Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 261929 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 329 PM EDT THU MAR 26 2015 .SYNOPSIS...
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A COLD FRONT WILL PASS THROUGH THE AREA THIS EVENING. AN UPPER- LEVEL TROUGH WILL SLOWLY MOVE THROUGH BEHIND THE FRONT LATE TONIGHT THROUGH SATURDAY. HIGH PRESSURE WILL BUILD OVERHEAD SUNDAY BEFORE MOVING OFF THE COAST EARLY NEXT WEEK.
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&& .NEAR TERM /THROUGH FRIDAY/...
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HIGH PRESSURE REMAINS OVER THE ATLANTIC THIS AFTERNOON AND A WARM FRONT LOCATED OVER NORTHEASTERN MARYLAND IS CONTINUING TO MOVE OFF TO THE NORTH AND EAST. A LULL IN THE PRECIPITATION HAS OCCURRED BEHIND THE WARM FRONT AND SOUTHERLY WINDS ALONG WITH SUNSHINE HAVER RESULTED IN UNUSUALLY WARM CONDITIONS. MAX TEMPS WILL REACH THE MIDDLE AND UPPER 70S ACROSS MOST LOCATIONS. HOWEVER...IT WILL BE COOLER RIGHT ALONG THE CHESAPEAKE BAY. A COLD FRONT WILL MOVE INTO THE POTOMAC HIGHLANDS LATE THIS AFTERNOON...THEN PASS THROUGH THE WASHINGTON AND BALTIMORE METROPOLITAN AREAS EARLY THIS EVENING BEFORE MOVING THROUGH SOUTHERN MARYLAND LATE THIS EVENING INTO THE OVERNIGHT. A LINE OF SHOWERS AND POSSIBLY EVEN A COUPLE THUNDERSTORMS WILL DEVELOP ALONG THE FRONT. AS OF NOW...IT APPEARS THAT INSTABILITY IS LIMITED AND THERE IS A STABLE LAYER IN THE LOWER LEVELS OF THE ATMOSPHERE. HOWEVER...THERE IS PLENTY OF STRONG WIND ALOFT TO MIX DOWN. THEREFORE...GUSTY WINDS ARE EXPECTED WITH THE FRONTAL PASSAGE IN HEAVIER SHOWERS OR ISOLATED THUNDER. THE THREAT FOR SEVERE THUNDERSTORMS REMAINS LOW DUE TO THE LOW INSTABILITY...BUT IT MAY BE CLOSE ACROSS THE EASTERN PANHANDLE OF WEST VIRGINIA INTO NORTHERN MARYLAND AND EXTREME NORTHERN VIRGINIA. THIS IS WHERE FORCING ALONG THE COLD FRONT WILL BE STRONGEST...AND THIS MAY HELP UPDRAFTS BREAK THROUGH THE STABLE LAYER. NORTHWEST WINDS BEHIND THE FRONT OVERNIGHT WILL USHER IN MUCH COLDER CONDITIONS. A COLD RAIN IS EXPECTED ACROSS MOST AREAS AS AN UPPER-LEVEL DISTURBANCE SWINGS THROUGH IN THE SOUTHWEST FLOW ALOFT. HOWEVER...THERE WILL BE ENOUGH COLD AIR FOR SNOW ALONG THE RIDGE TOPS OF THE ALLEGHENY HIGHLANDS AND BLUE RIDGE MOUNTAINS. SNOW ACCUMULATIONS WILL MOST LIKELY BE CONFINED TO ELEVATIONS ABOVE 2500 FEET. LOW PRESSURE DEVELOP ALONG THE NORTH CAROLINA COAST FRIDAY MORNING BEFORE MOVING OUT TO SEA LATER IN THE DAY. AN UPPER-LEVEL TROUGH WILL BUILD OVERHEAD DURING THIS TIME. A NORTHWEST FLOW WILL CONTINUE TO USHER IN CHILLY CONDITIONS FOR THIS TIME OF YEAR. RAIN ACROSS THE SOUTHEASTERN PORTION OF THE CWA...CLOSER TO THE LOW WILL MOVE OUT OF THE AREA DURING THE LATE MORNING AND EARLY AFTERNOON HOURS. ELSEWHERE...IT WILL BE DRY FOR MOST OF THE DAY BUT A COUPLE SHOWERS CANNOT BE RULED OUT DUE TO THE INSTABILITY FROM THE UPPER-LEVEL TROUGH BUILDING OVERHEAD. THERE WILL BE MORE UPSLOPE SNOW SHOWERS ALONG AND WEST OF THE ALLEGHENY FRONT...BUT ANY ACCUMULATION WILL BE LIGHT. MAX TEMPS WILL RANGE FROM THE UPPER 20S AND LOWER 30S ALONG THE RIDGE TOPS OF THE ALLEGHENY HIGHLANDS TO THE UPPER 40S AND LOWER 50S ACROSS MOST OTHER LOCATIONS.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
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MODERATE CAA WILL PERSIST THROUGH THE OVERNIGHT FRI AS THE SFC LOW BEGINS TO MOVE AWAY FROM OUR AREA...ALTHOUGH CLOUDY SKIES AND BREEZY WINDS WILL PREVENT TEMPERATURES FROM PLUMMETING TOO MUCH. EXPECT SAT MORNING LOWS IN THE MID 30S NEAR THE BAY...LOW 30S IN THE METROS...AND MID/UPPER 20S TO THE WEST. LEFT A CHANCE OF UPSLOPE SNOW SHOWERS IN FAVORED WESTERN REGIONS...AND SLT CHANCE POPS ELSEWHERE TO ACCOUNT FOR ANY RESIDUAL PRECIP. CAA CONTINUES DURING THE DAY SAT AND WINDS INCREASE AS THE PRESSURE GRADIENT INCREASES DUE TO THE STRENGTHENING DEPARTING SFC LOW. SNOW/RAIN IS POSSIBLE SATURDAY AS THE UPPER LOW SWINGS OVER OUR AREA...FOR NOW LEFT ONLY CHANCE POPS WITH THE BEST CHANCES OVER MD. SAT NIGHT WILL BE UNSEASONABLY COLD...WITH TEMPERATURES AREA WIDE IN THE MID/LOW 20S AND IN THE TEENS TO THE WEST. IT COULD BE EVEN COLDER IF CLOUDS CLEAR SOONER.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
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SUNDAY WILL BE SUNNY...CONTINUED CAA THROUGH THE DAY AND BREEZY WINDS WILL MAKE IT FEEL MUCH COLDER...WITH APPARENT TEMPS IN THE MID/UPPER 40S. UPPER LEVEL RIDGE OVER REGION SHIFTING OFFSHORE BY MONDAY MORNING. PACKETS OF PVA EMBEDDED IN TROUGH ON NORTHERN TRACK CROSSING THE REGION DURING THE DAY MONDAY...MONDAY NIGHT...TUESDAY NIGHT...AND THURSDAY. RIDGE BUILDING OVER THE REGION AT MIDWEEK WILL FLATTEN AS TROUGH PASSES NORTH OF AREA AT WEEKS END. SURFACE HIGH ALONG EASTERN SEABOARD MOVING OFFSHORE ALLOWING COLD FRONT AND LIGHT PRECIPITATION TO AFFECT AREA MONDAY. NEXT SESSION OF PRECIPITATION TRIGGERED BY LOW SYSTEM AT MIDWEEK. TEMPERATURE PROFILE SUPPORTS BRIEF PERIODS OF MIXED PRECIPITATION TUESDAY MORNING AND AGAIN WEDNESDAY MORNING NEAR THE MASON-DIXON LINE. PASSAGE OF WEAK FRONTAL SYSTEM WILL AFFECT THE REGION LATE WEDNESDAY AND THURSDAY. TIGHTENING GRADIENT BETWEEN FRONT AND HIGH PRESSURE OFFSHORE PRODUCING WINDS OF 10 TO 15 KNOTS.
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&& .AVIATION /19Z THURSDAY THROUGH TUESDAY/...
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SUBVFR CONDITIONS ACROSS KBWI AND KMTN WILL IMPROVE BY 20Z. A COLD FRONT IS EXPECTED TO PASS THROUGH THE TERMINALS BETWEEN 21 AND 02Z. FIRST ACROSS KMRB AROUND 21Z...THEN ACROSS THE REST OF THE TERMINALS BETWEEN 23 AND 02Z. A LINE OF SHOWERS IS EXPECTED ALONG THE FRONT AND THERE MAY EVEN BE AN ISOLATED THUNDERSTORM. THE SHOWERS WILL BE CAPABLE OF PRODUCING LOCALLY GUSTY WINDS. HOWEVER...THE PROBABILITY FOR DAMAGING WINDS REMAINS LOW DUE TO LIMITED INSTABILITY. A WIND SHIFT TO THE NORTHWEST IS EXPECTED BEHIND THE FRONT. RAIN WILL ALSO OVERSPREAD THE TERMINALS LATE TONIGHT BEFORE ENDING FROM NORTHWEST TO SOUTHEAST FRIDAY MORNING. MVFR CONDITIONS ARE EXPECTED DURING THIS TIME. MVFR CIGS MAY HANG AROUND FRIDAY WITH A BKN STRATOCU DECK AROUND 3KFT. GUSTY NORTHWEST WINDS ARE EXPECTED FRIDAY NIGHT THROUGH SUNDAY. VFR CONDITIONS ARE EXPECTED MOST OF THE TIME SUNDAY NIGHT THROUGH TUESDAY.
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&& .MARINE...
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SOUTHERLY WINDS WILL CONTINUE TO INCREASE AHEAD OF A COLD FRONT LATE THIS AFTERNOON. THE COLD FRONT WILL PASS THROUGH THE WATERS BETWEEN 00Z AND 04Z THIS EVENING. A LINE OF GUSTY SHOWERS AND ISOLATED THUNDERSTORMS IS POSSIBLE ALONG THE FRONT. NORTHWEST WINDS ARE EXPECTED BEHIND THE FRONT. A SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH FRIDAY. HOWEVER...IT MAY BE MARGINAL ON FRIDAY. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FRIDAY NIGHT INTO SUNDAY DUE TO GUSTY NORTHWEST WINDS.
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&& .TIDES/COASTAL FLOODING...
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SOUTHERLY FLOW WILL INCREASE AHEAD OF A COLD FRONT THIS AFTERNOON CAUSING A RISE IN WATER LEVELS. TIDAL ANOMALIES MAY BE HIGH ENOUGH FOR MINOR FLOODING DURING THE TIDE CYCLE THIS EVENING AND OVERNIGHT. HOWEVER...CONFIDENCE IS LOW BECAUSE A WIND SHIFT TO THE NORTHWEST WILL BE TAKING PLACE AT THAT TIME AND IT IS ALSO THE LOWER OF THE TWO ASTRONOMICAL NORMS. NORTHWEST WINDS WILL CONTINUE OVERNIGHT AND FRIDAY...CAUSING ANOMALIES TO DECREASE.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT FRIDAY FOR ANZ530>543. && $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...IR/MSE LONG TERM...CEM AVIATION...BJL/IR/MSE MARINE...BJL/IR/MSE TIDES/COASTAL FLOODING...BJL

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