Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 271937 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 337 PM EDT WED MAY 27 2015 .SYNOPSIS...
-- Changed Discussion --
HIGH PRESSURE WILL REMAIN OFFSHORE THIS WEEK. 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.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --
A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR PARTS OF NORTH-CENTRAL MARYLAND...NORTHERN VIRGINIA AND WASHINGTON DC. SHOWERS AND THUNDERSTORMS HAVE FORMED ON THE LEADING EDGE OF A WAVE OF LOW PRESSURE THAT MOVED OVER THE HIGHLANDS THIS MORNING. SURFACE HEATING AND MARGINAL SHEAR HAVE LED TO STRONG THUNDERSTORMS PRODUCING GUSTY WINDS...HAIL...HEAVY RAIN AND LIGHTNING. A BROKEN LINE OF SHOWERS AND THUNDERSTORMS LOCATED ON THE WESTERN METRO SUBURBS WILL CONTINUE TO MOVE EASTWARD INTO A UNSTABLE ENVIRONMENT. THIS REGION INCLUDING THE I-95 CORRIDOR IS AN AREA OF CONCERN DUE TO THE HIGHER DEWPTS AND MAXIMUM OF DOWNWARD CAPE AS EVIDENT ON THE MESOANALYSIS. THIS POSES THE THREAT FOR DAMAGING WINDS. REPORTS OF HEAVY RAIN OCCURRED IN NRN MD. PLEASE USE CAUTION WHILE TRAVELING OR IF OUTSIDE LATE THIS AFTERNOON AND EVENING. A SECOND AREA OF CONVECTION IS EXPECTED TO FORM ACROSS CENTRAL-SOUTHERN VA AND MOVE NORTHWARD LATE THIS AFTERNOON AND EVENING IN VICINITY OF A LEE TROUGH. THIS ACTIVITY WILL MOVE N-NE AND MAY IMPACT THE PIEDMONT...SOUTHERN MARYLAND AND SURROUNDING WATERS. AT THIS TIME...NO WATCH HAS BEEN ISSUED. SHOWERS AND THUNDERSTORMS WILL MOVE OFF TO THE EAST THIS EVENING. SOUTHERLY WINDS WILL CONTINUE OVER NIGHT RESULTING IN HUMID CONDITIONS. PATCHY FOG IS POSSIBLE INTO THURSDAY MORNING.
-- End Changed Discussion --
&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
-- Changed Discussion --
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.
-- End Changed Discussion --
&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
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.
-- End Changed Discussion --
&& .AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
TSRA AND SHRA EXPECTED THIS AFTERNOON AND SUB-VFR CONDITIONS EXPECTED WITHIN ACTIVITY. SOME TSRA MAY PRODUCE GUSTY WINDS AND HAIL AS WELL AS HEAVY RAIN THAT WILL REDUCE VSBYS. TEMPO ADDED FOR IAD BUT WILL LIKELY BE ADDED FOR BWI/MTN/DCA SHORTLY. HUMID CONDITIONS PERSIST TONIGHT AND PATCHY FOG MAY IMPACT THE TERMINALS INTO EARLY THURSDAY. SUB-VFR CONDITIONS POSSIBLE. 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.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS THE WATERS THIS AFTERNOON AND EVENING. GUSTY WINDS...HEAVY RAIN ARE EXPECTED. SMW`S WILL LIKELY BE ISSUED INTO THE EARLY EVENING. S WINDS CONTINUE ON THE WATERS THROUGH THURSDAY...WITH SCATTERED SHOWERS AND THUNDERSTORMS AGAIN POSSIBLE DURING THE AFTERNOON AND EVENING. THEY SHOULD DIMINISH TONIGHT AND SCA WILL END OVERNIGHT. 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.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ531>533- 537>542. SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ534-543. SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ530. && $$ SYNOPSIS...ADS NEAR TERM...HAS SHORT TERM...ADS LONG TERM...KLW AVIATION...ADS/HAS/KLW MARINE...ADS/HAS/KLW

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.