Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 191440 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 940 AM EST WED NOV 19 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD OVER THE DEEP SOUTH THROUGH TONIGHT. A DRY COLD FRONT WILL PASS THROUGH THE REGION LATE THURSDAY INTO THURSDAY EVENING. 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. && .NEAR TERM /THROUGH TONIGHT/...
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HIGH PRESSURE IS DIRECTLY OVER THE MID-ATLANTIC THIS MORNING. THE HIGH WILL SLIDE OFF THE EAST COAST TODAY AS AN UPPER TROUGH SWINGS EAST ACROSS THE GREAT LAKES. MID AND HIGH LEVEL CLOUDS ASSOCIATED WITH THIS SYSTEM HAVE MOVED INTO EASTERN OHIO AND PORTIONS OF WV. THESE CLOUDS WILL MOVE ACROSS THE FORECAST AREA FROM WEST TO EAST DURING THE DAY AND WINDS WILL ALSO SHIFT INTO THE SOUTH. EVEN WITH A SOUTHERLY WIND COMPONENT IN PLACE...TEMPERATURES WILL STILL REMAIN WELL BELOW NORMAL DURING THE DAY. HIGHS WILL ONLY REACH THE 30S...WITH 20S OVER THE HIGHER ELEVATIONS. TONIGHT 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 WITH LIGHT ACCUMULATIONS UNDER AN INCH EXPECTED. ADJUSTED POTENTIAL ONSET OF SNOW EARLIER A FEW HRS IN THE MORNING UPDATE BASED ON NEW 12Z NAM AND WRF MODELS. OVERNIGHT LOWS WILL NOT BE AS COLD. READINGS WILL RANGE FROM THE LOWER TO MIDDLE 20S IN THE COLDER LOCALES TO THE UPPER 20S TO NEAR 30 IN THE METRO AREAS.
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&& .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... BREEZY WESTERLY WINDS WILL DEVELOP ON THURSDAY. TEMPERATURES ARE EXPECTED TO MODERATE INTO THE 40S EAST OF THE BLUE RIDGE WITH 30S OVER THE HIGHER TERRAIN. ANOTHER RE-ENFORCING SHOT OF COLD AIR WILL FILTER INTO THE REGION DURING THE DAY...SETTING UP COLDER TEMPERATURES OVERNIGHT. THE DRY COLD FRONT WILL MOVE OFF TO OUR EAST THURSDAY NIGHT WHILE ARCTIC HIGH PRESSURE APPROACHES FROM THE OHIO VALLEY. A WEST TO NORTHWEST FLOW BETWEEN THESE SYSTEMS WILL CONTINUE TO USHER IN UNUSUALLY COLD CONDITIONS FOR THIS TIME OF YEAR. MIN TEMPS WILL RANGE FROM THE SINGLE DIGITS AND LOWER TEENS IN THE ALLEGHENY HIGHLANDS TO THE MID AND UPPER 20S IN DOWNTOWN WASHINGTON AND BALTIMORE. && .LONG TERM /FRIDAY THROUGH TUESDAY/... ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD TOWARD THE REGION FRIDAY AND A NORTHWEST FLOW WILL CONTINUE TO USHER IN VERY COLD CONDITIONS FOR THIS TIME OF YEAR. IN FACT...MAX TEMPS WERE TWEAKED DOWN CLOSER TO THE MAV/MET GUIDANCE WHICH SEEMS TO FIT GIVEN THE TEMPS ALOFT. THE HIGH WILL SETTLE OVERHEAD FRIDAY NIGHT. LEANED COLDER WITH THE FORECAST SINCE THERE WILL BE LIGHT WINDS...DRY AIR AND MAINLY CLEAR SKIES THAT WILL ALLOW FOR RADIATIONAL COOLING. THE HIGH WILL MOVE OFF THE COAST SATURDAY AND A SOUTHERLY FLOW WILL DEVELOP...ALLOWING FOR MILDER CONDITIONS COMPARED TO RECENT DAYS. HOWEVER...IT WILL REMAIN CHILLY FOR THIS TIME OF YEAR. THE NEXT STORM SYSTEM OVER THE GULF COAST STATES SATURDAY NIGHT IS EXPECTED TO MOVE NORTHEAST INTO THE GREAT LAKES SUNDAY AND INTO CANADA MONDAY. WITH THE STORM TRACK TO OUR WEST...THIS WILL ALLOW FOR WARMER AIR TO MOVE INTO THE AREA DURING THIS TIME. IN FACT...THE WARM FRONT FROM THIS SYSTEM IS MOST LIKELY TO MOVE THROUGH SUNDAY INTO EARLY MONDAY. THERE SHOULD BE DEEP OVERRUNNING AHEAD OF THE BOUNDARY AS WARM AND MOIST AIR FROM THE GULF OF MEXICO AND ATLANTIC OCEAN OVERRUN THE SURFACE COOLER AIR IN PLACE. THIS WILL RESULT IN A PERIOD OF RAIN AND ALTHOUGH TIMING IS UNCERTAIN THIS FAR OUT IT DOES APPEAR THAT THE BEST CHANCE FOR RAIN WILL BE SUNDAY AFTERNOON AND EVENING. THE LOW WILL TRACK TOWARD THE HUDSON BAY MONDAY AND THE COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL APPROACH FROM THE WEST. A STRONG SOUTHERLY FLOW AHEAD OF THE BOUNDARY WILL USHER IN MUCH WARMER CONDITIONS COMPARED TO RECENT DAYS. IN FACT...MAX TEMPS WELL INTO THE 60S ARE EXPECTED AND A FEW AREAS MAY EVEN APPROACH THE 70 DEGREE MARK. THE COLD FRONT WILL PASS THROUGH THE AREA MONDAY NIGHT AND A RETURN OF DRIER AND SEASONABLE CONDITIONS ARE EXPECTED TOWARD THE MIDDLE PORTION OF NEXT WEEK. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... VFR CONDITIONS EXPECTED TODAY. AN INCREASE IN MID TO HIGH LEVEL CLOUDS CAN BE EXPECTED A BIT LATER IN THE DAY AS A TROUGH OF LOW PRESSURE CROSSES THE GREAT LAKES. WINDS WILL ALSO SHIFT INTO THE SOUTH AT AROUND 10KTS DURING THE DAY. VFR CONDITIONS WILL PERSIST WEDNESDAY NIGHT AND THURSDAY WITH BREEZY CONDITIONS DEVELOPING WITH THE NEXT FRONT. VFR CONDITIONS ARE EXPECTED THURSDAY NIGHT THROUGH SATURDAY NIGHT. RAIN AND SUBVFR CONDITIONS WILL DEVELOP LATER SUNDAY THROUGH SUNDAY NIGHT. && .MARINE...
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STILL MARGINAL SCA GUSTS ON PORTIONS OF CHESAPEAKE BAY AND LOWER TIDAL POTOMAC...SO EXTENDED THE MORNING ADVISORY UNTIL 16Z FOR ALL OF THE BAY EXCEPT FOR THE NORTHERNMOST ZONE. ALL ZONES WILL BE WITHOUT AN ADVISORY FROM 11 AM UNTIL 3 PM. THEN ANOTHER SCA GOES INTO 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. A DRY COLD FRONT WILL MOVE OFF TO THE EAST THURSDAY NIGHT. A NORTHWEST FLOW IS EXPECTED BEHIND THIS SYSTEM THROUGH FRIDAY AND INTO FRIDAY NIGHT. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FOR PORTIONS OF THE WATERS DURING THIS TIME. THE HIGH WILL BUILD OVERHEAD LATER FRIDAY NIGHT BEFORE MOVING OFF THE COAST SATURDAY. A SOUTHERLY FLOW WILL INCREASE SUNDAY AND MONDAY AHEAD OF A COLD FRONT. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FOR PORTIONS OF THE WATERS DURING THIS TIME.
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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 IS 19 DEGREES ** AT IAD NEW RECORD LOW SET EARLY THIS MORNING IS 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 11 AM EST THIS MORNING FOR ANZ531>534-537>543. SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 6 PM EST THURSDAY FOR ANZ530>534-537>543. SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EST THURSDAY FOR ANZ535- 536.
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&& $$ SYNOPSIS...BJL NEAR TERM...KS/KRW SHORT TERM...BJL/KRW LONG TERM...BJL AVIATION...BJL/KRW MARINE...BJL/KS/KRW CLIMATE...

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