Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 251830
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
230 PM EDT TUE AUG 25 2015

.SYNOPSIS...
HIGH PRESSURE OVER THE CENTRAL UNITED STATES WILL SLOWLY MOVE EAST
OVER THE NEXT SEVERAL DAYS. IT WILL BECOME CENTERED OVER THE
REGION BY FRIDAY AND GENERALLY REMAIN OVER THE REGION INTO EARLY
NEXT WEEK.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
MUCH DRIER AIR MASS CURRENTLY IN PLACE BEHIND THE FRONT WHICH
PASSED LATE LAST NIGHT. TEMPERATURES ALSO SEVERAL DEGREES COOLER
BUT NOT TOO FAR BELOW NORMAL FOR LATE AUGUST. COLD FRONT
CURRENTLY LOCATED ALONG THE EAST COAST WILL CONTINUE SLIDING
EASTWARD TONIGHT AND WEDNESDAY AS HIGH PRESSURE GRADUALLY BUILDS
IN FROM THE WEST. ALOFT...WE REMAIN UNDER THE INFLUENCE OF THE
CLOSED LOW IN SOUTHEASTERN CANADA AND IT WILL REMAIN IN THE SAME
GENERAL AREA THROUGH WEDNESDAY. THERE IS A VERY WEAK DISTURBANCE
PASSING AROUND THE LOW AND ACROSS OUR REGION OVERNIGHT...AND SOME
MESOSCALE MODELS INDICATE A SHOWER OR TWO FORMING AS IT DOES SO.
HOWEVER...BELIEVE THAT THE DRY AIR MASS WITH PW`S BELOW AN INCH
AND STRONG INVERSION NOW IN PLACE ALOFT WILL LIKELY KEEP ANY
SHOWERS FROM FORMING. LOWS WILL BE COOLER THAN LAST NIGHT WITH 50S
IN MANY AREAS AND 60S IN THE URBAN CENTERS. PATCHY FOG MAY ALSO
DEVELOP...MOST LIKELY ACROSS INLAND PORTIONS OF VIRGINIA. HIGHS ON
WEDNESDAY WILL REBOUND TO SIMILAR...PERHAPS SLIGHTLY
COOLER...READINGS ON WEDNESDAY AND HUMIDITY WILL REMAIN LOW UNDER
A GOOD DEAL OF SUNSHINE.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH THE SHORT
TERM...ALLOWING FOR DRY WEATHER AND TEMPERATURES A FEW DEGREES
BELOW NORMAL. THURSDAY WILL BE THE COOLER OF THE TWO DAYS...AS
COOLER AND DRIER AIR CONTINUES TO ADVECT IN FROM THE NORTH AND
WEST. WEAK RETURN FLOW BEGINS FRIDAY...WITH A WEAK WARM FRONT
LIFTING NORTH THROUGH THE AREA. THIS WILL HELP TO INCREASE
TEMPERATURES A FEW DEGREES...THOUGH THEY WILL STILL BE BELOW
NORMAL. QUALITY MOISTURE WILL BE LOCATED WELL SOUTH AND EAST...SO
DEWPOINTS EXPECTED TO REMAIN AOB 60 EVEN WITH SOUTHERLY FLOW. LACK
OF LOW-LEVEL MOISTURE AND/OR LIFTING MECHANISM WILL PRECLUDE
SHOWER/THUNDERSTORM DEVELOPMENT DURING THE SHORT TERM.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
HIGH PRESSURE WEAKENS ITS GRIP SLIGHTLY OVER THE WEEKEND...AS
WEAK WARM FRONT CONTINUES TO LIFT NORTH THROUGH THE MID-ATLANTIC.
SOUTHERLY FLOW CONTINUES...BUT QUALITY LOW-LEVEL MOISTURE WILL
STILL REMAIN SOUTH AND EAST OF OUR AREA...WHICH WILL KEEP SFC
DEWPOINTS AOB 65. HOWEVER...ENOUGH MOISTURE WILL BE PRESENT OVER
THE WEEKEND TO ALLOW FOR A FEW SPOTTY SHOWERS AND ISOLATED STORMS
OVER THE HIGHER TERRAIN...WITH SOME SPILLAGE TO THE EAST SUNDAY.
LACK OF DECENT LIFT AND MARGINAL INSTABILITY SHOULD KEEP MOST
AREAS DRY MOST OF THE TIME. HIGH PRESSURE THEN BEGINS TO
REASSERT ITS CONTROL MONDAY INTO TUESDAY.

CONTINUED SOUTHERLY FLOW WILL USHER IN SLIGHTLY WARMER
TEMPERATURES OVER THE WEEKEND AND INTO EARLY NEXT WEEK...WITH
TEMPERATURES A FEW DEGREES ABOVE NORMAL. HOWEVER...HUMIDITY SHOULD
REMAIN LOW ENOUGH TO HAVE LITTLE-TO-NO ADDED IMPACT ON HEAT.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
VFR THROUGH THE PERIOD. LIGHT WEST TO NORTHWEST WINDS TONIGHT AND
WEDNESDAY GENERALLY 10 KNOTS OR LESS. PATCHY FOG EXPECTED IN THE
AREA LATE TONIGHT AND WEDNESDAY NIGHT BUT AT THIS TIME WE ARE NOT
EXPECTING ANY FOG TO IMPACT THE TERMINALS.

&&

.MARINE...
HIGH PRESSURE WILL PROBABLY KEEP THE WINDS BELOW SCA LEVELS
TONIGHT THROUGH WEDNESDAY NIGHT. PRESSURE GRADIENT DOES TIGHTEN UP
TONIGHT AND AGAIN WEDNESDAY NIGHT...SO THERE IS A SMALL CHANCE
WINDS COULD BE HIGHER THAN EXPECTED...BUT MIXED LAYER WINDS ARE
GENERALLY BELOW 18 KNOTS SO HAVE NOT ISSUED ANYTHING YET.

FEW MARINE CONCERNS THROUGH THE EXTENDED UNDER HIGH PRESSURE WITH
DRY WEATHER AND LIGHT WINDS. AN ISOLATED SHOWER OR THUNDERSTORM IS
POSSIBLE BY LATE SUNDAY...BUT MOST OF THE DAY SHOULD REMAIN DRY.

&&

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

&&

$$

SYNOPSIS...RCM
NEAR TERM...RCM
SHORT TERM...MSE
LONG TERM...MSE
AVIATION...MSE/RCM
MARINE...MSE/RCM


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