Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 182003 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 303 PM EST TUE NOV 18 2014 .SYNOPSIS...
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SURFACE HIGH PRESSURE CENTERED OVER EASTERN TEXAS WILL BUILD SHIFT EAST ACROSS THE DEEP SOUTH THROUGH WEDNESDAY. A WARM FRONT WILL LIFT NORTH OVER THE AREA LATE WEDNESDAY...WITH A DRY COLD FRONT PASSING FROM THE WEST LATE THURSDAY. HIGH PRESSURE WILL CROSS THE AREA FRIDAY NIGHT. THE HIGH WILL MOVE OFF THE COAST SATURDAY AND A WARM FRONT WILL CROSS THE AREA SUNDAY.
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&& .NEAR TERM /THROUGH WEDNESDAY/...
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AS OF 19Z...977MB SFC LOW IS OVER THE QUEBEC/LABRADOR BORDER WITH A 1033MB SFC HIGH OVER THE TX/LA COAST. A VERY AMPLIFIED UPR TROUGH IS IN BETWEEN WITH A 180KT SWLY JET (AT 300MB) UP THE NORTHEASTERLY SEABOARD. THE POLAR COLD FRONT IS OVER THE UPR MIDWEST AND WILL MOVE INTO NEW ENGLAND TONIGHT. MIXING CONTINUES THROUGH THE OVERNIGHT IN THE PRESSURE GRADIENT. NEW WIND CHILL CRITERIA DO NOT GO INTO EFFECT FOR THE WESTERN HALF OF THE CWA (FIVE DEGREES LOWER FOR ADVISORIES AND WARNINGS)...SO THE WIND CHILL ADVISORY REMAINS IN EFFECT THROUGH TONIGHT FOR -5F TO -15F WIND CHILLS IN THE EXTREME SOUTHWESTERN FIVE ZONES. ELSEWHERE...THE STRONG WLY/NWLY WIND GUSTS WILL EASE THROUGH THE EVENING WITH WIND CHILLS REMAINING IN THE TEENS TO 20S AS TEMPERATURES DROP QUICKLY IN THE CLEAR CONDITIONS. MIN TEMPS GENERALLY MID TO UPR TEENS INLAND...SINGLE DIGITS IN ALLEGHENY HIGHLANDS...LOW 20S NEAR SHORE. WEDNESDAY...A SFC HIGH RIDGE WILL SHIFT OFF THE CAROLINA COAST DURING THE DAY WITH AFTERNOON SWLY FLOW. THIS CONTINENTAL AIR IS DRY AND WILL HAVE LITTLE SENSIBLE EFFECT OTHER THAN MID-LEVEL CLOUDS. TEMPS SLOWLY RISE IN THE MORNING DUE TO LACK OF MIXING AND POSSIBLE CLOUDS. MAX TEMPS GENERALLY MID 30S...UPR 20S FOR RIDGES AND AROUND 30 FOR NERN MD WHERE THE SWLY FLOW REACHES LAST.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
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LOW PRESSURE IS EXPECTED TO BE ACROSS THE NRN GREAT LAKES WITH A COLD FRONT MOVING THROUGH THE OHIO VALLEY WEDNESDAY NIGHT. HIGH PRESSURE WILL BE MOVING OFF THE SE COAST DURING THIS TIME. WINDS WILL BE OUT OF THE SOUTH WED EVENING AHEAD OF THE ADVANCING COLD FRONT. CLOUDS WILL INCREASE FROM WEST TO EAST AS THE COLD FRONT NEARS. SNOW SHOWERS ARE POSSIBLE ALONG THE WESTERN SLOPES OF THE ALLEGHENY FRONT LATE WEDNESDAY NIGHT AND THURSDAY. FURTHER EAST...LITTLE MOISTURE WILL LEAD TO A DRY FRONTAL PASSAGE BY THURSDAY AFTERNOON. WINDS WILL BECOME WESTERLY THURSDAY. THIS WILL LEAD TO ANOTHER ROUND OF COLD AIR ADVECTION BY THURSDAY EVENING. MOSTLY SUNNY CONDITIONS EAST OF THE BLUE RIDGE WILL ALLOW TEMPS TO RISE INTO THE MID TO UPPER 40S. HIGH PRESSURE MOVES INTO THE REGION THURSDAY NIGHT. FCST MIN TEMPS WILL BE IN THE 20S.
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&& .LONG TERM /FRIDAY THROUGH TUESDAY/...
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A BUILDING RIDGE OF HIGH PRESSURE EXPECTED FRIDAY AND FRIDAY NIGHT. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH FRIDAY NIGHT. THE HIGH WILL SHIFT TO THE COAST AND THEN OFFSHORE SATURDAY AND SATURDAY NIGHT. WINDS WILL SHIFT TO THE SOUTH AHEAD OF A STORM SYSTEM AND COLD FRONT MOVING ACROSS THE WESTERN OHIO VALLEY. TEMPERATURES WILL MODIFY SATURDAY NIGHT THROUGH MONDAY. DRY CONDITIONS SATURDAY WITH A SLIGHT CHANCE OF SOME WARM-FRONTAL PERIODS OF LIGHT SNOW...MIXING WITH RAIN SHOWERS...SATURDAY NIGHT FROM THE POTOMAC HIGHLANDS TOWARD THE WASHINGTON D.C. AREA. SOME LIGHT RAIN WILL MOVE IN AS TEMPERATURES MODIFY 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.
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&& .AVIATION /20Z TUESDAY THROUGH SUNDAY/...
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VFR THROUGH TAF PERIOD. WLY/NWLY WINDS GUSTING AROUND 25 KT CONTINUE UNTIL SUNSET...SLOWLY EASING THROUGH THE NIGHT AS THE PRESSURE GRADIENT REMAINS STRONG. FLOW EASES WEDNESDAY MORNING...SHIFTING SWLY WEDNESDAY AFTERNOON. CLEAR SKIES OVERNIGHT WITH MID-LEVEL CLOUDS WEDNESDAY. VFR CONDITIONS EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. A COLD FRONT WILL CROSS THE REGION CAUSING S WINDS TO BECOME WEST BY THURSDAY EVENING. LACK OF MOISTURE WILL ONLY ALLOW A MID-HIGH LEVEL CLOUD DECK TO MOVE ACROSS THE TERMINALS. VFR CONDITIONS FRIDAY AND FRIDAY NIGHT. WINDS COULD GUST OVER 20 KNOTS LATE FRIDAY MORNING INTO MIDDAY AS HIGH PRESSURE BUILDS IN FROM THE WEST. WINDS WILL BECOME LIGHT AND VARIABLE LATE FRIDAY AND FRIDAY NIGHT. VFR CONDITIONS SATURDAY INTO SATURDAY NIGHT. WINDS WILL BECOME SOUTHERLY AT 5 TO 10 KNOTS.
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&& .MARINE...
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NWLY/WLY WINDS SLOWLY EASING. GALE WARNING NORTH OF NORTH BEACH EXPECTED TO BE DROPPED AS SCHEDULED AT 4PM WITH SCA FOR ALL WATERS INTO LATE TONIGHT. NRN TIDAL POTOMAC DROPS OFF AT 3AM...WITH ALL HEADLINES DOWN BY 9AM OVER THE WATERS AS PRESSURE GRADIENT SLACKENS. RETURN FLOW WEDNESDAY AFTERNOON...CHANNELING BY THE EVENING. SOUTHERLY FLOW WILL INCREASE AHEAD OF A COLD FRONT WED NIGHT AND A SCA IS IN EFFECT THROUGH WED NIGHT. THE COLD FRONT WILL CROSS THE WATERS BY THURS AFTERNOON AND A WESTERLY PRESSURE SURGE WILL CAUSE WINDS TO INCREASE ACROSS THE WATERS THURSDAY NIGHT. SMALL CRAFT ADVISORIES ARE POSSIBLE FRIDAY. WINDS COULD GUST OVER 20 KNOTS FROM THE WEST TO NORTHWEST DUE TO BUILDING HIGH PRESSURE. SMALL CRAFT ADVISORIES ARE POSSIBLE AGAIN LATER SATURDAY AFTERNOON AS HIGH PRESSURE SHIFTS TO THE EAST COAST AND WINDS BECOME SOUTHERLY.
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&& .CLIMATE...
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RECORD COLD AIR WILL CONTINUE TO BUILD OVER THE AREA INTO WEDNESDAY. TEMPERATURES WILL REMAIN 10 AND 20 DEGREES BELOW NORMAL. IN FACT... TEMPERATURES THROUGH WEDNESDAY WOULD BE SEVERAL DEGREES BELOW NORMAL IN JANUARY. BELOW IS A LIST OF RECORD DAILY MINIMUM AND RECORD DAILY LOW MAXIMUM TEMPERATURES THROUGH THE 19TH (WEDNESDAY). NEW LOW MAX RECORDS ARE EXPECTED AT IAD BOTH DAYS AND POSSIBLE AT BWI WEDNESDAY. NEW MIN RECORDS ARE POSSIBLE AT IAD AND BWI FOR WEDNESDAY. SITE 11/18 LOW MAX 11/19 MIN 11/19 LOW MAX DCA 30 (1924) 18 (1891) 33 (1880) BWI 31 (1959) 20 (1936) 35 (1880) IAD 39 (2008) 20 (1990) 38 (2008)
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...NONE. VA...WIND CHILL ADVISORY UNTIL 7 AM EST WEDNESDAY FOR VAZ503-504. WV...WIND CHILL ADVISORY UNTIL 7 AM EST WEDNESDAY FOR WVZ501-505- 506. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EST WEDNESDAY FOR ANZ530>532- 539-540. SMALL CRAFT ADVISORY FROM 3 PM WEDNESDAY TO 6 AM EST THURSDAY FOR ANZ530>534-537>543. GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ANZ530>532- 538>540. SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ538. SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ536-542. SMALL CRAFT ADVISORY UNTIL 9 AM EST WEDNESDAY FOR ANZ533-534- 537-541-543. SMALL CRAFT ADVISORY UNTIL 3 AM EST WEDNESDAY FOR ANZ535.
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&& $$ SYNOPSIS...BAJ NEAR TERM...BAJ SHORT TERM...HAS LONG TERM...KLW AVIATION...BAJ/HAS/KLW MARINE...BAJ/HAS/KLW CLIMATE...DFH/BAJ

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