNNY CONDITIONS LASTING INTO THE AFTERNOON HOURS AND 10C
850MB TEMPS CROSSING THE AREA...THURSDAY MAY BE WARMEST DAY OF THE
WEEK. THIS IS PARTICULARLY THE CASE IF THE 00Z GFS IS ANYWHERE CLOSE
TO BEING RIGHT WITH A MORE PROGRESSIVE COLD FRONT. MAX TEMPS
THURSDAY LOW TO MID 70S FOR MUCH OF THE CWA...LOW 60S ON WRN SHORE
OF BAY. HUMID FRIDAY WITH AREAS S/E OF DC WARMEST (MID 70S) AS
CLOUDS MOVE IN AHEAD OF COLD FRONT WITH UPR 60S/LOW 70S REST OF THE
CWA.

UPPER PATTERN BECOMES MORE ZONAL FRIDAY INTO THE WEEKEND WITH LOW
PRESSURE MOVING EAST FROM CO...LIFTING NE ALONG THE CENTRAL
APPALACHIANS. BERMUDA HIGH AND THIS LOW OPENS THE GULF. 1.2 INCH
PWATS PROGGED BY 00Z GFS WHICH IS NEAR THE MAX FOR EARLY APRIL.
LATER SHIFTS COULD PROBABLE ADD SOME HEAVY RAIN WORDING FOR
TIMEFRAME IMMEDIATELY AHEAD OF THE COLD FRONT. HOPEFULLY GREATER
CONSENSUS ON CDFROPA OCCURS. CURRENT THOUGHT IS CDFROPA LATE FRIDAY
AFTERNOON THROUGH FRIDAY NIGHT.

BELOW NORMAL TEMPERATURES ON TAP FOR SATURDAY IN WAKE OF COLD FRONT.
WILL NEED TO MONITOR BROAD NRN STREAM TROUGH DIPPING INTO THE AREA
SUNDAY.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
SHOWERS WILL MOVE THROUGH THE REGION DURING THE AFTERNOON...WITH
POTENTIAL VSBY REDUCTIONS AND MVFR CIGS. ISOLATED TSTMS POSSIBLE
LATE IN THE AFTN. GUSTY SOUTHWEST WINDS WILL DEVELOP LATE IN THE
MORNING AND CONTINUE INTO THE AFTERNOON. GUSTS AROUND 25 TO 30
KNOTS ARE EXPECTED. GUSTS TO 35 KTS COULD DEVELOP IN THE HEAVIER
SHOWERS/STORMS.

A WIND SHIFT TO THE NORTHWEST IS EXPECTED BEHIND THE FRONT WITH
GUSTS AROUND 20 KNOTS. VFR CONDITIONS AND DRY CONDITIONS WILL
PERSIST OVERNIGHT.

VFR WEDNESDAY WITH NW WINDS 5-10KT.

HIGH PRESSURE SHIFTS OFFSHORE WEDNESDAY EVENING AND BECOMES A
BERMUDA HIGH THURSDAY. SLY FLOW UNTIL A COLD FRONT WHICH IS LIKELY
TO CROSS FRIDAY NIGHT. POSSIBLE HEAVY RAIN AHEAD OF THAT COLD FRONT
FRIDAY EVENING.

&&

.MARINE...
POTENT LOW PRESSURE WILL MOVE TOWARD THE REGION THIS AFTERNOON
BEFORE PASSING THROUGH THE WATERS LATE AFTERNOON OR EARLY EVENING..

A GALE WARNING IS IN EFFECT FOR THE WATERS LATE MORNING THROUGH
THE AFTERNOON. HOWEVER...IT WILL BE MARGINAL AND MOST GUSTS MAY
END UP BEING HIGH-END SCA CRITERIA DUE TO THE RELATIVELY COOLER
WATERS. HOWEVER...THERE WILL BE A FEW SHOWERS AND PERHAPS EVEN A
COUPLE THUNDERSTORMS THAT PASS THROUGH THE WATERS AHEAD OF THE
COLD FRONT LATE TUESDAY AFTERNOON AND EVENING. DESPITE LIMITED
INSTABILITY...THERE IS THE POTENTIAL FOR GUSTY WINDS AND SMALL
HAIL IN HEAVIER SHOWERS AND THUNDERSTORMS DURING THIS TIME.

THE COLD FRONT WILL MOVE SOUTH OF THE WATERS TONIGHT AND
NORTHWEST WINDS ARE EXPECTED BEHIND THE BOUNDARY. A SMALL CRAFT
ADVISORY IS IN EFFECT FOR ALL OF THE WATERS THIS EVENING...AND
FOR THE MIDDLE PORTION OF THE BAY AND LOWER TIDAL POTOMAC RIVER
OVERNIGHT. WINDS WILL FALL BELOW SCA LEVELS ON WEDNESDAY.

SCA EXPECTED ALL WATERS THURSDAY INTO FRIDAY IN BROAD RETURN FLOW AS
A BERMUDA HIGH SETS UP AND A COLD FRONT APPROACHES. COLD FRONTAL
PASSAGE LIKELY FRIDAY NIGHT. EXPECT HIGH END SCA/POSSIBLE GALE IN
POST FROPA NWLY FLOW LATE FRIDAY NIGHT AND SATURDAY.&&

.FIRE WEATHER...
A RED FLAG WARNING HAS BEEN ISSUED FOR SEVERAL VIRGINIA COUNTIES
IN THE HIGHLANDS...SHENANDOAH VALLEY...BLUE RIDGE AND CENTRAL
FOOTHILLS. SUSTAINED WIND ARE EXPECTED AROUND 20 MPH WITH HIGHER
GUSTS...AND LOWEST RH WILL DROP BELOW 30 PERCENT THIS AFTERNOON.
FUEL MOISTURE IS BELOW REQUIRED THRESHOLDS IN THIS AREA. FURTHER
EAST ALONG THE I-95 CORRIDOR AND SOUTHERN MD...FUEL MOISTURE
INCREASES QUICKLY ABOVE 9 PERCENT...SO THE WATCH HAS BEEN DROPPED.
AN ELEVATED RISK CONTINUES HOWEVER DUE TO GUSTY WINDS AND LOW RH.
ANY RAIN THIS AFTERNOON WILL DIMINISH THE THREAT...SO THE WARNING
MAY BE ABLE TO EXPIRE EARLY IN SOME LOCATIONS. OTHERWISE THE
THREAT WILL DIMINISH BY THIS EVENING WITH DIURNALLY DECREASING RH.

&&

.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES HAVE DECREASED DUE TO THE OFFSHORE FLOW. ANOTHER
SURGE OF SWLY WINDS WILL START UP ON TUE MRNG AND AFTERNOON AHEAD
OF A COLD FRONT. ANOMALIES MAY QUICKLY INCREASE DURING THIS TIME
AND WATER LEVELS MAY APPROACH MINOR FLOODING THRESHOLDS DURING THE
HIGH TIDE CYCLE THIS AFTERNOON INTO THIS EVENING.

GUSTY NORTHWEST WINDS WILL CAUSE ANOMALIES TO RAPIDLY FALL BEHIND
A COLD FRONT LATER TONIGHT.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...RED FLAG WARNING UNTIL 6 PM EDT THIS EVENING FOR VAZ025>027-
     029-030-036>040-050-051-501-502-504-507-508.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT
     WEDNESDAY FOR ANZ532>534-537-540>543.
     GALE WARNING UNTIL 6 PM EDT THIS EVENING FOR ANZ530>543.
     SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EDT
     TONIGHT FOR ANZ530-531-535-536-538-539.

&&

$$
SYNOPSIS...KRW
NEAR TERM...KRW
SHORT TERM...KS
LONG TERM...BAJ
AVIATION...BAJ/KRW
MARINE...BAJ/KRW
FIRE WEATHER...
TIDES/COASTAL FLOODING...



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