Mountain Area Forecast ( Dec 2-4 )
Overnight Into Friday Morning
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.
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 ).
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.
Rime formation started during evening hours of December 2 and continued into the afternoon of December 3 at highest elevations.
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.
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 ).