Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 221914 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 314 PM EDT TUE APR 22 2014 .SYNOPSIS...
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A COLD FRONT WILL PASS THROUGH THIS EVENING. HIGH PRESSURE RETURNS FOR WEDNESDAY AND THURSDAY BEFORE MOVING OFF THE COAST FRIDAY. A COLD FRONT IS EXPECTED TO PASS THROUGH THE AREA SATURDAY.
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&& .NEAR TERM /THROUGH WEDNESDAY/...
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18Z SFC ANALYSIS SHOWS A 998 MB LOW JUST NORTH OF THE ADIRONDACKS. A COLD FRONT EXTENDS TO THE SW OF THE LOW IN CENTRAL NY-WRN PA AND BACK TOWARD THE OH RVR. A BAND OF SHOWERS ASSOCIATED WITH A PRE-FRONTAL TROUGH AND MOISTURE PLUME WILL CONTINUE TO PROGRESS EWD THRU THE I-95 CORRIDOR BEFORE MOVING EAST OF THE CHSPK BAY LATE THIS AFTN. FARTHER UPSTREAM...A NARROW LINE OF CONVECTION HAS DEVELOPED ALONG THE COLD FRONT NEAR PIT. HI-RES REFLECTIVITY MODELS THAT CAPTURED THIS CONVECTION SIMULATE THIS LINE TO REACH THE ALLEGHENY FRONT BY 4 OR 5 PM BEFORE MOVING SEWD THRU PORTIONS OF THE CWA DURING THE ERY EVE. KEPT POPS HIGHEST ACROSS NRN PORTIONS OF THE CWA WHERE THE BEST FORCING ASSOCIATED WITH THE UPPER SHORTWAVE TROUGH WILL BRUSH. TSTM POTENTIAL IS LOW WITH PRE-FRONTAL SHOWERS AND CLOUD COVER LIMITING DESTABILIZATION. THE COLD FRONT WILL MOVE THRU THE AREA THIS EVE. GUSTY NW WINDS WILL USHER IN COLDER AIR BEHIND THE COLD FRONT. CLEARING SKIES FROM WEST TO EAST TNGT AS WELL...ALTHOUGH STRATOCU WILL KEEP SKIES MOSTLY CLOUDY ALONG THE WRN SIDE OF THE ALLEGHENY FRONT DUE TO UPSLOPE FLOW. WINDS WILL STAY MIXED SO ADVECTION WILL BE MAIN SOURCE OF AIRMASS COOLING TNGT. MIN TEMPS TNGT RANGE FROM THE NEAR 30F IN THE WRN HIGHLANDS TO MID AND UPPER 40S EAST OF THE BLUE RIDGE. HIPRES BUILDS IN FROM THE GREAT LAKES ON WED. PRESSURE RISES WILL BE ACCOMPANIED BY BREEZY NW WINDS THAT GUST 30-40 MPH DURING THE DAY. COLD AIRMASS WILL BE MODERATED A BIT BY THE HIGH SUN ANGLE. FCST WEIGHTED TOWARD THE WARMER BIAS CORRECT MARV GUIDANCE WITH SUNNY SKIES AND DOWNSLOPING FLOW. MAX TEMPS GENERALLY RANGE FROM THE MID 50S TO MID 60S EXCEPT FOR COOLER HIGHS IN THE 40S ALONG HIGHER ELEVATIONS RIDGES.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
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SFC LOW PRESSURE SHOULD BE MOVING TOWARDS NEWFOUNDLAND WED NIGHT AND HIGH PRESSURE WILL MOVE INTO THE MID ATLANTIC FROM THE WEST. THE PRESSURE GRADIENT RESPONSIBLE FOR THE GUSTY WINDS WEDNESDAY WILL DEPART TO OUR EAST WED EVENING. TEMPS WILL REACH THE LOW 30S WEST OF THE BLUE RIDGE AS CLEARING AND CALM WINDS WILL ALLOW FOR TEMPS TO DROP. ELSEWHERE...MID TO UPPER 30S EXPECTED TO AROUND 40 IN THE METROS. UPPER LEVEL RIDGING WILL MOVE OVERHEAD THURSDAY RESULTING IN A SUNNY DAY WITH TEMPS IN THE 60S. A WEAK COLD FRONT ASSOCIATED WITH LOW PRESSURE ACROSS THE NRN PLAINS WILL APPROACH THE REGION. CLOUDS WILL INCREASE FROM THE WEST THURSDAY AS HIGH PRESSURE WILL MOVES OFF THE COAST BY THURSDAY NIGHT. A BRIEF PERIOD OF RETURN FLOW WILL INCREASE ACROSS THE REGION THURSDAY NIGHT AND FRIDAY. TEMPS WILL REACH 70-75 DEGREES FRIDAY AFTERNOON. THE WEAK COLD FRONT WILL CROSS THE APPALACHIANS FRIDAY AFTERNOON AND SHOWERS ARE EXPECTED TO MOVE AHEAD OF THE FRONT.
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&& .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
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AN UPPER-LEVEL TROUGH...ACCOMPANIED BY A SECONDARY COLD FRONT AND STRONG PRESSURE SURGE/COLD ADVECTION WILL MOVE THROUGH THE AREA TO BEGIN THE WEEKEND. THE BOUNDARY LOOKS MOISTURE STARVED...SO ANY ISOLATED SHOWER ACTIVITY WOULD REMAIN CONFINED TO AREAS ALONG THE MASON-DIXON LINE CLOSEST TO THE FORCING FROM THE SHORTWAVE TROUGH SATURDAY. THUS SLIGHT CHANCE POPS HAVE BEEN CONFINED TO THESE AREAS. AT THE MOMENT...THE MEDIUM RANGE GUIDANCE HAS COME INTO BETTER WITH THE TIMING AND STRENGTH OF THE FRONT. STRONG AND GUSTY WINDS ARE APPEARING INCREASINGLY LIKELY FOR SATURDAY...ESPECIALLY CONSIDERING THE STRONGEST WINDS ACCOMPANYING THE PRESSURE SURGE WILL OCCUR DURING PEAK HEATING WHEN LAPSE RATES ARE STEEPEST AND MIXING DOWN HIGHER WIND GUSTS WOULD BE EASIEST. WINDS DIMINISH SATURDAY NIGHT INTO SUNDAY MORNING AS AN AREA OF HIGH PRESSURE NOSES OVER THE REGION...BUT ITS STAY OVER OUR AREA IS SHORT-LIVED AS A LARGE AND SLOW-MOVING AREA OF LOW PRESSURE APPROACH FROM THE WEST BRINGING A RETURN TO UNSETTLED WEATHER EARLY NEXT WEEK.
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&& .AVIATION /19Z TUESDAY THROUGH SUNDAY/...
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LGT SHRA AHEAD OF THE FRONT HAS SHIFTED EAST OF IAD AND WILL IMPACT DCA/BWI/MTN THRU ABOUT 21Z. INTENSITY HAS BEEN SO LGT THAT NO FLGT RESTRICTION WERE ACCOMPANIED WITH THIS ACTIVITY. WINDS HAVE SHIFTED OUT OF THE WEST AS THESE SHOWERS AND ASSOCIATED SFC TROUGH MOVE THRU BUT WILL BE LGT UNTIL THE COLD FRONT MOVES THRU THIS EVE. ANY TSRA WITH THE FRONT THIS EVE WILL BE LOCALIZED AND PROBS TOO CHANCE TOO LOW TO INCLUDE IN TAFS. NW WINDS 10-15 KT WILL GUST TO 25 KT BEHIND THE FRONT THRU MUCH OF TNGT. NW WINDS INCREASE ON WED DUE TO DAYTIME MIXING WITH GUSTS TO 35 KT POSSIBLE. VFR ON WED. NW FLOW WILL SUBSIDE WED NIGHT. HIGH PRESSURE MOVES INTO THE REGION THURSDAY BEFORE MOVING OFF THE COAST AHEAD OF A WEAK COLD FRONT THURSDAY NIGHT. SHOWERS MAY CROSS THE TERMINALS FRIDAY. MODERATE CONFIDENCE IN VFR CONDITIONS AND WESTERLY WINDS AROUND 10 KNOTS FRIDAY NIGHT...WITH MODERATE CONFIDENCE IN WINDS INCREASING TO BETWEEN 15 AND 20 KNOTS WITH GUSTS UP TO 30 KNOTS DURING THE DAY SATURDAY.
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&& .MARINE...
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SCA REMAINS IN EFFECT FOR THE WATERS THRU TNGT. SCA LVL REPORTS ONLY ISOLATED THUS FAR BUT ANY SHOWERS MOVING THRU COULD DRAG DOWN LOCALLY HIGHER WINDS. WINDS BECOME GUSTY FOLLOWING A COLD FROPA DURING THE MID TO LATE EVE AND INTO THE OVNGT. WIDESPREAD SCA CONDITIONS EXPECTED BEHIND THE FRONT. A GALE WARNING IS IN EFFECT WEDNESDAY FOR ALL OF THE WATERS WITH GUSTS UP TO 35 KT EXPECTED DURING THE DAY. THE GALE WARNING MAY BE ABLE TO BE DOWNGRADING SOMETIME DURING THE AFTN AS THE PRESSURE GRADIENT AND ASSOCIATED WIND FIELD WEAKENS A BIT. NORTHWEST WINDS WILL CONTINUE ON THE WATERS WEDNESDAY NIGHT AND A SCA IS IN EFFECT. WINDS WILL SUBSIDE FROM WEST TO EAST THEREFORE THE SCA FOR THE UPPER TIDAL POTOMAC WILL DROP LATE WED NIGHT. WINDS WILL CONTINUE TO CAUSE SCA CONDITIONS ACROSS THE BAY INTO THURSDAY. A SCA MAY BE EXTENDED FOR THURSDAY. HIGH PRESSURE MOVES INTO THE REGION THURSDAY AND THURSDAY NIGHT. SOUTHERLY FLOW WILL INCREASE ACROSS THE WATERS FRIDAY. A PERIOD OF HIGH-END SMALL CRAFT ARE EXPECTED BEHIND A STRONG BUT MOISTURE-STARVED COLD FRONT SATURDAY. WINDS DIMINISH THROUGH THE NIGHT SATURDAY AND LIKELY DROP BELOW SMALL CRAFT LEVELS DURING THE DAY SUNDAY.
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&& .FIRE WEATHER...
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A COLD FRONT WILL PASS THROUGH THE AREA THIS EVENING AND GUSTY NORTHWEST WINDS ARE EXPECTED BEHIND THE COLD FRONT WEDNESDAY. A DEEP MIXING LAYER WILL ALLOW FOR DRIER AIR TO MIX DOWN...CAUSING LOW RELATIVE HUMIDITY VALUES DURING THE LATE MORNING THROUGH THE AFTERNOON. THE COMBINATION OF GUSTY WINDS...LOW FUEL MOISTURE AND LOW RELATIVE HUMIDITY WILL ENHANCE THE THREAT FOR THE SPREAD OF WILDFIRES WEDNESDAY. AFTER COORDINATION WITH STATE OFFICIALS AND SURROUNDING WFOS...A FIRE WEATHER WATCH WAS ISSUED.
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&& .TIDES/COASTAL FLOODING...
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POSITIVE TIDAL ANOMALIES REMAIN STEADY AROUND THREE-QUARTERS OF A FOOT THIS AFTN. SLY WINDS WILL BECOME WLY WITHIN THE NEXT FEW HRS AND ANOMALIES WILL DECREASE SUBSEQUENTLY. GUSTY NORTHWEST WINDS WILL DEVELOP TONIGHT AND CONTINUE THROUGH WEDNESDAY. BLOWOUT TIDES ARE EXPECTED WEDNESDAY.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR DCZ001. MD...FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR MDZ003>007-009>011-013-014-016>018-502. VA...FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR VAZ025>031-036>040-042-050>057-501-502-504. WV...FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR WVZ050>053-055-502-504-506. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ530>543. SMALL CRAFT ADVISORY FROM 6 PM WEDNESDAY TO 6 AM EDT THURSDAY FOR ANZ530>534-537>543. GALE WARNING FROM 6 AM TO 6 PM EDT WEDNESDAY FOR ANZ530>543. SMALL CRAFT ADVISORY FROM 6 PM WEDNESDAY TO MIDNIGHT EDT WEDNESDAY NIGHT FOR ANZ535-536.
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&& $$ SYNOPSIS...JRK NEAR TERM...JRK SHORT TERM...HAS LONG TERM...DFH AVIATION...JRK/HAS/DFH MARINE...JRK/HAS/DFH FIRE WEATHER...JRK TIDES/COASTAL FLOODING...JRK

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