Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 110221 AAB
AFDLWX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1021 PM EDT THU JUL 10 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OVER THE ATLANTIC THROUGH THE WEEKEND
WHILE A SURFACE TROUGH REMAINS OVERHEAD. A COLD FRONT WILL
APPROACH THE AREA MONDAY BEFORE PASSING THROUGH LATER TUESDAY.
HIGH PRESSURE WILL RETURN FOR THE MIDDLE PORTION OF NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
UPDATE...CANCELLED FLASH FLOOD WATCH FOR MUCH OF THE DC METRO
AREA. STILL UP FOR BALT AND HARFORD CO`S...FOR THE INCOMING LINE
OF STORMS.

THIRD-STRAIGHT EVE OF CONVECTIVE ACTIVITY...EACH W/ A DIFFERENT
LOOK/FEEL/COVERAGE/INTENSITY BUT STILL UNDER GENERALLY THE SAME
MOIST/HUMID AIRMASS. EACH DAY...THE DAILY TEMPS HAVE DROPPED OFF A
COUPLE OF DEGREES BUT DEWPOINTS HAVE REMAIN FAIRLY STEADY ALL THE
WHILE. SUBTLE BOUNDARIES AND LARGER OUTFLOW BOUNDARIES HAVE BEEN
THE MAIN MECHANISM OF TODAY`S ACTIVITY. THERE`S ALSO AN
INTERESTING DICHOTOMY IN THE TROPOSPHERE...W/ PLENTY OF WIND IN
THE UPPER HALF AND BARELY A BREEZE IN THE LOWER HALF. TALL-ENOUGH
STORMS HAVE HAD SOME STEERING FLOW...BUT A GOOD PORTION OF THE
ACTIVITY HAS BEEN SUBJECT TO THE MOVEMENT OF OUTFLOW/COLD POOL.

MID-LEVEL SUBSIDENCE ON THE WAY...BISECTING THE NRN/SRN HALF OF
THE CONUS FROM KS TO WV...W/ THE LEADING EDGE NOW PUSHING OVER
THE CNTRL APLCNS. THIS WILL BRING SLOW/STEADY END TO OUR MULTI-DAY
ACTIVE PERIOD AND PULL IN DRIER MORE STABLE CONDITIONS TO CLOSE
OUT THE WEEK.

FROM PREV DISC...
THE UPPER LEVEL TROUGH WILL SHIFT TOWARD THE MID-ATLANTIC COAST
LATE TONIGHT AND SHOWERS AND THUNDERSTORMS WILL MOVE OFF TO THE
EAST BY FRIDAY MORNING. THE TROUGH AXIS WILL REMAIN NEAR THE MID-
ATLANTIC COAST FRIDAY. AN ISOLATED SHOWER OR THUNDERSTORM CANNOT
BE RULED OUT...BUT MOST AREAS WILL END UP DRY SINCE WE WILL BE ON
THE SUBSIDENCE SIDE OF THE TROUGH.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
ANY ISOLATED CONVECTION FRIDAY EVENING WILL DISSIPATE DUE TO THE
LOSS OF DAYTIME HEATING. LOW-LEVEL MOISTURE TRAPPED UNDERNEATH THE
NOCTURNAL INVERSION WILL RESULT IN PATCHY FOG OVERNIGHT. MIN TEMPS
WILL RANGE FROM THE 50S IN THE ALLEGHENY HIGHLANDS TO THE LOWER
AND MIDDLE 70S IN DOWNTOWN WASHINGTON AND BALTIMORE.

WEAK RIDGING WILL BUILD OVERHEAD SATURDAY...ALLOWING FOR DRY
CONDITIONS ACROSS MOST LOCATIONS. HOWEVER...TERRAIN CIRCULATION
MAY LEAD TO AN ISOLATED SHOWER OR THUNDERSTORM DURING THE
AFTERNOON...MAINLY ALONG AND WEST OF THE BLUE RIDGE MOUNTAINS.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
LEESIDE TROUGH SHOULD FORM EAST OF THE MOUNTAINS SATURDAY NIGHT
INTO SUNDAY...BECOMING THE FOCAL POINT FOR ADDITIONAL CHANCES OF
SHOWERS AND THUNDERSTORMS SUNDAY AND SUNDAY NIGHT.

A SURFACE COLD FRONT WILL TRY TO PUSH THROUGH THE REGION SUNDAY
NIGHT INTO MONDAY BUT MODELS INDICATE THAT THIS FRONT MAY STALL
ACROSS THE MID ATLANTIC. SHOWERS AND THUNDERSTORMS COULD DEVELOP
ALONG AND JUST AHEAD OF THIS FRONT MONDAY AND MONDAY NIGHT.

DURING THE DAY TUESDAY...A STRONGER SURFACE COLD FRONT IS EXPECTED
TO PUSH ACROSS THE MID ATLANTIC REGION AND MOVE TO THE EAST COAST
TUESDAY NIGHT. HEAVY SHOWERS AND STRONG THUNDERSTORMS COULD
ACCOMPANY THIS FRONT.

A WEAK RIDGE OF HIGH PRESSURE WILL BUILD IN FROM THE WEST WEDNESDAY
AND WEDNESDAY NIGHT.

UPPER LEVEL ENERGY WILL SLIDE ACROSS THE GREAT LAKES REGION THURSDAY
AND SAG INTO PARTS OF THE EASTERN OHIO VALLEY AND MID ATLANTIC
THURSDAY NIGHT. A CHANCE OF SHOWERS AND THUNDERSTORMS WILL RE-EMERGE
THURSDAY NIGHT AND LINGER THROUGH FRIDAY NIGHT.

A DEVELOPING SURFACE FRONT ACROSS THE MID ATLANTIC REGION FRIDAY
NIGHT COULD STALL SATURDAY AND BRING ADDITIONAL CHANCES OF SHOWERS.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS ARE EXPECTED MOST OF THE TIME THROUGH THIS EVENING.
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE LATER THIS
AFTERNOON AND EVENING. A FEW THUNDERSTORMS WILL BE CAPABLE OF
PRODUCING GUSTY WINDS AND HAIL ALONG WITH LOCALLY HEAVY RAINFALL
THAT CAN REDUCE CIGS/VSBYS TO IFR LEVELS. FOG/BR IS EXPECTED LATE
TONIGHT INTO EARLY FRIDAY MORNING. VFR CONDITIONS AND LIGHT WINDS
ARE EXPECTED FRIDAY.

MVFR CONDITIONS POSSIBLE WITH ANY SHOWERS OR THUNDERSTORMS NEAR
MRB AND CHO TERMINALS SATURDAY AFTERNOON AND EVENING.

BRIEFLY VFR CONDITIONS SATURDAY NIGHT...FOLLOWED BY POSSIBLE MVFR OR
IFR CONDITIONS SUNDAY THROUGH TUESDAY NIGHT WITH CHANCES OF HEAVY
SHOWERS AND THUNDERSTORMS WITH A STALLED FRONT FOLLOWED BY A
STRONGER COLD FRONT.

&&

.MARINE...
SHOWERS AND THUNDERSTORMS CONTINUE INTO THE LATE NIGHT HRS. SOME
STORMS WILL BE CAPABLE OF PRODUCING GUSTY WINDS AND HAIL ALONG
WITH LOCALLY HEAVY RAINFALL THAT MAY REDUCE VSBYS BELOW ONE MILE
AT TIMES. A WEAK SURFACE TROUGH WILL REMAIN OVER THE WATERS FRIDAY
AND SATURDAY...BUT MOST OF THE TIME WILL BE DRY AND WINDS SHOULD
REMAIN BELOW SCA CRITERIA.

SMALL CRAFT ADVISORIES MAY BE NEEDED SUNDAY NIGHT AND MONDAY AS HIGH
PRESSURE OFFSHORE INTERACTS WITH A PERSISTENT TROUGH OF LOW PRESSURE.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR MDZ006-007-
     011.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...BJL
NEAR TERM...BJL
SHORT TERM...BJL
LONG TERM...KLW
AVIATION...BJL/KLW
MARINE...BJL/KLW






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