Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 141824 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 124 PM EST Sun Jan 14 2018 .SYNOPSIS... High pressure today exits tonight. Low pressure drags a cold front across Monday night, followed by arctic air for mid week. Moderating temperatures for the end of the week. && .NEAR TERM /THROUGH MONDAY/...
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As of 100 PM Sunday... High pressure retreats into New England tonight, giving way to developing sw flow aloft ahead of the next system. Expect temps to fall quickly this evening, especially over the deeper snowpack across southeast Ohio. Meanwhile, mid deck will be rapidly approaching from the west and southwest, ahead of an amplifying upper level system. This will probably allow temps to level off, especially combined with the increase in low level moisture ahead of developing warm front late. Weak isentropic lift should allow an area of light snow to break out across the Ohio Valley during the predawn hours and clip portions of southeast Ohio. Given how dry the low level airmass, much of this may fall as virga, though do expect some flurries/light snow for a time early Monday morning, perhaps as far south as the Kentucky counties. The warm front quickly shifts into western Pennsylvania, allowing for a brief lull. The upper level system and associated frontal boundary will gradually pivot southeast Ohio heading into the afternoon, allowing light snow to overspread that area. Used a blend of NAM/GFS for qpf which yields 1 to 2 inches by 00Z across Perry County with a few tenths across the remainder Ohio counties. Elsewhere, expect a decent rebound in temps during the afternoon, with upper 30s to perhaps lower 40s across the Coal Fields and up along the I79 corridor. Perry County may eventually need an advisory, but given how marginal the amounts are and the fact most of the accumulation would be Monday afternoon, elected to punt for this package.
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&& .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 455 AM Sunday... An upper level low pivots through the midwest and Great Lakes states this period. A lead short wave trough rotating around it, and associated low pressure system tracking north of the area, could push light snow into the middle Ohio Valley on Monday. As the lead short wave trough lifts out, a second, positively tilted elongated short wave trough approaches Monday night through Tuesday night, as it becomes oriented parallel to and northwest of the cold front associated with the surface low. This will create a zone of undercutting, likely resulting in a band of snow sliding southeast across the area Monday night into Tuesday. Model QPF consensus and snow ratios suggest only an inch or two. However, embedded bands of frontogenesis and associated wave development may enhance snowfall Monday night or Tuesday, within a more limited band and time period. This would introduce some bust potential with the forecast snowfall amounts. The precipitation shifts east Tuesday night, even with the upper level trough still approaching. Upslope precipitation is minimized via the lack of coupling of low level moisture and low level upslope flow this time around. Central guidance temperatures looked good, including its depiction of the baroclinic zone moving through the area. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 455 PM Saturday... There may be upslope snow showers in the mountains Wednesday, depending on the low level flow associated with an east coast low, as an upper level trough crosses. Otherwise, Arctic high pressure will rule the frozen roost through Thursday night, before giving way to a southerly flow of milder air for Friday and the weekend. A strong southern stream system approaches Sunday, with surface low pressure destined to track toward the Great Lakes states. Central guidance temperatures looked good, other than to lower in the valleys a bit beneath arctic high pressure Thursday and Friday mornings. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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As of 115 PAM Sunday... 18Z Sunday through 18Z Monday... The pesky stratocu is finally dissipating across KCRW, allowing for areawide VFR conditions amid light flow. VFR conditions continue tonight for all terminals amid intervals of mid deck that will eventually lower into 4 to 6 thousand foot cigs. A brief period of MVFR/IFR conditions may develop during the predawn across southeast Ohio in light snow from an advancing warm front. A cold front will slowly approach southeast Ohio during the day Monday, with developing MVFR/IFR conditions in light snow. VFR conditions will hold for the terminals thru 18Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: None. 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 18 19 20 21 22 23 00 01 02 03 04 05 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 CRW CONSISTENCY M H H H H H H H H H H M HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H H H H H H H H H H H M EKN CONSISTENCY H H H H H H H H H H H M PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H H H H M AFTER 18Z MONDAY... IFR possible in snow Monday night into Wednesday.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...RPY/30 NEAR TERM...30 SHORT TERM...TRM LONG TERM...TRM AVIATION...30

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