Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 220056
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
856 PM EDT TUE OCT 21 2014

.SYNOPSIS...
AN UPPER LEVEL LOW WILL MOVE ACROSS THE MID-ATLANTIC TONIGHT. LOW
PRESSURE WILL PERSIST ALONG THE COAST THROUGH THURSDAY. HIGH
PRESSURE WILL RETURN FOR THE END OF THE WORKWEEK AND INTO THE
WEEKEND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
LOW PRESSURE IS LOCATED ALONG THE MID-ATLANTIC COAST THIS EVENING.
NORTHWEST WINDS HAVE MOVED INTO THE REGION AS PRESSURE CONTINUES
TO RISE BEHIND THE LOW. AN UPPER LEVEL LOW WILL MOVE OVER THE MID-
ATLANTIC TONIGHT. THE DYNAMICS WITH THIS FEATURE...COOLER AIR
ALOFT AND VORTICITY ADVECTION HAS MADE FOR AN ACTIVE AFTERNOON AND
EVENING TODAY. SHOWERS AND SCATTERED THUNDERSTORMS MOVED WEST TO EAST
ACROSS THE REGION TODAY. ACTIVITY WAS CAPABLE OF HEAVY RAIN AND
SMALL HAIL. OUTFLOW BOUNDARIES LED TO INCREASED COVERAGE OF
SHOWERS AS WELL. AS OF 00Z...THE PRESSURE SURGE WAS AT THE WATERS AND
GUSTS UP TO 25KTS HAVE BEEN OBSERVED. WINDS BEHIND THE SURGE ARE EXPECTED
TO LESSEN TONIGHT BUT THE PRESSURE GRADIENT WILL CONTINUE AS THE
SFC LOW MOVES TO THE EAST. NW WINDS AROUND 10-15 MPH ARE EXPECTED
TONIGHT. WINDS WILL CONTINUE TONIGHT AND LIMIT THE FORMATION OF
FOG DEVELOPMENT.

SHOWERS WILL CONTINUE TO MOVE EASTWARD TONIGHT. AS THE UPPER LOW
SPINS OVER THE REGION...MORE SHOWERS WILL ENTER THE REGION BUT THE
COVERAGE WILL BE LESS THAN EARLIER. ADDITIONAL RAINFALL AMTS OF A
QUARTER INCH OR LESS ARE EXPECTED TONIGHT. SHOWERS ARE EXPECTED
ACROSS THE UPSLOPE REGION AS AN UPSLOPE COMPONENT WILL LEAD TO
CONSTANT LIFT.

LOWS TONIGHT RANGE FROM THE LOW 40S IN THE HIGHLANDS TO THE LOW
50S ALONG AND EAST OF I-95.

&&

.SHORT TERM /WEDNESDAY NIGHT/...
SURFACE LOW PRESSURE MOVES OFFSHORE AND BEGINS TO STRENGTHEN AS IT
REACHES THE GULF STREAM. WINDS STRENGTHEN TO AROUND 15-20 MPH WITH
HIGHER GUSTS AS THE PRESSURE GRADIENT BETWEEN THE STRENGTHENING
LOW AND HIGH PRESSURE OVER THE OHIO VALLEY. WRAPAROUND RAINFALL
LIKELY AT TIMES OVER EASTERN MD AND PORTIONS OF VA. UPSLOPE RAIN
WILL DEVELOP OVER THE POTOMAC HIGHLANDS AND CONTINUE WEDNESDAY
NIGHT. LOOKS LIKE OVERNIGHT TEMPS WILL FAVOR LIQUID RAIN OVER MOST
OF THE HIGHLANDS...BUT THE HIGHEST ELEVATIONS IN GRANT...PENDLETON
AND HIGHLAND MAY SEE SNOW MIXED IN. LOW TEMPS IN THE 40S ACROSS
MOST OF THE FORECAST AREA.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
BLUSTERY CONDITIONS WILL CONTINUE INTO THE DAY THURSDAY AS SURFACE
LOW PRESSURE  SLOWLY SLIDES UP THE NEW ENGLAND COAST. DOWNSLOPING OF
NORTHEASTERLY WINDS WILL ELIMINATE POPS LOCALLY DURING THE DAY
THURSDAY EVERYWHERE EXCEPT THE POTOMAC HIGHLANDS...WHERE UPSLOPE
RAIN IS POSSIBLE...AND THE FAR NORTHEASTERN PORTION OF THE CWA ALONG
THE CHESAPEAKE BAY.

HIGH PRESSURE WILL BEGIN TO FILL IN THURSDAY NIGHT AND WINDS WILL BE
WEAKER FRIDAY. THE REST OF THE LONG TERM PERIOD WILL SEE QUIET/DRY
WEATHER AS BROAD SURFACE HIGH PRESSURE MOVES OVERHEAD AND UPPER
LEVEL RIDGING KEEPS PLENTY OF SUNSHINE ACROSS THE AREA. EXPECT TEMPS
THIS WEEKEND TO BE RIGHT AROUND NORMAL...WITH HIGHS MOSTLY IN THE
MID-60S...AND TEMPS EARLY NEXT WEEK TO BE JUST A FEW DEGREES ABOVE
NORMAL.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
LOW PRESSURE WILL MOVE EAST OF THE TERMINALS TONIGHT AND NW WINDS
5-10KTS ARE EXPECTED. DCA/MTN WILL LIKELY SEE GUSTS UP TO 20KTS
OVERNIGHT. SHRA WILL MOVE EASTWARD TONIGHT IMPACTING DCA/BWI/MTN.
SOME SHOWERS ARE HEAVY RESULTING IN REDUCED VSBYS. THEY WILL
LIKELY STAY ABOVE IFR CONDITIONS. AS THE RAIN MOVES AWY FROM THE
TERMINALS...MVFR CIGS WILL MOVE IN. THE WIND FIELD ALOFT WILL
INCREASE OVERNIGHT AND ONLY ISOLATED IFR CONDITIONS ARE EXPECTED.

NW WINDS 10-15KTS WITH GUSTS AROUND 20KTS ARE EXPECTED EARLY WED
MORNING. THIS TREND WILL CONTINUE INTO WEDNESDAY. GUSTY NW WINDS
WITH GUSTS UP TO 30KTS POSSIBLE ESPECIALLY AT IAD/DCA/BWI/MTN BY
WED AFTERNOON.

THU...VFR. NW WINDS GUSTING TO 20-25KT.

FRI...VFR. NW WINDS AROUND 1OKT.

CONFIDENCE IS LOW IN THE OCCURRENCE OF AVIATION HAZARDS OVER THE
WEEKEND AS HIGH PRESSURE BUILDS IN.


CLDY WED NGT BUT CIGS XPCTD TO BE VFR. BRZY NW WINDS XPCTD WED NGT
AND THU. VFR/NO PROBS FRI AND SAT.

&&

.MARINE...
PRESSURE SURGE MOVED ACROSS THE WATERS THIS EVENING AND GUSTY NW
WINDS WILL CONTINUE THIS EVENING. A TIGHT PRESSURE GRADIENT WILL
MOVE ACROSS THE WATERS TONIGHT. A SCA IS NOW IN EFFECT FOR THE
WATERS.

PREVIOUS DISCUSSION...
POTENTIAL CONTINUES FOR GALES WEDNESDAY NIGHT AS LOW PRESSURE
STRENGTHENS OFF THE NJ/DELMARVA SHORE. MODEL FORECASTS ARE
MARGINAL FOR GALES...SO FOR NOW OPTED TO EXTEND SCA THROUGH
WEDNESDAY NIGHT WITH GUSTS LIKELY TO REACH 30KT IN SOME PARTS OF
CHES BAY AT LEAST.

A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED THURSDAY THROUGH FRIDAY
AND POSSIBLY INTO FRIDAY NIGHT IN GUSTY NORTHEASTERLY WINDS AS LOW
PRESSURE MOVES UP THE NORTHEAST COAST. WINDS MAY APPROACH GALE FORCE
THURSDAY AFTERNOON OVER THE WATERS...THOUGH CURRENTLY THINK THEY
WILL STAY MOSTLY IN THE MID TO UPPER 20 KNOT RANGE.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ530>534-
     538>543.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ535>537.

&&

$$
SYNOPSIS...KS
NEAR TERM...HAS/KS
SHORT TERM...KS
LONG TERM...CEB
AVIATION...HAS/KS/CEB
MARINE...HAS/KS/CEB







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