Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 010754 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 354 AM EDT TUE SEP 1 2015 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OFFSHORE TODAY. AN UPPER-LEVEL DISTURBANCE ALONG WITH ITS ASSOCIATED SURFACE TROUGH WILL PASS THROUGH THE REGION WEDNESDAY. WEAK HIGH PRESSURE WILL BUILD OVERHEAD THURSDAY BEFORE A BACKDOOR COLD FRONT MOVES INTO THE AREA LATE FRIDAY INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... SFC HIPRES ANALYZED ACRS THE MID ATLC/SERN CONUS. HWVR WK LOPRES INVOF HSE IS RESULTING IN LCL ONSHORE FLOW. MARINE STRATUS RAPIDLY BCMG THE BIGGER ISSUE ACRS SERN VA...AND ITS CREEPING NWWD. ITS ALREADY ENGULFED EZF/GVE/OMH/CJR. SUSPECT IT/LL MAKE FURTHER INROADS ACRS THE PIEDMONT OF VA. ACRS PA FOG HAS BEGUN TO FORM...AND IT SEEMS AS THO THERE ARE PATCHES OF IT ACRS NRN MD AS WELL. MESOSCALE GDNC PERFORMING BETTER THAN SYNOP MDLS IN TERMS OF IDENTIFYING THE LLVL MSTR. HWVR...IT WASNT DELINIATING BTWN FOG/LOW CLD VERY WELL...PROVIDING SOME UNCERTAINITES AS TO HOW EXTENSIVE THE SHIELD WL BECOME. AM CONCERNED THAT IT CUD REACH THE NRN VA DC BURBS. IF IT DID...IT WUD HV BIG IMPLICATIONS ON THE FCST EVOLUTION LATER TDA. FOR NOW AM HOLDING A RIBBON LOW CLD IN VA E OF THE BLURDG UP TO ABT HEF. WL BE MONITORING OBS AND ADJUSTING GRIDS AS NEEDED. THE SYNOP HGT PTTN FEATURES A RDG ACRS THE APLCNS/GRTLKS/MIDWEST. THERES A WK CUTOFF H5 LOW IN/NEAR OH...WHICH SHUD STAY W OF AREA TDA. THEREFORE...MAIN FORCING WL COME FM TRRN CICRULATIONS...AS INSTBY/SHEAR MINIMAL. CONFINING 20-30 POP TO THE APLCNS S OF W99. OTRW JUST BILLOWING DIURNAL CU...WHICH WL DSPT AFTR SUNSET. ASSUMING MARINE CLDS ERODE JUST AFTER SUNRISE...WL BE ABLE TO ACCESS THE WARMTH IN THE COLUMN...AND BE ABLE TO REACH LWR 90S. AM STILL HOLDING ONTO THAT SOLN...BUT THE ONLY THING THATS ERODING RIGHT NOW IS FCSTR CONFIDENCE. UNDERNEATH THE RDG TNGT SKIES SHUD BE MOCLR AND WNDS LGT. DEWPTS IN THE UPR 60S. THUS... PTTN SHUD FAVOR FOG DVLPMNT SINCE THERES NO FEATURE THAT CUD BRING A MARINE LYR INLAND. WL HV PATCHY FOG ACRS MUCH OF THE CWFA. MIN-T CLOSE TO GDNC. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... THE MIDWEST H5 LOW SHUD BE OPENING UP AND HEADING EAST. THIS CUD PROVIDE A MECHANSIM FOR A SLGTLY MORE ORGANIZED AND WIDESPREAD TSRA DVLPMNT. FCST WL FEATURE SCT POPS ACRS MUCH OF THE AREA FOR TSRA. METRO BALT FURTHEST AWAY FM THIS FORCING FEATURE AND HAS ONLY SCHC POPS. EMPHASIS WL BE ON MIDDAY-AFTN HRS. THE S/WV WL BE SHEARING OUT AND HEADING SE WED EVNG. WL BE KEEPING SOME LINGERING POPS...BUT GRDLY TAPERING CHCS OFF OVNGT. CAPE WASNT HIGH TO START WITH AND WL BE DIMINISHING. THEREFORE HV TRANSITIONED TSRA TO SHRA. ANY ADDTL PCPN SHUD BE MINIMAL. TEMPS ON WED SHUD BE FAIRLY SIMLR TO TUE...AS NOT MUCH HAS CHGD INTHE OVERALL PTTN BTWN THESE TWO DAYS. && .LONG TERM /THURSDAY THROUGH MONDAY/... AN UPPER LEVEL DISTURBANCE SHOULD BE SOUTH OF THE REGION THURSDAY MORNING. LINGERING SHOWERS ARE POSSIBLE IN THE MORNING MAINLY ACROSS THE SOUTHERN MID-ATLANTIC. A SURFACE TROUGH SHOULD BE LOCATED TO THE SOUTH AND EAST THURSDAY AFTERNOON AND WINDS SHOULD BECOME NRLY THURSDAY. ANOTHER UPPER LEVEL DISTURBANCE WILL APPROACH THE REGION THURSDAY AFTERNOON AND WARM CONDITIONS WITH DEWPTS IN THE MID 60S MAY RESULT IN A FEW SHOWERS AND THUNDERSTORMS MAINLY WEST OF THE BLUE RIDGE. COVERAGE WILL LIKELY BE GREATER TO THE NORTH AND SOME ACTIVITY MAY MOVE INTO THE REGION THURSDAY NIGHT. THE DISTURBANCE MOVES THROUGH THE REGION FRIDAY AND FRIDAY NIGHT. TEMPS IN THE 90S WITH DEWPTS IN THE MID 60S WILL LEAD TO ANOTHER CHANCE FOR SHOWERS AND THUNDERSTORMS. TEMPS ABOVE NORMAL THURSDAY-FRIDAY. HIGH PRESSURE BUILDS INTO THE MID-ATLANTIC FROM NEW ENGLAND FRIDAY NIGHT AND INTO SATURDAY. A BACKDOOR COLD FRONT IS EXPECTED TO MOVE INTO THE REGION AND BRING DRIER AND COOLER CONDITIONS FROM NORTHEAST TO SOUTHWEST. SHOWERS AND THUNDERSTORMS ARE POSSIBLE ALONG AND AHEAD OF THE FRONT MAINLY ACROSS THE SW SATURDAY. HIGH PRESSURE BUILDS INTO THE REGION SUNDAY BEFORE DRIFTING OFF THE COAST MONDAY. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... AM WATCHING AREA OF LOW CLD ACRS SERN VA THAT CREEPING NEWD. TAFS ATTM DO NOT FEATURE THESE SUB-IFR RESTRICTIONS. GDNC SUGGESTING THAT THE NRN PROGRESS WL STOP SHORT OF CHO/IAD/DCA. W/O EVIDENCE TO THE CONTRARY...FCST BASED ON THESE MODEL SOLNS. INSTEAD AM FEATURING PREDAWN MVFR FOG. MUST ADMIT LOW CONFIDENCE. AFTER DAYBREAK...AND LOW CLD OR FOG THAT DOES MANIFEST ITSELF SHUD ERODE. DIURNAL CU SHUD DVLP...BUT BASES 050-060 WL HV NO OPERATIONAL IMPACT...NOR WL LGT WNDS. ANTHR FOG OPPORTUNITY COMES TNGT. WL KEEP ANY RESTRICTIONS AT MVFR TIL CONFIDENCE IN ITS OCCURENCE GROWS. S/WV CROSSING TERMINALS WED WL PROVIDE A SLGTLY BETTER CHC AT TSRA. SCT CVRG SO DIRECT HIT/TERMINAL IMPACTS STILL UNCERTAIN. BWI/MTN SEEMS TO BE AWAY FROM PATH OF HIEST RISK. BRIEF FLGT RESTRICTIONS PSBL W/IN ANY TSRA. PREVAILING VFR CONDITIONS EXPECTED THU-SAT. SHRA/VCTS POSSIBLE THURSDAY-FRIDAY...MAINLY IN THE AFTERNOON. && .MARINE... W/SW FLOW AOB 10 KT ATTM. WNDS SHUDNT BE MUCH HIER THAN THAT TDA OR THIS EVNG. ANTICIPATE FLOW BCMG ONSHORE DURING THE AFTN. MAY BE A FEW TSRA CROSSING WATERS WED. LGT NWLY FLOW BHD S/WV. A SFC TROUGH WILL LIKELY BE NEAR THE WATERS THURSDAY. AN UPPER LEVEL DISTURBANCE MAY BRING SHOWERS AND THUNDERSTORMS FRIDAY. HIGH PRESSURE IN CONTROL AND WILL LIKELY KEEP WINDS BELOW SCA CONDITIONS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...HTS NEAR TERM...HTS SHORT TERM...HTS LONG TERM...HAS AVIATION...HAS/HTS MARINE...HAS/HTS

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