Area Forecast Discussion


053 
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