Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 191917 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 217 PM EST WED NOV 19 2014 .SYNOPSIS...
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HIGH PRESSURE OVER THE SOUTHEASTERN US WILL MOVE OFFSHORE TONIGHT. A DRY COLD FRONT WILL PASS THROUGH THE REGION THURSDAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS FRONT FRIDAY THROUGH FRIDAY NIGHT BEFORE MOVING OFF THE COAST SATURDAY. A WARM FRONT WILL CROSS THE AREA SUNDAY INTO MONDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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HIGH PRESSURE HAS MOVED INTO EASTERN NC THIS AFTERNOON...WITH A LIGHT S-SW TURN FLOW ACROSS THE MID-ATLANTIC. MID-HIGH LEVEL CLOUDS ARE STREAMING ACROSS THE AREA WELL AHEAD OF AN UPPER TROUGH OVER THE OHIO VALLEY. AFTER A VERY COLD MORNING...TEMPERATURES HAVE MODERATED INTO THE LOW TO MID 30S. WARMING FOR THE REST OF THE AFTERNOON WILL BE LIMITED BY CLOUD COVER OVER ALONG AND EAST OF THE BLUE RIDGE. TONIGHT...LOW PRESSURE WILL SLIDE ACROSS THE UPPER GREAT LAKES AND INTO ONTARIO/QUEBEC. TRAILING COLD FRONT WILL REACH THE WESTERN PORTION OF THE CWA BY EARLY MORNING. VERY LITTLE MOISTURE ASSOCIATED WITH THE FRONT...BUT OROGRAPHIC LIFT MAY AID IN SOME LIGHT SNOW OVER THE POTOMAC HIGHLANDS. ACCUMULATION WILL BE MINOR...LIKELY LESS THAN AN INCH. WINDS WILL SHIFT BACK TO THE WEST AS A WEAK FRONT PUSHES EAST ACROSS THE REGION. UPSLOPE COMPONENT TO THE FLOW WILL AID IN THE DEVELOPMENT OF SOME SNOW SHOWER ACTIVITY OVER THE POTOMAC HIGHLANDS. LIGHT ACCUMULATION OF LESS THAN AN IS INCH EXPECTED. OVERNIGHT LOWS WILL NOT BE AS COLD AS LAST NIGHT DUE TO RETURN FLOW AND CLOUD COVER. MOST AREAS WILL BE IN THE MID 20S...WITH UPPER 20S TO AROUND 30 IN THE METRO AREAS AND NEAR CHESAPEAKE BAY.
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&& .SHORT TERM /THURSDAY/...
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THE COLD FRONT WILL MOVE ACROSS THE AREA THURSDAY. SOME ADDITIONAL UPSLOPE SNOW IS POSSIBLE OVER THE POTOMAC HIGHLANDS...BUT ALL OTHER AREAS ARE EXPECTED TO REMAIN DRY. WINDS WILL SHIFT TO THE WEST AFTER THE FRONTAL PASSAGE...WITH POTENTIAL FOR SOME GUSTS OF 15-20 KTS. DOWNSLOPING WILL CONTRIBUTE TO WARMER HIGH TEMPS IN THE AFTERNOON....WITH HIGHS IN THE LOW TO MID 40S. IT WILL BE COOLER IN THE POTOMAC HIGHLANDS..WITH HIGHS IN THE UPPER 20S AND 30S.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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AN UPPER LEVEL TROUGH WILL BE MOVING ACROSS NEW ENGLAND THURSDAY NIGHT WHILE SFC LOW PRESSURE HEADS TOWARDS NOVA SCOTIA. THE MID-ATLANTIC WILL BE POST-FRONTAL AND WESTERLY WINDS WILL LEAD TO COLD AIR ADVECTION THURSDAY NIGHT AND INTO FRIDAY. FCST MIN TEMPS WILL RANGE FROM THE TEENS ACROSS THE HIGHLANDS TO THE MID TO UPPER 20S ACROSS THE I-95 CORRIDOR. W-NW WINDS AGAINST THE ALLEGHENY FRONT SHOULD PRODUCE SNOW SHOWERS ACROSS THE WESTERN SLOPES THURSDAY NIGHT. SNOW SHOWERS AND UPSLOPE CONDITIONS WILL DIMINISH BY FRIDAY AS SUBSIDENCE SETS IN. LITTLE TO NO ACCUMULATION IS EXPECTED. HIGH PRESSURE WILL MOVE INTO THE REGION FRIDAY. NW WINDS WILL CONTINUE FRIDAY WITH FCST MAX TEMPS STAYING BELOW NORMAL...UPPER 20S/LOW 30S ACROSS THE HIGHLANDS TO THE MID TO UPPER 30S ACROSS THE PIEDMONT AND SOUTHERN MARYLAND. HIGH PRESSURE WILL MOVE OVERHEAD FRIDAY NIGHT LEADING TO ANOTHER CHILLY NIGHT...FCST MIN TEMPS WILL RANGE FROM THE TEENS IN THE MTNS OUT WEST AND THE LOW TO MID 20S ELSEWHERE. HIGH PRESSURE WILL MOVE OFFSHORE SATURDAY AND SATURDAY NIGHT. WINDS WILL BECOME SOUTHERLY AHEAD OF A STORM SYSTEM AND COLD FRONT WHICH WILL PIVOT NORTHEASTWARD FROM THE CENTRAL OHIO VALLEY TO THE GREAT LAKES DURING THE DAY SUNDAY. THERE IS A SLIGHT CHANCE OF A FEW RAIN OR SNOW SHOWERS ALONG THE MASON DIXON LINE LATE SATURDAY NIGHT AND EARLY SUNDAY AS UPPER LEVEL ENERGY SLIDES ACROSS THE LOWER GREAT LAKES REGION. TEMPERATURES WILL MODIFY SATURDAY NIGHT THROUGH MONDAY. SOME LIGHT RAIN WILL MOVE INTO THE REGION SUNDAY AND QUICKLY OVERSPREADING THE ENTIRE REGION LATER SUNDAY AND SUNDAY NIGHT. THERE IS A CHANCE OF A FEW LINGERING RAIN SHOWERS MONDAY INTO MONDAY NIGHT BUT THE HIGHER PROBABILITIES OF RAIN WOULD BE SUNDAY AND SUNDAY NIGHT. A TRAILING COLD FRONT WILL GRADUALLY MOVE EAST MONDAY NIGHT INTO TUESDAY. ALTHOUGH MOST RAIN ACTIVITY SHOULD BE OFFSHORE TUESDAY...WE CAN`T RULE OUT A FEW LINGER RAIN SHOWERS ALONG AND ON THE COLD SIDE OF THE TRAILING FRONT. AN AREA OF LOW PRESSURE COULD DEVELOP ALONG THE FRONT NEAR THE CAROLINAS AND TREK NORTHEAST ACROSS THE OPEN ATLANTIC. THERE IS A SLIGHT CHANCE OF RAIN SHOWERS NEAR THE CHESAPEAKE BAY AREA. HIGH PRESSURE WILL NOSE ITS WAY INTO THE REGION FROM THE WEST WEDNESDAY. TEMPERATURES WILL BE ABOUT 10 DEGREES COOLER THAN TUESDAY ONCE THE COASTAL LOW PULLS AWAY AND CHILLY HIGH PRESSURE SETTLES INTO THE REGION.
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&& .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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VFR CONDITIONS THIS AFTERNOON WITH MID-HIGH CLOUDS. AN INCREASE IN MID TO HIGH LEVEL CLOUDS CAN BE EXPECTED A BIT LATER IN THE DAY AS A SOUTHERLY WINDS 5-10KTS. A FEW GUSTS TO 15KTS POSSIBLE...BUT SHOULD BE INFREQUENT. VFR CONDITIONS CONTINUE OVERNIGHT AND THROUGH THURSDAY AFTERNOON. WINDS WILL SHIFT TO THE SW OVERNIGHT AND TO THE WSW THURSDAY. GUSTS UP TO 15KT LIKELY LATE THURSDAY MORNING AND AFTERNOON. VFR CONDITIONS EXPECTED THURSDAY NIGHT THROUGH FRIDAY NIGHT. W-NW WINDS EXPECTED DURING THIS TIME. VFR CONDITIONS SATURDAY INTO SATURDAY NIGHT. WINDS WILL BECOME SOUTHERLY AT 5 TO 10 KNOTS. VFR CONDITIONS SUNDAY MORNING COULD QUICKLY BECOME IFR OR EVEN LIFR AS LIGHT TO OCCASIONALLY MODERATE RAIN OVERSPREADS THE REGION FROM THE SOUTHWEST. WINDS WILL START SOUTHERLY BUT BECOME MORE EASTERLY AT 10 TO 20 KNOTS GUSTING 25 TO 30 KNOTS.
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&& .MARINE...
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SCA IN EFFECT FOR ALL ZONES IN THE BAY AND THE LOWER TIDAL POTOMAC THROUGH TONIGHT...EXPANDING TO ALL WATERS THURSDAY MORNING AS ANOTHER COLD FRONT APPROACHES. THE WATERS WILL BE POST-FRONTAL THURSDAY NIGHT AND GUSTY W-NW WINDS ARE EXPECTED ACROSS THE LOWER TIDAL POTOMAC AND MARYLAND CHESAPEAKE BAY SOUTH OF POOLES ISLAND. AS HIGH PRESSURE MOVES INTO THE REGION FRIDAY...WINDS WILL STILL BE GUSTY AS A TIGHT PRESSURE GRADIENT WILL BE OVER THE WATERS. THE SCA WILL LIKELY NEED TO BE EXTENDED INTO FRIDAY. SMALL CRAFT ADVISORIES ARE POSSIBLE SATURDAY NIGHT THROUGH SUNDAY. WINDS WILL BE MAINLY SOUTHWEST 15 KNOTS GUSTS TO 25 KNOTS SATURDAY NIGHT. WINDS WILL BECOME SOUTH TO SOUTHEASTERLY 15 TO 20 KNOTS GUSTS TO 30 KNOTS SUNDAY.
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&& .CLIMATE...
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RECORD LOWS WERE RECORDED THIS MORNING AT BWI AND IAD. BWI DROPPED TO 19...BREAKING THE OLD RECORD BY 1 DEGREE...WHILE IAD DROPPED TO 13...BREAKING THE OLD RECORD BY 7 DEGREES. BELOW IS A LIST OF THE RECORD LOW TEMPERATURES AND RECORD LOW MAXIMUM TEMPERATURES FOR TODAY...NOVEMBER 19TH. SITE 11/19 RECORD LOW 11/19 LOW MAX DCA 18 (1891) 33 (1880) BWI* 20 (1936) 35 (1880) IAD** 20 (1990) 38 (2008) * AT BWI NEW RECORD LOW SET EARLY THIS MORNING WAS 19 DEGREES. ** AT IAD NEW RECORD LOW SET EARLY THIS MORNING WAS 13 DEGREES.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ531>534- 537>543. SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ530. SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EST THURSDAY FOR ANZ535- 536.
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&& $$ SYNOPSIS...KCS NEAR TERM...KCS SHORT TERM...KCS LONG TERM...HAS/KRW AVIATION...HAS/KCS/KLW MARINE...HAS/KCS/KLW CLIMATE...KCS

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