Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 201040 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 640 AM EDT Tue Mar 20 2018 .SYNOPSIS... Low pressure system will bring unsettled weather to the region into Thursday. High pressure takes control late week with another low pressure system next weekend. && .NEAR TERM /THROUGH TONIGHT/...
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As of 640 AM Tuesday... Temperatures are a bit cooler over far NW corner of forecast area than previously forecast. Have lowered temps a bit and added some sleet for the next several hours. As of 345 AM Tuesday... Surface low currently moving by south of the CWA, and you can start to see the portion that will break off and park over the forecast area over the next couple days in response to a couple upper level systems. First area of precip associated with this now moving across the northern half of the forecast area, and down the Appalachian spine. Dry slot already moving into the WV lowlands. Did not go completely dry in this dry slot...instead maintaining slight chance to low end chance POPs for any isolated to scattered showers...such as the ones moving through eastern KY right now. Still have a bit of wintry mix across the far northern mountains early this morning so will leave current winter weather advisory in place. Otherwise, for today expect rain across the forecast area. The first upper level low passes quickly today and does not pull in any significantly colder air. Attention then turns to the second upper level low, which will reinvigorate the surface feature tonight and pull in much colder air. This will bring a transition from rain to snow this evening into tonight....beginning first across SE Ohio and in the WV mountains. Main concern with snow tonight is warmer boundary layer and surface temperatures which will eat into snow accumulations at first. But we also have a decent area of strong frontogenesis on the N/E side of the surface low. This should drive a mesoscale type area of heavier snow which may be able to overcome the less than ideal low level temps. Even outside of this area, more synoptic level forcing should still drive decent snowfall rates. Snow should be a wetter, heavier snow with ratios starting out in the 5-10:1 range and increasing to 10-15:1 late tonight. Have upgraded the winter storm watch to a warning across generally the mountains. And then converted the rest of the watch to a winter weather advisory. Main concern is whether any mesoscale features could push localized areas into warning criteria.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 325 AM Tuesday... Snow will continue across the area on Wednesday as an upper level low and surface low continue to wrap rounds of precipitation across the region. Could be some heavier bands at times on Wednesday, and current thinking is this will generally be the case across the central mountains, and across Ohio, just north of our CWA, but any sort of heavy bands are very difficult to predict, and with the flip flopping of models over time, leads to even less confidence in pinpointing heavier bands. Overall, leaned towards WPC guidance with respect to snowfall totals, which leans heavily on the NAM and SREF. There is a bit of a concern as to how much snow will actually be able to accumulate across our lowland counties on Wednesday, with models suggesting boundary layer temperatures hovering around the 40 degree mark, or warmer. Elected to lower temperatures a bit Wednesday afternoon from the blended guidance, but even with doing that, still looking at minimal accumulations across much of the lowland counties Wednesday afternoon, but with moderate accumulations continuing across the mountains at times. Precipitation will gradually taper off across the area Wednesday evening as the low moves off to the east, with just some light upslope snow showers lingering across the higher terrain through early Thursday. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 330 AM Tuesday... Overall dry through much of Friday with high pressure in control. Weather becomes more unsettled from the weekend onward, as a low pressure system, and multiple upper waves move through the area. Precipitation could be heavy at times early next week with Gulf moisture surging into the region. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/...
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As of 200 AM Tuesday... An area of rain showers lifting through the forecast area early this morning. As upper and surface lows drift in today expect ceilings to lower with MVFR area wide. Expect a lull in precipitation drifting through from SW to NE this morning into this afternoon, but then will be on the increase again by late afternoon as better forcing arrives. Rain will change over to snow tonight as colder air arrives with MVFR to IFR expected. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of precipitation and associated restrictions may vary from 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. UTC 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21 EDT 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 CRW CONSISTENCY H L M H H H M H H H M M HTS CONSISTENCY H H H M M H H H H H L L BKW CONSISTENCY H H H H H H M M M M L L EKN CONSISTENCY H H H H H H M M H M L L PKB CONSISTENCY M M H M H H M M M M L L CKB CONSISTENCY H H H H M M M L H H L L AFTER 12Z WEDNESDAY... IFR possible in precipitation through Thursday.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...Winter Storm Warning from 8 PM this evening to 11 PM EDT Wednesday for WVZ032-039-040-516-518-520>526. Winter Weather Advisory from 1 AM to 8 PM EDT Wednesday for WVZ005>007-013>015-024>026. Winter Weather Advisory until 2 PM EDT this afternoon for WVZ523-526. Winter Weather Advisory from 8 PM this evening to 8 PM EDT Wednesday for WVZ008>011-016>020-029. Winter Weather Advisory from 8 PM this evening to 11 PM EDT Wednesday for WVZ027-028-030-031-033-034-515-517-519. OH...Winter Weather Advisory from 1 AM to 8 PM EDT Wednesday for OHZ083-086-087. Winter Weather Advisory from 8 PM this evening to 8 PM EDT Wednesday for OHZ066-067-075-076-084-085. KY...Winter Weather Advisory from 1 AM to 8 PM EDT Wednesday for KYZ101>103-105. VA...Winter Weather Advisory from 8 PM this evening to 11 PM EDT Wednesday for VAZ003-004. && $$ SYNOPSIS...MZ/SL NEAR TERM...ABE/JSH/MZ SHORT TERM...SL LONG TERM...SL AVIATION...MZ is the U.S. government's official web portal to all federal, state and local government web resources and services.