Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 280129 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 929 PM EDT WED MAY 27 2015 .SYNOPSIS...
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HIGH PRESSURE WILL REMAIN OFFSHORE THROUGH FRIDAY. A SOUTHERLY FLOW WILL BRING WARM HUMID CONDITIONS TO THE MID-ATLANTIC THROUGH SATURDAY. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE EACH AFTERNOON AND EVENING. A WEAK COLD FRONT WILL APPROACH THE REGION THURSDAY BUT WEAKEN AND STALL OVER THE REGION. A STRONGER COLD FRONT WILL ARRIVE SUNDAY. THE ACTIVE PATTERN CONTINUES INTO NEXT WEEK.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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IT WAS A MARGINAL SEVERE CASE TODAY WITH 1000 TO 1500 J/KG MLCAPE AND BULK SHEAR AROUND 30 KT. OUTFLOW FROM EARLY ACTIVITY OVERSWEPT THE AREA AND LIMITED THE SEVERE THREAT...HENCE THE SEVERE THUNDERSTORM WATCH WAS CANCELLED EARLY. MOISTURE CONTINUES TO ADVECT INTO THE REGION WITH DEWPOINTS BACK UP TO MID 60S TO AROUND 70F. THIS LEVEL OF MOISTURE...ALONG WITH BOUNDARIES FROM EARLIER ACTIVITY SHOULD ENABLE ISOLATED SHOWERS AND POSSIBLE THUNDERSTORMS THROUGH THE REST OF THE EVENING. A BOUNDARY IS EVIDENT ACROSS THE DELMARVA SOUTH TO SERN VA...SO THE GREATEST CHANCE FOR MORE RAIN IS OVER SRN MD WATERS. WITH DECENT CLEARING AND SOME PLACES DECOUPLING...EXPECT PATCHY RADIATIONAL FOG TO DEVELOP...PARTICULARLY IN VALLEYS AND IN THE PIEDMONT. MIN TEMPS HIGH TONIGHT...LOW TO MID 70S.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... SHORTWAVE TROUGH WILL BE MOVING INTO NEW ENGLAND ON THURSDAY AS A SFC COLD FRONT APPROACHES FROM THE NW. HOWEVER...THE FRONT WILL NOT MAKE A LOT OF SOUTHERN PROGRESS THROUGH THE REGION. WHILE THESE FEATURES WILL ONCE AGAIN ALLOW SCATTERED SHOWERS AND THUNDERSTORMS TO ONCE AGAIN FORM...BULK SHEAR IS ON THE WEAK SIDE...SO SEVERE WX THREAT IS MINIMAL. HUMIDITY WILL STILL BE HIGH THOUGH SO LOCALLY HEAVY DOWNPOURS POSSIBLE. HIGHS TEMPS WELL INTO THE 80S. FRONT BEGINS TO LOSE DEFINITION OVERNIGHT AS PRECIP CHANCES DIMINISH. SOME SLIGHTLY DRIER AIR MAY WORK INTO THE NORTHERN PART OF THE CWA. LOWS WILL DROP INTO THE 60S...EXCEPT 50S IN HIGHER ELEVATIONS AND AROUND 70 URBAN CENTERS. BY FRIDAY...THE MID AND UPPER LEVEL RIDGES BUILD BACK TO THE NORTH...AS WHAT/S LEFT OF THE SFC FRONT LIFTS BACK TO THE NORTH. WITHOUT A DEFINED FORCING MECHANISM...CONVECTIVE DEVELOPMENT WILL BE BE MORE DIURNALLY AND TERRAIN DRIVEN. THUS COVERAGE SHOULD BE LOWER THAN WED/THU...ESPECIALLY EAST OF THE BLUE RIDGE. DAYTIME HIGHS A TOUCH LOWER ON FRIDAY...BUT THE OVERALL LOOK AND FEEL OF THE FORECAST REMAINS THE SAME...WARM AND MUGGY. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A COLD FRONT WILL APPROACH THE REGION SATURDAY...BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS TO THE REGION INTO SATURDAY NIGHT. TEMPERATURES SATURDAY WILL REACH THE MIDDLE TO UPPER 80S WITH LOWS SATURDAY NIGHT GETTING INTO THE MIDDLE 60S. THE COLD FRONT SHOULD SLOWLY PUSH THROUGH THE REGION SUNDAY. THE EUROPEAN MODEL STILL REMAINS THE SLOWER MODEL OVER THE GFS. SHOWERS AND THUNDERSTORMS WILL FORM AHEAD OF AND ALONG THE FRONT. TEMPERATURES WILL BE ABOVE NORMAL SUNDAY. A WEDGE OF HIGH PRESSURE WILL BUILD SOUTHWARD ALONG THE EAST COAST SUNDAY NIGHT AND MONDAY...HELPING TO COOL CONDITIONS DOWN A LITTLE. HOWEVER...OVERRUNNING MOISTURE AND MID-LEVEL DISTURBANCES APPROACHING FROM THE WEST WILL BRING YET ANOTHER THREAT FOR RAIN SHOWERS AND PERHAPS A THUNDERSTORM. TEMPERATURES MAY BE A FEW DEGREES ABOVE NORMAL EACH PERIOD BUT COOLER THAN RECENT DAYS. AS THE RIDGE OF HIGH PRESSURE BREAKS DOWN TUESDAY...UPPER LEVEL DISTURBANCES ARE EXPECTED TO MOVE ACROSS THE OHIO VALLEY INTO THE LOWER GREAT LAKES. THESE DISTURBANCES COULD POSE A SHOWER THREAT TUESDAY WITH HIGH TEMPERATURES ONLY IN THE LOWER 80S. A SHOWER OR THUNDERSTORM IS POSSIBLE WEDNESDAY...BUT THE STRENGTH OF THE HIGH PRESSURE ALONG THE EASTERN SEABOARD MAY REDUCE THAT THREAT EVEN FURTHER. IT WILL BE A FEW DEGREES WARMER WEDNESDAY. && .AVIATION /01Z THURSDAY THROUGH MONDAY/...
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HUMID CONDITIONS PERSIST TONIGHT AND IFR VSBYS/FOG MAY IMPACT THE TERMINALS INTO EARLY THURSDAY. SUB-VFR CONDITIONS POSSIBLE. HIGH PRESSURE BUILDS NORTH OF THE AREA...SHOULD ENABLE LOW CHANCES FOR THUNDERSTORMS GENERALLY EAST FROM THE BLUE RIDGE AGAIN. SCATTERED THUNDERSTORMS POSSIBLE FRIDAY AFTERNOON...WITH SLIGHTLY HIGHER CHANCES NEAR/WEST OF BLUE RIDGE. OVERALL LOWER COVERAGE THAN PREVIOUS DAYS. THERE IS A CHANCE OF SUB-VFR VSBYS IN BR EARLY FRIDAY AND SATURDAY MORNINGS...MAINLY IN THE TYPICAL LOCATIONS...BUT OVERALL CONFIDENCE IS NOT GREAT. LOCALIZED SUB-VFR CONDITIONS POSSIBLE SATURDAY THROUGH SUNDAY WITH SHOWERS AND THUNDERSTORMS IN PARTS OF THE AREA.
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&& .MARINE...
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SLY CHANNELING WITH GUSTS TO 20 KT STILL OCCURRING SOUTH OF SANDY POINT. THIS WILL CONTINUE TO EASE THROUGH THE OVERNIGHT WITH LOWER SRN MD WATERS GUSTING LONGEST. SCA REFLECTS THIS. LIGHT AND VARIABLE FLOW THURSDAY WITH A BAY BREEZE EXPECTED. UP TO SCATTERED GUSTY SHOWERS AND THUNDERSTORMS THURSDAY AFTERNOON. LIGHT/VRB WINDS THURSDAY NIGHT WILL BECOME SOUTHERLY AGAIN FRIDAY AS HIGH PRESSURE RE-ESTABLISHES OFFSHORE. GUSTS MAY COME CLOSE TO SCA CRITERIA BY LATE FRIDAY AFTERNOON OVER THE BAY DUE TO CHANNELING...BUT CONFIDENCE IS TOO LOW TO ISSUE AT THIS TIME. WHILE THUNDERSTORMS WILL BE POSSIBLE FRIDAY AFTERNOON...OVERALL COVERAGE APPEARS FAIRLY ISOLATED. WIDESPREAD MARINE HAZARDS ARE UNLIKELY SATURDAY THROUGH SUNDAY...ALTHOUGH SCATTERED AFTERNOON/EVENING THUNDERSTORMS WILL POSE LOCALIZED THREATS.
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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 MIDNIGHT EDT TONIGHT FOR ANZ532-533- 537-540-541. SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ534-543.
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&& $$ SYNOPSIS...BAJ/ADS NEAR TERM...BAJ/HAS SHORT TERM...ADS LONG TERM...KLW AVIATION...BAJ/ADS/HAS/KLW MARINE...BAJ/ADS/HAS/KLW

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