Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 240800
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
400 AM EDT FRI JUL 24 2015

.SYNOPSIS...
HIGH PRESSURE OVER THE OHIO VALLEY WILL CONTINUE TO DOMINATE THE
WEATHER TODAY. IT WILL SHIFT EAST OVER THE AREA ON SATURDAY AND
CONTINUE SHIFTING EAST INTO THE WESTERN ATLANTIC OCEAN ON SUNDAY.
A WEAK COLD FRONT WILL SLIDE INTO THE AREA FROM THE NORTHWEST
SUNDAY NIGHT AND MONDAY BEFORE DISSIPATING TUESDAY. ANOTHER COLD
FRONT WILL APPROACH FROM THE NORTHWEST ON THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
FORECAST AREA IS SITUATED ON EASTERN SIDE OF BROAD SFC HIGH
PRESSURE STRETCHING FROM THE GREAT LAKES TO MID-ATLANTIC. A
STATIONARY FRONT REMAINS OVER THE SOUTHEASTERN STATES. ANOTHER
RELATIVELY COOL START TO THE DAY IN OUTLYING AREAS. SO FAR FOG HAS
BEEN TRANSIENT...DUE TO A COMBINATION OF A DRY ATMOSPHERE AND A
PATCH OF STRATOCUMULUS PARKED OVER THE MOST PRONE LOCATIONS
(CENTRAL VA/SHEN VALLEY). NAM/RAP SEEM TO HAVE HANDLE ON THIS
MOISTURE AND LINGER IT THROUGH MID-MORNING. HOWEVER...SOME PATCHY
FOG REMAINS POSSIBLE IN THE RURAL VALLEYS...ESPECIALLY WHERE IT IS
CLEAR.

ANOTHER QUIET WEATHER DAY IS IN STORE. ATMOSPHERE APPEARS DRY
ENOUGH FOR ONLY A FEW CLOUDS. HIGH TEMPS WILL LIKELY BE A DEGREE
OR TWO HIGHER THAN THURSDAY...BUT STILL BELOW 90F IN MOST
LOCATIONS.

TONIGHT...RIDGE AXIS AT THE SFC AND ALOFT MOVE NEARLY
OVERHEAD...RESULTING IN MAINLY CLEAR SKIES AND CALM WINDS. DEW
POINTS WILL STILL BE LOW ENOUGH TO SUPPORT UPPER 50S TO LOWER 60S
IN THE TYPICALLY COOLER OUTLYING AREAS...WITH MID 60S ELSEWHERE
AND NEAR 70 IN URBAN CENTERS.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
THE SFC HIGH BEGINS TO MOVE OFFSHORE ON SATURDAY...WHILE THE MID
AND UPPER RIDGE BEGIN TO BE SUPPRESSED BY APPROACHING TROUGH IN
ONTARIO. IN TERMS OF SENSIBLE WEATHER...THIS JUST LEADS TO A FEW
MORE CLOUDS AND A FEW MORE DEGREES TO THE HIGH TEMPERATURE...WHICH
COULD HIT 90F IN A FEW SPOTS IN THE EAST. HOWEVER DEW POINTS WILL
REMAIN IN THE LOWER TO MID 60S. THINK DEPICTIONS OF TERRAIN- BASED
CONVECTION ARE OVERDONE GIVEN WARM AND DRY MID-LEVELS...SO HAVE
MAINTAINED A DRY FORECAST.

HIGH PRESSURE SHIFTS FURTHER EAST SATURDAY NIGHT AND SUNDAY AS A
WEAKENING COLD FRONT APPROACHES FROM THE NORTHWEST. THE RETURN
SOUTHWEST FLOW WILL BRING AN INCREASE IN HUMIDITY AND HOLD TEMPS
UP SOMEWHAT ON SATURDAY NIGHT...WITH TEMPS RETURNING TO THE LOW
90S IN MANY AREAS ON SUNDAY ALONG WITH HIGHER HUMIDITY.
ESSENTIALLY...A RETURN TO SOMETHING MORE TYPICAL FOR JULY. THE
FRONT WILL STALL IN THE AREA SUNDAY NIGHT AND MONDAY. THE THREAT
OF STORMS IS GREATEST DURING THE AFTERNOON HOURS MONDAY AS THE
STRONGEST IN A SERIES OF FAIRLY WEAK SHORTWAVES PUSHES SOUTHEAST
ACROSS THE AREA. TEMPERATURES WILL COOL A LITTLE MONDAY COMPARED
TO SUNDAY DUE TO MODEST COLD ADVECTION AND INCREASED CLOUDS/PRECIP
COVERAGE...BUT STILL WARM AND SOMEWHAT MUGGY.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
THE WEAKENING FRONT WILL REMAIN IN THE AREA TUESDAY AS IT
DISSIPATES. A FEW SCATTERED THUNDERSTORMS ARE STILL POSSIBLE WITH
THE WEAKENING BOUNDARY AS A TRIGGER BUT COVERAGE LOOKS LOWER THAN
MONDAY WITH LESS SUPPORT ALOFT. AFTER THE FIRST FRONT
DISSIPATES...THE RIDGE TO THE SOUTHWEST WILL BUILD NORTHEAST
BRIEFLY ON WEDNESDAY WITH DRIER AND WARMER WEATHER...BEFORE THE
NEXT COLD FRONT APPROACHES FROM THE NORTHWEST ON THURSDAY.
SOUTHWESTERLY FLOW AHEAD OF THE THAT FRONT WILL CONTINUE TO ADVECT
WARM AIR NORTHWARD...AND THURSDAY CURRENTLY LOOKS LIKE THE HOTTEST
DAY SINCE EARLY THIS PAST WEEK WITH WIDESPREAD LOW-MID 90S
EXPECTED. THUNDERSTORMS WILL BECOME A RISK AS THE FRONT APPROACHES
LATER IN THE DAY.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
UNCERTAIN WHETHER KCHO WILL BRIEFLY HAVE MVFR VSBY EARLY THIS
MORNING...AND COULD DEPEND ON AMOUNT OF CLOUDS AT 4 KFT. THOSE
CLOUDS COULD BECOME A CIG AT TIMES UNTIL MID-MORNING. OTHERWISE
VFR EXPECTED TODAY UNDER HIGH PRESSURE. NW WINDS LESS THAN 10 KT
DURING THE DAY. WINDS CALM TONIGHT. STILL DOES NOT LOOK LIKE A
GOOD FOG SET- UP WITH A RATHER DRY ATMOSPHERE. VFR CONTINUES
SATURDAY AS THE HIGH PUSHES OFFSHORE...WITH SE WINDS LESS THAN 10
KT.

THE MAIN CONCERN SUNDAY THROUGH TUESDAY APPEARS TO BE SCATTERED
THUNDERSTORMS WITH POTENTIAL BRIEF MVFR/IFR CIGS AND VIS AS A
COLD FRONT APPROACHES LATER SUNDAY...WITH THE THREAT OF STORMS
CONTINUING MONDAY AND TUESDAY AS THE FRONT STALLS IN THE AREA AND
THEN DISSIPATES. WINDS WILL BE MOSTLY 10 KNOTS OR LESS...EXCEPT
POSSIBLY SW 10-20 KNOTS LATER SUNDAY AS THE FRONT APPROACHES.

&&

.MARINE...
HIGH PRESSURE WILL PROVIDE DRY WEATHER AND WINDS GENERALLY 10 KT
OR LESS THROUGH SATURDAY. PREVAILING WINDS WILL BE NW OR N THROUGH
TONIGHT...BECOMING SE BY SATURDAY AFTERNOON.

WINDS MAY APPROACH SCA LEVELS LATER SUNDAY AS A COLD FRONT
APPROACHES FROM THE NORTHWEST. OTHERWISE...WINDS ARE EXPECTED TO
REMAIN BELOW SCA LEVELS THROUGH THE LONG TERM. THE MAIN CONCERN
APPEARS TO BE SCATTERED THUNDERSTORMS LATER SUNDAY...WITH THE
THREAT OF STORMS CONTINUING MONDAY AND TUESDAY.

&&

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

&&

$$
SYNOPSIS...RCM
NEAR TERM...ADS
SHORT TERM...ADS/RCM
LONG TERM...RCM
AVIATION...ADS/RCM
MARINE...ADS/RCM


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