Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 090727
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
327 AM EDT WED APR 9 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE SOUTHEASTERN STATES TODAY AND INTO
THURSDAY. A WEAK COLD FRONT WILL APPROACH FROM THE NORTH LATE
THURSDAY AND DRIFT SOUTH INTO THE AREA THURSDAY NIGHT INTO
SATURDAY. HIGH PRESSURE WILL THEN SETUP OFFSHORE INTO NEXT WEEK.
&&

.NEAR TERM /THROUGH THURSDAY/...
A CLEAR AND CALM NIGHT WILL CONTINUE THIS MORNING IN THE MID
ATLANTIC. WEAK LOW PRESSURE HAS MOVED OFF THE CAROLINA COAST AND
SFC PRESSURE SHOULD STAY NEARLY CONSTANT INTO THE MORNING HRS.
MOST OF THE REGION HAS DECOUPLED WITH THE EXCEPTION OF COASTLINE
LOCATIONS AND TEMPS HAVE DROPPED INTO THE UPPER 30S TO LOW 40S.

A POSITIVELY TILTED UPPER LEVEL TROUGH EXTENDS ACROSS THE EASTERN
THIRD OF THE US. SHORTWAVE ENERGY AND MOISTURE HAS LED TO SHOWERS IN
THE OHIO VALLEY EARLY THIS MORNING. THE TROUGH WILL MOVE EASTWARD
TODAY AND CLOUDS WILL INCREASE ALONG THE WESTERN SLOPES OF THE
ALLEGHENY FRONT AND CENTRAL VA THIS MORNING. FSCT SOUNDINGS SHOW
SOME INSTABILITY AS THE ENERGY MOVES ACROSS THE REGION AND SCT
SHOWERS WILL BE POSSIBLE IN THE MTNS THIS MORNING AND IN THE CENTRAL
FOOTHILLS INCLUDING CHO THIS AFTERNOON. THE COVERAGE WILL BE SMALL
AND DRY SFC CONDITIONS WILL ONLY LEAD TO A QUICK SHOWER OR SPRINKLES
DURING THIS PERIOD. ELSEWHERE...CU WILL DEVELOP THIS AFTERNOON BUT
MOSTLY SUNNY AND DRY CONDITIONS ARE EXPECTED. CAA IS EXPECTED
TODAY AS N-NW FLOW CONTINUES ACROSS THE REGION. TEMPS IN THE 60S ARE
EXPECTED FOR THE REGION.

THE UPPER LEVEL TROUGH WILL MOVE TO THE EAST THIS EVENING AND
CLEARING WILL OCCUR BEHIND IT. HIGH PRESSURE WILL BUILD IN FROM THE
SW AND RADIATIONAL COOLING WILL LEAD TO TEMPS IN THE 30S AND 40S
ALONG I-95 AND EAST TONIGHT. RIDGE LINES WILL BE WARMER DUE TO THE
SFC INVERSION THAT WILL FORM.

HIGH PRESSURE WILL MOVE OFF THE COAST THURSDAY AND SOUTHERLY RETURN
FLOW WILL BRING TEMPS UP INTO THE UPPER 60S AND NEAR 70.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
HIGH PRESSURE WILL MOVE OFF THE COAST THURSDAY NIGHT. A RETURN FLOW
OFF THE ATLANTIC WILL BRING IN WARMER TEMPERATURES AND HIGHER
HUMIDITY. THE NEXT COLD FRONT WILL APPROACH FROM THE GREAT LAKES
STATES FRIDAY. AN AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP ALONG
THE BOUNDARY AND INCREASE COVERAGE OF SHOWERS FRIDAY. THE GFS AND
NAM MODELS SHOW A 100KT JET AND STRONGER DYNAMICS (AND HEAVIER
RAINFALL) TAKING AIM AT PENNSYLVANIA AND JUST ALONG THE MD/PA
BORDER.  ESRL REANALYSIS GRAPHICS FROM BOULDER COLORADO SUGGEST 0.25
TO 0.5 INCHES OF RAIN WILL BE PREVALENT ACROSS OUR REGION FRIDAY
INTO FRIDAY NIGHT. HOWEVER THE GFS DEVELOPS THE SURFACE LOW OVER THE
EASTERN WV PANHANDLE FRIDAY EVENING...AND WITH THE 925-850MB FLOW
PARALLEL TO THE FRONT INDICATES A GOOD BAND OF RAIN COULD DEVELOP IN
MARYLAND. WE HAVE INCREASED WORDING TO RAIN LIKELY FRIDAY EVENING
AND NIGHT.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
THE ECMWF IS TRENDING TOWARD A HIGH AMPLITUDE BLOCK REDEVELOPING
OFF THE ATLANTIC COAST AND AN INLAND PROGRESSION OF THE EASTERN
PACIFIC RIDGE. THIS PATTERN COULD DRIVE COLD CANADIAN AIR DEEP
INTO THE PLAINS AND SET UP A PERIOD OF SEVERE WEATHER THERE.
PREVIOUS RUNS OF THE ECMWF AND THE 00Z GFS SUGGEST A VERY WET
PERIOD DEVELOPING FOR THE MID-ATLANTIC BY TUESDAY. SATURDAY LOOKS
LIKE A PLEASANT DAY UNDER SURFACE HI PRESSURE. TEMPERATURES WILL
WARM INTO THE 70/S...AND EVEN APPROACH 80 ACROSS THE SOUTHERN
AREAS BY SUNDAY. THE COLD FRONT THAT IS TO BE TO OUR SOUTH BY
EARLY SUNDAY MORNING WILL TRY TO PROPAGATE NORTHWARD AS A WARM
FRONT SUNDAY. WITH SOME DAYTIME HEATING...RAIN SHOWERS AND A FEW
THUNDERSTORMS COULD FORM ON THE NORTH SIDE AND ALONG THIS WARM
FRONT. A SURFACE LOW COULD TRAIL A COLD FRONT ACROSS THE AREA
MONDAY WITH SOME SHOWERS AND THUNDERSTORMS. WARM TEMPERATURES WILL
CONTINUE. THE FRONT COULD PUSH THROUGH TUESDAY WITH RAIN.


&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
VFR CONDITIONS EXPECTED TODAY AND TONIGHT. -RA IS POSSIBLE AT CHO
LATE THIS MORNING AND AFTERNOON AS A DISTURBANCE CROSSES. CU WILL
DEVELOP ACROSS THE TERMINALS TODAY. NW WINDS WITH GUSTS UP TO 25
KTS WILL BE POSSIBLE THIS AFTERNOON.

VFR CONDITIONS WILL PREVAIL THURSDAY THROUGH EARLY FRIDAY FOR THE
TERMINAL SITES. A PERIOD OF MVFR TO IFR CEILINGS IS LIKELY FRIDAY
AFTERNOON THROUGH FRIDAY NIGHT WITH OCCASIONAL MODERATE RAIN
SHOWERS. VFR CONDITIONS RETURN SATURDAY. AFTERNOON CUMULUS BUILDUPS
AND SHOWERS OR THUNDERSTORMS ARE POSSIBLE SUNDAY.

&&

.MARINE...

SCA IS IN EFFECT FOR THE WATERS TODAY AS NW FLOW ALLOWS GUSTS UP TO
25 KTS ON THE WATERS. HIGH PRESSURE WILL MOVE INTO THE REGION
TONIGHT AND WINDS WILL SUBSIDE. SOUTHERLY FLOW WILL INCREASE ACROSS
THE WATERS THURSDAY AND SCA WILL BE POSSIBLE.

A STRONG SOUTHERLY SURGE COULD BRING SMALL CRAFT ADVISORY
CONDITIONS TO THE WATERS THURSDAY NIGHT INTO FRIDAY. SATURDAY LOOKS
LIKE WINDS WILL BE LIGHTER. BY SUNDAY NIGHT AND MONDAY GUSTY WINDS
COULD DEVELOP ONCE AGAIN AHEAD OF A COLD FRONT...DUE TO ARRIVE
TUESDAY WITH PERIODS OF RAIN.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR
     ANZ530>543.

&&

$$
SYNOPSIS...HAS
NEAR TERM...HAS
SHORT TERM...SDG
LONG TERM...SDG
AVIATION...SDG/HAS
MARINE...SDG/HAS







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