Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 222109
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
509 PM EDT WED APR 22 2015

.SYNOPSIS...
COOLER AND DRIER AIR WILL FOLLOW A STRONG COLD FRONT AS IT MOVES
OFF THE COAST THIS EVENING. HIGH PRESSURE WILL BUILD IN FOR THE
END OF THE WEEK...BUT STILL KEEP BREEZY CONDITIONS OCCURRING EACH
OF THE NEXT COUPLE OF DAYS. ANOTHER LOW PRESSURE SYSTEM IS
EXPECTED TO MOVE THROUGH THE AREA THIS WEEKEND.

&&

.NEAR TERM /UNTIL 10 PM THIS EVENING/...
THE COLD FRONT HAS MOVED OFF TO OUR EAST AND COOLER AIR IS MOVING
IN ON A WESTERLY FLOW. HAVE CONTINUED WITH THE WIND ADVISORY FOR
THE RIDGE TOPS OF THE BLUE RIDGE MOUNTAINS AND ALLEGHENY/POTOMAC
HIGHLANDS UNTIL 8 PM THIS EVENING. WINDS OF 35 TO 40 KNOTS AT THE
TOP OF THE MIXING LAYER MAY AFFECT THE HIGHER ELEVATIONS.
ELSEWHERE...THE GUSTY WINDS HAVE SUBSIDED DUE TO COOLER AIR AND
LESS MIXING. HOWEVER...IT WILL TURN OUT BREEZY WITH WINDS GUSTING
AROUND 20 TO 30 MPH DUE TO THE COLD ADVECTION BEHIND THE FRONT.

MOST SHOWER ACTIVITY IS NEAR AND EAST OF INTERSTATE 95 AND THIS
WILL CONTINUE TO MOVE OFF TO THE NORTHEAST OVER THE NEXT COUPLE
HOURS. SUBSIDENCE BEHIND THE COLD FRONT WILL ALLOW FOR DRY
CONDITIONS LATER THIS EVENING.

A FEW UPSLOPE RAIN AND SNOW SHOWERS ARE POSSIBLE ALONG AND WEST OF
THE ALLEGHENY FRONT...BUT PRECIPITATION AMOUNTS WILL BE LIGHT DUE
TO LITTLE MOISTURE.

&&

.SHORT TERM /10 PM THIS EVENING THROUGH SATURDAY NIGHT/...
AS PRECIP ENDS ACROSS THE REGION THIS EVE...DRIER AIR WILL FILTER
INTO THE AREA AND ALLOW TEMPS TO DROP BACK INTO THE U30S FOR
OVERNIGHT LOWS. SOME GUIDANCE GOING A BIT LOWER...KEEPING A
MODERATED REGIME OVER THE I-95 CORRIDOR AND MUCH COOLER FOR THE
MTNS AND SHEN VLY REGION.

UPSLOPE AREAS MAY CONTINUE TO RECEIVE SOME POST-FRONTAL RAIN/SNOW
MIX EARLY THURSDAY AS A VORT MAX SWINGS THRU. EAST OF THE
MOUNTAINS...THERE WILL ONLY BE AN INCREASE IN CLOUDS THURSDAY.
EXPECT BREEZY CONDITIONS ONCE AGAIN ON THURSDAY...BUT MORE IN THE
25 KT RANGE. LOWS MAY FALL BELOW FREEZING IN THE HIGHLANDS
TONIGHT...WITH MID 30S-LOW 40S EAST. 850 MB TEMPS DROP BELOW 0C
THURSDAY...RESULTING IN HIGHS ONLY IN THE 50S TO AROUND 60.

CHILLY OVERNIGHT TEMPERATURES WILL FOLLOW ONCE AGAIN FOR THURSDAY
NIGHT WITH LOWS DROPPING BACK TO THE LOW 30S NORTH AND WEST OF THE
METRO AREAS TO THE UPPER 30S TO THE LOWER 40S ACROSS THE I-95
CORRIDOR AND SOUTHERN MARYLAND. PATCHY FROST WILL BE POSSIBLE.

HIGH PRESSURE WILL REMAIN IN PLACE ON FRIDAY BUT TEMPERATURES WILL
REMAIN BELOW NORMAL WITH READINGS MOSTLY IN THE 50S...EXCEPT LOW
60S OVER CENTRAL VA. PATCHY FROST WILL BE POSSIBLE AGAIN FRIDAY
NIGHT INTO SATURDAY MORNING.

CLOUDS WILL INCREASE FROM WEST TO EAST LATE FRIDAY NIGHT AS LOW
PRESSURE APPROACHES FROM THE WEST. LIGHT RAIN/SHOWERS WILL
INCREASE FROM SOTHWEST TO NORTHEAST ON SATURDAY AND CONTINUE INTO
SATURDAY NIGHT.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
LOW PRESSURE TO THE SOUTH
WILL DEPART INTO THE ATLANTIC SATURDAY NIGHT...WITH ANY RAIN
GRADUALLY ENDING. HIGH PRESSURE WILL RETURN FOR THE SECOND HALF OF
THE WEEKEND INTO EARLY NEXT WEEK...BEFORE A STRONG TROUGH OF LOW
PRESURE APPROACHES THE AREA DURING THE MIDDLE OF NEXT WEEK.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
THE STRONGEST WINDS HAVE DISSIPATED ACROSS THE TERMINALS. WEST TO
NORTHWEST WINDS WILL GUST AROU8ND 20 TO 25 KNOTS THIS EVENING
BEFORE DIMINISHING LATE TONIGHT. EXPECT ANOTHER BREEZY DAY ON
THURSDAY WITH WNW WINDS GUSTING AROUND 20-25 KT.

VFR CONDITIONS THURSDAY NIGHT THROUGH FRIDAY NIGHT. MVFR OR IFR
CONDITIONS POSSIBLE SATURDAY AND SATURDAY NIGHT DUE TO THE CHANCE OF
LIGHT RAIN. VFR CONDITIONS SUNDAY.

MAINLY VFR SUN-MON W/ NWLY FLOW 10-15 KT.

&&

.MARINE...
WINDS HAVE ARLEADY BEGAN TO DIMINISH ACROSS THE WATERS. ALTHOUGH
MOST WIND SPEEDS ARE AT SCA CRITERIA...THE GALE WARNING REMAINS IN
EFFECT UNTIL 8 PM DUE TO THE POSSIBILITY OF LOCALLY STRONGER WIND
GUSTS IN ANY SHOWERS EARLY THIS EVENING. WINDS WILL DIMINISH
OVERNIGHT...BUT A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE
MARYLAND CHESAPEAKE BAY AND LOWER TIDAL POTOMAC RIVER. SCA
CONTINUES FOR ALL WATERS THURSDAY AS W WINDS GUST UP TO 25 KT.

NO MARINE HAZARDS THURSDAY NIGHT. SMALL CRAFT ADVISORIES POSSIBLE
FRIDAY. NO MARINE HAZARDS FRIDAY NIGHT THROUGH SUNDAY.

SCA LIKELY SUNDAY IN NWLY SURGE BEHIND FRONT.

&&

.TIDES/COASTAL FLOODING...
TIDE LEVELS HAVE BECOME ELEVATED OVER THE PAST SEVERAL HRS...ESPEC
OVER THE UPPER TIDAL POTOMAC W/ THE PRE-FRONTAL WIND BUILD UP AND
THEN EVEN AS THE FRONT MOVED THRU...CHANGING WINDS TO A MORE WLY
DIRECTION. WINDS WILL NOW STAY OUT OF THE WEST INTO THE NIGHT
HRS...OCCASIONALLY GUSTY AND IS EXPECTED TO BEGIN DROPPING THE
POSITIVE ANOMALIES BUT MAY ALSO AFFECT THE NEXT HIGH TIDE CYCLE.

WILL MONITOR THESE TRENDS FOR THE NEXT COUPLE OF DAYS...AS WATER
LEVELS WILL AT THE VERY LEAST REMAIN ELEVATED.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MDZ501.
VA...WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR VAZ025>027-029-
     030-503-504-507-508.
WV...WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR WVZ055-501>503-
     505-506.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THURSDAY FOR ANZ530>534-
     537>543.
     GALE WARNING UNTIL 8 PM EDT THIS EVENING FOR ANZ530>543.
     SMALL CRAFT ADVISORY FROM 10 AM TO 8 PM EDT THURSDAY FOR
     ANZ535-536.

&&

$$
SYNOPSIS...GMS
NEAR TERM...BJL/GMS
SHORT TERM...GMS
LONG TERM...DFH
AVIATION...BJL/GMS/KRW/DFH
MARINE...BJL/GMS/KRW/DFH
TIDES/COASTAL FLOODING...GMS


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