Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 010759 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 359 AM EDT MON SEP 1 2014 .SYNOPSIS... BERMUDA HIGH PRESSURE WILL PERSIST THROUGH TUESDAY. A BOUNDARY WILL PERSIST OVER THE AREA TODAY. A WEAK COLD FRONT WILL CROSS THE AREA TUESDAY NIGHT...FOLLOWED BY HIGH PRESSURE INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A REMNANT BOUNDARY FROM EVENING ACTIVITY IS STILL LYING EAST-WEST ACROSS THE AREA THIS MORNING. THIS DIFFUSE BOUNDARY IS CONVERGENCE BETWEEN THE BERMUDA HIGH AND LOW PRESSURE OVER THE WRN GREAT LAKES AND WILL PERSIST OVER THE AREA INTO TONIGHT. ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THE DAY. A DIURNAL RESURGENCE ALONG THIS BOUNDARY WILL BRING SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING. PWATS AROUND 2 INCHES WILL LEAD TO MORE LOCALLY HEAVY RAINFALL AND THE POTENTIAL FOR ISOLATED FLASH FLOODING. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... WEAK SFC RIDGING CROSSES THE CENTRAL MID-ATLANTIC TONIGHT INTO TUESDAY...MAKING FOR AN OVERNIGHT/MOST OF TUESDAY REPRIEVE FROM THUNDERSTORMS. WITH THE BERMUDA HIGH IN PLACE...EXPECT TUESDAY TO HAVE THE HIGHEST TEMPERATURE DAY SINCE JULY. MAX TEMPS LOW TO MID 90S ACROSS LOWER ELEVATIONS. TEMPERATURES MAY BE LOWER OUT WEST WHERE ACTIVITY WILL FIRE FIRST AHEAD OF AN APPROACHING WEAK COLD FRONT. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... BEHIND A SHARP AND POTENT UPPER TROUGH AXIS WILL BE LARGE ZONAL FLOW PATTERN ABOVE THE NRN HALF OF THE CONUS DURING THE MIDDLE OF THE CURRENT WEEK. THIS UPPER-LEVEL HIGHWAY OF FAST-MOVING FLOW WILL NOT ONLY TAKE THE TUE TROUGH PASSAGE QUICKLY AWAY FROM THE AREA AND OFF TOWARD NEW ENGLAND...BUT BRING ANOTHER TOWARD THE AREA JUST A COUPLE OF DAYS LATER - ALL THE WAY FROM THE NRN ROCKIES. THE UPPER RIDGE LAID OUT ACROSS THE SRN HALF OF THE CONUS HOWEVER...WILL KEEP THESE LOW PRES SYSTEM PASSES FROM MAKING A RUN TOO FAR SOUTH. THE FRONTAL PASSAGE OF THE TUE/EARLY WED SYSTEM AND THE LATE WEEK ONE WILL LARGELY SKIM THE REGION W/ THE JUST THE RESIDUAL/LEFTOVER EFFECTS OF THE MORE POTENT SYSTEM FURTHER TO THE NORTH. EVEN W/ THE COLD FRONT EXPECTED TO MOVE ACROSS THE AREA LATE TUE W/ MORE SHOWER/TSTM ACTIVITY...THE UPPER DYNAMICS BEHIND THE STRENGTH OF THE FRONT WILL TAKE OFF TO THE NE. THE LEFTOVER BOUNDARY WILL STALL-OUT TO OUR SOUTH AND ALLOW FOR WEAK HIGH PRES TO BUILD IN ACROSS THE MID-ATLC STATES WED INTO THU. ONLY A SLIGHT AIRMASS CHANGE BEHIND THE FRONT WILL PREVENT TEMPS FROM REACHING THE HIGHER LEVELS EXPECTED ON TUE - THAT OF L-M90S. INSTEAD...MUCH OF THE AREA WILL TOP OUT IN THE M80S...W/ U80S DOTTING THE I-95 CORRIDOR AREA AND EAST. SKIES WILL CLEAR OUT AND A LIGHT WNW WIND WILL DOWNSLOPE AND HELP BUMP UP TEMPS A COUPLE MORE DEG. WITH THE STALLED BOUNDARY TO OUR SOUTH TO CLOSE OUT THE WEEK...DAILY DIURNAL SHOWERS/TSTMS WILL BE DEVELOPING ALONG IT - ACROSS THE CAROLINAS AND POSSIBLY UP INTO CNTRL VA...BUT LIKELY JUST SHY OF THE SRN PERIPHERY OF THE CWA. THE NEXT UPPER LEVEL DISTURBANCE WILL BE THE FAST-MOVING SYSTEM COMING OUT OF THE NRN PLAINS AND OVER THE GREAT LAKES REGION TO CLOSE OUT THE WEEK. THE SFC HIGH WILL ROLL OFF THE COAST AND START UP AN ONSHORE FLOW AS THE COLD FRONT APPROACHES. THIS WILL HELP TO START OUR COOL-DOWN FROM THE ABNORMALLY HOT/HUMID CONDITIONS OF THE PAST FEW DAYS. PRECIP CHANCES WILL INCREASE W/ THE FRONTAL PASSAGE ON FRI INTO SAT. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... ACTIVE PATTERN CONTINUES TODAY AS SCATTERED HEAVY THUNDERSTORMS FORM ALONG A BOUNDARY THAT IS LYING WEST TO EAST ACROSS THE AREA THIS MORNING. EXPECT IFR CONDS UNDER THUNDERSTORMS. LIGHT SOUTHWEST OR WEST FLOW TODAY AND TUESDAY. COLD FRONT APPROACHES TUESDAY WITH LEADING THUNDERSTORM ENTERING FROM THE WEST LATE IN THE DAY. THE HOT/HUMID AIRMASS WILL BEGIN TO WANE TOWARD THE MIDDLE OF THE WEEK. SKIES WILL CLEAR OUT ON WED...W/ WINDS SHIFTING TOWARD NWLY AND HIGH PRES BUILDING IN FROM THE NORTH. THE HIGH WILL KEEP CONDITIONS QUIET INTO FRI...AS A COLD FRONT APPROACHES FROM THE UPPER MIDWEST. THE FRONT IS EXPECTED TO BRING MORE PRECIP FROM FRI INTO SAT...SAGGING JUST S OF THE AREA FOR THE COMING WEEKEND. && .MARINE... 10 TO 15KT SWLY/WLY FLOW THROUGH TUESDAY. ISOLATED THUNDERSTORMS THIS MORNING...THEN SCATTERED THUNDERSTORMS LATE THIS AFTERNOON AND EVENING OVER THE WATERS. HIGH PRESSURE WILL BUILD BEHIND A COLD FRONT LATE TUE EVE. THE FRONT WILL DRIFT JUST SOUTH OF THE AREA...TOWARD THE CAROLINAS. THE SFC HIGH WILL LARGELY KEEP WINDS LIGHT INTO THE LATTER HALF OF THE WEEK...MOVING OFF THE COAST BY EARLY FRI - AHEAD OF ANOTHER COLD FRONT. SCA CONDITIONS NOT ANTICIPATED FOR THE MED/LONG RANGES OF THE FORECAST. && .TIDES/COASTAL FLOODING... TIDAL DEPARTURES WILL CONTINUE TO DECREASE ACROSS THE WATERS THROUGH THE MORNING AS SWLY FLOW UP TO 15 KT PERSISTS. WATER LEVELS ARE EXPECTED TO RETURN TO NORMAL BY MIDDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BAJ NEAR TERM...BAJ SHORT TERM...BAJ LONG TERM...GMS AVIATION...BAJ/GMS MARINE...BAJ/GMS TIDES/COASTAL FLOODING...BAJ

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