Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 200153 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 853 PM EST WED NOV 19 2014 .SYNOPSIS...
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A 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 /UNTIL 6 AM THURSDAY MORNING/...
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MID-LEVEL SHORTWAVE APPROACHES THE MID-ATLANTIC FROM THE WEST TONIGHT. AT 01Z...THERE WAS AN ASSOCIATED COLD FRONT AT THE SURFACE LOCATED OVER THE EASTERN OHIO VALLEY. SHORTWAVE WILL BRING SOME CLOUDS INTO THE CWA...BUT IS RATHER MOISTURE STARVED /LOW LEVELS ARE STILL VERY DRY TOO/ AND THEREFORE ONLY EXPECT SNOW SHOWERS OVER THE POTOMAC HIGHLANDS WHERE OROGRAPHIC LIFT WILL PLAY A ROLE...PARTICULARLY OVER THE WESTERN SLOPES AFTER WINDS SHIFT TO THE WEST BEHIND THE COLD FRONT. FOR TEMPERATURES...CLOUDS WILL BE A FACTOR HOW LOW WE GO. OVERALL TREND IS FOR IT TO NOT BE AS COLD AS LAST NIGHT WITH SOME CLOUDS/WARM ADVECTION/SOUTHERLY WINDS. RE-POPULATED USING A BLEND OF LATEST BC ADJMET AND BC SREFS.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... 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. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... 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. && .AVIATION /01Z THURSDAY THROUGH MONDAY/...
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VFR CONDITIONS CONTINUE OVERNIGHT AND THROUGH THURSDAY AFTERNOON. WINDS WILL SHIFT TO THE SW OVERNIGHT AND TO THE W THURSDAY BEHIND A COLD FRONT. GUSTS 15 TO 20 KT 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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SOUTHERLY WINDS WERE EFFICIENTLY CHANNELLING UP THE BAY THIS EVENING...WITH TPLM2 LAST HOUR 25G29KT. DON/T EXPECT WINDS TO GO OVER 30 KT...BUT HIGH END SCA IS EXPECTED THROUGH THE NIGHT UP THE BAY AND ALSO ACROSS THE EXTREME LOWER TIDAL POTOMAC RIVER. COLD FRONT MOVES THROUGH THURSDAY...WITH WINDS SWITCHING TO THE WEST AND LIKELY GUSTING AOA 20 KT ALL WATERS BY AFTERNOON. 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 COLD IS JUST ABOUT TO RELEASE ITS HOLD ON THE AREA...ONLY TO GIVE WAY TO ANOTHER SHOT OF COLD AIR BEHIND A COLD FRONT TOMORROW. THIS SECOND WAVE OF COLD AIR WILL NOT BE AS SEVERE...BUT WILL KEEP TEMPERATURES BELOW NORMAL THROUGH THE FIRST HALF OF THE WEEKEND. IN FACT...HIGH TEMPERATURES ARE FORECAST TO REMAIN BELOW 50 DEGREES AT IAD AND BWI THROUGH SATURDAY. IF THIS HAPPENS...BOTH SITES WILL HAVE THE LONGEST STRETCH OF DAYS BELOW 50 DEGREES IN NOVEMBER ON RECORD.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... 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. && $$ SYNOPSIS...KS NEAR TERM...BPP SHORT TERM...KS LONG TERM...HAS/KLW AVIATION...BPP/HAS/KS/KLW MARINE...BPP/HAS/KS/KLW CLIMATE...DFH

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