Partly to mostly clear. Cold. Winds W-NW 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges. Temperatures varying from 10s to low 20s in colder valleys to the upper 20s to lower 30s. Wind chills in the 10s & 20s along higher ridges.
Friday Afternoon
Mostly sunny. Seasonally cold. W-NW winds 5-15 mph with some higher gusts ( especially along ridges ). Temperatures varying from upper 20s to lower 30s in upper elevations to the upper 30s to lower-middle 40s. Wind chills in the 20s and 30s, with 10s in stronger gusts on the highest peaks.
Friday Night Into Saturday Morning
Becoming cloudy. Chance of a few flurries. Low clouds possible into morning with dense fog & riming at highest elevations along-north of the High Knob Massif-Tennessee Valley Divide ( mainly above 3000 feet ). Winds NW-N 5-15 mph along mid-upper elevation mountain ridges. Temps varying from around 20 degrees on highest peaks to the middle 20s to lower 30s. Wind chills in single digits & 10s across upper elevations to the 20s.
Saturday Mid-Morning Into The Afternoon
Morning low clouds giving way to sunshine and high clouds. Light NNW-NNE winds. Temperatures varying from upper 20s to lower 30s in upper elevations to the upper 30s to low 40s ( milder in valleys of the Clinch, Powell, and Holston ).
Saturday Night Into Sunday Morning
Increasing clouds. Mixed precipitation or snow becoming possible into morning. Light winds, except becoming SSE-SW at 5-10 mph on mid-upper elevation ridges. Temps in the 20s to mid 30s ( steady or slowly rising along upper elevation mountain ridges before precipitation onset ).
Sunday Afternoon
Any high elevation snow or mixed precipitation changing to rain. Otherwise, raw and rainy with nasty conditions. Increasing SE-S winds at 5-15 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet. Winds SSE-SSW 10-20 mph, with higher gusts, along upper elevation mountain ridges. Temperatures in the 30s to low-mid 40s. Wind chills in the 20s and 30s along higher ridges.
A chance for development of mixed precipitation, or snow at upper elevations, will be possible Sunday before a change to rain at all elevations by later Sunday into Monday. Some light accumulations, up to 1″ or locally more on the highest peaks, will be possible before a change to rain.
Weather Discussion ( Active Pattern )
Late Saturday Night Update
A nice riming event into Saturday morning capped the high country with super-cooled water deposited upon vegetation and trees, producing growth into the wind.
Majestic Rime Caps The High Knob Massif – December 3, 2016
Rime formation started during evening hours of December 2 and continued into the afternoon of December 3 at highest elevations.
High Knob Massif MesoNET – Eagle Knob At 4188 Feet
The day ( Saturday ) was cold as even valleys in the high country struggled to break freezing, with 34 degrees being reached in the Big Cherry Lake basin by late afternoon.
Regional Doppler Composite At 2:47 AM Sunday – December 4, 2016
Initially dry air is causing evaporation as a large shield of precipitation begins moving into the region. Evaporative cooling is expected to cause a period of snow and/or mixed precipitation into Sunday AM before a change to all rain. Lower-middle elevations are likely to have little to no accumulation, with locations above 3000 to 3500 feet having the best opportunity for some sticking.
This continues the active pattern and marks the start of another period with significant precipitation. A major blast of cold air follows by late week as the polar jet stream slips farther and farther south over time, following the baroclinic zone that is developing southward ( a natural, predictable tendency driven through increasing snow cover to the north as I taught my class weeks ago in our Field Studies course at UVA-Wise ).
Previous Discussion
An active weather pattern continues in wake of a heavy rainfall event. A few preliminary totals included:
Clintwood 1 W: 2.87″ Nora 4 SSE: 2.96″ Coeburn ( In Town ): 3.61″ UVA-Wise NWS: 3.62″ Appalachia ( In Town ): 3.97″ City of Norton WP: 3.98″ Black Mountain Mesonet: 5.00″
Widespread 4.00″ to 5.00″ rain amounts were common from the High Knob Massif to Black Mountain and northern parts of Lee County. A general 3 to 4 vertical feet of rise occurred on steep creeks ( like Big Stony ) draining the high country surrounding High Knob, with similar rises observed so far on water supply lakes in the City of Norton & Big Stone Gap.
High Knob Massif Webcam – University Of Virginia’s College At Wise
Some minor systems will impact the mountain area this weekend with a chance for lowering cloud bases into early Saturday that could generate a flake and/or some riming in upper elevations before giving way to high altitude clouds ahead of the next system.
NAM 12 KM Model Total Precipitation Forecast Up To 7 AM Monday ( Dec 5 )
Another healthy precipitation event is on tap for Monday into Tuesday ( December 5-6 ), with the latest run of the 51-Member European Ensemble group forecasting a MEAN basin average total of 1.00″ to 2.00″ ( again implying, as observed during the last event, some heavier totals ).
With chilly, drier low-level air in place initially by later Saturday into early Sunday the leading edge of developing precipitation could begin as some mixture or snow early on Sunday before changing into all rain at all elevations. At least, that is the current thinking. Stay tuned for updates.
European Ensemble MEAN Sea Level Pressure Anomalies – 7 AM December 7
In the extended, building Arctic High Pressure over northwestern Canada will become a major player in weather conditions across the USA by middle to latter portions of this first full week of December ( above ).
European Ensemble MEAN 850 MB Temperature Anomalies – DAYS 6 to 10
The coldest air will ooze its way down the eastern side of the Rockies before spreading eastward, with modification over mostly snow-free ground. This will turn temperatures well below average by later next week, with the magnitude of the cold yet to be determined ( as is any snowfall ).
