Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 231544 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1044 AM EST FRI JAN 23 2015 .SYNOPSIS... HIGH PRESSURE OVER THE MID ATLANTIC WILL MOVE OFFSHORE THIS AFTERNOON. LOW PRESSURE OVER THE SOUTHEASTERN STATES WILL TRACK NORTHEAST TO A POSITION EAST OF THE DELMARVA SATURDAY MORNING AND MOVE INTO THE GULF OF MAINE SATURDAY NIGHT. HIGH PRESSURE WILL BRIEFLY RETURN TO THE AREA BEFORE A FAST MOVING LOW PRESSURE SYSTEM WILL CROSS THE AREA FROM THE WEST SUNDAY NIGHT THROUGH MONDAY. HIGH PRESSURE IS THEN EXPECTED THROUGH THE MIDWEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CIRRUS WERE ADVANCING NORTHWARD INTO THE CWA LATE THIS MORNING. EXPECT CLOUDS TO THICKEN AND LOWER THROUGHOUT THE DAY. PRECIP HAS ALREADY BEGUN ACROSS SOUTHWEST VIRGINIA...GENERALLY IN THE FORM OF SNOW. PRECIP WILL CONTINUE SPREADING NORTHWARD...MAKING INTO THE LOWER POTOMAC HIGHLANDS/CENTRAL SHENANDOAH VALLEY/FOOTHILLS MID AFTERNOON. P-TYPE AT ONSET LOOKS LIKE SNOW OR SLEET...BUT MAY MIX WITH RAIN AS WELL ESPECIALLY OVER THE FOOTHILLS WHERE BOUNDARY LAYER TEMPS WILL BE A LITTLE WARMER. PRECIP WILL CONTINUE TO SPREAD NORTHWARD DURING THE EVENING. SEE SHORT TERM SECTION BELOW FOR HEADLINE CHANGES. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... WE WILL BE UPGRADING THE WINTER WEATHER ADVISORY TO A WINTER STORM WARNING ACROSS THE NORTHWEST CORNER OF THE CWA...ESSENTIALLY WASHINGTON AND ALLEGANY COUNTY IN MARYLAND...MUCH OF THE EASTERN WEST VIRGINIA PANHANDLE AND INTO FREDERICK COUNTY VIRGINIA. WE EXPECT A SW TO NE STRIPE OF SNOW TO OCCUR AND BRING 5 OR MORE INCHES OF SNOW IN THIS UPGRADED AREA. IN ADDITION...END TIMES WILL BE ADJUSTED FOR SOME OF THE REMAINING ADVISORY AREA. SNOW AMOUNTS WILL LIKELY TAPER OFF SIGNIFICANTLY TO THE SOUTHEAST AS A TIGHT GRADIENT OF SNOWFALL ACCUMULATIONS IS LIKELY TO OCCUR. PREV... A WINTER WEATHER ADVISORY IS IN EFFECT FOR MUCH OF THE CWA FROM EITHER LATE THIS AFTN OR EVE INTO MID-LATE MRNG SAT. A WINTRY MIX IS POSSIBLE AND EXPECTED FOR MUCH OF THE ADVISORY AREA W/ FREEZING RAIN THE OVER-ARCHING THEME...THOUGH ACCUMUATLING SNOW WILL BE POSSIBLE FOR THE NRN AND WRN HALVES OF THE CWA...INCLUDING JUST INTO THE WRN DC/BALT SUBURBS. IMMEDIATE DC/BALT AREAS SHOULD SEE A BRIEF PERIOD OF SNOW AND SLEET MIX LATE TONIGHT BUT THE ACCUMULATION/DURATION WILL BE CUT DOWN BY THE WAVERING FREEZING RAIN WHICH IS EXPECTED TO BE NESTLED RIGHT AROUND/NEAR I-95 THRU THE DURATION OF THE EVENT. && .LONG TERM /SATURDAY THROUGH THURSDAY/... FAST FLOW CONTINUES ACROSS THE U.S. IN THE XTND PD. LOW PRES MOVG OFF THE DELMARVA WL BE DRAWING COLDER AIR INTO THE MID ATLC AS IT EXITS. I-95 MRNG RA XPCTD TO MIX W/ SN DURG THE AFTN WHILE POP CHCS DCRS. W OF I-95 MRNG MIXED PCPN WL BE COMING TO AN END DURG THE AFTN. XCPTN WL BE THE WRN UPSLOPE AREAS. HIGH PRES ACROSS THE AREA SAT NGT/1ST PART OF SUN WL QUICKLY MOVE E AS A CLIPPER SYSTEM DROPS INTO THE AREA SUN NGT AS THE LONG WV PATTERN RMNS IN THE WRN RDG/ERN TROF THAT HAS BEEN WRITTEN ABT MANY TIMES IN JAN. WINTRY PCPN WL BE PSBL SUN AFTN W OF I-81...BCMG LKLY OVR THE AREA SUN NGT. LGT ACCUMS WL BE PSBL. COLD AND DRY CONDS OVR THE MID ATLC DURG THE MIDWK. HIGHS IN THE U20S/M30S W/ LOWS RANGING FM THE SINGLE DIGITS IN THE HIGHLANDS TO THE UPR TEENS/M20S IN THE CITIES. ANOTHER CLIPPER COULD IMPACT THE AREA AT THE END OF NEXT WK. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... VFR CONDS THRU MUCH OF THE TAF PERIOD...UNTIL LATE AFTN TDA. A WINTRY MIX WILL ARRIVE MID TO LATE EVE FOR THE DC/BALT METRO - SLIGHTLY EARLIER FOR AREAS S AND W. THIS SYSTEM WILL LINGER INTO MIDDAY SAT...W/ MAINLY AND FZRA/IP MIX N AND W OF DC...MORE FZRA FOR THE DC AREA AND S/IP/FZRA FOR BALT AND NORTH. CIGS DOWN INTO IFR CAT XPCTD SAT MRNG...IMPRVG DURG THE AFTN. VFR SAT NGT AND SUN...THEN LKLY DIMINISHING SUN NGT AS THE NEXT LOW PRES AREA MOVES INTO THE MID ATLC. && .MARINE... LIGHT WINDS TODAY AND INTO TONIGHT...SLY THEN TURNING SE AS HIGH PRES MOVES OFF THE COAST. A STORM SYSTEM OFF DELMARVA WILL SWITCH WINDS TO NLY AND GUSTY OVER THE WATER INTO EARLY SAT. SCA HAS BEEN ISSUED FOR SAT AFTN AS LOW PRES DEPARTS AREA AND HIGH PRES RETURNS TO THE WATERS. NO MARINE HAZARDS SUNDAY THROUGH MONDAY MORNING. SMALL CRAFT ADVISORIES MAY BE NEEDED MONDAY AFTERNOON. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON EST SATURDAY FOR DCZ001. MD...WINTER STORM WARNING FROM 6 PM THIS EVENING TO NOON EST SATURDAY FOR MDZ003. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON EST SATURDAY FOR MDZ004>006-011-013-014-503>508. WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO NOON EST SATURDAY FOR MDZ501-502. VA...WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 10 AM EST SATURDAY FOR VAZ025-026-036-037-503-504-508. WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO NOON EST SATURDAY FOR VAZ027-029>031-038>040-050-051-501-502-507. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON EST SATURDAY FOR VAZ052>054-505-506. WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO NOON EST SATURDAY FOR VAZ028. WV...WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 10 AM EST SATURDAY FOR WVZ505-506. WINTER STORM WARNING FROM 6 PM THIS EVENING TO NOON EST SATURDAY FOR WVZ051-052. WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO NOON EST SATURDAY FOR WVZ053. WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO NOON EST SATURDAY FOR WVZ050-055-501>504. MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST SATURDAY FOR ANZ532>534-537-540>543. SMALL CRAFT ADVISORY FROM NOON TO 6 PM EST SATURDAY FOR ANZ530- 531-535-536-538-539. && $$ BPP/GMS/WOODY!

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