Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 111853 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 253 PM EDT THU SEP 11 2014 .SYNOPSIS... A COLD FRONT WILL APPROACH THE AREA FROM THE WEST TODAY BEFORE PASSING THROUGH THE AREA TONIGHT. THE FRONT WILL STALL OUT TO THE SOUTH FRIDAY...BUT IT WILL RETURN NORTH AS A WARM FRONT FRIDAY NIGHT INTO SATURDAY. A REINFORCING COLD FRONT WILL PASS THROUGH THE AREA SATURDAY NIGHT AND HIGH PRESSURE WILL RETURN FOR SUNDAY. ANOTHER COLD FRONT MAY PASS THROUGH THE AREA EARLY NEXT WEEK. && .NEAR TERM /THROUGH FRIDAY/... A COLD FRONT STRETCHES FROM CENTRAL PA TO THE POTOMAC HIGHLANDS AND CENTRAL FOOTHILLS THIS AFTERNOON. SHOWERS HAVE DISSIPATED AS THEY MOVED ACROSS THE APPALACHIANS AND INTO THE MID-ATLANTIC. WEAK LAPSE RATES AND INHIBITION HAS LED TO A CAPPED ENVIRONMENT ACROSS THE REGION. MIXING HAS BEEN SLOW TO START TODAY BUT WILL CONTINUE THIS AFTERNOON. SBCAPE AMTS AROUND 500 J/KG ARE EXPECTED. THE WIND FIELD IS LAGGING BEHIND THE COLD FRONT. PER THE MESOANALYSIS...BEST SHEAR IN THE MID-ATLANTIC IS NEAR NRN MARYLAND WHERE THE LEAST AMT OF INSTABILITY IS. BOTTOM LINE...NOT THE BEST SETUP FOR SEVERE WEATHER IN THE MID ATLANTIC. DUE TO THE SEPT SUN...HEATING WILL END LATE THIS AFTERNOON. AS THE COLD FRONT CROSSES THE REGION SHOWERS ARE POSSIBLE. ANY HEATING OR SEA BREEZE BOUNDARIES MAY LEAD TO AN ISOLATED THUNDERSTORM BUT CONFIDENCE IS LOW. THE COLD FRONT WILL CROSS THE REGION BY THIS EVENING AND NORTHWESTERLY WINDS WILL USHER IN COOL AND DRY CONDITIONS. WINDS WILL LIKELY GUST UP 15-25 MPH BEHIND THE FRONT. FCST MIN TEMPS WILL RANGE FROM THE LOW 50S IN THE POTOMAC HIGHLANDS TO THE LOW 60S IN THE PIEDMONT AND SOUTHERN MD TONIGHT. THE COLD FRONT WILL STALL ACROSS THE CAROLINAS FRIDAY AND NORTHERLY WINDS 10-15 MPH WILL CONTINUE FRIDAY. HIGH PRESSURE WILL MOVE INTO THE REGION FRIDAY WHILE SHORTWAVE TROUGH MOVES INTO THE GREAT LAKES REGION. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... THE FRONTAL BOUNDARY THAT MOVES THROUGH THE REGION TODAY IS EXPECTED TO MOVE BACK NORTH FRIDAY NIGHT. SHOWERS WILL ENTER THE CENTRAL FOOTHILLS SATURDAY AND CONTINUE TO MOVE NORTHWARD DURING THE DAY SATURDAY. A WEAK COLD FRONT WILL APPROACH THE REGION SATURDAY AFTERNOON AND SHOWERS WILL OVERSPREAD THE AREA. CLOUDS AND SCT RAIN SHOWERS ARE EXPECTED THROUGH SATURDAY. FCST MAX TEMPS WILL REACH THE MID 60S TO LOW 70S SATURDAY. HIGH PRESSURE WILL MOVE INTO THE REGION SATURDAY NIGHT AND SUNDAY. LIGHT NRLY WINDS ARE EXPECTED DURING THE DAY WITH SUNSHINE. FCST MAX TEMPS WILL RANGE FROM THE 60S IN THE HIGHLANDS TO THE LOW TO MID 70S NEAR THE I-95 CORRIDOR. && .LONG TERM /MONDAY THROUGH THURSDAY/... HIGH PRESSURE WILL BUILD OVER THE MIDDLE ATLANTIC REGION TO CLOSE THE WEEKEND. PRIMARILY DRY WEATHER WITH A LINGERING CHANCE OF RAIN OVER THE VIRGINIA PIEDMONT AND SOUTHWARD. HIGH TEMPERATURES MOSTLY IN THE 70S. ANOTHER TROUGH OF LOW PRESSURE WILL APPROACH THE REGION MONDAY BRINGING INCREASING CLOUDS AND A CHANCE FOR SHOWERS LATER MONDAY INTO TUESDAY. HIGH PRESSURE IS PROGGED BY LONG RANGE GUIDANCE TO RETURN TO THE MIDDLE ATLANTIC FOR THE MIDDLE PART OF NEXT WEEK. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... A COLD FRONT WILL MOVE ACROSS THE REGION THIS AFTERNOON AND EVENING. -SHRA AND VCTS IS POSSIBLE MAINLY FOR CHO-DCA LATE THIS AFTERNOON. CONFIDENCE IS LOW FOR VCTS AT THIS TIME AND KEPT IT OUT OF THE TAF FOR DCA. NW WINDS WILL USHER IN DRY CONDITIONS BEHIND THE FRONT AND NW WINDS 10-15KTS WITH GUSTS UP TO 20 KTS WILL BE POSSIBLE THIS EVENING BEHIND THE FRONT. WINDS WILL RELAX TO AROUND 10 KTS BY FRIDAY MORNING. VFR CONDITIONS EXPECTED TODAY AND TONIGHT. HIGH PRESSURE WILL BE ACROSS THE AREA FRIDAY. A STALLED FRONTAL BOUNDARY MAY LEAD TO A BKN-OVC DECK NEAR CHO FRIDAY. SHRA WILL BE POSSIBLE FRI NIGHT AT CHO AND SPREAD NORTHWARD THROUGH THE DAY SATURDAY. MVFR AND SHRA ARE POSSIBLE SATURDAY. HIGH PRESSURE MOVES INTO THE REGION SUNDAY. && .MARINE... THE PRESSURE GRADIENT WILL TIGHTEN OVER THE WATERS THROUGH EARLY THIS AFTERNOON AHEAD OF A COLD FRONT. THIS WILL CAUSE SOUTH TO SOUTHWEST WINDS TO STRENGTHEN. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS TODAY. SCT SHOWERS AND ISOLATED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING WHILE WINDS WILL LIKELY RELAX AS THE GRADIENT RELAXES AHEAD OF A COLD FRONT. THE COLD FRONT WILL PASS THROUGH THE WATER LATE THIS EVENING INTO THE OVERNIGHT HOURS AND A PRESSURE SURGE BEHIND THE BOUNDARY WILL CAUSE NORTHERLY WINDS TO INCREASE. THEREFORE...THE SMALL CRAFT ADVISORY CONTINUES THROUGH TONIGHT FOR THE WATERS. THE FLOW WILL GRADUALLY WEAKEN FRIDAY AS THE FRONT STALLS TO OUR SOUTH AND THE PRESSURE GRADIENT WEAKENS. HOWEVER...A SMALL CRAFT ADVISORY IS IN EFFECT FRIDAY MORNING FOR THE MARYLAND CHESAPEAKE BAY SOUTH OF POOLES ISLAND AND THE LOWER TIDAL POTOMAC RIVER. SMALL CRAFT CONDITIONS MAY RETURN SATURDAY NIGHT INTO SUNDAY OVER A PORTION OF THE WATERS ALONG WITH REDUCED VISIBILITY IN SHOWERS. SCA CONDITIONS MAY BE POSSIBLE AT LEAST OVER THE LOWER WATERS TUESDAY NIGHT INTO WEDNESDAY OF NEXT WEEK. && .TIDES/COASTAL FLOODING... TIDAL ANOMALIES ARE STILL RUNNING AROUND A FOOT AND A HALF ABOVE NORMAL ON THE WESTERN SHORE OF THE BAY AND AROUND A FOOT ABOVE NORMAL ON THE UPPER POTOMAC. A COLD FRONT WILL CROSS THE WATERS THIS EVENING AND OVERNIGHT. TIDAL ANOMOALIES WILL DROP AFTER THIS BUT A HIGH TIDE WILL HAPPEN BEFORE THE NRLY SURGE ON THE WATERS. THEREFORE A COASTAL FLOOD ADVISORY IS IN EFFECT FOR THE WESTERN SHORE OF THE BAY FROM BALTIMORE COUNTY TO ST. MARYS COUNTY. THE FRONT SHOULD CROSS THE UPPER TIDAL POTOMAC BEFORE THE HIGH TIDE TONIGHT HOWEVER IF IT DOESNT...COASTAL FLOODING WILL BE POSSIBLE AT DC/ALEX AND PRINCE GEORGES COUNTY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...COASTAL FLOOD ADVISORY UNTIL 11 PM EDT THIS EVENING FOR MDZ011- 014-017-018. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT FRIDAY FOR ANZ531>534-537- 539>541-543. SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ530-535-536- 538-542. && $$ SYNOPSIS...HAS NEAR TERM...HAS SHORT TERM...HAS LONG TERM...CEM AVIATION...HAS MARINE...HAS TIDES/COASTAL FLOODING...HAS

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