694 FXUS61 KRNK 121146 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 646 AM EST Sat Jan 12 2019 .SYNOPSIS... A storm system over the Southern Plains will move east into the southeast U.S. today into Sunday. A variety of precipitation can be expected from this storm system with a wintry mix anticipated for much of our forecast area. This system moves offshore by Sunday evening, but residual upper level disturbances will keep some light wintry precip around into Monday. && .NEAR TERM /THROUGH SUNDAY/... As of 320 AM EST Saturday... 1040 High centered over Ontario stretches southeast into the mid- Atlantic south into NC this morning. Low pressure was over Oklahoma/Texas. Regional radar showing light returns, but dry airmass in place and no surface reports as of 300AM in our immediate area. Closest report of snow is London and Jackson KY. This will change starting later this morning, and followed close the the HiResNMM showing light snow work into far SW VA mainly by 5am, then struggling to eat away at the dry air until after 12z/7am, but expect better lift associated with inverted trough and upper jet to arrive later this morning across WV into the Alleghanys where will have likely pops going with a chancey pops further east of this area, and south along the Appalachians, as better isentropic lift over wedge works in. This first piece starts to lift out later this afternoon, and should see possible lull in precip later this afternoon, but overall not playing too cute with this. For daytime snowfall, looking at 1-3" along the I-64 corridor, south to about the James River, with up to an inch possible north of U.S 460 from Bluefield to Lynchburg as well as portions of the NC mountains. As we head into tonight, the forecast headlines have not changed as warnings will remain. The issues as usual will be thermal profiles and ptype. The 00z NAM and CMC initialized fairly well, as did the ECM, so leaned toward its thermal atmospheric profile with this system. Overall models have shown a northward trend in the warm air overrunning the cold surface, so the snow area has shifted slightly north and will be a mix of snow/sleet further south along and south of U.S 460 overnight, with freezing rain becoming an issue across southside VA into the NC foothills/piedmont, as well as portions of the Mountain Empire west of I-77 from Bluefield to Wytheville, but more so toward Tazewell/Richlands and Marion. Based on QPF and best lift expecting a little more ice (over 1/4") to accrete from south of US 421 in Wilkes and Yadkin county, the northeast to south of US 58 from Martinsville to north of Danville, northeast to the Staunton River State Park. Not out of the question, that half inch ice could occur in portions of the NW NC piedmont south of Danbury to Yanceyville. Further north we start transition to sleet and think most of the forecast area between U.S. 58 and U.S. 460 will have to deal with more sleet, compared to ice or snow. Total QPF for this event will be in the 2/3rds to just under an inch. Will see 6-8 inches of snow roughly along north of I-64 and U.S 60, with 4-6" north of U.S. 460 from Pearisburg to Lynchburg, and more of 2-4" further south, with half of this being sleet. The only changes to the headlines will be to break up counties based on the new ice amounts in southside VA and far SW VA/NW NC. Still looks like best lift and impacts will be late this evening through midday Sunday, with precip as low pressure starts to form along the southeast coast, with weakening low moving into the TN Valley after midnight tonight, then that low dissipates as the one off the coast of NC starts to strengthen slowly as it pulls away from the coast by dusk Sunday. Strong wedge will keep temps today in the upper 20s to lower 30s from SE WV to the Blue Ridge of NC, northeast to Lynchburg, with mid to upper 30s across far SW VA and the foothills/piedmont of NC into southside VA. Temps dip into the 20s tonight, except lower 30s across far SW VA, and around 30 in southside VA/NC piedmont. Once the low shifts east Sunday and main bulk of precip leaves, temps may warm a little quicker outside the residual wedge to the upper 30s in far SW VA toward the NC/TN border, but leaning toward it struggling to rise above freezing over most of the CWA, especially from the New River Valley, north and east to the Greenbrier Valley to north of Danville/South Boston. Colder air slides back in aloft to turn a wintry mix back to snow in the afternoon as far south as the Roanoke River with rain mixing in across the Mountain Empire. And by dusk colder air aloft should allow for any precip to be all snow as far south as Danville. But overall snow accumulations Sunday afternoon, with an inch or less. Forecast confidence is high in winter storm warnings, but medium on warm nose aloft vs depth of colder and transition zone from snow/sleet to freezing rain. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 315 AM EST Saturday... During this period, we'll be in the post-storm/recovery period. Though the potential for significant snow/sleet/ice accumulations have ended, trace amounts of freezing drizzle or very light snow/flurries may be possible Sunday night. A potential transportation hazard to keep in mind will be nightly instances of patchy black ice from melted snow/sleet, as low temperatures get below freezing Sunday and Monday nights. The winter storm that will affect the region later today into Sunday will begin to pull eastward into the eastern Virginia Tidewater/coastal area by early Sunday night. Most of the 00z guidance suite shows some residual and frankly rather nebulous model QPF Sunday night, mainly a few hundreths of an inch or less, trailing back westward along a inverted trough with a considerable amount of cloud cover. The best dynamic forcing will be well to our east. Thermally, weak cold advection should be taking place on north/northeast winds. Closer inspection of BUFKIT soundings from most model sources indicates that the ice crystal nuclei layer (roughly at or above -8C) in the sounding profile becomes increasingly less saturated as the evening progresses. This indicates that ice nuclei will become less active and support either very light snow/flurries or patchy freezing drizzle, with the latter becoming more dominant as the column dries out aloft. Any accumulation of either is nil and doesn't warrant expansion in time of the Winter Storm Warnings already in place. That being said, we may have some patchy black ice in areas potentially affected by freezing rain or if/where any snow should melt. Looking at overall cloudy to mostly cloudy skies with lows in the upper 20s to low 30s in most places. Overall synoptic regime is generally similar Monday into Tuesday, as high pressure will increasingly build into the region from the mid- Mississippi Valley with cyclonic northwest flow aloft. Monday is generally a mostly cloudy day as shallow moisture remains trapped, with either very light snow or patchy freezing drizzle mainly for areas along and west of I-77. Highs should only be in the 30s in most areas. Trending towards less cloud cover moving into Monday evening, though there may still be a threat for patchy black ice with lows in the 20s. Tuesday looks mostly sunny/dry and trending milder with highs in the upper 30s to mid 40s. Forecast confidence this period id moderate to high. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... As of 300 PM EST Friday... The pattern will transition to a progressive quasi zonal regime for the latter portion of the workweek. Tuesday Night and Wednesday look to be fairly quiet under high pressure. A weak backdoor front on the leading edge of a wedge surging in from the north may bring some spotty sprinkles/flurries mainly to the Alleghany highlands Wednesday night into Thursday. By Thursday night the Appalachians and central mid Atlantic region will start to feel the influence of a sharpening upper trof driving a surface low into the midwest, with isentropic lift ahead of this system overrunning the wedge and bringing a better chance of precipitation back to the forecast. Temperatures will moderate a bit and be above normal through the latter portion of the week, though conditions in the wedge in Thursday will be on the cool side. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... As of 640 AM EST Saturday... VFR conditions expected this morning but trend will be deterioting flying conditions through the day with mainly light snow across most of the area except perhaps DAN especially between 14-19z. The brunt of lower cigs/vsbys and wintry wx will occur after 00z Sunday with freezing rain at DAN overnight, a mix of sleet/fzra at BLF with sleet and snow at the other sites. Forecast confidence is high in poor conditions later today and especially tonight, but medium as far as how low vsbys/cigs go. Extended Aviation Discussion... Winter storm will track east and across the Mid-Atlantic Sunday with very poor flight conditions. Look for mainly IFR- LIFR ceilings and visibilities through this time frame. Slowly improving conditions are expected on Monday as the storm pulls away and high pressure builds in although lingering sub- VFR in low clouds may persist over the mountains into Tuesday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Winter Storm Warning from 10 AM this morning to 7 PM EST Sunday for VAZ011-018>020-023-024. Winter Storm Warning from 1 PM this afternoon to 7 PM EST Sunday for VAZ007-009-010-012>017-022-032>035-043>047-058- 059. NC...Winter Storm Warning from 1 PM this afternoon to 7 PM EST Sunday for NCZ001>006-018>020. WV...Winter Storm Warning from 10 AM this morning to 7 PM EST Sunday for WVZ042>044-507-508. && $$ SYNOPSIS...PM/WP NEAR TERM...WP SHORT TERM...AL LONG TERM...MBS AVIATION...PM/RAB/WP