Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 120543 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 1243 AM EST Tue Dec 12 2017 .SYNOPSIS... Cold front moves across the area tonight. Strong upper trough brings cold air and snow showers Tuesday. Another system arrives by late week with another chance for snow showers. && .NEAR TERM /THROUGH TODAY/... As of 1238 AM Tuesday...Forecast remains on track and no changes are needed at this time. As of 640 PM Monday... Made a few tweaks to the forecast this evening, mainly to hourly temperature grids and winds. Upped wind forecast slightly for tomorrow, based on strong winds aloft/caa taking hold throughout the day. In addition, added blowing snow to the forecast across the higher terrain counties. As of 110 PM Monday... The nice start to the workweek will quickly give way to the reality of winter as snow showers return. A warm front lifted north across the Mid Atlantic this afternoon. A trailing cold front will begin to slide east overnight tonight. This front will bring a reinforcing shot of cold air to the entire region. Along with this front, enough moisture will be in place that some snow showers will be likely. Expect to see some light snow flying by tomorrow morning across the entire area. As this front moves east, blustery condition will set in. Lake enhanced snow showers will reduce visibilities with any heavier squalls during the day. Areas where these streamers set up could pick up a small amount of accumulating snows across the lowlands. Upslope snow in the higher elevations will add to any snowfall accumulations. Have issued a Winter Weather Advisory for these higher elevations where a combination of dangerous wind chill, snow and blowing snow will be more likely. Overnight lows will in the lower to mid 30s. Highs on Tuesday will occur in the morning and fall throughout the day. This is due to the arctic air filtering in behind the cold front. By Tuesday afternoon, temperatures will be in the 20s. && .SHORT TERM /TONIGHT THROUGH 6 PM WEDNESDAY/... As of 315 PM Monday... As the upper trough moves away, northwest flow again returns with models starting to agree on narrow corridors of higher RH stemming from Lake Michigan and reaching into the region. Should these corridors of high RH come to fruition, there would be a corresponding corridor of higher snowfall - especially in the mountains. Given the fickle nature of these narrow corridors, though, have opted to spread accumulation throughout the mountains and in areas immediately adjacent to the west with somewhat lower amounts. Gusty northwest winds will again increase with these snow showers, and cold air advection will drop temperatures further. Wednesday morning temperatures are looking to be in the teens in the lowlands, and in the single digits in the mountains. The aforementioned winter weather and wind chill advisories extend through Wednesday morning to cover these hazards. Went with model blends for temperatures through the period. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... As of 335 PM Monday... Another system swings through during this period. However. models are somewhat different with the timing and the track of the feature. Because of this uncertainty, have gone with the model blend for the forecast. At this time, models are converging a surface low tracking squarely through this area, attached to yet another clipper-type trough aloft. Heavier snowfall would therefore be across the northern counties with upslope enhancement. Cold air remains in place for Thursday and Friday with warmer weather anticipated for Saturday and Sunday. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... As of 1245 AM Tuesday... Most of the region will remain VFR through about daybreak and then conditions will start to deteriorate. Scattered snow showers are forecast to develop area wide, with widespread MVFR and local IFR conditions developing, as strong cold front and upper level system pushes through. Mountains especially will be prone to IFR or worse conditions through the day and into tonight. In addition to the snow showers, gusty westerly/northwesterly winds will develop Tuesday, particularly after 12Z, with sustained winds in the teens, with gusts in the 20 to 30 kt range, with higher gusts around 40 kts possible across the higher terrain, with blowing snow and reduced visibility. Snow will decrease in intensity and coverage across much of the area after 20Z, however, will continue to see lake effect bands/squalls for the remainder of the TAF period and conditions will likely remain IFR in the mountains well into Tuesday evening. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of snow showers and deteriorating conditions on Tuesday may vary from forecast. Conditions may be worse than currently forecast. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE TUE 12/12/17 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12 CRW CONSISTENCY H H H H H H H M M H H L HTS CONSISTENCY M M M M M L L L L H L L BKW CONSISTENCY M M M M M M M M L L L L EKN CONSISTENCY M M M M M M L H M M M M PKB CONSISTENCY H H H H H M M M L M M L CKB CONSISTENCY H H H H H M H M M M L M AFTER 06Z WEDNESDAY... Scattered snow showers and gusty winds will result in continued areas of IFR through Wednesday morning particularly across the mountains. Another round of snow is expected Wednesday night and Thursday, particularly across the north, with IFR conditions possible. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Winter Weather Advisory from 7 AM this morning to 7 AM EST Wednesday for WVZ518-520-522>526. Wind Chill Advisory from 4 PM this afternoon to 1 PM EST Wednesday for WVZ518-520-522>526. OH...None. KY...None. VA...None. && $$ SYNOPSIS...JB/MC NEAR TERM...JB/MPK/SL SHORT TERM...MC LONG TERM...MC AVIATION...MPK

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