Area Forecast Discussion
Issued by NWS Sterling, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KLWX 200735
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
335 AM EDT WED AUG 20 2014

.SYNOPSIS...
A STATIONARY BOUNDARY WILL REMAIN OVER THE REGION THROUGH THURSDAY.
THE BOUNDARY WILL SLOWLY DROP SOUTH AND WEST AS A COLD FRONT FRIDAY
AND HIGH PRESSURE OVER NEW ENGLAND WILL EXTEND INTO OUR AREA FOR THE
WEEKEND. HOWEVER...UNSETTLED CONDITIONS MAY PERSIST DURING THIS TIME
DUE TO PLENTY OF MOISTURE FROM THE ATLANTIC.
&&

.NEAR TERM /THROUGH TONIGHT/...
A STATIONARY BOUNDARY REMAINS DRAPED ACROSS CENTRAL MARYLAND INTO
CENTRAL VIRGINIA EARLY THIS MORNING. A DECAYING MCS IS MOVING
THROUGH SOUTHWESTERN PENNSYLVANIA AND AN UPPER-LEVEL LOW IS LOCATED
OVER THE GREAT LAKES.

THE DECAYING MCS MAY CLIP THE ALLEGHENY HIGHLANDS WITH A FEW SHOWERS
EARLY THIS MORNING. A STRAY SHOWER CANNOT RULED OUT ACROSS PORTIONS
OF CENTRAL MARYLAND INTO NORTHERN AND CENTRAL VIRGINIA...BUT MOST OF
THE TIME WILL TURN OUT DRY. LOW-LEVEL MOISTURE TRAPPED UNDERNEATH
THE SUBSIDENCE INVERSION WILL RESULT IN SOME LOW CLOUDS AND
FOG...ESPECIALLY NEAR AND WEST OF THE BOUNDARY.

THE UPPER-LEVEL LOW WILL CONTINUE TO TRACK THROUGH THE GREAT LAKES
TODAY AND THE BOUNDARY WILL REMAIN OVER THE AREA. THERE WILL BE A
WEAK DEWPOINT GRADIENT ASSOCIATED WITH THE BOUNDARY...BUT THERE WILL
BE LITTLE TO NO TEMPERATURE GRADIENT. SHORTWAVE ENERGY AHEAD OF THE
UPPER-LEVEL LOW WILL ROTATE THROUGH THE AREA LATER THIS MORNING
THROUGH TONIGHT. SHOWERS AND THUNDERSTORMS WILL INCREASE IN
COVERAGE...ESPECIALLY NEAR AND WEST OF THE BLUE RIDGE MOUNTAINS LATE
THIS MORNING INTO THIS AFTERNOON...AND EVENTUALLY TOWARD THE
WASHINGTON AND BALTIMORE METROPOLITAN AREAS LATE THIS AFTERNOON AND
EVENING. SHEAR PROFILES WILL REMAIN RELATIVELY WEAK...AND PLENTY
OF MOISTURE WILL LIMIT DCAPE...SO ANY SEVERE THREAT WOULD BE LIMITED
AT BEST. HOWEVER...THUNDERSTORMS WILL BE CAPABLE OF PRODUCING
LOCALLY HEAVY DOWNPOURS...WITH THE HEAVIEST RAIN NEAR AND WEST OF
THE BOUNDARY WHERE DEWPOINTS WILL BE HIGHEST. THERE WILL BE SOME
BREAKS OF SUNSHINE THIS AFTERNOON ALLOWING FOR SEASONABLY WARM AND
HUMID CONDITIONS. MAX TEMPS WILL RANGE FROM THE 70S IN THE MOUNTAINS
TO THE MIDDLE 80S ACROSS MOST OTHER LOCATIONS.

COVERAGE IN CONVECTION SHOULD DIMINISH OVERNIGHT...BUT WITH THE
BOUNDARY NEARBY AND SHORTWAVE ENERGY MOVING THROUGH...A FEW SHOWERS
CANNOT BE RULED OUT. AREAS OF LOW CLOUDS AND FOG WILL DEVELOP LATE
TONIGHT AS WELL. WARM AND HUMID CONDITIONS WILL PERSIST WITH MIN
TEMPS RANGING FROM NEAR 60 IN THE ALLEGHENY HIGHLANDS TO THE LOWER
70S IN DOWNTOWN WASHINGTON AND BALTIMORE.
&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
THE UPPER-LEVEL LOW WILL MOVE INTO NEW ENGLAND THURSDAY THROUGH
THURSDAY NIGHT. SHORTWAVE ENERGY WILL CONTINUE TO ROTATE THROUGH THE
AREA IN A NORTHWEST FLOW ALOFT. THE BOUNDARY WILL REMAIN NEARLY
STATIONARY FROM CENTRAL MARYLAND THROUGH CENTRAL VIRGINIA AND THE
WARM AND HUMID AIRMASS WILL REMAIN OVERHEAD. MORE SHOWERS AND
THUNDERSTORMS ARE EXPECTED WITH COVERAGE BEING SCATTERED TO
NUMEROUS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS. MAX
TEMPS THURSDAY WILL RANGE FROM THE 70S IN THE MOUNTAINS TO THE MID
AND UPPER 80S ACROSS MOST OTHER LOCATIONS. MIN TEMPS THURSDAY NIGHT
WILL RANGE FROM THE LOWER 60S IN THE ALLEGHENY HIGHLANDS TO THE
LOWER 70S IN DOWNTOWN WASHINGTON AND BALTIMORE. PATCHY LOW CLOUDS
AND FOG ARE EXPECTED OVERNIGHT AS MOISTURE GETS TRAPPED UNDERNEATH
THE NOCTURNAL INVERSION.
&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
H5 PTTN MUCH MORE AMPLIFIED/ACTIVE THAN NORMAL FOR LT AUG...BUT THEN
AGAIN THIS HASNT BEEN A TYPICAL SUMMER. A SUBTROPICAL RDG WL BE
ANCHORED OVER THE MS VLY THRU MUCH OF THE PD. THAT LEAVES CWFA IN NW
FLOW ALOFT...AND TEMPS COOLER THAN CLIMO. WUD LOVE TO BE AS
DEFINITIVE W/ POPS. HWVR...SUBSIDENCE WL BE CONFINED TO OVER NEW
ENGLAND. WHILE AMS LKLY WONT BE OUTRIGHT CAPPED...THERE ARENT
SPECIFIC DISCERNABLE FORCING MECHANISMS EITHER...BUT THERE WL BE THE
JETSTREAM ABV AREA AT HIER LVLS. THAT LEAVES SENSIBLE WX SUSCEPTIBLE
TO MID-UPA DYNAMICS SUCH AS S/WV IMPULSES EMBEDDED W/IN MEAN LYR
FLOW. IT APPEARS AS THOUGH THERE WL BE SUCH A DISTURBANCE FRI NGT
INTO SAT. INSTBY MEAGER...AND BECOME INCREASINGLY LMTD AS SFC FLOW
BECOMES ELY.

BYD THAT...EVEN BROAD DETAILS BECOME PROBLEMATIC. BY ELY NXT WK...
RDGG SHUD RETROGRADE...PROVIDING A BETTER BET AT SOME DRY CONDS IN
THE CSTL PLAIN. STILL CANT RULE OUT A SHRA IN THE MTNS...BUT THE
CHCS FAR LESS.
&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
AREAS OF LOW CLOUDS AND FOG ARE EXPECTED EARLY THIS MORNING WITH
MVFR CONDITIONS. BRIEF IFR CONDITIONS ARE POSSIBLE...ESPECIALLY
ACROSS THE WESTERN TERMINALS. A FEW SHOWERS AND THUNDERSTORMS ARE
POSSIBLE THIS AFTERNOON AND EVENING. MORE LOW CLOUDS AND FOG WILL
DEVELOP LATE TONIGHT INTO THURSDAY MORNING. SHOWERS AND
THUNDERSTORMS ARE POSSIBLE THURSDAY AND THURSDAY NIGHT...ESPECIALLY
DURING THE AFTERNOON AND EVENING HOURS.

FLGT RESTRICTIONS PROBABLE W/IN SHRA/TSRA THRU THE WKND. HWVR...
AREAL CVRG A WILD CARD. FRI NGT-SAT LOOK TO BE THE WETTEST PART OF
THE OUTLOOK ATTM.
&&

.MARINE...
A BOUNDARY WILL REMAIN NEAR THE WATERS THROUGH THURSDAY NIGHT...BUT
THE PRESSURE GRADIENT SHOULD BE WEAK ENOUGH TO PREVENT SCA CRITERIA
WINDS DURING THIS TIME. A FEW SHOWERS AND THUNDERSTORMS ARE
POSSIBLE...ESPECIALLY LATE THIS AFTERNOON THROUGH THIS EVENING...AND
AGAIN THURSDAY AFTERNOON AND THURSDAY NIGHT.

ATTM NO ADVYS XPCTD THRU THIS WKND. HWVR UNSTTLD CONDS WL PREVAIL...
AND CANNOT PRECLUDE A FEW MARINE WRNGS INVOF TSRA.
&&

.TIDES/COASTAL FLOODING...
AN ONSHORE FLOW WILL CONTINUE THROUGH TONIGHT...BUT IT WILL REMAIN
WEAK. THE FLOW MAY TURN MORE TOWARD THE SOUTHEAST WHICH WOULD CAUSE
WATER LEVELS TO BE SLIGHTLY HIGHER THAN THEY HAVE BEEN RECENTLY.
THIS WILL CAUSE WATER LEVELS TO BE CLOSE TO MINOR FLOODING
THRESHOLDS DURING THE HIGH TIDE CYCLE LATE TONIGHT INTO EARLY
THURSDAY MORNING.
&&

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

&&

$$
SYNOPSIS...BJL
NEAR TERM...BJL
SHORT TERM...BJL
LONG TERM...HTS
AVIATION...BJL/HTS
MARINE...BJL/HTS
TIDES/COASTAL FLOODING...BJL






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.