Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 311405
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1005 AM EDT FRI JUL 31 2015

.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVERHEAD THROUGH TONIGHT. A WEAK COLD
FRONT WILL PASS THROUGH SATURDAY AND HIGH PRESSURE WILL RETURN FOR
SUNDAY. A COLD FRONT WILL APPROACH THE AREA FROM THE NORTH EARLY
NEXT WEEK. LOW PRESSURE WILL RIDE ALONG THE BOUNDARY...PASSING
THROUGH OUR AREA WEDNESDAY NIGHT INTO THURSDAY BEFORE THE BOUNDARY
SAGS TO OUR SOUTH LATE NEXT WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
DRIER AIR HAS INVADED THE FORECAST AREA THIS MORNING...WITH THE
COLD FRONT NOW FIRMLY SOUTHEAST OF THE CWA. THE DEWPOINT DROP IS
THE MAIN SIGNAL...DROPPING 10-15 DEGREES BEHIND THE FRONT COMPARED
TO 24 HOURS AGO.

WITH DOWNSLOPING WESTERLY WINDS...A DRY DAY IS ON TAP TODAY.
TEMPERATURES WILL BE FAIRLY SIMILAR TO YESTERDAY DESPITE BEING
BEHIND AN IN-NAME-ONLY COLD FRONT SINCE THE DRIER AIR AND WESTERLY
WINDS WILL COMBINE TO PROMOTE HEATING. CLEAR AND COOL TONIGHT WITH
LOWS DROPPING INTO THE 50S IN MOST AREAS WEST OF THE BLUE RIDGE. 60S
ALMOST EVERYWHERE ELSE. SOME PATCHY FOG IS POSSIBLE IN THE TYPICAL
INLAND LOCALES AS TEMPS SLIDE DOWN TOWARDS THE DEW POINT.

A VERY WEAK REINFORCING IN-NAME-ONLY COLD FRONT WILL PUSH THROUGH
THE REGION ON SATURDAY...BUT THERE IS SIMPLY NO TIME FOR RETURN
FLOW...SO THE FROPA IS LIKELY TO BE DRY. SOME GUIDANCE HAS TRIED
TO DEVELOP SHOWERS...BUT THE LATEST WE HAVE AVAILABLE IS PRETTY
DRY. WHILE WE CANNOT RULE OUT A SHOWER OR TWO...THE CHANCES SEEM
TOO SMALL TO INCLUDE IN THE FORECAST AT THIS TIME. WILL KEEP IT
DRY BUT WARM WITH HIGHS AROUND 90 IN THE URBAN CORRIDOR. GREAT
WEEKEND FOR A MOUNTAIN GETAWAY...WHERE HIGHS WILL STAY IN THE 70S.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
HIGH PRESSURE WILL BUILD BUILD IN FROM THE WEST SATURDAY NIGHT
THROUGH SUNDAY...BRINGING DRY CONDITIONS. MORE PATCHY FOG POSSIBLE
LATE SATURDAY NIGHT INTO EARLY SUNDAY MORNING...IT IS AUGUST AFTER
ALL AND NIGHTS ARE STARTING TO LENGTHEN NOTICEABLY. A DOWNSLOPING
WESTERLY FLOW WILL KEEP HUMIDITY DOWN DURING THIS TIME...BUT IT
WILL TURN OUT TO BE A HOT AFTERNOON SUNDAY WITH MAX TEMPS IN THE
UPPER 80S AND LOWER 90S ACROSS MOST LOCATIONS.

HIGH PRESSURE WILL CONTINUE TO BRING DRY CONDITIONS FOR SUNDAY
NIGHT.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
A LONGWAVE UPPER-LEVEL TROUGH WILL REMAIN OVER THE REGION FOR THE
EARLY AND MIDDLE PORTIONS OF NEXT WEEK. MOST OF THE ENERGY
ASSOCIATED WITH THE TROUGH WILL REMAIN TO OUR NORTH DURING THIS
TIME.

HIGH PRESSURE WILL MOVE OFF THE COAST MONDAY AND A SOUTHWEST FLOW
WILL ALLOW FOR MORE HOT CONDITIONS...BUT HUMIDITY MAY BE DOWN A
BIT WITH DEWPOINTS REMAINING IN THE 50S AND 60S. A COLD FRONT WILL
APPROACH THE AREA MONDAY NIGHT THROUGH WEDNESDAY...BUT IT SHOULD
REMAIN TO THE NORTH. THEREFORE...MORE HOT CONDITIONS ARE
EXPECTED. A SHOWER OR THUNDERSTORM CANNOT BE RULED OUT DURING
THIS TIME...BUT MOST AREAS WILL BE DRY. PERHAPS THERE WILL BE A
BETTER CHANCE FOR A THUNDERSTORM ACROSS CENTRAL AND SOUTHERN AREAS
WEDNESDAY AFTERNOON/EVENING...WHEN THE HUMIDITY WILL BE A BIT
HIGHER DUE TO LESS OF A DOWNSLOPING WESTERLY FLOW.

LOW PRESSURE WILL RIDE ALONG THE BOUNDARY...PASSING THROUGH THE
AREA WEDNESDAY NIGHT OR THURSDAY. TIMING IS UNCERTAIN AT THIS
TIME...BUT THERE WILL BE A BETTER CHANCE FOR SHOWERS AND
THUNDERSTORMS WHEN THIS SYSTEM PASSES THROUGH. THE COLD FRONT WILL
DROP TO OUR SOUTH LATE IN THE WEEK BEHIND THE DEPARTING WAVE OF
LOW PRESSURE.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
PRIMARILY VFR THROUGH THE VALID TAF PERIOD WITH WINDS GENERALLY 10
KNOTS OR LESS. PATCHY FOG INLAND (CHO/MRB) POSSIBLE AGAIN LATER
TONIGHT...BUT THATS THE ONLY CONCERN.

VFR CONDITIONS ARE EXPECTED SATURDAY NIGHT THROUGH MONDAY ASIDE
FROM PATCHY FOG RISK DURING THE LATE NIGHT/EARLY MORNING PERIODS.
THERE MAY BE A SHOWER OR THUNDERSTORM MONDAY NIGHT AND
TUESDAY...BUT MOST OF THE TIME WILL BE DRY AND ANY CONVECTION WILL
BE ISOLATED.

&&

.MARINE...
LIGHT WINDS ARE EXPECTED THROUGH EARLY SATURDAY. A PUSH OF
SLIGHTLY STRONGER WINDS MAY OCCUR BEHIND A COLD FRONT SATURDAY
AFTERNOON...APPROACHING SCA CRITERIA. FOR NOW...CAPPED THE
FORECAST AT 15 KTS.

A COLD FRONT WILL APPROACH FROM THE NORTH MONDAY AND TUESDAY. THE
GRADIENT MAY BE STRONG ENOUGH FOR SOUTHERLY WINDS TO CHANNEL UP
THE BAY AND LOWER TIDAL POTOMAC RIVER MONDAY NIGHT INTO
TUESDAY...CAUSING WIND GUSTS AROUND SCA CRITERIA. A SHOWER OR
THUNDERSTORM IS POSSIBLE MONDAY NIGHT/TUESDAY...BUT MOST AREAS
WILL BE DRY AND ANY CONVECTION WILL BE ISOLATED.

AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE WEDNESDAY AS
WELL...BUT THERE WILL BE A BETTER CHANCE FOR SHOWERS AND
THUNDERSTORMS WEDNESDAY NIGHT OR THURSDAY AS A WAVE OF LOW
PRESSURE PASSES THROUGH THE AREA.

&&

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

&&

$$
SYNOPSIS...BJL/RCM
NEAR TERM...JCE/RCM
SHORT TERM...BJL
LONG TERM...BJL
AVIATION...JCE/BJL/RCM
MARINE...JCE/BJL/RCM


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