Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 271424 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1024 AM EDT WED AUG 27 2014 .SYNOPSIS...
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A COLD FRONT OVER THE MIDWEST WILL APPROACH TODAY...AND CROSS THE AREA TONIGHT. HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN MID- ATLANTIC THURSDAY NIGHT...LINGERING OFF THE COAST INTO THE WEEKEND. THE NEXT COLD FRONT WILL APPROACH THE MID-ATLANTIC EARLY NEXT WEEK.
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&& .NEAR TERM /THROUGH THURSDAY/...
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AS OF 14Z...SFC PRESSURE IS DROPPING ACROSS THE AREA AS CRISTOBAL MOVES NORTH (WELL OFFSHORE) AND A WEAK COLD FRONT APPROACHES FROM THE MIDWEST. CLEAR AND LIGHT/VARIABLE WINDS. MAV/MET/GMOS BLEND RAISED MAX TEMPS TO LOW 90S IN BALT-WASH CORRIDOR AND UPR 80S ELSEWHERE. SFC HEATING AND DEWPTS IN THE UPPER 60S WILL LEAD TO 500-1000 J/KG OF MLCAPE THIS AFTERNOON. ISO-SCT SHOWERS AND THUNDERSTORMS ARE EXPECTED AS WEAK FORCING IS EXPECTED ALONG THE FRONT AND SINCE THE PARENT LOW WILL BE NORTH IN CANADA MOST OF THE UPPER LEVEL FORCING WILL ALSO BE NORTH OF THE MID ATLANTIC. MARGINAL SHEAR OF 20 KT IS EXPECTED. THE BEST CHANCE FOR THUNDERSTORMS WILL BE NEAR THE MASON-DIXON LINE (BEST FORCING IS IN PA) LATE THIS AFTERNOON. ACTIVITY WILL DISSIPATE DUE TO THE LOSS OF DAYTIME HEATING THIS EVENING. QUESTION IS WHETHER THE BALT-WASH CORRIDOR WILL SEE THUNDERSTORMS. STILL HAVE AN ISO COVERAGE IN THE GRIDS FOR THIS EVENING. NW FLOW AND DRIER AIR WILL MOVE IN BEHIND THE FRONT. THE FRONT SHOULD BE IN SRN VA BY THURSDAY MORNING AND CLOUDS WILL CLEAR FROM NORTH TO SOUTH THURSDAY MORNING. NW FLOW WILL DROP DEWPTS INTO THE 50S THURSDAY. FCST MAX TEMPS ARE IN THE LOW 80S NEAR THE MASON DIXON LINE TO THE MID 80S IN CENTRAL VA. THE MID TO UPPER 80S ARE EXPECTED IN DC/BALTIMORE.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/... FRONT WILL STALL OUT OVER THE CAROLINAS THURSDAY NIGHT INTO FRIDAY...AS HIGH PRESSURE BUILDS ACROSS THE NORTHEAST AND THEN PUSHES OFF THE COAST. MUCH OF THE CWA SHOULD BE DRY DURING THIS TIME ALTHOUGH CAN/T RULE OUT AN ISOLATED THUNDERSTORM ACROSS THE EXTREME SOUTHWEST CWA MAINLY NEAR THE HIGHER ELEVATIONS. EASTERLY WIND ON FRIDAY WILL LIKELY KEEP TEMPERATURES NEAR NORMAL. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... HEIGHTS INCREASE ON SATURDAY AS THE UPPER RIDGE BUMPS NORTHWARD. BOUNDARY WILL ALSO LIFT NORTH INTO THE MID-ATLANTIC AS A WARM FRONT. DESPITE HIGHER HEIGHTS...MOISTURE RETURN/ADVECTION MAY PROMOTE DIURNAL ISOLATED TO SCATTERED THUNDERSTORMS PARTICULARLY ACROSS THE NORTHWEST PORTION OF THE CWA. BETTER CHANCE OF CONVECTION IS EXPECTED SUNDAY AS RIDGE FLATTENS OUT AND SURFACE TROUGH DEVELOPS. TROUGH WILL REMAIN IN PLACE THROUGH MID-WEEK...AND A SUMMER-LIKE SCENARIO IS EXPECTED WITH A CHANCE OF MAINLY DIURNAL CONVECTION AND ABOVE NORMAL TEMPERATURES /HIGHS AROUND 90/ EACH DAY. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
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A WEAK COLD FRONT WILL MOVE ACROSS THE REGION LATE THIS AFTERNOON THROUGH TONIGHT. VARIABLE WINDS WILL BECOME N-NW 5-10KTS BEHIND THE FRONT TONIGHT. -SHRA AND VCTS LATE THIS AFTERNOON NEAR THE FRONT AT MRB. LESS LIKELY FOR DC METROS. VFR CONDITIONS EXPECTED TONIGHT AND THURSDAY. HIGH PRESSURE BUILDS FROM THE NORTH AND THEN PUSHES OFF THE COAST TO END THE WEEK. WARM FRONT LOOKS TO LIFT NORTH ON SATURDAY...USHERING IN A SUMMER-LIKE PATTERN WITH A CHANCE OF AFTERNOON/EVENING TSRA SUNDAY INTO EARLY NEXT WEEK.
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&& .MARINE...
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A WEAK COLD FRONT WILL MOVE ACROSS THE WATERS THIS EVENING AND NLY FLOW WILL INCREASE ACROSS THE WATERS. NEAR SCA NWLY FLOW LATE TONIGHT AND INTO THURSDAY ACROSS THE MAIN CHANNEL OF THE CHESAPEAKE BAY AS A PRESSURE SURGE MOVES ACROSS THE WATERS. NW WINDS WILL CONTINUE THURSDAY AS HURRICANE CRISTOBAL MOVES AWAY FROM THE EAST COAST. WILL NEED TO WATCH SOUTHERLY FLOW FOR CHANNELING EFFECTS AND POSSIBLE SCA CONDITIONS UP THE BAY OVER THE WEEKEND...PARTICULARLY DURING THE EVENINGS. SUMMER-LIKE PATTERN DEVELOPS LATER IN THE WEEKEND INTO EARLY NEXT WEEK WITH AFTERNOON AND EVENING THUNDERSTORMS POSSIBLE EACH DAY.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BAJ/BPP/HAS NEAR TERM...BAJ/HAS SHORT TERM...BPP LONG TERM...BPP AVIATION...BAJ/BPP/HAS MARINE...BAJ/BPP/HAS

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