Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 020131
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
931 PM EDT WED APR 1 2015

.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFF THE COAST TONIGHT AND THURSDAY. A
WARM FRONT WILL SETUP OVER THE NORTHERN MID-ATLANTIC THURSDAY
NIGHT AND FRIDAY. A COLD FRONT WILL MOVE THROUGH THE REGION FRIDAY
NIGHT AND SATURDAY. HIGH PRESSURE WILL RETURN FOR SUNDAY AND
REMAIN PLACE INTO THE FIRST PART OF NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
HIGH PRESSURE WILL BEGIN TO MOVE OFF THE COAST TONIGHT...BUT IT
WILL REMAIN CLOSE ENOUGH TO BRING DRY CONDITIONS ALONG WITH MAINLY
CLEAR SKIES. DID TWEAK MIN TEMPS DOWN A FEW DEGREES IN THE
SHELTERED VALLEYS AND RURAL AREAS DUE TO A GOOD SETUP FOR
RADIATIONAL COOLING. MIN TEMPS WILL RANGE FROM THE MIDDLE 30S IN
SHELTERED VALLEYS AND RURAL AREAS TO THE MIDDLE 40S IN DOWNTOWN
WASHINGTON AND BALTIMORE.

HIGH PRESSURE WILL BE OFF THE MIDDLE ATLANTIC COAST ON THURSDAY AS
LOW PRESSURE AND AN ASSOCIATED COLD FRONT TRACKS TOWARD THE MID
WEST. THE PRESSURE GRADIENT BETWEEN THE TWO SYSTEMS WILL INCREASE
OVER THE FORECAST AREA DURING THE DAY. SOUTHERLY WINDS WILL BE ON
THE BREEZY SIDE AND TEMPERATURES WILL RISE INTO THE 60S AND 70S
AREA WIDE. STRONGER WINDS ARE EXPECTED ALONG THE RIDGE TOPS OF THE
BLUE RIDGE MOUNTAINS AND POTOMAC HIGHLANDS. A WIND ADVISORY MAY BE
NEEDED FOR THESE AREAS. PORTIONS OF CENTRAL VA AND SOUTHERN MD
COULD SEE AN ENHANCED FIRE THREAT DURING THE AFTERNOON DUE TO
BREEZY AND DRY CONDITIONS. PLEASE REFER TO THE FIRE WEATHER
DISCUSSION BELOW.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
SFC HIGH PUSHES OFFSHORE BY THURSDAY NIGHT AS LOW PRESSURE PUSHES
INTO SOUTHEASTERN CANADA...WITH THE ASSOCIATED COLD FRONT
EXTENDING BACK ACROSS THE WESTERN GREAT LAKES. WARM AIR AND
MOISTURE ADVECTION IS EXPECTED AS SOUTHERLY FLOW INCREASES ON THE
BACKSIDE OF THE HIGH. LIGHT PCPN WILL BE PSBL THRU THURS
NIGHT...MAINLY TO THE NORTH AND WEST AS A WEAK SHORTWAVE PASSES
THROUGH THE REGION. BETTER CHC FOR PCPN WILL COME DURING THE DAY
FRIDAY WITH THE COLD FRONT POSITIONED ACROSS CENTRAL PA AND TO THE
WEST INTO THE OHIO RIVER VALLEY AS THE LLJ ALIGNS SOUTHWEST TO
NORTHEAST ACROSS THE CWA. WAA PUSHES 850MB TEMPS TO AROUND 10
DEGREES CELSIUS...RESULTING IN HIGHS IN THE LOWER TO MID 70S FOR
MOST OF THE AREA. THIS COMBINING WITH DEW PTS NEARING 60 SHOULD
RESULT IN SOME INSTABILITY...AS INDICATIVE ON BUFKIT SOUNDINGS
WITH BOTH THE GFS AND NAM INDICATING CAPE VALUES AROUND 500
J/KG...AND SHEAR VALUES AROUND 40 KTS. AS SUCH...WILL CONTINUE TO
MENTION THE CHC FOR TSTM DURING THE DAY FRIDAY. RIGHT NOW THE BEST
CHC FOR ANY SVR WX LOOKS TO REMAIN TO THE SOUTH AND WEST...BUT
WITH 850MB WINDS BETWEEN 40-60 KTS...IT IS NOT OUT OF THE QUESTION
THAT ANY HEAVIER SHOWERS/TSTMS COULD BRING DOWN STRONGER WINDS.

THE COLD FRONT REMAINS WEST OF THE AREA DURING THE DAY FRIDAY...WITH
A SECOND LOW THEN LIFTING NORTH...EVENTUALLY DRAGGING THE FRONT
THROUGH FRIDAY NIGHT. EXPECTING THE TIMING OF THE FRONTAL PASSAGE TO
BE THE SECOND HALF OF THE NIGHT...SO WILL MAINTAIN POPS IN FOR THE
NIGHT...THOUGH WITH A DECREASING THUNDER THREAT. AS THE FRONT CLEARS
THE AREA SATURDAY MORNING...HIGH PRESSURE BUILDS IN...BRINGING ABOUT
DRY WX. CLOUDY CONDITIONS THOUGH STILL PSBL DURING THE DAY SAT AS
THE UPPER LVL TROUGH PIVOTS THROUGH.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SHORT WAVE OVER THE NORTHERN PLAINS WILL MOVE EAST PASSING NORTH
OF THE REGION LATE SUNDAY AND MONDAY MORNING. SHORT WAVE OFF THE
NORTHERN CALIFORNIA COAST SATURDAY WILL TAKE THE SOUTHERN TRACK
INTO WEST TEXAS BY WEDNESDAY. MEANWHILE AREAS OF WEAK PVA IN ZONAL
FLOW WILL AFFECT THE MID ATLANTIC REGION.

SURFACE HIGH PRESSURE BUILDING OVER THE REGION SATURDAY NIGHT WILL
MOVE OFFSHORE SUNDAY NIGHT. COLD FRONT ATTACHED TO LOW PRESSURE
SYSTEM ASSOCIATED WITH SHORT WAVE ON NORTHERN TRACK WILL PUSH INTO
CENTRAL VIRGINIA BEFORE STALLING TUESDAY. DYNAMICS SUPPORT INCREASED
CHANCES FOR RAIN.

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
VFR CONDITIONS WILL PERSIST THROUGH THURSDAY AT ALL TERMINAL
SITES. SOUTHERLY WINDS WILL BECOME BREEZY DURING THURSDAY. WIND
SPEEDS IN THE 15-20 KTS RANGE WITH GUSTS AROUND 25 KTS ARE
EXPECTED AT ALL TAF SITES.

VFR CONDITIONS INITIALLY THURS NIGHT...WITH PSBL MVFR CIGS MOVING
IN AFTER 06Z. MVFR OR LOWER CONDITIONS LIKELY FRIDAY-FRIDAY NIGHT
WITH SHOWERS AND ISO TSTMS. GUSTY WINDS PSBL WITH SOME OF THE
HEAVIER SHOWERS AND TSTMS. CONDITIONS IMPROVE LATE FRI
NIGHT...WITH VFR CONDITIONS RETURNING FOR SAT INTO MON.

&&

.MARINE...
SURFACE HIGH PRESSURE WILL BUILD OVER THE WATERS TONIGHT. WINDS
WILL BE LIGHT OVERNIGHT BUT WILL INCREASE ON THURSDAY OUT OF THE
SOUTH. SOUTHERLY CHANNELING WILL LEAD TO SCA CONDITIONS ON ALL THE
WATERS DURING THE DAY.

SCA CONDITIONS LIKELY THURSDAY NIGHT THROUGH FRIDAY
EVENING. BRIEF PERIOD OF SUB-SCA CONDITIONS FRI NIGHT WITH THE
PASSAGE OF THE FRONT...THEN SCA CONDITIONS LIKELY AGAIN SATURDAY AS
NW WINDS INCREASE. SHOWERS AND ISO TSTMS WILL BE PSBL FRI-FRI
NIGHT...WITH THE BEST CHC FOR TSTMS LATE FRI AFTN/EVENING. SCA
CONDITIONS POSSIBLE ON SATURDAY.

&&

.FIRE WEATHER...
SOUTHERLY FLOW WILL INCREASE ACROSS THE FORECAST AREA ON THURSDAY.
TEMPERATURES WILL ALSO MODERATE INTO THE 60S AND 70S AREA WIDE.
SUSTAINED WIND SPEEDS AND HUMIDITIES LOOK TO BE MARGINAL THURSDAY
AFTERNOON. AT THIS TIME IT APPEARS THAT THE THREAT FOR CRITICAL
FIRE WEATHER IS LOW. WILL NOT ISSUE A WATCH AT THIS TIME. MORE
LIKELY TO SEE A SPECIAL WEATHER STATEMENT ISSUED ON LATER SHIFTS
WITH THE FOCUS AREA OVER PORTIONS OF THE VIRGINIA PIEDMONT...CENTRAL
VA AND SOUTHERN MD.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM TO 6 PM EDT THURSDAY FOR
     ANZ530>543.

&&

$$
SYNOPSIS...KRW
NEAR TERM...BJL/KRW
SHORT TERM...BJL/SEARS
LONG TERM...CEM
AVIATION...BJL/CEM/SEARS/KRW
MARINE...BJL/CEM/SEARS/KRW
FIRE WEATHER...KRW


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