Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 270739 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 339 AM EDT WED AUG 27 2014 .SYNOPSIS... HIGH PRESSURE WEAKENS THIS MORNING. A COLD FRONT WILL MOVE THROUGH THE AREA TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR THURSDAY...MOVING OFF THE COAST FOR FRIDAY. THE NEXT COLD FRONT WILL APPROACH THE MID-ATLANTIC EARLY NEXT WEEK. && .NEAR TERM /THROUGH THURSDAY/... HIGH PRESSURE WILL CONTINUE TO WEAKEN ACROSS THE MID ATLANTIC THIS MORNING. LOW PRESSURE IS LOCATED NEAR HUDSON BAY WHILE A COLD FRONT STRETCHES ALONG THE LOWER GREAT LAKES THIS MORNING. HURRICANE CRISTOBAL WILL MOVE PARALLEL TO THE EAST COAST BEFORE MOVING NORTHEAST AND AWAY FROM THE MID ATLANTIC TODAY. CLEAR AND CALM CONDITIONS OVERNIGHT HAS LED TO FOG DEVELOPMENT IN VALLEY LOCATIONS AND NEAR RIVERS THIS MORNING. FOG WILL CONTINUE TO FORM EARLY THIS MORNING BEFORE MIXING OUT SHORTLY AFTER SUNRISE. FOG MAY BE DENSE IN LOCALIZED AREAS SUCH AS THE SHENANDOAH VALLEY...ALONG I-81 THIS MORNING. SUN AND INCREASING DEWPTS WILL LEAD TO WARM AND HUMID CONDITIONS TODAY. FCST MAX TEMPS WILL REACH THE UPPER 80S AND LOW 90S IN DC AND BALTIMORE. A WEAK COLD FRONT WILL APPROACH THE POTOMAC HIGHLANDS LATE THIS MORNING. SFC HEATING AND DEWPTS IN THE UPPER 60S WILL LEAD TO 500-1000 J/KG OF MLCAPE THIS AFTERNOON. ISO-SCT SHOWERS AND THUNDERSTORMS ARE EXPECTED AS WEAK FORCING IS EXPECTED ALONG THE FRONT AND SINCE THE PARENT LOW WILL BE NORTH IN CANADA MOST OF THE UPPER LEVEL FORCING WILL ALSO BE NORTH OF THE MID ATLANTIC. MARGINAL SHEAR OF 20-25 KTS IS EXPECTED. THE BEST CHANCE FOR THUNDERSTORMS WILL BE NEAR THE MASON DIXON LINE LATE THIS AFTERNOON. ACTIVITY WILL DISSIPATE DUE TO THE LOSS OF DAYTIME HEATING THIS EVENING. NW FLOW AND DRIER AIR WILL MOVE IN BEHIND THE FRONT. THE FRONT SHOULD BE IN SRN VA BY THURSDAY MORNING AND CLOUDS WILL CLEAR FROM NORTH TO SOUTH THURSDAY MORNING. NW FLOW WILL DROP DEWPTS INTO THE 50S THURSDAY. FCST MAX TEMPS ARE IN THE LOW 80S NEAR THE MASON DIXON LINE TO THE MID 80S IN CENTRAL VA. THE MID TO UPPER 80S ARE EXPECTED IN DC/BALTIMORE. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/... FRONT WILL STALL OUT OVER THE CAROLINAS THURSDAY NIGHT INTO FRIDAY...AS HIGH PRESSURE BUILDS ACROSS THE NORTHEAST AND THEN PUSHES OFF THE COAST. MUCH OF THE CWA SHOULD BE DRY DURING THIS TIME ALTHOUGH CAN/T RULE OUT AN ISOLATED THUNDERSTORM ACROSS THE EXTREME SOUTHWEST CWA MAINLY NEAR THE HIGHER ELEVATIONS. EASTERLY WIND ON FRIDAY WILL LIKELY KEEP TEMPERATURES NEAR NORMAL. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... HEIGHTS INCREASE ON SATURDAY AS THE UPPER RIDGE BUMPS NORTHWARD. BOUNDARY WILL ALSO LIFT NORTH INTO THE MID-ATLANTIC AS A WARM FRONT. DESPITE HIGHER HEIGHTS...MOISTURE RETURN/ADVECTION MAY PROMOTE DIURNAL ISOLATED TO SCATTERED THUNDERSTORMS PARTICULARLY ACROSS THE NORTHWEST PORTION OF THE CWA. BETTER CHANCE OF CONVECTION IS EXPECTED SUNDAY AS RIDGE FLATTENS OUT AND SURFACE TROUGH DEVELOPS. TROUGH WILL REMAIN IN PLACE THROUGH MID-WEEK...AND A SUMMER-LIKE SCENARIO IS EXPECTED WITH A CHANCE OF MAINLY DIURNAL CONVECTION AND ABOVE NORMAL TEMPERATURES /HIGHS AROUND 90/ EACH DAY. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... MVFR VSBY ARE POSSIBLE AT IAD-CHO-MRB THIS MORNING AS FOG CONTINUES TO FORM. VFR CONDITIONS EXPECTED TODAY. A WEAK COLD FRONT WILL MOVE ACROSS THE REGION THIS AFTERNOON AND VARIABLE WINDS WILL BECOME N-NW 5-10KTS BEHIND THE FRONT TONIGHT. -SHRA AND VCTS ARE POSSIBLE LATE THIS AFTERNOON NEAR THE FRONT AT MRB. AT THIS TIME CONFIDENCE IS LOW FOR TS POTENTIAL. VFR CONDITIONS EXPECTED TONIGHT AND THURSDAY. HIGH PRESSURE BUILDS FROM THE NORTH AND THEN PUSHES OFF THE COAST TO END THE WEEK. WARM FRONT LOOKS TO LIFT NORTH ON SATURDAY...USHERING IN A SUMMER-LIKE PATTERN WITH A CHANCE OF AFTERNOON/EVENING TSRA SUNDAY INTO EARLY NEXT WEEK. && .MARINE... A WEAK COLD FRONT WILL MOVE ACROSS THE WATERS THIS EVENING AND NRLY WINDS WILL INCREASE ACROSS THE WATERS. A SCA IS POSSIBLE LATE TONIGHT AND INTO THURSDAY ACROSS THE MAIN CHANNEL OF THE CHESAPEAKE BAY AS A PRESSURE SURGE MOVES ACROSS THE WATERS. NW WINDS WILL CONTINUE THURSDAY AS HURRICANE CRISTOBAL MOVES AWAY FROM THE EAST COAST. WILL NEED TO WATCH SOUTHERLY FLOW FOR CHANNELLING EFFECTS AND POSSIBLE SCA CONDITIONS UP THE BAY OVER THE WEEKEND...PARTICULARLY DURING THE EVENINGS. SUMMER-LIKE PATTERN DEVELOPS LATER IN THE WEEKEND INTO EARLY NEXT WEEK WITH AFTERNOON AND EVENING THUNDERSTORMS POSSIBLE EACH DAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...HAS/BPP NEAR TERM...HAS SHORT TERM...BPP LONG TERM...BPP AVIATION...HAS/BPP MARINE...HAS/BPP

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.