Mountain Area Forecast ( January 4-7 )
ALERT For Accumulating Snow & Hazardous Travel Developing Thursday Afternoon Into Friday Morning
Low dewpoint air moving into the Cumbeland Mountains will allow temperatures to drop significantly into Thursday Morning, followed by increasing clouds that keep temperatures cold during Thursday to set the stage for development of a moderate impact snowfall event by late Thursday into Friday.
Widespread hazardous travel conditions are expected to develop during Thursday PM-Evening into Friday Morning. Bitter temps and wind chills will add to these hazardous conditions.
An ALERT For Accumulating Snow May Be Needed For Late Friday Into Saturday Morning As A Second Wave Impacts The Mountain Region
Overnight Into Thursday Morning
Mostly clear into the overnight then increasing high clouds. Cold. W-NW winds 5-15 mph, with higher gusts, becoming light. Temps in the 10s to low-mid 20s, varying from 10-15 degrees in high valleys of the High Knob Massif to low-mid 20s along exposed middle elevation ridges.
Mid-Morning Thru Thursday Afternoon
Cloudy. Cold. Light winds. Virga developing aloft, then flurries and light snow reaching the surface. Temperatures generally varying from the 20s to the lower 30s.
Thursday Night Into Friday Morning
Snow. Turning bitter. Winds WNW-NNW at 5-15 mph, with higher gusts. Temperatures dropping into 10s to around 20 degrees ( as cold as 10 degrees at highest elevations ). Wind chills in the single digits and 10s, except below zero in gusts along upper elevation mountain ridges. Rime formation in upper elevations.
Morning snow tapering to flurries and snow showers. Bitter cold. Winds NW to N at 5-10 mph. Temps varying from lower-mid 10s in upper elevations to lower-middle 20s. Wind chill factors in single digits & 10s ( coldest at highest elevations ).
Snowfall Forecast: Late Thursday to Late Friday
A general 1″ to 4″ of snowfall is expected in counties along the Virginia-Kentucky border, with locally higher amounts possible at upper elevations of the High Knob Massif ( least snowfall amounts are expected across central-western Lee County and portions of the Clinch & Holston river valleys ).
Target Snowfall 3″ In Norton-Wise ( +/- ) 1″ Error Potential. This suggests a possible range from 2″ to 4″ in Norton-Wise during this period. Snow Density will be lower than 10:1 in locations along & north to northwest of the High Knob Massif and Tennessee Valley Divide to generate more “fluff factor” than in locations farther to the southeast ( i.e., the snow to water ratio will be locally higher ).
Friday Night Into Saturday Morning
Periods of snow & snow showers. Heavy at times. Bitterly cold. NNW-N winds 5-15 mph, with higher gusts on middle-upper elevation mountain ridges. Temperatures varying from 0 to 12 degrees. Wind chills from 5 above to -10 below, except -10 to -20 degrees below zero upper elevation ridges.
A second storm system lifting northeast out of the Gulf of Mexico is now forecast to impact the mountains late Friday into Saturday morning, with an update to the forecast noted above.
Sunday & Monday morning’s ( January 8-9 ) will both feature bitterly cold temperatures, especially in mountain valleys, with single digits and sub-zero temperatures being possible. Please stay tuned for later updates.
Weather Discussion ( Harsh Period )
Thursday Afternoon Update
An initial wave of snow dropped 0.5″ to 1″ of accumulation across portions of northern Wise and Dickenson counties into early afternoon Thursday, before waning.
I officially measured 0.5″ of snow in Clintwood, with heavier snow to the north and northeast toward Pine Mountain and Breaks Park.
Although flurries and light snow showers have occurred throughout Wise County, the lower atmosphere south of Pound has not yet been able to saturate with abundant amounts of low-level dry air.
A developing area near Middlesboro on Doppler radar is expected to be the beginning of saturation and sticking snow as it lifts northeast across Lee-Wise counties and northern portions of Scott County into this evening.
This system is coming in waves instead of one consolidated area of energy ( at least at this time ), with an initial wave impacting sites to the north while the current developing area of snow denotes a wave that will impact locations farther to the south ( e.g., Wise County which mostly missed sticking early afternoon snow ).
Conditions for snowfall will be improving into Thursday evening as a low-level wind shift to the NW-N increases upslope into the High Knob Massif area and temperatures begin to turn colder.
Meanwhile, the past several runs of the NAM Model group have become aggressive in spreading the heaviest snow across the Mountain Empire late Friday into Saturday.
The Morristown NWS Forecast Office has issued a Winter Storm Watch for later Friday into Saturday. I will wait to this initial period passes tonight before updating my snow forecast for this second event. There remains substantial model disagreement with respect to how much moisture reaches the area. Stay tuned for later updates.