Low Wind Chill Factors Will Continue To Be Felt Overnight Into Thursday & Friday Across Middle-Upper Elevation Mountain Ridges and Plateaus ( SSW-WSW winds ).
Overnight Into This Morning
Mostly clear. Windy across middle to upper elevation ridges & plateaus. SSW-WSW winds at 10 to 25 mph, with higher gusts. Temperatures varying from 10s in colder mountain valleys with calm winds to readings steady or slowly rising through the 20s on exposed middle-upper elevation ridges & plateaus ( low-mid 30s on mid-elevation thermal belt sites ). Wind chill factors in the 10s to lower 20s, except single digits along upper elevation mountain ridges.
This Afternoon
Partly to mostly sunny. Gusty SSW-SW winds 10-20 mph, with higher gusts ( gusts to 30+ mph possible above 3000 to 3500 feet ). Temperatures in the 30s to lower-mid 40s in SW upslope flow locations ( e.g., Norton-Wise ) verses upper 40s to lower 50s in downslope flow communities ( e.g., Pound to Grundy corridor ). Wind chill factors in the 20s and 30s, coldest at elevations above 2700-3000 feet.
Tonight Into Friday Morning
Mostly clear with increasing high clouds overnight. Continued gusty across mid-upper elevation mountain ridges and plateaus. SSW to SW winds 5-15 mph, with higher gusts. Substantial vertical temperature spread developing from MINS in upper 10s to low 20s in valleys with calm winds to 30s on exposed middle elevation plateaus and ridges.
My Weather Discussion ( January 13-14 )
A frigid beginning to January 13 featured MIN temperatures in the single digits to lower 10s within most locations amid Wise, northern Scott, Lee and Dickenson counties and the City of Norton ( single digits ). Cold conditions considering the limited snow cover across the area.
Nora 4 SSE NWS Cooperative Station
The day featured mostly sunny skies with high clouds filtering sunshine a little during the afternoon. Temps struggled to reach around 30 degrees in the Norton-Wise and Long Ridge-Sandy Ridge communities, with low-mid 20s all day at upper elevations in the High Knob Massif.
*Downslope locations in the Russell Fork & Levisa Fork basins managed to break freezing with a MAX of 34 degrees being observed officially at Clintwood 1 W.
Lonesome Pine Airport In Wise
SW winds began increasing during the evening and have since become a significant factor across middle to upper elevations in Wise, northern Scott, northern Lee and Dickenson counties. Wind chills from 10s to lower 20s across middle elevations, and single digits at highest elevations, have been felt into this overnight period.
Flatwoods Mountain MesoNET ( 11:30 to 10:30 PM January 13, 2016 )
Temperatures above 3000 feet have been colder, with readings rising slowly into mid 20s atop the High Knob Massif by midnight ( but conditions have felt like single digits due to wind chills ).
Flatwoods Mountain MesoNET ( 10:30 to 9:30 PM January 13, 2016 )
The coldest air of the winter to date continues to be on track to arrive by Sunday into Monday ( January 17-18 ).
Bitter cold with partly to mostly clear skies. W to WNW winds decreasing to around 10 mph or less along lower to middle elevation ridges & plateaus below 3000 feet. W to WNW winds 10-15 mph, with gusts to 20+, across upper elevation mountain ridges. Temperatures dropping into single digits to lower 10s. Wind chill factors of from 0 to 10 above along middle elevation ridges and plateaus to 0 to -10 below on upper elevation ridges.
This Afternoon
Partly to mostly sunny. Cold. W winds becoming SSW-SW at 5-10 mph below 2700 feet. W winds shifting WSW-SW at 5-15 mph, with higher gusts, above 2700 feet. Temperatures widespread in the 20s to lower 30s. Wind chills in the 10s and 20s ( coldest at highest elevations ).
Tonight Into Thursday Morning
Partly to mostly clear. Becoming windy across middle to upper elevation ridges & plateaus. SSW-WSW winds at 5-15 mph, with higher gusts, below 2700 feet. WSW-W winds of 15-25 mph, with 30-40 mph gusts, along mountain ridges above 2700 feet. Temperatures varying from 10s in colder mountain valleys with calm winds to readings steady or rising through the 20s to around 30 degrees on exposed middle-upper elevation ridges & plateaus. Wind chill factors in the 10s & 20s ( a few single digits in gusts at highest elevations ).
My Forecast Discussion ( January 12-13 )
Windy conditions greeted January 12 in advance of a fast moving cold front and band of snow.
*Based upon all other available stations, as I have noted many times in the past, Lonesome Pine Airport temperatures tend to run 1 to 2 degrees F too warm ( at least relative to all other area sites around this elevation ).
Lonesome Pine Airport In Wise ( Temp Error of 1-2 degree F ) at 2684 feet
This is illustrated well by Nora 4 SSE, at essentially the same elevation, located ENE of LNP in extreme southern Dickenson.
Nora 4 SSE on Long Ridge of Sandy Ridge at 2650 feet
A burst of snow, as expected, overspread the mountain area from northwest to southeast during early afternoon with a moderate to heavy, wind driven snowfall and a quick .5″ to 1.5″ of accumulation amid the area of projected highest impact ( reference My 011216 Forecast for details ).
*Especially across Dickenson County and much of Wise County.
University of Virginia’s College At Wise
Visibility quickly dropped after snow began as the lower atmosphere became saturated, with large flakes observed.
University of Virginia’s College At Wise
Looking ahead, a moderation of temperatures by day back to near seasonal January levels during Thursday-Friday will never feel like it across our middle-upper elevations where persistently gusty S-SW winds will continue to generate substantial chill factors.***
***An important and always highligted factor ( is wind chills ) in my forecast’s since they are critical to me and anyone out amid our mid-upper elevation mountain terrain ( as our many residents and outdoor enthusiasts of these places know so very well ).
European Ensembles 500 MB Height Anomalies Forecast – 7 AM Thursday
This continues to be a progressive pattern, such that late week warming will quickly give way to yet another surge of bitter cold air by this weekend into early next week.
European Ensembles 500 MB Height Anomalies Forecast – 7 AM Sunday
More snow, to some extent, is likely and that is what will be tracked in upcoming days as this typically snowy mountain area ( of the High Knob Massif ) is currently running at a record low snowfall pace for the 2015-16 season.
*ALERT For Accumulating Snow Today With Potential For Near Zero-Visibility And Rapid Development Of Hazardous Driving-Walking Conditions Amid A Fast Hitting Cold Front ( Between Noon to 4:00 PM ).
*Locations Along and northwest to north of the High Knob Massif – Tennessee Valley Divide and Clinch Mountain Will Be Favored For The Worst Conditions & Highest Impacts
Generalized Map For Hazardous Snow Burst Impact
Overnight Into Sunrise
Increasing clouds. Windy across mid-upper elevation mountain ridges and plateaus. SSW-SW winds 10-20 mph, with higher gusts below 2700 feet, verses near calm winds in sheltered mountain valleys. SW-WSW winds of 20 to 30 mph, with gusts to 40+ mph, along mountain ridges above 2700 feet. MIN temps from 10s in colder mountains valleys, and at highest elevations early, to the 20s. Wind chills from 10s to lower 20s on lower-middle elevation plateaus-ridges to as cold as 0 to -5 degrees below at the High Knob Lookout.
Sunrise Through Mid-Morning
Mostly cloudy & windy. Chance of flurries. Becoming gusty in mountain valleys ( where overnight winds were calm ). SW-WSW winds 10-20 mph, with gusts to 30+ mph at high elevations. Temperatures rising into the 20s to lower 30s. Wind chills in the 10s and 20s, except some single digits at highest elevations in the High Knob Massif.
Mid-Morning Through This Afternoon
Flurries, snow showers and local snow squalls developing. A burst of intense snow becoming possible from northwest to southeast during the Noon to 4 PM period ( i.e., near zero visibility and rapid development of hazardous conditions ). SW-WSW winds shifting WNW at 10-20 mph, with gusts to 30+ mph. Temperatures dropping into the 20s, with upper 10s at highest elevations. Wind chill factors in the 10s at lower to middle elevations ( 0 to 10 at upper elevations ).
*Localized lightning-thunder is possible amid the cold frontal snow band as it drops southeast through Kentucky into the Cumberland Mountains. The best chances of this being across northern Kentucky into Ohio and parts of West Virginia.
Tonight Into Wednesday Morning
Chance of flurries & snow showers into the evening. Becoming bitter with decreasing clouds overnight into the predawn-morning. W to WNW winds of 10-20 mph, with higher gusts, decreasing across lower-middle elevations overnight. Temperatures falling into the single digits to lower 10s. Wind chill factors in the single digits to lower 10s, except 0 to -15 below in gusts on middle-upper elevation mountain ridges & plateaus.
Snowfall Forecast Today Into Tonight
As during the previous event, which I well highlighted, moisture will again be limited with a westerly ( not a NW Upslope Flow ) stream of air from mid-continent into the mountains. The period for accumulating snowfall will therefore be limited, with most occurring rapidly in association with the cold front and wind shift.
A general 1″ to 1.5″ along upslope side of mountains
Generally less than 1″ on downslope side of mountains
Target snowfall of 1.2″ at 2500 feet ( +/- ) 1″ error potential. This implies that snowfall of .2″ to 2.2″ is possible in Norton-Wise and adjacent communities of similar elevation along the upslope side of the High Knob Massif & Tennessee Valley Divide. Extremes of a dusting up to 2-3″ are possible.
Snow totals of 1″ or less are expected in downslope locations amid river valleys of the Clinch, Powell, and Holston into the Tri-Cities.
My Forecast Discussion ( January 11-12 )
A bitter start to January 11 featured morning low temps in the single digits to lower 10s, with coldest conditions amid the High Knob Massif where wind chills during the predawn dropped to around 10 degrees below zero over a light snow cover ( generally 1″ or less of depth ).
Wind Blown Eagle Knob of High Knob Massif – January 11, 2016
Afternoon hours of January 11 were chilly with some very nice lenticular wave clouds developing over the High Knob Massif, as featured by the web cam at UVA-Wise.
High Knob Massif Webcam – University of Virginia’s College At Wise
Beautiful waves caught enough moisture to form lenticular clouds above the High Knob Massif, illuminated by the late afternoon sun, as temps reached lower 20s on High Knob and 30 to 35 degrees in lower-middle elevations of the area.
High Knob Massif Webcam – University of Virginia’s College At Wise
It has all been about gusty winds and bitter wind chills during evening hours of January 11 into the overnight of January 12, especially at middle to upper elevations.
Gusty SSW-SW winds have been making it feel like 10 to 15 degrees in Norton-Wise, with even colder conditions along mountain ridges above 2700 feet.
Black Mountain MesoNET ( 10:45 to 11:45 PM on January 11, 2016 )
Wind chills have consistently been in single digits above and below zero along high mountain crestlines, with anyone brave enough to have ventured to the High Knob Lookout experiencing even colder conditions than highlighted above by the somewhat lower elevation mesonet station on nearby Black Mountain.
Focus now shifts to a reinforcing blast of arctic air that will begin pouring into the mountains behind the passage of a cold front during the afternoon-evening of Tuesday.
250 MB Jet Stream Forecast – Left Front Exit Region of 120+ Knot Streak
The area will be in a very favorable position with divergence and rising air amid the left front exit region of a powerful 120+ knot jetstreak in the Polar Stream but, as with the last event, moisture will be a limiting factor and the best overall moisture + lift will remain north of the southern Appalachians.
As the NAM Model forecast sounding below illustrates, the air saturates aloft before it does in low-levels where very dry air is present initially.
NAM Model Forecast Sounding Above Wise At 1 PM Tuesday
Lapse rates become moderately steep and a little CAPE is present during the favorable early-mid afternoon time period, such that convergence along the front is likely to aid in generation of some convective elements ( graupel snow is often an indicator of strong upward vertical motion associated with convective activity which can occur without actually generating lightning and thunder ).
HRRR Model Forecast Doppler At 1:00 PM Tuesday
The midnight run of the HRRR Model is forecasting a band of snow to be crossing the Virginia-Kentucky border by 1:00 PM, above, and to have some convective type squalls-streaks forming behind it at around 3:00 PM ( below ).
HRRR Model Future Doppler At 3:00 PM Tuesday
The bulk of snowfall today is likely between Noon and 4 PM, with flurries and snow showers possible before and after this main time period that is targeted for the heaviest frontal and post-frontal activity.
The Bottom Line…Flurries and snow showers will develop today with potential for an intense snow band and/or squalls to form along a cold front during early-mid afternoon ( with brief visibility to near zero and strong, gusty winds ). For this reason an ALERT has been issued for the possibility of rapid deterioration in driving-walking conditions.
Given recent cold nights it will take only a little snow to cause hazardous travel conditions.
*Winter Weather Advisories have been issued for Dickenson, Buchanan counties in southwestern Virginia and for most of eastern Kentucky and West Virginia.
