Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 250756
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
356 AM EDT WED MAR 25 2015

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO DRIFT OFF THE ATLANTIC COAST TODAY.
A COLD FRONT WILL PASS THROUGH THE AREA LATE THURSDAY INTO
FRIDAY. CANADIAN HIGH PRESSURE WILL RETURN FOR FRIDAY INTO THE
WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
A FREEZING RAIN ADVISORY IS IN EFFECT FOR PORTIONS OF THE BLUE
RIDGE MTNS...SHENANDOAH VALLEY AND POTOMAC HIGHLANDS THIS MORNING.

HIGH PRESSURE IS WEDGED ACROSS THE MID-ATLANTIC WHILE CLEAR SKIES
HAVE LED TO TEMPS DROPPING INTO THE 20S ACROSS MUCH OF THE AREA.

WARM AIR ADVECTION ALOFT HAS LED TO OVERRUNNING AND A BAND OF LIGHT
PRECIPITATION EXTENDS FROM S MI TO CENTRAL VA THIS MORNING.
PRECIPITATION HAS BLOSSOMED ACROSS WV OVERNIGHT AND WILL CONTINUE TO
LIFT NORTHEAST INTO THE ALLEGHENY HIGHLANDS THIS MORNING. LIGHT
FREEZING RAIN IS EXPECTED ACROSS PORTIONS OF THE BLUE RIDGE
MTNS...SHENANDOAH VALLEY AND POTOMAC HIGHLANDS. LIGHT FREEZING RAIN
WILL LEAD TO TRACE TO A FEW HUNDREDTHS OF AN INCH OF ACCUMULATION
THIS MORNING. THE HRRR AND WRFARW HAVE BEEN PERSISTENT ALL NIGHT
BRINGING PRECIPITATION INTO THE REGION. QUESTION EXISTS HOW FAR EAST
THE PRECIPITATION WILL TRAVEL BEFORE TEMPS RISE ABOVE FREEZING THIS
MORNING. WILL BE MONITORING SFC TEMPS AND RADAR AND EXTENSION MAY BE
NEEDED FURTHER NORTH AND EAST.

HIGH PRESSURE WILL STAY WEDGED ACROSS THE REGION THROUGH THE
AFTERNOON. SOUTHERLY FLOW WILL ALLOW TEMPS TO RISE INTO THE 40S BUT
AREAS ACROSS THE HIGHLANDS WILL LIKELY REACH THE UPPER 50S TODAY AS
A WARM FRONT MOVES THROUGH. THE WEDGE WILL KEEP EAST OF THE BLUE
RIDGE IN LOW CLOUDS THROUGH THE DAY. LIGHT RAIN IS POSSIBLE ACROSS
THE REGION TODAY AS WARM AIR ADVECTION CONTINUES. HIGH PRESSURE WILL
MOVE OFF THE COAST WEDNESDAY NIGHT AND LIGHT SOUTHERLY FLOW IS
EXPECTED.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
A BULK OF THE DAY THU LOOKS RELATIVELY WARM/DRY...ALBEIT W/ A
LARGE WAA REGION OVERHEAD DURING THAT TIME. VERY LIGHT AND POORLY
ORGANIZED SHOWERS CAN CERTAINLY DEVELOP ANYWHERE IN SUCH A REGION
BUT MUCH OF THE ACTIVITY FOR THU MAY ACTUALLY OCCUR EARLY AND
AGAIN LATE IN THE DAY. TO START THE DAY...ROUNDING THE OUTER
REACHES OF AN OFFSHORE HIGH...SCATTERED SHOWERS WILL SLIDE ACROSS
PORTIONS OF THE AREA FROM SW-TO-NE COINCIDENT W/ A LOW LEVEL JET
MAX. AS THIS FEATURE GETS BUMPED OFF THE COAST...SOME SINKING
AIR...DEPARTING CLOUDS AND WARMING TEMPS SHOULD BE MORE COMMON
HEADING INTO THE LATE MRNG/AFTN HRS.

MEANWHILE...TWO SEPARATE PIECES OF AN INTENSIFYING AND SYSTEM TO
OUR WEST WILL APPROACH FROM THE LOWER OHIO/TENN RVR VLY. THIS
FIRST FEATURE WILL BE A LOW PRES SYSTEM SLIDING OVER THE OHIO VLY
AND EVENTUALLY OFF TO OUR NORTH...STAYING NORTH AND ALLOWING WARM
AIR TO CONTINUE BUILDING INTO THE REGION DURING THE AFTN/EVE. A
DEEPENING UPPER WAVE WELL WEST OF THIS ACTIVITY WILL DIVE DOWN
FROM THE NRN MS VLY AND STRENGTHEN THE PRECIP ACROSS AREAS JUST
AFFECTED BY THE FIRST FEATURE. THIS PIECE OF ENERGY WILL THEN MAKE
ITS WAY ACROSS THE APLCNS LATER THAT EVE...NOT EXPECTED TO MOVE
ACROSS OUR REGION UNTIL FRI. THE POTENTIAL CONVECTIVE ACTIVITY OUT
AHEAD OF THIS DIGGING TROUGH LOOKS TO BE LATE THU NIGHT INTO THE
EARLY MRNG HRS FRI. RESIDUAL INSTABILITY MAY BE MARGINAL AT THAT
POINT...THOUGH LOW LEVEL STEERING FLOW AND NOCTURNAL JET ACTIVITY
MAY MAKE UP FOR IT IN THE WAY OF GUSTY WINDS W/ HEAVIER LOCALIZED
DOWNPOURS. WILL KEEP A PERIOD OF LIKELY POPS IN FOR THE OVERNIGHT
PERIOD...W/ A SLIGHT REDUCTION IN THE DAYTIME POPS FOR THU.

FRI WILL BE ANOTHER USHERING-IN OF CAA W/ DRIER AIR AND
OCCASIONALLY BREEZY NW WINDS. A NOTICEABLE TEMP DROP WILL OCCUR
FROM THU GOING INTO FRI W/ THE COLD FRONT PASSING THRU...AS TEMPS
DROP FROM THE 70S THU AFTN TO THE 40S OVERNIGHT. MAX TEMPS BARELY
REACH THE 50 DEG MARK ON FRI...W/ LOWS FRI NIGHT BACK TOWARD THE
FREEZING MARK. SOME SCATTERED RAIN SHOWERS AND POSSIBLY SOME BRIEF
SNOW MIXING IN W/ THE ISOLATED BATCHES ON FRI W/ THE STRONG
PASSAGE OF THE UPPER VORT OVERHEAD.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AN UPPER-LEVEL TROUGH WILL SWING THROUGH THE AREA FRIDAY NIGHT
INTO SATURDAY BEFORE COLD HIGH PRESSURE BUILDS OVERHEAD SATURDAY
NIGHT INTO SUNDAY. A NORTHWEST FLOW AHEAD OF THE HIGH WILL USHER
IN UNUSUALLY COLD CONDITIONS FOR THIS TIME OF YEAR. THE HIGH WILL
MOVE OFF THE COAST LATER SUNDAY AND MILDER CONDITIONS ARE EXPECTED
IN THE AFTERNOON DUE TO A RETURN FLOW...BUT TEMPS WILL LIKELY
REMAIN BELOW CLIMO.

A COLD FRONT WILL PASS THROUGH THE AREA MONDAY...BRINGING A CHANCE
FOR SHOWERS. MILDER CONDITIONS ARE EXPECTED WITH A SOUTHWEST FLOW
AHEAD OF THE FRONT. HIGH PRESSURE WILL RETURN FOR THE MIDDLE
PORTION OF NEXT WEEK.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
A WARM FRONT WILL APPROACH THE REGION TODAY AND CIGS WILL LOWER
REACHING MVFR/IFR THIS EVENING. A 40KT LLJ MAY PRODUCE LLWS LATE
TONIGHT AND INTO THURSDAY MORNING. MVFR/IFR CIGS ARE EXPECTED TO
CONTINUE TONIGHT BEFORE MIXING OUT THURSDAY MORNING.

BRIEF MVFR CIGS POSSIBLE...SOME IFR LATE WED NIGHT. SOME IMRVMNT
XPCTD THU MRNG INTO THE AFTN...THEN DEGRADING AGAIN LATE IN THE
DAY AND OVRNGT AHD OF A CD FNT. RA XPCTD THU AFTN/OVRNGT W/ ISOLD
TSTMS PSBL. CONDS SHOULD BEGIN IMPRVG AS WINDS TURN TO THE NW FRI.

VFR CONDITIONS ARE EXPECTED THROUGH THE WEEKEND.

&&

.MARINE...
S WINDS EXPECTED ON THE WATERS TODAY. HIGH PRESSURE WILL MOVE OFF
THE COAST THIS AFTERNOON AND EVENING AND RETURN FLOW WILL ALLOW
WINDS TO INCREASE. A SCA IS IN EFFECT FOR THE BAY NORTH OF DRUM
POINT. S WINDS WILL CONTINUE TONIGHT AND GUSTS SHOULD SUBSIDE.

SCA CONDS XPCTD THU AHD OF A CD FNT...W/ ISOLD TSTMS PSBL...THEN
TURNING TO THE NW AFTR MDNGT THU W/ WINDS CONTINUING ABV SCA VALUES
INTO FRI MRNG. HIGH PRESSURE WILL BUILD OVER THE WATERS FOR THE
WEEKEND.

&&

.TIDES/COASTAL FLOODING...
SOUTHERLY WINDS WILL DEVELOP WEDNESDAY AND THE SOUTHERLY FLOW WILL
INCREASE AHEAD OF A COLD FRONT THURSDAY. THE INCREASED SOUTHERLY
FLOW WILL CAUSE WATER LEVELS TO ELEVATE...AND TIDAL ANOMALIES MAY
BE HIGH ENOUGH FOR MINOR FLOODING NEAR TIMES OF HIGH TIDE THURSDAY
INTO THURSDAY NIGHT.

THE COLD FRONT WILL PASS THROUGH LATER THURSDAY EVENING AND A
NORTHWEST FLOW WILL CAUSE WATER LEVELS TO DECREASE LATE THURSDAY
NIGHT INTO FRIDAY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...FREEZING RAIN ADVISORY UNTIL NOON EDT TODAY FOR MDZ501-502.
VA...FREEZING RAIN ADVISORY UNTIL NOON EDT TODAY FOR VAZ026-027-029-
     507-508.
WV...FREEZING RAIN ADVISORY UNTIL NOON EDT TODAY FOR WVZ050-055-
     501>506.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 6 PM EDT THIS EVENING
     FOR ANZ530>533-538>541.
     SMALL CRAFT ADVISORY FROM 10 AM TO 6 PM EDT THURSDAY FOR
     ANZ530>543.

&&

$$
SYNOPSIS...GMS
NEAR TERM...HAS
SHORT TERM...GMS
LONG TERM...GMS/IR
AVIATION...HAS/GMS
MARINE...HAS/GMS


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