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/...
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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.
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&& .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/...
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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.
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&& .MARINE...
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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.
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&& .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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