Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 011906
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
306 PM EDT FRI AUG 1 2014

.SYNOPSIS...
A COASTAL FRONT WILL REMAIN NEARLY STATIONARY ALONG THE MID-
ATLANTIC COAST THROUGH THE WEEKEND. A TROUGH IS EXPECTED TO MOVE
THROUGH MONDAY. WEAK HIGH PRESSURE BUILDS IN TUESDAY.

&&

.NEAR TERM /THROUGH SATURDAY/...
ANALYSIS THIS AFTERNOON SHOWS A COASTAL FRONT ALONG THE MID-
ATLANTIC COAST AND AN UPPER-LEVEL DISTURBANCE MOVING THROUGH NORTH
CAROLINA INTO SOUTHERN VIRGINIA. SURFACE HIGH PRESSURE REMAINS
ALONG THE NEW ENGLAND COAST AND IT EXTENDS TOWARD THE MID-
ATLANTIC COAST.

RAIN IS STEADIEST ACROSS SOUTHERN MARYLAND INTO PORTIONS OF THE
VIRGINIA PIEDMONT THIS AFTERNOON...WHERE ISENTROPIC LIFT IS DEEPER
CLOSER TO THE COASTAL FRONT. THE HEAVIER SHOWERS AND THUNDERSTORMS
TO OUR NORTH HAVE DEVELOPED DUE TO MORE INSTABILITY SINCE SUNSHINE
BROKE OUT ACROSS THESE AREAS. FARTHER SOUTH INTO OUR AREA...CLOUD
COVER HAS LIMITED INSTABILITY AND CAUSED UNUSUALLY COOL CONDITIONS
FOR THIS TIME OF YEAR. HOWEVER...A COUPLE HEAVIER SHOWERS AND
ISOLATED THUNDERSTORMS CANNOT BE RULED OUT NEAR THE MASON-DIXON
LINE INTO THE POTOMAC HIGHLANDS.

THE UPPER-LEVEL DISTURBANCE WILL MOVE THROUGH THE AREA LATE THIS
AFTERNOON AND EVENING. THE BAND OF STEADIER RAIN IS EXPECTED TO
DEVELOP A BIT FARTHER NORTHWEST DURING THIS TIME. CERTAINTY IS LOW
BECAUSE OF THE TIGHT GRADIENT BETWEEN A STEADY RAIN VS. LITTLE TO
NO PRECIPITATION. AS OF NOW...IT APPEARS THAT THE BEST CHANCES FOR
PRECIPITATION LATE THIS AFTERNOON AND EVENING WILL BE ACROSS THE
WASHINGTON AND BALTIMORE METROPOLITAN SOUTH AND EAST INTO
SOUTHERN MARYLAND AND CENTRAL VIRGINIA. THE UPPER-LEVEL
DISTURBANCE WILL MOVE AWAY FROM THE AREA OVERNIGHT...BUT PLENTY OF
MOISTURE AND OVERRUNNING WILL LEAD TO SOME SHOWERS...ESPECIALLY
ACROSS THE SOUTHEASTERN PORTION OF THE CWA CLOSER TO THE COASTAL
FRONT. MIN TEMPS TONIGHT WILL RANGE FROM THE 50S IN THE ALLEGHENY
HIGHLANDS TO THE UPPER 60S IN WASHINGTON AND BALTIMORE.

THE COASTAL FRONT WILL REMAIN ALONG THE MID-ATLANTIC COAST
SATURDAY AND OUR AREA WILL LIKELY REMAIN WEDGED IN COOLER AIR FROM
HIGH PRESSURE OFF THE NEW ENGLAND COAST. THERE WILL BE LESS IN THE
WAY OF UPPER-LEVEL ENERGY FOR FORCING...BUT PLENTY OF MOISTURE AND
ANY LIMITED HEATING WILL LEAD TO A FEW SHOWERS SATURDAY. COVERAGE
MAY REMAIN SCATTERED ACROSS MOST AREAS DUE TO A LACK OF FORCING.
MAX TEMPS SATURDAY WILL REMAIN QUITE COOL FOR THIS TIME OF
YEAR...RANGING FROM THE 60S IN THE MOUNTAINS TO NEAR 80 IN
WASHINGTON AND BALTIMORE.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
AN UPPER-LEVEL TROUGH WILL BUILD OVERHEAD SATURDAY NIGHT AND
SUNDAY WHILE THE COASTAL FRONT IS EXPECTED TO SHIFT NORTHWEST
INTO OUR AREA DURING ON SUNDAY. MORE SHOWERS AND THUNDERSTORMS
ARE POSSIBLE DURING THIS TIME...ESPECIALLY SUNDAY WHERE HIGHER
DEWPOINTS AND WARMER TEMPERATURES WILL LEAD TO MORE INSTABILITY.
MAX TEMPS SUNDAY WILL BE A BIT WARMER WITH SOME BREAKS OF
SUNSHINE...RANGING FROM THE 70S IN THE MOUNTAINS TO THE MIDDLE 80S
NEAR WASHINGTON AND BALTIMORE.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
LOWER MEAN HEIGHTS WILL PERSIST OVER THE EAST COAST OVER MUCH OF
NEXT WEEK. AT THE SURFACE...A FRONT WILL MOVE SLOWLY OFFSHORE EARLY
IN THE WEEK. THIS WILL NOT ONLY BRING AN END TO SHOWER AND
THUNDERSTORM CHANCES...BUT SHOULD ALSO ACT TO STEER TROPICAL CYCLONE
BERTHA WELL OFFSHORE. /FOR THE LATEST ON BERTHA...PLEASE REFER TO
NHC ADVISORIES./

NEAR TO BELOW NORMAL TEMPERATURES ARE ANTICIPATED GIVEN THE PATTERN
OF WEAK TROUGHING ALOFT AND HIGH PRESSURE MOVING OVER THE AREA AT
THE SURFACE DURING THE MIDDLE PART OF NEXT WEEK.

RIDGING BUILDS IN ALOFT AS HIGH PRESSURE MOVES OFFSHORE...RESULTING
IN WARMER AND MORE HUMID CONDITIONS DURING THE SECOND HALF OF NEXT
WEEK. AN APPROACHING TROUGH WILL BREAK DOWN THE RIDGE AND RESULT IN
A CHANCE OF SHOWERS AND THUNDERSTORMS BY THE END OF NEXT WEEK.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL WEDGE INTO OUR AREA THROUGH SATURDAY WHILE A
COASTAL FRONT REMAINS TO OUR EAST. WARM AND MOIST AIR WILL OVERRUN
COOLER AIR IN PLACE...RESULTING IN PERIODS OF PRECIPITATION.
HOWEVER...ANY THUNDERSTORM CHANCE WILL BE LIMITED AT BEST DUE TO
A STABLE ATMOSPHERE. LOW CLOUDS MAY DEVELOP OVERNIGHT INTO
SATURDAY MORNING...BUT CONFIDENCE IS LOW. MORE SHOWERS ARE
POSSIBLE SATURDAY NIGHT...BUT THERE IS A BETTER CHANCE FOR SHOWERS
AND THUNDERSTORMS SUNDAY. THERE IS ALSO A HIGHER DEGREE OF
CERTAINTY THAT LOW CLOUDS WILL DEVELOP SATURDAY NIGHT INTO SUNDAY
MORNING.

LIGHT/VARIABLE WINDS SUN NIGHT BECOME NORTHEASTERLY MON LESS THAN 10
KTS. LIGHT/VARIABLE WINDS AGAIN MON NIGHT INTO TUE...THEN WESTERLY
AROUND 10 KTS WED. GENERALLY VFR...EXCEPT SUB-VFR POSSIBLE IN
SHOWERS/ISO TSTMS SUN NIGHT-MON NIGHT.

&&

.MARINE...
A COASTAL FRONT WILL REMAIN ALONG THE MID-ATLANTIC COAST THROUGH
SATURDAY NIGHT. THE PRESSURE GRADIENT WILL STRENGTHEN A BIT
TONIGHT AS WEAK LOW PRESSURE RIDES ALONG THE FRONT. WIND GUSTS
WILL APPROACH SCA CRITERIA ALONG THE BAY AND LOWER TIDAL POTOMAC
RIVER. HOWEVER...WIND GUSTS HAVE BEEN CAPPED AROUND 15 KNOTS FOR
NOW SINCE THE LOW WILL BE WEAK. WINDS WILL REMAIN BELOW SCA
CRITERIA SATURDAY THROUGH SATURDAY NIGHT.

SHOWERS AND THUNDERSTORMS ARE LIKELY SUNDAY...BUT THE GRADIENT
WINDS SHOULD REMAIN BELOW SCA CRITERIA.

SUB SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED INTO THE MIDDLE
OF NEXT WEEK WITH WEAK FLOW OVER THE AREA. SHOWERS AND POSSIBLE
THUNDERSTORMS WILL DIMINISH AS A FRONT DEPARTS THE COAST EARLY IN
THE WEEK.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...BJL
NEAR TERM...BJL
SHORT TERM...BJL
LONG TERM...DFH
AVIATION...BJL/DFH
MARINE...BJL/DFH







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