Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 311348 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 948 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/...
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OUR AREA WILL REMAIN BETWEEN AN UPPER-LEVEL DISTURBANCE MOVING INTO NEW ENGLAND TODAY...AND ANOTHER ONE PASSING THROUGH THE SOUTHEASTERN CONUS. HIGH PRESSURE WILL REMAIN ALONG THE EASTERN SEABOARD...AND A SOUTHWEST FLOW IS EXPECTED AROUND THIS HIGH. THIS WILL CAUSE SOMEWHAT WARMER AND MORE HUMID CONDITIONS COMPARED TO RECENT DAYS...BUT STILL COMFORTABLE FOR THIS TIME OF YEAR. MAX TEMPS WILL RANGE FROM THE 70S IN THE MOUNTAINS TO THE MIDDLE 80S ACROSS MOST OTHER LOCATIONS. A STRAY SHOWER CANNOT BE COMPLETELY RULED OUT THIS AFTERNOON...BUT THE FORECAST REMAINS DRY. THIS IS DUE TO WEAK INSTABILITY ALONG WITH LITTLE TO NO FORCING SINCE SHORTWAVE ENERGY IS BOTH TO OUR NORTH AND SOUTH. THERE WILL BE A SCT/BKN CU DECK DEVELOPING THIS AFTERNOON. 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.
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&& .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 /14Z THURSDAY THROUGH MONDAY/...
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VFR CONDS XPCTD TDA-TNGT. A SCT/BKN CU DECK WILL DEVELOP AROUND 5-7KFT. 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.
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&& .MARINE...
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SOUTHERLY FLOW IS EXPECTED THIS AFTERNOON...BUT WIND SPEEDS SHOULD REMAIN BELOW SCA CRITERIA DUE TO THE RELATIVELY COOLER WATERS. LLJ INCR 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.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...HTS NEAR TERM...BJL/HTS SHORT TERM...HTS LONG TERM...HAS AVIATION...BJL/HAS/HTS MARINE...BJL/HAS/HTS

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