Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 231847
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
247 PM EDT TUE SEP 23 2014

.SYNOPSIS...
HIGH PRESSURE WILL HOLD OVER THE REGION THROUGH EARLY WEDNESDAY.
LOW PRESSURE WILL MOVE NORTH ALONG ATLANTIC COAST FROM LATE
WEDNESDAY THROUGH THROUGH THURSDAY NIGHT. MORE HIGH PRESSURE IS ON TAP
FOR THIS WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
LARGE AREA OF HIGH PRESSURE EXTENDS FROM THE LOWER GREAT LAKES
INTO THE MID-ATLANTIC TODAY. SOME HIGH CLOUDS REMAIN ALONG THE
SOUTHERN AND EASTERN PERIPHERY OF THE HIGH...FROM NEAR CHESAPEAKE
BAY ACROSS THE PIEDMONT INTO THE SOUTHERN TIER COUNTIES OF THE
CWA. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE UPPER
60S TO THE LOW 70S OVER MOST OF THE FORECAST AREA...A FEW DEGREES
BELOW NORMAL.

TONIGHT...UPPER LEVEL CUTOFF LOW OVER THE SOUTHEASTERN STATES WILL
GRADUALLY WEAKEN...BUT A SURFACE LOW PRESSURE IS EXPECTED TO
DEVELOP ALONG THE SOUTHEASTERN COAST AND BEGIN MOVING NORTHWARD
ALONG THE COAST. CLOUD COVER WILL BEGIN TO SPREAD INTO SOUTHERN
AND EASTERN PARTS OF THE CWA...BUT DRY WX IS EXPECTED. LOW TEMPS
NOT AS COOL AS MONDAY NIGHT...SO NO FROST EXPECTED. LOWS RANGE
FROM THE LOW 40S IN THE POTOMAC HIGHLANDS TO THE UPPER 50S NEAR
CHESAPEAKE BAY.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
LOW PRESSURE BECOMES GRADUALLY MORE ORGANIZED AS IT MOVES UP THE
COAST. FORECAST FOLLOWS ECMWF AND GFS MORE CLOSELY...AS NAM IS AN
OUTLIER IN ORGANIZING THE LOW MORE FULLY AND A MORE EASTWARD
TRACK. INTRODUCED LIKELY POPS FOR RAIN INTO SRN MARYLAND...BUT
PRECIP SHIELD MAY REACH FURTHER NORTHWARD TOWARDS WASHINGTON DC
AND CHARLOTTESVILLE BY THE END OF THE DAY. HIGHS GENERALLY IN THE
UPPER 60S AND LOW 70S AGAIN...POSSIBLY MID 70S IN BALTIMORE AREA
WITH LESS CLOUD COVER.

THE LOW CONTINUES TO PUSH NORTHWARD WEDNESDAY NIGHT...REACHING THE
DELMARVA BY EARLY THURSDAY MORNING. BREEZY EASTERLY WINDS EXPECTED
AS THE LOW INTERACTS WITH A HIGH ALONG THE NEW ENGLAND COAST.
LIKELY POPS PRETTY MUCH EVERYWHERE EAST OF THE BLUE RIDGE. CLOUD
COVER AND MARINE MOISTURE WILL KEEP TEMPS FROM DROPPING MUCH
WEDNESDAY NIGHT...WITH LOWS OVER MOST OF THE AREA IN THE UPPER 50S
AND LOW 60S.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS AN AREA OF LOW PRESSURE MOVES NORTHEAST FROM THE DELMARVA
PENINSULA OUT INTO THE OPEN ATLANTIC OCEAN THURSDAY...RAIN CHANCES
WILL DECREASE FROM WEST TO EAST. HIGH PRESSURE WILL PROVIDE GOOD
SUBSIDENCE IN THE WESTERN HALF OF THE REGION.

THIS HIGH WILL DOMINATE THE REGION THURSDAY NIGHT THROUGH SUNDAY
MORNING...PROVIDING PLENTY OF SUNSHINE WHICH WILL LEAD TO WARM
AFTERNOONS AND COMFORTABLE NIGHTS. HIGHS SHOULD REACH 80 IF NOT A
FEW DEGREES ABOVE DURING EACH AFTERNOON.

A WEAK...YET MOISTURE-STARVED...COLD FRONT COULD DROP IN ACROSS THE
REGION LATE SUNDAY INTO SUNDAY NIGHT. LEFT POPS AROUND 10 PERCENT OR
LESS FOR NOW...CONSIDERING THE LIMITING MOISTURE FACTOR AHEAD OF THE
FRONT.

A REINFORCING AREA OF HIGH PRESSURE WILL BUILD BEHIND THE FRONT
MONDAY THROUGH TUESDAY. THIS WILL LEAD TO HIGHS REACHING THE UPPER
70S TO NEAR 80 AND BEAUTIFUL AFTERNOONS.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
VFR CONDITIONS EXPECTED THROUGH WEDNESDAY MORNING AT THE
TERMINALS. CIGS AT BALTIMORE AND WASHINGTON DC TERMINALS MAY DROP
TO MVFR BY LATE AFTERNOON...BUT CONFIDENCE TOO LOW TO INCLUDE AT
THE END OF THE TAF PERIOD. LIGHT N-NE WINDS TONIGHT. WINDS BECOME
MORE EASTERLY AND INCREASE TO AROUND 10KT AT BALTIMORE AND
WASHINGTON DC TERMINALS WEDNESDAY. SOME GUSTS TO 15KT POSSIBLE.
RAIN EXPECTED TO MOVE INTO THE BALTIMORE/WASHINGTON TERMINALS
WEDNESDSAY EVENING AND WEDNESDAY NIGHT...WITH MVFR OR IFR CIGS/VSBYS.

MVFR OR IFR CONDITIONS MORE PROBABLE AT THE IAD...DCA...BWI AND MTN
TERMINALS THURSDAY AS RAIN SHOWERS AND A GUSTY BREEZE LINGER ON THE
BACKSIDE OF A DEPARTING LOW PRESSURE SYSTEM. WINDS NORTH TO
NORTHEAST 10 TO 20 KNOTS GUSTING 25 KNOTS THURSDAY.

VFR CONDITIONS AT ALL TERMINALS THURSDAY NIGHT AND FRIDAY. WINDS
NORTH TO NORTHWEST 5 TO 10 KNOTS GUSTS 15 KNOTS THURSDAY NIGHT AND
FRIDAY.


&&

.MARINE...
N-NE WINDS OVER THE WATERS 10KT OR LESS THIS AFTERNOON. WINDS
BEGIN TO INCREASE TONIGHT OVER THE SOUTHERN MARINE ZONES...BUT
SHOULD REMAIN BELOW SCA CRITERIA.

WINDS CONTINUE TO INCREASE WEDNESDAY AS LOW PRESSURE APPROACHES
FROM THE SOUTH. SCA BEGINS 10AM WEDNESDAY FOR THE SOUTHERN PORTION
OF THE TIDAL POTOMAC AND CHESAPEAKE BAY SOUTH OF SANDY POINT.
PERIODS OF RAIN LIKELY WEDNESDAY AFTERNOON THROUGH WEDNESDAY
NIGHT. SCA HAS BEEN EXTENDED THROUGH WEDNESDAY NIGHT FOR THESE
AREAS AS THE LOW APPROACHES THE TIDEWATER/DELMARVA REGION AND THE PRESSURE
GRADIENT NEAR THE LOW INCREASES. THE SCA MAY NEED TO BE EXPANDED
FURTHER NORTHWARD IN FUTURE UPDATES.

SMALL CRAFT ADVISORIES MAY BE NEEDED THURSDAY INTO THURSDAY NIGHT.
SMALL CRAFT ADVISORIES ARE POSSIBLE...ONCE AGAIN...FRIDAY AS A LOW
PRESSURE SYSTEM NEAR THE EAST COAST INTERACTS WITH BUILDING HIGH
PRESSURE.

&&

.TIDES/COASTAL FLOODING...
WATER LEVELS ARE AROUND A QUARTER TO HALF FOOT BELOW NORMAL
TUESDAY AFTERNOON. A COASTAL LOW PRES SYSTEM WELL TO OUR SOUTH
WILL SLOWLY APPROACH THE AREA WEDNESDAY INTO WEDNESDAY NIGHT.
THIS WILL LEAD TO HIGHER THAN NORMAL WATER LEVELS PARTICULARLY
OVER THE WESTERN SHORE OF THE CHESAPEAKE BAY. MINOR TIDAL
INUNDATION WILL BE POSSIBLE DURING THE TIMES OF HIGH TIDE. EFFECTS
FOR THURSDAY WILL BE HIGHLY DEPENDENT ON THE TRACK OF THIS SYSTEM.
WINDS WILL SHIFT TO THE NORTH OF THE LOW TRACKS EAST OF THE
BAY...WHICH WOULD REDUCE OR ELIMINATE TIDAL ANOMALIES.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM WEDNESDAY TO 6 AM EDT THURSDAY
     FOR ANZ532>534-537-540>543.

&&

$$
SYNOPSIS...KCS
NEAR TERM...KCS
SHORT TERM...KCS
LONG TERM...KLW
AVIATION...KCS/KLW
MARINE...KCS/KLW
TIDES/COASTAL FLOODING...KCS






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