Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 310739 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 339 AM EDT THU JUL 31 2014 .SYNOPSIS... SURFACE HIGH PRESSURE REMAINS OVER THE WESTERN ATLANTIC...AND WILL SPREAD ITS INFLUENCE INLAND. MEANWHILE...UPPER LEVEL LOW PRESSURE OVER EASTERN ONTARIO CONTINUES TO SEND UPPER LEVEL DISTURBANCES EASTWARD. A COASTAL FRONT WILL DEVELOP FRIDAY NIGHT...LASTING THROUGH THIS WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... LTST SFC ANALY DEPICTS BROAD HIPRES ALONG THE ERN SEABRD OF THE CONUS...WITH LOPRES N OF THE GRTLKS. THE LOW IS AN ARTIFACT OF THE LINGERING ULVL CYCLONE...WHICH IS ROTATING SPOKES OF PVA ACRS THE GRTLKS TWD NEW ENGLAND AND THE MID ATLC. ONE SUCH VORT...EVIDENT ON WATER VAPOR...DEPARTING NERN MD ATTM. THERE HV BEEN A FEW ASSOCD SPRINKLES THRU THE NGT...BUT THE PREDAWN HRS SHUD BE DRY...AS RECENT RDR TRENDS HV BEEN DECLINING...W/ THE NEAREST COLD CLD TOPS HEADED TWD BUF. WL STILL HV INTERVALS OF CLDS THRU SUNRISE. THRU THE DAYTIME HRS TDA...THE RDG FM THE ATLC WL GNLY BE THE CONTROLLING WX FACTOR. FORCING NIL AT BEST...AND INSTBY VALUES MEAGER. AM CARRYING A DRY FCST W/ MOSUN OR SUNNY SKIES. DUE TO THIS INSOLATION AND WAA...MAXT WL BE WARMER THAN RECENT PAST. MOS GDNC IN GNRL AGREEMENT...AND BLEND TAKEN. THTE RDGG AND MID-LVL CNVGNC INCR TNGT. THUS...WUD ANTICIPATE BLDG MID DECK CLDS...RISING DEWPTS AND POTL CRRDR OF PCPN. BOTH NAM/GFS HV THIS...THO THE NAM SEEMS EXCESSIVELY WET FOR THE SITUATION. HV SIDED W/ GFS...WHICH BRINGS CHC POPS JUST E OF THE SPINE OF THE BLURDG PAST CHO TWD DC. LLVL WNDS IN THIS AREA SELY ARND PERIPHERY OF RDG...WHICH WUD ADD A LTL UPSLOPE SUPPORT FOR PCPN DVLPMNT. QPF LGT...AND AM KEEPING POPS NO HIER THAN 30 PCT...GNLY LT NGT/OVNGT HRS. SINCE DEWPTS SHUD BE ABLE TO CRACK THE 60 DEGF BARRIER...MIN-T WL BE IN THE 60S...AND A BIT HIER THAN THAT FOR DCA/DMH. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... PTTN CHG WL MANIFEST ITSELF FRI...AS H9-7 CONFLUENCE WL COAX GLFMEX MSTR NEWD. WL STILL HV A THTE RDG SITUATED OVER THE MTNS...SO A CRRDR OF FVRBL ISENT UPGLIDE WL RESIDE COINDICENT W/ LLVL LIFT. WL RAISE POPS TO LKLY BY AFTN. SNDGS LOOK FAIRLY SATD THRUT...AND AM OVERALL NOT TOO IMPRESSED BY CNVCTV POTL-- SHRA NOT TSRA. A CSTL FNT MAY DVLP BY EVNG...W/ A S/WV RIDING NWD LT NGT. GDNC STRUGGLING A BIT W/ ITS DVLPMNT/PLACEMENT VS RDGG ON THE BACK SIDE DOWN THE I-95 CRRDR. THAT WL DICATE PCPN TIMING FRI NGT. THTE SEEMS TO BE SHUNTED TWD THE CST...AND SINCE FRONTOGENESIS PLAUSIBLE...WL AIM POPS THAT WAY. PER TEMPS...MAXT FRI WL BE HELD DOWN BY CLDS AND PSBL PCPN. MOST GDNC SUGGESTING UPR 70S/LWR 80S. ECMWF DISTINCTLY LWR...SPCLY IN CENTRL SHEN VLY AND PTMC HIGHLANDS. HV MINIMZED RANGE FOR MIN-T FRI NGT DUE TO WET AMS. DEWPTS LED THE WAY. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... THE MID-ATLANTIC WILL CONTINUE TO BE INFLUENCED BY CYCLONIC FLOW ALOFT THROUGH THE LONG TERM. AN UPPER LEVEL TROUGH WILL APPROACH THE OHIO VALLEY SATURDAY. HIGH PRESSURE IS EXPECTED TO LIFT TO THE NORTHERN ATLANTIC WHILE A COASTAL FRONT REMAINS ALONG THE EAST COAST. SHOWERS WILL BE POSSIBLE ALONG THE FRONTAL BOUNDARY NEAR THE CHESAPEAKE BAY SATURDAY. SHOWERS AND THUNDERSTORMS WILL ALSO BE POSSIBLE ACROSS THE OHIO VALLEY AND WEST OF THE BLUE RIDGE SATURDAY AFTERNOON AS THIS REGION WILL GAIN INSTABILITY THROUGHOUT THE DAY. THE TROUGH WILL APPROACH THE MID-ATLANTIC SUNDAY AND LARGE SCALE FORCING WILL INCREASE ACROSS THE REGION AS PVA INCREASES AND THE ENTRANCE REGION OF THE JET MOVES CLOSE BY. SOUTHERLY FLOW WILL CONTINUE TO DRAW MOISTURE INTO THE REGION AND SHOWERS AND THUNDERSTORMS ARE EXPECTED. A WEAK FRONT WILL CROSS THE REGION SUNDAY NIGHT INTO MONDAY AND SHOWERS SHOULD MOVE TO THE EAST BY MONDAY MIDDAY. FCST MAX TEMPS WILL BE BELOW NORMAL THIS WEEKEND...IN THE LOW TO MID 80S. THE START OF THE WORK WEEK LOOKS QUIET AT THIS TIME AS HIGH PRESSURE MOVES IN BEHIND THE WEAK COLD FRONT. BY WEDNESDAY AND THURSDAY...RETURN FLOW BEGINS AND SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE. FCST MAX TEMPS WILL BE NEAR NORMAL NEXT WEEK. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... VFR CONDS XPCTD TDA-TNGT. THERE ARE PATCHES OF FOG PRESENT ATTM. DO NOT BELIEVE THAT ANY WL DVLP OVER TERMINALS FOR MRNG PUSH. IF INCORRECT...THEN FLGT RESTRICTIONS PLAUSIBLY CUD BRIEFLY REACH IFR. LATER TDA...CU WL DVLP...BASES 050-070. THESE WL THICKEN TNGT...W/ CIGS FCST AT SAME RNG. FOG WL AGN BE A WILD CARD PREDAWN TMRW...BUT SO MAY SCT SHRA. DUE TO LOW CONFIDENCE...WL BE KEEPING VFR FCST. MSTR PROFILE INCREASES FRI-FRI NGT...SO SHRA CHCS INCR. THESE MAY PROMPT FLGT RESTRICTIONS...W/ PDS VFR IN BTWN. SHRA/TSRA POSSIBLE SATURDAY AFTERNOON AND SUNDAY AS AN UPPER LEVEL DISTURBANCE APPROACHES. MVFR POSSIBLE EARLY SUNDAY MORNING. HIGH PRESSURE MOVES INTO THE REGION FOR THE START OF NEXT WORK WEEK. && .MARINE... SLY FLOW MAINLY AOB 10 KT ATTM. TPLM2 PROVING TO BE THE EXCEPTION... AS SENSOR ABLE TO TAP WNDS FM LLJ NEAR 15 KT. WL CONT TO MONITOR... BUT WRF-ARW4 GDNC SUGGESTING WNDS WL REMAIN BLO SCA THRESHOLDS. ONCE WNDS SUBSIDE BY DAWN...AOB 10 KT SLY FLOW REMAIN THRU THE DAY. LLJ INCR ONCE TNGT. NOT SOLD ON SCA CONDS YET...BUT WRF SUGGESTING WL HV A BETTER CHC AT IT. HV CAPPED GRIDS BLO SCA...BUT ITS NOT OUT OF THE REALM OF PSBLTYS. WNDS BACK ELY FRI-FRI NGT. SPDS NOT A FACTOR...MAINLY BLO 10 KT. PCPN CHCS DO INCR...WHICH WUD OBSTRUCT VSBY. A COASTAL FRONT WILL REMAIN NEAR THE CHESAPEAKE BAY SATURDAY AND SUNDAY BEFORE A WEAK COLD FRONT MOVES THROUGH THE REGION FROM THE WEST. SHOWERS AND ISO THUNDERSTORMS POSSIBLE ON THE WATERS DURING THIS TIME. && .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...HTS/HAS MARINE...HTS/HAS

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