Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 111919 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 319 PM EDT FRI APR 11 2014 .SYNOPSIS...
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A COLD FRONT WILL SLOWLY SAG SOUTHWARD OVER THE AREA LATER THIS EVENING...THEN SLIDING OFF THE COAST OVERNIGHT. HIGH PRESSURE WILL PARK OFF THE EASTERN SEABOARD THIS WEEKEND AND INTO EARLY NEXT WEEK...CREATING A MULTIPLE DAY FETCH OF WARMER SOUTHERLY FLOW OVER THE EASTERN SEABOARD. ANOTHER SLOW-MOVING COLD FRONT WILL ARRIVE NEXT TUESDAY...DRIFTING ACROSS THE REGION INTO THE LATE EVENING WITH MORE HIGH PRESSURE FOR THE MIDDLE OF NEXT WEEK.
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&& .NEAR TERM /THROUGH SATURDAY/...
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HIGH TEMPERATURES REACHING THE MIDDLE TO UPPER 70S ACROSS THE REGION. LIMITED LOW AND MID LEVEL CLOUDS THROUGH THE MIDDLE AFTERNOON HOURS...SUNSHINE...DRY AIR...AND A WARM SOUTHWEST FLOW. THE WESTERN SHORES OF THE CHESAPEAKE BAY MAY STRUGGLE TO GET TO 70F AS THERE WILL BE MORE OF AN ONSHORE FLOW. A FEW SPOTS ON THE LEESIDE OF THE HIGHER TERRAIN OF THE POTOMAC HIGHLANDS AND THE VIRGINIA PIEDMONT WILL REACH THE LOWER 80S. ONLY A SLIGHT CHANCE FOR A FEW THUNDERSTORMS ACCOMPANYING ANY SHOWER ACTIVITY LATE THIS AFTERNOON AND EVENING DESPITE THE WARMER THAN NORMAL TEMPERATURES. A SURFACE COLD FRONT WILL BE ACTING AS THE TRIGGER FOR THE SHOWERS AND ANY T-STORMS BUT MOST OF THE POTENT UPPER LEVEL ENERGY WILL SLIDE BY TO OUR NORTH...ACROSS PA AND SE NY. THE MAIN THREAT WITH ANY SHOWERS AND THUNDERSTORMS WILL BE GUSTY WINDS AS WINDS BETWEEN 3000 AND 5000 FEET ARE AROUND 30 TO 40 MPH. RAIN AMOUNTS WHERE THE SHOWERS PERSIST FOR AN HOUR OR TWO COULD AVERAGE ONE QUARTER TO ONE HALF OF AN INCH. OTHERWISE...RAIN AMOUNTS MAY AVERAGE A TENTH OF AN INCH. AS THE COLD FRONT SAGS FARTHER SOUTH ACROSS OUR REGION TONIGHT AND EARLY SATURDAY...SLIGHTLY COOLER AIR WILL MOVE IN FROM THE NORTH. HIGH PRESSURE WILL BUILD BEHIND THE FRONT AND HEAD TOWARDS DELMARVA. NW WINDS BEHIND THE FRONT TONIGHT WILL QUICKLY BECOME NE THEN SOUTHERLY AS THE HIGH MOVES OFFSHORE AND THE PREVIOUSLY-PRONOUNCED COLD FRONT STALLS THEN RETREATS NORTHWARD AS A WARM FRONT SATURDAY. WARM TEMPERATURES EXPECTED AGAIN ON SATURDAY WITH THE SOUTHERLY FLOW. WE MAY HAVE A DRY DAY ACROSS THE REGION WITH LIMITED MOISTURE TO WORK WITH ON THE RETURN FLOW SATURDAY. HIGHS SHOULD REACH THE LOWER TO MIDDLE 70S ONCE AGAIN.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
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A QUIET WX WEEKEND WILL STAY W/ US INTO EARLY NEXT WEEK AS HIGH PRESSURE SETTLES OFF THE ATLC COAST - THE BEST POSITION FOR ONE TO BE IN FOR WARMER WX OVER THE MID ATLC. THE WARMEST DAY OF THIS STRETCH LIKELY ON SUN...AS TEMPS ACROSS THE REGION EXPECTED TO APPROACH - IF NOT BREACH THE 80F DEG MARK...WELL BELOW ANY RECORD VALUES BUT WELL ABOVE WHAT WE`VE BEEN ACCUSTOMED TO EARLY THIS YEAR. AVG HIGHS ARE IN THE M60S FOR THIS TIME OF YEAR...SO WE`LL BE WELL ABOVE THAT BOTH SUN AND MON AFTN. DESPITE THE RELATIVELY LOW SUN ANGLE IN MID APRIL...KEEP SUNSCREEN IN MIND AND FLUIDS NEARBY IF PLANS ARE TO SPEND PART OR MUCH OF THE DAY OUTDOORS. AFTER A COOL/COLD WINTER SEASON...THE BODY MAY NOT BE SO ACCLIMATED TO SUCH WARM CONDITIONS IF OUTDOORS FOR SEVERAL HRS - SO MAKE PREPARATIONS AS IF IT WERE AN `AVERAGE SUMMER DAY`. GUSTY SLY WINDS WILL ALSO BE A PART OF THE STORY BOTH SUN AND MON AFTNS...W/ THE ENHANCED FLOW DUE TO THE RELATIVE STRENGTHS OF THE OFFSHORE HIGH AND IMPENDING STORM SYSTEM FROM THE WEST INCREASING THE PRES GRADIENT OVER THE EAST COAST. OVERNIGHT LOWS WILL ALSO BE RELATIVELY WARMER W/ L50S ON SAT NIGHT AND U50S SUN NIGHT...A GOOD 10-20F DEG ABOVE AVG. LATE MON EVE...THE NEXT LOW PRESSURE SYSTEM FROM THE WEST WILL BE INCHING ITS WAY TOWARD THE APCLNS AND EVENTUALLY ACROSS THE REGION LATE MON INTO TUE. THE 12Z GFS A BIT FASTER IN TERMS OF PRECIP ONSET...BUT FAIRLY CLOSE TO THE LATEST EURO W/ SOME SCATTERED SHOWERS DRIFTING TOWARD THE AREA LATE MON EVE BUT STAYING MAINLY OVER THE WRN HALF OF CWA - MORE COVERAGE INTO EARLY TUE MRNG FURTHER EAST.
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&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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COLD FRONT AND ASSCD PCPN CRSG AREA TUES INTO WED MRNG. BEST CHC OF PCPN OCCURRING IS TUES MRNG AND AFTN. ACCORDING TO GFS...VORT TRAINING ACRS AREA TUES THRU WED AFTN. WK VORT MAX DUE FRI. LATE SEASON CD AIR MVS INTO REG LT TUE NGT AND WED. ALTHOUGH NOT LKLY...CANNOT RULE OUT THE PSBLTY OF PCPN BRFLY MXG IN OR CHG TO SN IN HIER ELEVS ALG ALLEGHENY FNT BEFORE ENDING. TEMPS 10-15 DEG BLO NORM FOR MID OF NXT WK.
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&& .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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MVFR CONDITIONS MAY OCCUR IN PERSISTENT OR GUSTY RAIN SHOWERS AND ISOLATED THUNDERSTORMS LATER THIS AFTERNOON INTO THIS EVENING AT ANY OF THE TERMINALS...PARTICULARLY FROM MRB TO BWI AND MTN. THERE IS A LOT OF DRY AIR IN THE LOWER AND MID LEVELS THAT HAS TO SATURATE BEFORE WE ENCOUNTER THESE MVFR CONDITIONS. OTHERWISE...TERMINALS THAT SEE LIMITED TO NO RAIN COULD HAVE VFR CONDITIONS. SOUTHWEST WINDS COULD GUST TO 20KT OR HIGHER LATER THIS AFTN BEFORE BECOMING NORTHWESTERLY WITH SOME HIGHER GUSTS TONIGHT. THERE IS ALSO MINIMAL CHANCE OF SOME LOW LEVEL WIND SHEER ALONG AND BEHIND THE APPROACHING COLD FRONT. MUCH OF THIS THREAT WAS EARLIER IN THE DAY TODAY BUT WITH SHIFTING WINDS...IT CAN`T BE RULED OUT AGAIN. VFR CONDITIONS OVERNIGHT AND SATURDAY WITH CIGS GENERALLY 5000 FEET OR MORE. THERE MAY BE SOME LOW LEVEL STRATUS EARLY SATURDAY. HIGH PRESSURE FROM SUNDAY INTO MON...KEEPING THE SKIES GENERALLY CLEAR BUT INCREASING WINDS OUT OF THE SOUTH AT THE SFC EACH AFTN. GUSTY WINDS IN THE 15-25KT RANGE DURING THE DAYTIME HRS...THEN DROPPING OFF EACH NIGHT. A COLD FRONT WILL SWING THRU THE AREA BY LATE TUE...BUT FAIRLY SLOWLY W/ A BULK OF THE PRECIP AFFECTING THE AREA WELL AHEAD OF AND ALONG THE BOUNDARY. WIDESPREAD RAIN SHOWERS COULD ENCOMPASS THE REGION FROM EARLY TUE INTO THE OVERNIGHT HRS - ENDING EARLY WED.
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&& .MARINE...
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SMALL CRAFT ADVISORIES REMAIN IN EFFECT THROUGH 11PM THIS EVENING FOR GUSTY SOUTHWEST WINDS. CAN`T RULE OUT GUSTS OVER 20 KNOTS OVERNIGHT WITH WINDS SHIFTING TO THE NORTHWEST THEN NORTHEAST AS THE FRONT PUSHES TO OUR SOUTH. SOUTHERLY CHANNELING AND LOW-MED RANGE SCA WINDS BOTH SUN AND MON AFTNS...AS A LARGE AREA OF HIGH PRESSURE HOVERS OFF THE ATLC COAST BUT INCREASES THE SFC PRES GRADIENT AS A STORM SYSTEM APPROACHES FROM THE WEST. ANOTHER SLOW-MOVING COLD FRONT WILL THEN DRIFT OVER THE WATERS BY LATE TUE...W/ PERIODS OF RAIN SHOWER ACTIVITY THROUGHOUT THE DAY BEFORE THE FRONT. HIGH PRESSURE EXPECTED TO PUSH IN FOR MID NEXT WEEK.
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&& .FIRE WEATHER...
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THE SLOW-MOVING COLD FRONT NOW MAKING A STEADY BUT STILL SLOW PROGRESSION TOWARD THE SE AND INTO WRN MD/THE ERN WV PANHANDLE. THE HIGHER MOISTURE NEAR THE FRONT HASN`T MADE IT TO LOCATIONS FURTHER SOUTH WHERE THE SPECIAL WX STATEMENT FOR ENHANCED FIRE THREAT IS IN PLACE...NRN VA PIEDMONT. W-SW WINDS 15 TO 25 MPH WILL CONTINUE TO CAUSE HUMIDITY TO DROP TO 25 TO 35 PERCENT ACROSS PORTIONS OF CENTRAL VIRGINIA LATER OVER THE NEXT FEW HRS BUT THE THREAT WILL DROP OFF WITH THE FRONTAL PASSAGE LATER THIS EVE.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ530- 531-535-536-538-539-542. SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ532>534-537-540-541-543.
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&& $$ NEAR TERM...KLW SHORT TERM...GMS LONG TERM...CEM

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