567 FXUS61 KRLX 070248 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 948 PM EST Fri Jan 6 2017 .SYNOPSIS... Arctic air dominates this weekend as low pressure passes to the southeast clipping the southern and eastern zones. High pressure for Monday. A couple of systems provide precipitation for Tuesday through Friday. && .NEAR TERM /THROUGH SATURDAY/... As of 940 PM Friday... Per latest model guidance, opted to hoist a Winter Weather Advisory for SW VA and Southern WV counties where they could see 1-3 or maybe even 2-4 inches of snow as a band of snow sets up overnight. Excess moisture is being pulled north by a mid level wave and a stream of saturated 700 mb moisture is being advected into a strong dendritic growth zone, so snowfall rates may be high in the inch an hour range overnight tonight. Could have probably extended this to Wyoming and Fayette counties, but uncertainty is a little higher there due to the sharp gradient in snowfall that should result from straddling the counties, i.e. the western portion may see little snow while the eastern portions may see 2 or more inches. As of 700 PM Friday... Opted to increase PoPs and thus snowfall over zones southeast of Charleston and Clarksburg. HRRR guidance is trending more towards the snowy GFS. Also noted was a wave on satellite imagery over western Tennessee that has a trajectory that may help to pull a little more moisture to the north from the large system down south. Despite these changes, still hard pressed to reach advisory amounts, but still something to keep an eye on overnight. As of 210 PM Friday... For the immediate term...light snow from the sheared vorticity max is exiting southwest VA and the southern mountains. Lull in the activity will be relatively brief until effects from the Carolina winter storm reach the same area. Models still different in the northwestward extent of moisture and ultimate QPF into the far southern zones and into the Greenbrier Valley. NAM is less aggressive, as are the HRRR and the RAP models, which just clip these counties and produce an event total tonight and early Saturday of roughly an inch or less. GFS, however, paints a snowier picture, with output of multiple inches in places like BKW. Have gone with the more conservative route, along with WPC guidance which gives less than advisory criteria snow. No headlines for this issuance. From a temperature standpoint, going a couple degrees lower than previous forecast for tonight, and hopefully have done a better job with the far northwestern zones, especially Perry and Morgan counties, where the sky will better allow radiative cooling with snow on the ground. Poor temperatures recovery expected again Saturday, with a few locations hitting 20F only. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 330 PM Friday... With arctic air in place and northwest winds, will keep flurries Saturday evening where clouds exist. Deeper moisture arrives in the WV mountain upslope areas later Saturday night into Sunday, providing a chance of some light snow. With the arctic air and decent northwesterly winds, wind chills become an issue in the higher elevations. Will issue a wind chill advisory for the higher elevations of the northern WV mountains for Saturday night into Sunday. May need to expand this into the central and southern mountains as the event approaches. High pressure then builds in Sunday night and Monday. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 330 PM Friday... A warm front may provide a mix of precipitation types for Monday night into Tuesday, depending on the timing of the precipitation. This will be followed by a weak cold front Tuesday night or Wednesday. Timing of this system has varied considerably on the models, so confidence in the timing is not high. Yet another system arrives on Thursday. Operational models are showing a cold front stalling over the area and remaining into Friday. Once again, confidence in this scenario is fairly low. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... As of 945 PM Friday... A winter storm system to the southeast will move low level moisture into the mountains and adjacent lowlands tonight for MVFR conditions. For BKW, snow should bring IFR overnight. Conditions improve to VFR Saturday. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SUNDAY... FORECAST CONFIDENCE: Medium to high. ALTERNATE SCENARIOS: More moisture could move northward for more IFR in snow. 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 SAT 01/07/17 UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 EST 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09 CRW CONSISTENCY H H H M M M M M M H H L HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H M L L L L L M M L L L EKN CONSISTENCY H M H M H L L L M H M L 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 00Z SUNDAY... No widespread IFR conditions expected at this time. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Wind Chill Advisory from 7 PM Saturday to 1 PM EST Sunday for WVZ522>524-526. Winter Weather Advisory until 10 AM EST Saturday for WVZ033. OH...None. KY...None. VA...Winter Weather Advisory until 10 AM EST Saturday for VAZ003- 004. && $$ SYNOPSIS...RPY/JW/SL NEAR TERM...JW/26 SHORT TERM...RPY LONG TERM...RPY AVIATION...JW/26