Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 271424
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1024 AM EDT WED AUG 27 2014

.SYNOPSIS...
A COLD FRONT OVER THE MIDWEST WILL APPROACH TODAY...AND CROSS THE
AREA TONIGHT. HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN MID-
ATLANTIC THURSDAY NIGHT...LINGERING OFF THE COAST INTO THE WEEKEND.
THE NEXT COLD FRONT WILL APPROACH THE MID-ATLANTIC EARLY NEXT
WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 14Z...SFC PRESSURE IS DROPPING ACROSS THE AREA AS CRISTOBAL
MOVES NORTH (WELL OFFSHORE) AND A WEAK COLD FRONT APPROACHES FROM
THE MIDWEST. CLEAR AND LIGHT/VARIABLE WINDS.

MAV/MET/GMOS BLEND RAISED MAX TEMPS TO LOW 90S IN BALT-WASH
CORRIDOR AND UPR 80S ELSEWHERE. SFC HEATING AND DEWPTS IN THE
UPPER 60S WILL LEAD TO 500-1000 J/KG OF MLCAPE THIS AFTERNOON.
ISO-SCT SHOWERS AND THUNDERSTORMS ARE EXPECTED AS WEAK FORCING IS
EXPECTED ALONG THE FRONT AND SINCE THE PARENT LOW WILL BE NORTH IN
CANADA MOST OF THE UPPER LEVEL FORCING WILL ALSO BE NORTH OF THE
MID ATLANTIC. MARGINAL SHEAR OF 20 KT IS EXPECTED. THE BEST
CHANCE FOR THUNDERSTORMS WILL BE NEAR THE MASON-DIXON LINE (BEST
FORCING IS IN PA) LATE THIS AFTERNOON. ACTIVITY WILL DISSIPATE
DUE TO THE LOSS OF DAYTIME HEATING THIS EVENING. QUESTION IS
WHETHER THE BALT-WASH CORRIDOR WILL SEE THUNDERSTORMS. STILL HAVE
AN ISO COVERAGE IN THE GRIDS FOR THIS EVENING.

NW FLOW AND DRIER AIR WILL MOVE IN BEHIND THE FRONT. THE FRONT
SHOULD BE IN SRN VA BY THURSDAY MORNING AND CLOUDS WILL CLEAR FROM
NORTH TO SOUTH THURSDAY MORNING. NW FLOW WILL DROP DEWPTS INTO THE
50S THURSDAY. FCST MAX TEMPS ARE IN THE LOW 80S NEAR THE MASON DIXON
LINE TO THE MID 80S IN CENTRAL VA. THE MID TO UPPER 80S ARE EXPECTED
IN DC/BALTIMORE.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
FRONT WILL STALL OUT OVER THE CAROLINAS THURSDAY NIGHT INTO
FRIDAY...AS HIGH PRESSURE BUILDS ACROSS THE NORTHEAST AND THEN
PUSHES OFF THE COAST. MUCH OF THE CWA SHOULD BE DRY DURING THIS TIME
ALTHOUGH CAN/T RULE OUT AN ISOLATED THUNDERSTORM ACROSS THE EXTREME
SOUTHWEST CWA MAINLY NEAR THE HIGHER ELEVATIONS. EASTERLY WIND ON
FRIDAY WILL LIKELY KEEP TEMPERATURES NEAR NORMAL.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
HEIGHTS INCREASE ON SATURDAY AS THE UPPER RIDGE BUMPS NORTHWARD.
BOUNDARY WILL ALSO LIFT NORTH INTO THE MID-ATLANTIC AS A WARM FRONT.
DESPITE HIGHER HEIGHTS...MOISTURE RETURN/ADVECTION MAY PROMOTE
DIURNAL ISOLATED TO SCATTERED THUNDERSTORMS PARTICULARLY ACROSS THE
NORTHWEST PORTION OF THE CWA.

BETTER CHANCE OF CONVECTION IS EXPECTED SUNDAY AS RIDGE FLATTENS OUT
AND SURFACE TROUGH DEVELOPS. TROUGH WILL REMAIN IN PLACE THROUGH
MID-WEEK...AND A SUMMER-LIKE SCENARIO IS EXPECTED WITH A CHANCE OF
MAINLY DIURNAL CONVECTION AND ABOVE NORMAL TEMPERATURES /HIGHS
AROUND 90/ EACH DAY.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
A WEAK COLD FRONT WILL MOVE ACROSS THE REGION LATE THIS AFTERNOON
THROUGH TONIGHT. VARIABLE WINDS WILL BECOME N-NW 5-10KTS BEHIND
THE FRONT TONIGHT. -SHRA AND VCTS LATE THIS AFTERNOON NEAR THE
FRONT AT MRB. LESS LIKELY FOR DC METROS. VFR CONDITIONS EXPECTED
TONIGHT AND THURSDAY.

HIGH PRESSURE BUILDS FROM THE NORTH AND THEN PUSHES OFF THE COAST TO
END THE WEEK. WARM FRONT LOOKS TO LIFT NORTH ON SATURDAY...USHERING
IN A SUMMER-LIKE PATTERN WITH A CHANCE OF AFTERNOON/EVENING TSRA
SUNDAY INTO EARLY NEXT WEEK.

&&

.MARINE...
A WEAK COLD FRONT WILL MOVE ACROSS THE WATERS THIS EVENING AND NLY
FLOW WILL INCREASE ACROSS THE WATERS. NEAR SCA NWLY FLOW LATE
TONIGHT AND INTO THURSDAY ACROSS THE MAIN CHANNEL OF THE
CHESAPEAKE BAY AS A PRESSURE SURGE MOVES ACROSS THE WATERS. NW
WINDS WILL CONTINUE THURSDAY AS HURRICANE CRISTOBAL MOVES AWAY
FROM THE EAST COAST.

WILL NEED TO WATCH SOUTHERLY FLOW FOR CHANNELING EFFECTS AND
POSSIBLE SCA CONDITIONS UP THE BAY OVER THE WEEKEND...PARTICULARLY
DURING THE EVENINGS. SUMMER-LIKE PATTERN DEVELOPS LATER IN THE
WEEKEND INTO EARLY NEXT WEEK WITH AFTERNOON AND EVENING
THUNDERSTORMS POSSIBLE EACH DAY.

&&

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

&&

$$
SYNOPSIS...BAJ/BPP/HAS
NEAR TERM...BAJ/HAS
SHORT TERM...BPP
LONG TERM...BPP
AVIATION...BAJ/BPP/HAS
MARINE...BAJ/BPP/HAS





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