Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 170127 AAB AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 927 PM EDT TUE SEP 16 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH WEDNESDAY. A WEAK COLD FRONT WILL PASS THROUGH THE AREA LATE WEDNESDAY NIGHT INTO THURSDAY. HIGH PRESSURE WILL RETURN FOR FRIDAY AND SATURDAY BEFORE MOVING OFF THE COAST SUNDAY. && .NEAR TERM /THROUGH WEDNESDAY/...
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THE MOST PRONOUNCED KINK IN THE UPPER LEVEL FLOW OF A LARGER-SCALE UPPER TROUGH HAS BEEN WELL TO OUR SOUTH OVER THE PAST FEW HRS... CLOSER TO THE VA/NC BORDER. THE FEATURE HAS HELPED DEVELOP SOME CONVECTION ACROSS THE CAROLINAS...AND EVEN A WEAK FRONTAL BOUNDARY OVER CNTRL VA HAD SOME LIGHT SHOWERS ALONG IT EARLIER THIS EVE. FAIR WX STRATUS CLOUD BATCHES HAVE BEEN COMMON ACROSS OUR REGION DURING THE SECOND HALF OF THE DAY...WHICH ARE NOW DISSIPATING AND WILL GIVE US A MAINLY CLEAR OVERNIGHT PERIOD. THE ERN HALF OF THE CONUS IS ESSENTIALLY UNDER THIS LARGE UPPER TROUGH THAT HAS BEEN SPILLING COLD/COOL AND DRY CANADIAN AIR DOWN INTO THE NRN HALF OF THE US FOR THE PAST COUPLE OF DAYS. THE MID- ATLC IS NOW NEARLY ON THE BACK SIDE OF THE TROUGH AXIS...W/ HIGH PRESSURE BUILDING IN AT THE SFC FROM THE UPPER MIDWEST. THIS WILL CONTINUE OUR QUIET/TRANQUIL CONDITIONS THRU THE REMAINDER OF THE WORK WEEK. PREV DISC... MIN TEMPS WILL RANGE FROM THE UPPER 30S OVER THE ALLEGHENY HIGHLANDS WHERE RADIATIONAL COOLING IS EXPECTED...TO THE UPPER 50S AND LOWER 60S IN DOWNTOWN WASHINGTON AND BALTIMORE. PATCHY FOG IS EXPECTED OVERNIGHT...BUT IT WILL NOT BE WIDESPREAD DUE TO THE DRY ADVECTION CURRENTLY IN PLACE. WEDNESDAY... HIGH PRESSURE WILL GRADUALLY SHIFT TOWARD THE COAST BUT MORE DRY CONDITIONS ARE EXPECTED WITH MAX TEMPS SLIGHTLY BELOW CLIMO... RANGING FROM THE 60S IN THE POTOMAC HIGHLANDS TO THE MIDDLE 70S NEAR WASHINGTON AND BALTIMORE. A SCT-BKN CU DECK WILL DEVELOP DURING THE LATE MORNING AND AFTERNOON HOURS...BUT CLOUDS MAY BE MORE WIDESPREAD ACROSS PORTIONS OF CENTRAL VIRGINIA AND SOUTHERN MARYLAND WHERE OVERRUNNING WILL CONTINUE WELL BEHIND A COLD FRONT OVER THE SOUTHEASTERN CONUS.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... A WEAK COLD FRONT WILL PASS THROUGH THE REGION WEDNESDAY NIGHT INTO THURSDAY. LITTLE MOISTURE OR FORCING WILL BE ASSOCIATED WITH THE FRONT SO IT WILL HAVE LITTLE TO NO IMPACT AS IT MOVES THROUGH. A STRAY SHOWER CANNOT BE RULED OUT...BUT ANY SHOWER COVERAGE WILL BE QUITE LIMITED SO THE FORECAST REMAINS DRY FOR NOW. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THURSDAY NIGHT AND FRIDAY...BRINGING DRY CONDITIONS AND BELOW NORMAL TEMPERATURES. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... HIGH PRESSURE OVER NEW ENGLAND WILL WEDGE ITSELF SOUTHWARD BETWEEN THE APPALACHIAN MOUNTAINS AND EAST COAST FRIDAY NIGHT THROUGH SATURDAY NIGHT...KEEPING DRY CONDITIONS IN THE REGION. A COLD FRONT WILL MOVE FROM THE EASTERN GREAT LAKES TO THE EAST COAST SUNDAY AND SUNDAY NIGHT. THERE IS A CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS AHEAD OF AND ALONG THE FRONT WEST OF THE BLUE RIDGE SUNDAY AND IN ALL AREAS SUNDAY NIGHT. BECAUSE THE INITIAL PUSH OF UPPER LEVEL SUPPORT LOOKS TO PIVOT NORTHEAST INTO EASTERN CANADA BY SUNDAY NIGHT...THE FRONT COULD STALL ACROSS THE DELMARVA PENINSULA AND TIDEWATER OF VIRGINIA BRIEFLY. A REINFORCING PUSH OF UPPER LEVEL ENERGY MONDAY SHOULD PUSH THE FRONT OFFSHORE BY LATE MONDAY. HIGH PRESSURE WILL GRADUALLY BUILD INTO THE REGION MONDAY NIGHT AND TUESDAY TO ALLOW FOR THE NEXT PUSH OF COLDER AIR TO ARRIVE IN TIME FOR MIDWEEK ACTIVITIES. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... HIGH PRESSURE WILL REMAIN OVER THE TERMINALS THROUGH WEDNESDAY. PATCHY BR MAY BRIEFLY REDUCE VSBYS LATE TONIGHT INTO EARLY WEDNESDAY...ESPECIALLY ACROSS KCHO AND KMRB. A WEAK COLD FRONT WILL PASS THROUGH THE TERMINALS WEDNESDAY NIGHT INTO THURSDAY BEFORE HIGH PRESSURE RETURNS FOR LATER THURSDAY THROUGH FRIDAY. VFR CONDITIONS ARE EXPECTED MOST OF THE TIME...BUT PATCHY BR MAY BRIEFLY REDUCE VSBYS DURING THE LATE NIGHT AND EARLY MORNING HOURS. VFR CONDITIONS FRIDAY NIGHT THROUGH SATURDAY WITH LIGHT AND VARIABLE WINDS AS HIGH PRESSURE HUGS THE EASTERN SEABOARD. && .MARINE...
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WINDS DIMINISH TONIGHT AS HIGH PRESSURE BUILDS OVER THE WATERS. HOWEVER...GUSTS AROUND 15 KNOTS ARE EXPECTED ALONG THE MARYLAND CHESAPEAKE BAY AND LOWER TIDAL POTOMAC RIVER AS NORTHERLY WINDS CHANNEL. HIGH PRESSURE WILL SLOWLY DRIFT EAST WEDNESDAY BEFORE A COLD FRONT MOVES THROUGH LATE WEDNESDAY NIGHT INTO THURSDAY. THE GRADIENT SHOULD BE WEAK ENOUGH DURING THIS TIME FOR NO MARINE HEADLINES. HOWEVER...A PRESSURE SURGE AHEAD OF BUILDING HIGH PRESSURE MAY CAUSE WIND TO GUST PAST SCA CRITERIA FOR PORTIONS OF THE WATERS THURSDAY NIGHT INTO FRIDAY. HIGH PRESSURE WILL BUILD OVERHEAD FOR THE WEEKEND.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ UPDATE...GMS PREV DISCUSSION...BJL/KLW

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