Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 261741 AAB AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1241 PM EST MON JAN 26 2015 .SYNOPSIS... LOW PRESSURE WILL PASS BY TO THE SOUTH TODAY. THE LOW WILL RAPIDLY INTENSIFY AS IT MOVES OFF TO OUR NORTH AND EAST TONIGHT THROUGH TUESDAY. HIGH PRESSURE WILL BUILD OVERHEAD WEDNESDAY BEFORE ANOTHER CLIPPER SYSTEM SWINGS THROUGH THURSDAY INTO THURSDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... UPDATE FOR CANCELLATION OF THE WINTER STORM WARNING FOR THE NRN SHEN VLY AND POTOMAC HIGHLANDS...REMAINS IN EFFECT FOR THE ALLEGHANY HIGHLANDS. ALSO...MODIFIED THE EXPIRATION TIME FOR THE WRN HALF OF THE CWA TO END AT 7AM TUE MRNG...STILL 10AM FOR THE ERN HALF INCLUDING THE DC/BALT METRO AREAS. FROM PREV DISC... PLENTY OF DYNAMIC FORCES AT WORK THE ATMOS FROM THE OHIO VLY...TO THE SRN ATLC STATES...THEN BACK UP ACROSS THE ERN SEABOARD. ONE ALREADY POTENT UPPER VORT THAT INITIALLY CAME DOWN THE UPPER MIDWEST WILL BE GRADUALLY DISSIPATING OVER THE APLCNS AS THE COASTAL PORTION OF THE SYSTEM RAPIDLY INTENSIFIES. IN BETWEEN THIS OCCURRENCE LIES THE MID-ATLC REGION. AFTER A VERY SLOW AND STEADY TRANSITION OF MORNING RAINS OVER TO SNOW FROM NORTH-TO-SOUTH...THE FORCING FOR THE ADDITIONAL AND FUTURE SNOW BANDS WILL BE OF A SCATTERED AND INTERMITTENT NATURE. POCKETS OF MODERATE TO HEAVY SNOW WILL DEVELOP INTO THE AFTN HRS...BUT IN VERY LOCALIZED AND SHORT-LIVED AMOUNTS. COMPLEX RAIN/SNOW LINE STILL EXISTS MAINLY SOUTH AND EAST OF DC...INCHING OVER INTO PARTS OF THE NRN VA PIEDMONT...TOWARD KCHO AND THE I-64 CORRIDOR. AS THE COASTAL STORM CONTINUES TO DEVELOP WELL SOUTH OF OUR AREA...THE LOW LEVEL FLOW IN THE BOUNDARY LAYER WILL CONTINUE ADVECTING IN WARMER AIR TO THE SOUTH AND COLDER AIR TO THE NORTH. THE BATTLE BETWEEN THESE AREAS REMAINS CENTERED OVER SE MD. THE BATTLE WILL SHIFT SWD OVER TIME INTO THE AFTN HRS AND PTYPES WILL BECOME LESS OF AN ISSUE W/ ALL SNOW OVER MUCH OF THE REGION HEADING INTO THE LATE EVE HRS. TEMPERATURES AT THAT POINT WILL BE COLD ENOUGH TO SUPPORT SNOW AND THE HEAVIER WET FLAKES WILL LIKELY CAUSE TRAVEL DISRUPTION THIS EVENING. ONCE THE COASTAL DEVELOPS IT WILL INTENSIFY RAPIDLY AND PULL AWAY FROM THE REGION TONIGHT. EARLIER INDICATION OF MORE SIGNIFICANT WRAP AROUND SNOWFALL ALONG AND EAST OF THE I-95 CORRIDOR DOES NOT APPEAR AS SIGNIFICANT. THREAT FOR WARNING LEVEL SNOW HAS DIMINISHED. HAVE EXPANDED WINTER WEATHER ADVISORIES EAST THROUGH THE I-95 CORRIDOR AND ALSO EXPANDED FURTHER SOUTH THROUGH 15Z TUESDAY. IMPACTS TO THIS EVENING COMMUTE AND SOME INTO THE TUESDAY AM COMMUTE CAN BE EXPECTED. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... EARLY SNOW WILL PERSIST MAINLY ACROSS EASTERN SECTIONS AND SOME UPSLOPE OVER THE POTOMAC HIGHLANDS. THE COASTAL LOW WILL PULL AWAY TO THE NORTH AND SNOW WILL GRADUALLY END DURING THE DAY. COLD TEMPERATURES WILL REMAIN IN PLACE WITH HIGHS ONLY REACHING THE 20S OUT WEST WITH 30S EAST OF THE BLUE RIDGE. GUSTY NORTHWEST WINDS WILL DROP WIND CHILLS INTO THE SINGLE DIGITS AND TEENS OUT WEST TO THE LOWER 20S EAST. WINDS WILL GRADUALLY DIMINISH LATE IN THE DAY. STRONG LOW PRESSURE OFF THE NEW ENGLAND COAST TUESDAY EVENING WILL HEAD TOWARD NOVA SCOTIA TUESDAY NIGHT. HIGH PRESSURE WILL APPROACH FROM THE OHIO VALLEY. A NORTHWEST FLOW BETWEEN THESE SYSTEMS WILL USHER IN DRY AND COLD CONDITIONS FOR MOST AREAS. A FEW UPSLOPE SNOW SHOWERS ARE POSSIBLE ALONG AND WEST OF THE ALLEGHENY FRONT...BUT SNOW ACCUMULATION SHOULD BE LIGHT. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... HIGH PRESSURE WILL BUILD OVERHEAD WEDNESDAY...BRINGING DRY AND COLD CONDITIONS. A CLIPPER SYSTEM WILL PASS THROUGH THE AREA THURSDAY INTO THURSDAY NIGHT. A PERIOD OF SNOW IS POSSIBLE WITH THIS SYSTEM...ESPECIALLY ACROSS THE NORTHERN HALF OF THE CWA. HIGH PRESSURE WILL RETURN FOR FRIDAY WITH DRY AND COLD CONDITIONS. A STORM SYSTEM MAY IMPACT THE AREA NEXT WEEKEND. WINTRY PRECIPITATION IS POSSIBLE. TIMING AND DETAILS ARE HIGHLY UNCERTAIN AT THIS TIME. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... MVFR TO IFR TO PERSIST MUCH OF TODAY INTO TONIGHT WITH SNOW ACROSS THE NORTHERN TIER AND RAIN MIXING WITH AND CHANGING TO SNOW FROM BWI TO MTN TO IAD TO DCA THROUGH THE DAY. A STEADY LIGHT SNOW IS EXPECTED LATER THIS AFTERNOON AND EVENING ACROSS THE TERMINALS WITH TEMPERATURES AT OR BELOW FREEZING. THE SNOW WILL GRADUALLY END OVERNIGHT OR TUESDAY AM. NORTHWEST WINDS WILL CONTINUE TUESDAY NIGHT INTO WEDNESDAY WITH GUSTS AROUND 20 TO 25 KNOTS. VFR CONDITIONS ARE EXPECTED DURING THIS TIME. A CLIPPER SYSTEM MAY BRING A PERIOD OF SNOW TO THE TERMINALS LATER THURSDAY INTO THURSDAY NIGHT...ESPECIALLY ACROSS THE NORTHERN TERMINALS. HIGH PRESSURE WILL RETURN FRIDAY. && .MARINE... SCA CONDITIONS CONTINUE THRU THE DAYTIME HRS...W/ INCREASING WINDS ON THE WATERS ALONG WITH MIXED PRECIPITATION EVENTUALLY CHANGING TO SNOW LATER TODAY AND TONIGHT. GALE CONDITIONS ARE EXPECTED LATER TONIGHT INTO TUESDAY AS COASTAL LOW PRESSURE DEEPENS OFF THE MIDDLE ATLANTIC COAST. WINDS WILL EVENTUALLY DIMINISH LATE TUESDAY OR EARLY WEDNESDAY. GUSTY NORTHWEST WINDS ARE EXPECTED TUESDAY NIGHT THROUGH WEDNESDAY. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FOR THE WATERS DURING THIS TIME. A GALE WARNING MAY BE NEEDED FOR PORTIONS OF THE WATERS TUESDAY NIGHT. HIGH PRESSURE WILL BUILD OVERHEAD WEDNESDAY NIGHT. A CLIPPER SYSTEM WILL PASS THROUGH THURSDAY BEFORE HIGH PRESSURE RETURNS FRIDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER WEATHER ADVISORY UNTIL 10 AM EST TUESDAY FOR DCZ001. MD...WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR MDZ003-502. WINTER WEATHER ADVISORY UNTIL 10 AM EST TUESDAY FOR MDZ004>006- 011-013-014-503>508. WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 10 AM EST TUESDAY FOR MDZ016>018. WINTER STORM WARNING UNTIL 7 AM EST TUESDAY FOR MDZ501. VA...WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR VAZ025>031- 039-040-051-501>504-507-508. WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST TUESDAY FOR VAZ037-038-050. WINTER WEATHER ADVISORY UNTIL 10 AM EST TUESDAY FOR VAZ052>054- 505-506. WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 10 AM EST TUESDAY FOR VAZ055>057. WV...WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR WVZ050>053- 055-502-504>506. WINTER STORM WARNING UNTIL 7 AM EST TUESDAY FOR WVZ501-503. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ530>534-537>543. SMALL CRAFT ADVISORY FROM 7 AM TO 7 PM EST TUESDAY FOR ANZ530>534-537>543. GALE WARNING FROM 6 PM THIS EVENING TO 7 AM EST TUESDAY FOR ANZ530>534-537>543. SMALL CRAFT ADVISORY UNTIL 7 PM EST TUESDAY FOR ANZ535-536. && $$ UPDATE...GMS PREV DISCUSSION...KLW/BJL

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