Area Forecast Discussion
Issued by NWS Sterling, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KLWX 270739
AFDLWX

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

.SYNOPSIS...
HIGH PRESSURE WEAKENS THIS MORNING. A COLD FRONT WILL MOVE THROUGH
THE AREA TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR
THURSDAY...MOVING OFF THE COAST FOR FRIDAY. THE NEXT COLD FRONT
WILL APPROACH THE MID-ATLANTIC EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
HIGH PRESSURE WILL CONTINUE TO WEAKEN ACROSS THE MID ATLANTIC THIS
MORNING. LOW PRESSURE IS LOCATED NEAR HUDSON BAY WHILE A COLD FRONT
STRETCHES ALONG THE LOWER GREAT LAKES THIS MORNING. HURRICANE
CRISTOBAL WILL MOVE PARALLEL TO THE EAST COAST BEFORE MOVING
NORTHEAST AND AWAY FROM THE MID ATLANTIC TODAY.

CLEAR AND CALM CONDITIONS OVERNIGHT HAS LED TO FOG
DEVELOPMENT IN VALLEY LOCATIONS AND NEAR RIVERS THIS MORNING. FOG
WILL CONTINUE TO FORM EARLY THIS MORNING BEFORE MIXING OUT SHORTLY
AFTER SUNRISE. FOG MAY BE DENSE IN LOCALIZED AREAS SUCH AS THE
SHENANDOAH VALLEY...ALONG I-81 THIS MORNING. SUN AND INCREASING
DEWPTS WILL LEAD TO WARM AND HUMID CONDITIONS TODAY. FCST MAX TEMPS
WILL REACH THE UPPER 80S AND LOW 90S IN DC AND BALTIMORE. A WEAK
COLD FRONT WILL APPROACH THE POTOMAC HIGHLANDS LATE THIS MORNING.
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 20-25 KTS
IS EXPECTED. THE BEST CHANCE FOR THUNDERSTORMS WILL BE NEAR THE
MASON DIXON LINE LATE THIS AFTERNOON. ACTIVITY WILL DISSIPATE DUE TO
THE LOSS OF DAYTIME HEATING 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 /07Z WEDNESDAY THROUGH SUNDAY/...
MVFR VSBY ARE POSSIBLE AT IAD-CHO-MRB THIS MORNING AS FOG CONTINUES
TO FORM. VFR CONDITIONS EXPECTED TODAY. A WEAK COLD FRONT WILL MOVE
ACROSS THE REGION THIS AFTERNOON AND VARIABLE WINDS WILL BECOME N-NW
5-10KTS BEHIND THE FRONT TONIGHT. -SHRA AND VCTS ARE POSSIBLE LATE
THIS AFTERNOON NEAR THE FRONT AT MRB. AT THIS TIME CONFIDENCE IS
LOW FOR TS POTENTIAL. 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 NRLY
WINDS WILL INCREASE ACROSS THE WATERS. A SCA IS POSSIBLE 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 CHANNELLING 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...HAS/BPP
NEAR TERM...HAS
SHORT TERM...BPP
LONG TERM...BPP
AVIATION...HAS/BPP
MARINE...HAS/BPP





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.