FXUS61 KRNK 040234 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 934 PM EST Tue Dec 3 2024 .SYNOPSIS... High pressure returns tonight and Wednesday, allowing for clearing skies and slightly warmer temperatures Wednesday afternoon. Another cold front is expected to bring mountain snow showers Wednesday night into Thursday, along with very gusty northwest winds. Another round of cold air arrives behind the system for Friday into the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... As of 932 PM EST Tuesday... Cloud cover is eroding across the mountains, and flurries have ended. Perhaps another hour or two for clear skies for everyone. Have made only minor adjustments to hourly temperatures, dew points, sky cover, and wind speeds/gusts to better match the latest conditions and expected trends into the early morning hours of Wednesday. As of 645 PM EST Tuesday... Cloud cover continues to hold fast over portions of the mountains. Although we still do expect a trend to clear/clearer skies through the evening, the rate at which this decrease occurs is expected to be slower than earlier advertised. Additionally, stray flurries cannot be ruled out completely until the cloud cover completely dissipates. Have adjusted hourly sky cover and weather grids through the early part of the overnight hours accordingly. No other significant changes were made. Have tweaked hourly temperature, dew point, and wind speed/gusts to better reflect the latest conditions and expected trends through the evening hours. As of 130 PM EST Tuesday... Key Messages: 1) Snow showers over the mountains will become more intermittent this evening. 2) A strong cold front arrives Wednesday night bringing strong winds and another chance of snow. Upslope clouds and snow have lingered a bit long than originally forecast. Locations from Richlands, Wytheville, and north into southeast West Virginia have seen continued snow showers all day. Though guidance has this activity already gone, it is still currently snowing in many of the aforementioned areas. Have extended the chance of snow showers through this evening. Some minor accumulations possible and certainly some slick spots on roadways with temperatures still in the lows 20s, and especially tonight with temperatures dropping into the teens. Attention then turns to the north where a strong low pressure system is expected to rapidly develop and strengthen over southern Canada and the Great Lakes on Wednesday. Ahead of this system, weak southerly flow will allow for a day of thawing with temperatures Wednesday afternoon in the upper 30s and low 40s. A trailing surface cold front associated with the strengthening low will quickly enter the area Wednesday night. Bands of snow are possible with the passage of the front, some of which could be heavy at times and quickly coat untreated roadways, especially during the very early morning hours on Thursday. Highest confidence for accumulating snows will be at the higher elevations along the western slopes where an inch to two inches of snow could fall before daybreak. Confidence has also increased in the potential for high winds with the passage of the cold front. Guidance now consistently indicating a strong 850mb jet around 60kts entering the region late Wednesday evening and lingers through Wednesday night. Taking a look at HREF probabilities of gusts greater than 55mph, it highlights portions of the southern Blue Ridge from Boone and northward into the Grayson Highlands with very high probability of gusts exceeding 55mph through Wednesday night. With increasing probabilities of strong wind gusts and the advertised jet on multiple runs of recent guidance, a High Wind Watch will be issued for the Southern Blue Ridge. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 110 PM EST Tuesday... Key Messages: 1) Confidence is high for gusty northwest winds, mountain snow showers, and Arctic air for Thursday and Thursday night. 2) Dry weather prevails during Friday and Friday night. Thursday morning will feature the highest northwest wind gusts as an 850 mb jet reaching up to 55 knots passes overhead. Snow showers should fly in the wind along and west of the Blue Ridge, but the coverage will wane by Thursday afternoon into Thursday night as the wind gradually weakens. Cold air advection should cause temperatures to plummet into the teens by Friday morning. The combination of the Arctic air mass and the northwest wind could drop wind chill values below zero across western Greenbrier County, Mount Rogers, Mountain Lake, Burkes Garden, and the higher elevations of Ashe and Watauga counties during late Thursday into early Friday. Canadian high pressure will eventually arrive to bring dry weather for Friday. The drier air and lighter winds should stop the upslope snow showers by this point in time. Skies should clear to allow plentiful sunshine, but high temperatures on Friday may only reach the 20s and 30s for most locations. Another frigid night is expected during Friday night with lows falling into the teens due to good radiational cooling from light winds and mainly clear skies. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 110 PM EST Tuesday... Key Messages: 1) Confidence is high for dry weather and a warming trend during the upcoming weekend. 2) Rain chances will increase from a low pressure system arriving by Sunday night and lingering through Tuesday. High pressure will maintain control across the Appalachian Mountains through Saturday and Saturday night to keep conditions dry. Meanwhile, heights aloft should begin to climb as an upper level ridge builds over the Southeast. The flow at the surface will turn towards the southwest during the weekend. Adding all of these factors together yields a warming trend with temperatures climbing into the 40s and 50s by Sunday afternoon. The models continue to trend slower with the arrival of a low pressure system developing in the southern Plains. Moisture from the Gulf of Mexico should spread northeastward by Sunday night into Monday to provide increasing chances of rain. Although there is a low chance of frozen precipitation initially on Sunday night, the warm air advection should quickly switch anything over to just rain by Monday morning. Confidence in the evolution of the low pressure system diminishes notably by Monday night into Tuesday as the models struggle with timing and subtle waves of low pressure developing within the overall system. Thus, rain chances will linger through Tuesday, but temperatures should remain milder. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... As of 635 PM EST Tuesday... Residual MVFR ceilings continue generally along and west of a KLWB-KBCB-KTNB line along with enough of northwest upslope fetch to wring out a few flurries. Visibilities remain VFR. By 04Z/11pm EST most, if not all, of the MVFR ceilings will have either scattered out, or cleared. VFR conditions are expected for the entire area the second half of the night through Wednesday. Although, ceilings of 5000-7000ft AGL return to the mountains during the afternoon. Low level southwest winds are expected to increase Wednesday in advance of an approaching cold front. An 850mb jet of 40 to 50kts is expected by the afternoon, with pockets of LLWS expected as surface winds will still generally be out of the south with sustained speeds more in the 10 to 15 kt range. Confidence in the above aviation scenario is high. EXTENDED AVIATION OUTLOOK... Primarily VFR conditions are expected in the foothills and piedmont through Friday. Wednesday night into Thursday, upslope snow showers and sub-VFR conditions are expected over parts of southeast West Virginia. Very gusty northwest winds are expected for all locations Wednesday night into Thursday, especially across the mountains. Dry, cold, VFR conditions are expected Thursday night through Saturday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...High Wind Watch from Wednesday evening through Thursday afternoon for VAZ015. NC...High Wind Watch from Wednesday evening through Thursday afternoon for NCZ001-002-018. WV...None. && $$ SYNOPSIS...BMG NEAR TERM...BMG/DS SHORT TERM...PW LONG TERM...PW AVIATION...BMG/DS