Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 040759 CCA AFDLWX AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 359 AM EDT FRI SEP 4 2015 .SYNOPSIS...A BACKDOOR COLD FRONT WILL SINK SOUTH ACROSS THE WATERS TODAY. HIGH PRESSURE BUILDS IN THE WAKE FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/...AN UPPER LEVEL LOW OVER THE GREAT LAKES WILL WEAKEN TODAY WHILE HIGH PRESSURE OVER NEW ENGLAND BUILDS SOUTHWARD. CLOUDS ARE DISSIPATING FROM EARLIER CONVECTION ACROSS THE REGION THIS MORNING MAKING FOR MOSTLY CLEAR SKIES. PATCHY FOG HAS DEVELOPED THIS MORNING DUE TO THE CALM WINDS AND RECENT MOISTURE FROM SHOWERS AND THUNDERSTORMS. PATCHES OF DENSE FOG ARE POSSIBLE IN LOW LYING AREAS. FOG WILL DISSAPATE SHORTLY AFTER SUNRISE. HIGH PRESSURE ACROSS NEW ENGLAND WILL BUILD SOUTH TODAY PUSHING A BACKDOOR COLD FRONT INTO THE REGION. THE FRONT WILL SLOWLY SAG SOUTHWARD TODAY MOVING ACROSS THE MD/PA BORDER THIS MORNING AND REACHING NOVA/DC/S MD BY THIS AFTERNOON. WINDS BECOME EASTERLY AS THE FRONT SAGS SOUTHWARD WHICH WILL ADVECT IN MARINE CONDITIONS TODAY. DUE TO THE HIGH DEWPTS AND THE SLOW MOVEMENT OF THE FRONT...SHOWERS AND THUNDERSTORMS WILL FORM MAINLY WEST OF THE BLUE RIDGE AND SOUTH OF DC TODAY AS THIS AREA WILL BE UNSTABLE THROUGH THE AFTERNOON. A FEW STORMS MAY BECOME STRONG WITH GUSTY WINDS AND HEAVY RAIN. ACTIVITY WILL DIMINISH AFTER SUNSET TONIGHT. TEMPS WILL LIKELY BE COOLER THAN PREV DAYS THIS WEEK WITH TEMPS RISING INTO THE UPPER 70S TO LOW TO MID 80S. THE FRONT WILL MOVE SOUTH AND LIKELY STALL ACROSS CENTRAL VA OVERNIGHT. THIS WILL LEAD TO THE CHANCE FOR SHOWERS OVERNIGHT IN VICINITY OF THE FRONT. EASTERLY FLOW WILL CAUSE LOW CLOUDS TO FORM LATE TONIGHT AND LAST THROUGH SATURDAY MORNING. STRATUS WILL BE SLOW TO DISSAPATE ACROSS CENTRAL VA AND AGAINST THE EASTERN SLOPES OF THE BLUE RIDGE. && .SHORT TERM /SATURDAY/...HIGH PRESSURE CONTINUES TO MOVE SOUTHWARD SATURDAY AND COOLER DRIER AIR WILL MAKE ITS WAY INTO THE REGION. CLEARING WILL INCREASE FROM N- S AS WELL WITH THE EXCEPTION OF THE SW WHERE THE FRONT MAY STILL BE LOCATED. TEMPS IN THE 70S TO LOW 80S ARE EXPECTED SATURDAY. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...SFC HIGH PRES OVER THE NORTHEAST WILL KEEP A DRY ENE FLOW AND COMFORTABLE TEMPS THROUGH MON. SFC HIGH WEAKENS MORE RAPIDLY MON THROUGH THE END OF NEXT WEEK WHILE MID-UPPER LEVEL HEIGHTS RISE OVER THE MID ATLC RESULTING IN A WARMING TREND. IS NOT REALLY UNTIL WED WHEN SFC HIGH WEAKENS ENOUGH TO ALLOW MOISTURE RETURN INTO THE AREA. WILL KEEP FCST DRY THROUGH TUE NIGHT THEN BRING CHANCES OF SHOWERS AND T-STORMS WED AFTERNOON WEST OF THE BLUE RIDGE INTO THU FOR THE ENTIRE AREA. GLOBAL MODELS SHOW A SLOW MOVING CDFNT CROSSING THE AREA THU OR THU NIGHT BUT SHOW SIG DIFFERENCES WITH RESPECT TO TIMING AND WHETHER FRONT CLEARS THE ENTIRE AREA OR NOT. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/...SUB-VFR CONDITIONS POSSIBLE THIS MORNING AS PATCHY FOG DEVELOPS AT MRB-CHO-IAD. IFR CONDITIONS LIKELY AT MRB/CHO THIS MORNING. FOG DISSAPATES AFTER SUNRISE AND DRY CONDITIONS ARE EXPECTED FOR THE REST OF THE MORNING. A COLD FRONT WILL MOVE S TODAY. N WINDS BECOME NE-E FROM N TO S TODAY AND TONIGHT. SHRA/VCTS EXPECTED ACROSS THE AREA WITH THE BEST CHANCE AT MRB-CHO-IAD. SOME STORMS MAY PRODUCE HEAVY RAIN AND GUSTY WINDS. ACTIVITY DIMINISHES TONIGHT. EASTERLY FLOW WILL LIKELY CAUSE SUB-MVFR CIGS TONIGHT ACROSS THE REGION. LOW CIGS WILL LIKELY TAKE THE LONGEST TO IMPROVE AT CHO SATURDAY MORNING. OTHERWISE...CLEAR OCCURS FROM N TO S SATURDAY. NO AVIATION CONCERNS BEYOND SAT NIGHT. && .MARINE...N WINDS BECOME NE-E TODAY AS A COLD FRONT SLOWLY MOVES ACROSS THE WATERS FROM N-S. WINDS WILL INCREASE THIS EVENING AND SCA CONDITIONS ARE EXPECTED TONIGHT AND INTO SATURDAY. THE PRESSURE GRADIENT WILL BE FAVORABLE FOR GUSTY WINDS ON THE BAY THROUGH SATURDAY. CONFIDENCE IS LOWER ACROSS THE UPPER TIDAL POTOMAC AS IT IS CLOSER TO THE CENTER OF THE HIGH. SCA MAY LINGER OVER THE MIDDLE AND LOWER BAY INTO THE FIRS PART OF SUN. && .TIDES/COASTAL FLOODING...ANOMALIES HAVE INCREASED TO ABOUT A HALF FOOT AS LIGHT N-NW FLOW OCCURS ON THE WATERS. THE FLOW WILL TURN TO THE EAST TODAY BUT IT SHOULD BE LIGHT ENOUGH TO KEEP WATER LEVELS BELOW FLOODING THRESHOLDS. THE EASTERLY FLOW WILL STRENGTHEN TONIGHT INTO SATURDAY. MINOR TIDAL FLOODING IS POSSIBLE NEAR TIME OF HIGH TIDE. && .CLIMATE...WELL ABOVE NORMAL TEMPERATURES ARE FORECAST TO PERSIST ACROSS THE AREA THROUGH FRIDAY. AS A RESULT...SOME SITES MAY APPROACH RECORD DAILY HIGH MINIMUM TEMPERATURES DURING THE NEXT 24 HOURS. BELOW IS A TABLE OF RECORD DAILY HIGH MINIMUM TEMPERATURES FOR SEPTEMBER 4TH. SITE.....RECORD MAX MIN FOR SEP 4................ DCA...76 (SET IN 2012 AND 1953).................. BWI...75 (SET IN 2012/1953/1944/1937 AND 1932)... IAD...71 (SET IN 2012)........................... && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 2 PM EDT SATURDAY FOR ANZ530>534-537>543. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EDT TONIGHT FOR ANZ535-536. && $$ SYNOPSIS...LFR NEAR TERM...HAS SHORT TERM...HAS LONG TERM...LFR AVIATION...HAS/LFR MARINE...HAS/LFR TIDES/COASTAL FLOODING...HAS

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