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...
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.

&&

.NEAR TERM /THROUGH FRIDAY/...
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.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
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.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
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.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
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.

&&

.MARINE...
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.

&&

.TIDES/COASTAL FLOODING...
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.

&&

.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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