Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 281453 AAA AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1053 AM EDT TUE JUL 28 2015 .SYNOPSIS... A WEAK STATIONARY FRONT WILL DISSIPATE OVER THE AREA TODAY. MEANWHILE...HOT AND HUMID WEATHER IS EXPECTED DURING THE MIDDLE PORTION OF THE WEEK AS HIGH PRESSURE STRENGTHENS OFFSHORE RESULTING IN SOUTHERLY FLOW. A COLD FRONT WILL CROSS THE REGION LATE THURSDAY BRINGING SCATTERED SHOWERS AND THUNDERSTORMS. HIGH PRESSURE BUILDS BACK IN FRIDAY AND REMAINS THROUGH THE WEEKEND. && .NEAR TERM /THROUGH WEDNESDAY/... UPDATE...FOG HAS BEEN SLOW TO DISSIPATE THIS MORNING LIKELY DUE TO VERY LIGHT WIND FLOW. OVERALL...ENVIRONMENT LOOKS DRIER TODAY WITH PWAT DOWN TO 1.44 INCHES FROM 1.74 INCHES YESTERDAY AND A TON OF DRY AIR ABOVE 700 MB. SO EXPECTING SIGNIFICANT LESS CVRG TODAY AND MAINLY CONFINED TO AREAS SOUTH OF I-66. SEASONABLY WARM/HOT AND HUMID FOR LATE JULY WITH HIGH TEMPS WITHIN A FEW DEGS OF 90 FOR MOST TODAY AND TOMORROW. DEWPOINTS AROUND 70 WILL FEEL UNCOMFORTABLE WITH THE HEAT IN THE AFTERNOON AND EVENING. NOT A LOT GOING ON SYNOPTICALLY WITH A WEAK STATIONARY FRONT DECAYING TODAY...FOLLOWED BY WEAK HIGH PRES REASSERTING ITSELF TOMORROW. SCATTERED SHOWERS AND TSTMS WILL BE MORE PRONOUNCED IN THE SW THAN THE NE TODAY AND WED. NOT EXPECTING ANY ORGANIZED CONVECTION. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/... WEDNESDAY NIGHT...STORM CHANCES IN SOUTHWEST DIMINISH FAIRLY RAPIDLY WEDNESDAY NIGHT AS INSTABILITY WANES AND INHIBITION STRENGTHENS. IT WILL REMAIN RATHER WARM AND MOIST...SO A STRAY SHOWER ALONG RESIDUAL BOUNDARY NOT ENTIRELY OUT OF THE QUESTION...THOUGH KEPT OUT OF GRIDS FOR NOW. THURSDAY...H5 HEIGHT RISES CONTINUE THROUGH EARLY THURSDAY...AS RIDGING OVER THE CENTRAL UNITED STATES CONTINUES TO EXPAND TOWARD OUR AREA. EXPECT HEIGHTS TO BEGIN TO LOWER SLIGHTLY BY MIDDAY AS WAVE APPROACHES FROM THE NORTHWEST. MAIN PIECE OF ENERGY WILL STAY TO OUR NORTH...BUT SAGGING COLD FRONT WILL IMPACT THE ENTIRE AREA THROUGH THE DAY. BEFORE FRONTAL PASSAGE...EXPECT TEMPERATURES TO WARM UP INTO THE 90S...AND WHEN COMBINED WITH SFC DEWPOINTS IN THE L/70S...EXPECT ANOTHER DAY OF HEAT INDICES AROUND 100F. NEAR/ALONG THE FRONT...CONFIDENCE CONTINUES TO INCREASE IN LINE OR BROKEN LINE OF SHOWERS AND THUNDERSTORMS IMPACTING THE AREA FROM NORTHWEST TO SOUTHEAST THURSDAY AFTERNOON AND EVENING. IT APPEARS THAT MOST AREAS WILL RECEIVE SOME PRECIP...THOUGH TIMING IS STILL UNCERTAIN. NAM/ECMWF MOVE FRONT THROUGH METROS BEFORE 8 PM...WHILE SLOWER GFS MOVES FRONT THROUGH METROS AFTER 8 PM. ANEMIC DEEP LAYER SHEAR CONTINUES TO BE THE LIMITING FACTOR TO MORE ROBUST SVR THREAT...AS BELT OF STRONGER WESTERLIES ALOFT REMAINS WELL TO THE NORTH...AND ITS HARD TO GET SUSTAINED ORGANIZED SVR WITH H5 WINDS AOB 20 KTS. HOWEVER...INSTABILITY WILL BE MODERATE OVER PARTS OF THE AREA...SO ISOLATED PULSE SVR WITH GUSTY WINDS A POSSIBILITY. ATTM THINK PROGRESSIVE NATURE OF BOUNDARY SHOULD PRECLUDE ANY WIDESPREAD FLASH FLOODING THREAT...DESPITE PWATS AOA 1.75 INCHES AND WEAK STEERING LAYER FLOW. SHOWER/STORM ACTIVITY COULD LINGER OVERNIGHT THURSDAY SOUTH AND EAST OF DC...BUT MOST ACTIVITY SHOULD MOVE THROUGH THE CWA BY 8 AM FRIDAY. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... SENSIBLE WX IMPACTS DURING THE LONG TERM RATHER BENIGN...AS PRIMARY FRONT REMAINS TO OUR SOUTH AND BROAD SFC HIGH PRESSURE OVER THE MIDWEST BUILDS INTO THE REGION. FRONTAL PASSAGE LATE THURSDAY WILL KNOCK THE DEWPOINTS BACK INTO THE U50S TO L/M60S...WHICH WILL BE MUCH MORE COMFORTABLE. EXPECT TEMPERATURES NEAR NORMAL (M/U 80S)...WITH A SLOW WARMING TREND THROUGH MONDAY. PRECIP CHANCES AT ANY ONE LOCATION DURING THE LONG TERM ARE VERY LOW...DUE TO THE LACK OF DISCERNIBLE LIFTING MECHANISMS AND POOR QUALITY MOISTURE. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... WITH THE WEAK STATIONARY FRONT SLOWLY DISSOLVING OVER THE REGION... THE WINDS WILL BE LIGHT AND MORE ERRATIC IN DIRECTION. WED THE SOUTHERLY FLOW WILL BECOME MORE ESTABLISHED. SCATTERED AND MAINLY AFTERNOON/EVENING SHOWERS/THUNDERSTORMS WILL PERSIST OVER THE REGION TODAY AND TOMORROW. FOG AND CIGS WILL ALSO BE ERRATIC OVERNIGHT AND THE FOLLOWING NIGHT AS WELL...WITH SOME VFR AND SOME IFR. VFR CONDITIONS EXPECTED OVERNIGHT WEDNESDAY UNDER HIGH PRESSURE. SUB- VFR CONDITIONS POSSIBLE AT ALL TERMINALS THURSDAY AFTERNOON AND EVENING NEAR SHOWERS AND THUNDERSTORMS ALONG COLD FRONT. VFR CONDITIONS RETURN TO MOST TERMINALS BY LATE THURSDAY NIGHT AND REMAIN THROUGH THE PERIOD AS HIGH PRESSURE BUILDS BACK IN. && .MARINE... WITH THE WEAK STATIONARY FRONT SLOWLY DISSOLVING OVER THE WATERS...THE WINDS WILL BE LIGHT AND MORE ERRATIC IN DIRECTION...ESP THE NORTH BAY. WED THE SOUTHERLY FLOW WILL BECOME MORE ESTABLISHED. SOUTHERLY CHANNELING COULD LEAD TO SCA GUSTS WEDNESDAY NIGHT ON THE BAY. SCA CONDITIONS COULD REDEVELOP THURSDAY AFTERNOON AS COLD FRONT APPROACHES THE WATERS. HIGH PRESSURE REGAINS CONTROL FRIDAY THROUGH THE REMAINDER OF PERIOD WITH SUB-SCA WINDS. && .TIDES/COASTAL FLOODING... COASTAL FLOOD ADVISORY WILL BE LOWERED FOR ANNE ARUNDEL AND ANNAPOLIS AS THE CURRENT HIGH TIDE IS REMAINING JUST BELOW THE THRESHOLD. THE AFTERNOON HIGH TIDE WILL BE LOWER...AND THE FOLLOWING EARLY WED MORNING SHOULD BE SIMILAR TO THE CURRENT TIDE. && .CLIMATE... FOR WASHINGTON...JUNE AND JULY HAVE BEEN CONSISTENTLY STORMY. THERE HAVE BEEN MORE DAYS WITH RAIN IN JUNE AND JULY THIS YEAR /30/...THAN ANY JUNE/JULY COMBO SINCE 2000 /31/. IF WE EXCEED 2000...THE ONLY YEAR ON RECORD /SINCE 1871/ WITH MORE IS 1906...WHICH HAD 33. BALTIMORE HAS HAD SIGNIFICANTLY FEWER DAYS WITH RAIN SHOWERS...25 DAYS THIS JUNE/JULY. THE RECORD IS MORE DISTANT...35 DAYS IN 1889. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...CAS NEAR TERM...LFR SHORT TERM...MSE LONG TERM...MSE AVIATION...CAS/MSE MARINE...CAS/MSE TIDES/COASTAL FLOODING... CLIMATE...

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