ALERT For Accumulating Snow Today Into Thursday Morning With Bitterly Cold Temperatures-Wind Chills During Tuesday Into Thursday. This Pattern Is Likely To Continue Through This Weekend Into Next Week To Mark A Harsh Period Of Winter In The Appalachians.
Although No Official Winter Storm Warning Has Been Issued For Wise County by MRX, Let There Be No Doubt That Conditions Tonight Into Tuesday Will Be Just As Bad Or Worse Than In Any Of The Tennessee Mountain Counties, That Currently Are Under A Warning, Amid The Norton-Wise & High Knob Massif Area
New high-resolution model runs are playing down the AM snow, via dry low-levels, despite a healthy looking Doppler to the west. As noted in my weather discussion, models will struggle in this type of pattern on daily details.
A break in activity will be possible behind any morning snow before new development begins Monday afternoon. Due to very cold air aloft, bursts of heavy snow ( amid general snowfall ) will be capable of producing whiteout conditions at times from this afternoon into Tuesday-Wednesday. Increasingly bad conditions are expected as air turns bitterly cold Tuesday & Wednesday, with the worst conditions likely to develop along W-NW facing slopes and interior crests of the High Knob Massif & Black Mountain.
Overnight Into Mid-Morning
Increasing clouds into morning with a chance for a period of snow. SSW to SW winds 5-15 mph, with higher gusts, along middle elevation ridges & plateaus below 2700 feet. SW to WSW winds increasing to 10-20 mph, with higher gusts, along upper elevation mountain ridges above 2700 feet. Temperatures mostly in the 20s to lower 30s. Wind chills in the 10s & 20s ( coldest highest elevations ).
Mid-Morning Through Monday Afternoon
Any AM snow giving way to a break. Then snow showers and snow squalls developing during the afternoon ( possible mixture at lower elevations, especially Russell Fork & Levisa Fork basins ). SW winds shifting W at 5-15 mph, with higher gusts along mid-upper elevation ridges & plateaus. Temps varying from 20s at highest elevations to the mid-upper 30s. Wind chills in the 10s & 20s across upper elevations.
Tonight Into Tuesday Morning
Light snow, snow showers & bursts of heavy snow. Turning bitter into morning. W-WNW winds 10-20 mph, with higher gusts, on mid-upper elevation mountain ridges & plateaus. Temps dropping into low 10s at highest elevations and into upper 10s to low-mid 20s at lower-middle elevations. Wind chills dropping into single digits & 10s, except 0 to -10 below zero at highest elevations in the High Knob Massif & Black Mountain. Extensive rime formation at highest elevations.
Snowfall Forecast – Monday Through Thursday AM
A general 6″ to 12″+ along upslope side of mountains
3″ to 6″ on downslope side of mountains
Target snowfall of 8″ in Norton-Wise ( +/- ) 2″ Error Potential. This implies a potential for 6″ to 10″ of snowfall. Snow depths at any given time, outside of drifting, are expected to be less than total snowfall by 1-3″ due to melting-sublimation-settlement.
Extreme snowfall totals are expected to vary from more than 12″ amid highest elevations in the High Knob Massif to 3″ or less in portions of the Tennessee Valley ( downslope of mountains ).
This snowfall will occur over a prolonged period of time and generally be of low to very low density ( fluffy ). This tends to enhance settlement over time as snow depth increases. Note snowfall totals are between Monday AM and Thursday AM ( i.e., snowfall totals by Thursday Morning are currently projected to reach forecast values ).
A prolonged rime event is expected for upper elevations, above 3300 feet, in the sprawling High Knob Massif where significant accumulations are likely during the next few days.
Stay tuned for updates on this preliminary forecast.
Weather Discussion ( February 8 )
My Afternoon Update
New model runs into the overnight were correct in playing down the morning snow, with no more than flurries as low level air remained dry.
High Knob Massif Webcam – University Of Virginia’s College At Wise
No more than a dusting was on the ground atop the High Knob Massif at early afternoon. That would soon change!
High Knob Massif Webcam – University Of Virginia’s College At Wise
Whiteout conditions developed in the Norton-Wise, Sandy Ridge and High Knob Massif area amid wind driven snow.
High Knob Massif Webcam – University of Virginia’s College At Wise
The mountain landscape was quickly transformed into a wintry wonderland, but at the price of catching motorists who had not kept up with my forecast of blinding snow squalls off-guard.
High Knob Massif Webcam – University Of Virginia’s College At Wise
This snow covered middle-upper elevations above 2000 feet, with sticking and melting to the northeast in lower elevations of the Russell Fork Basin ( Pound-Clintwood ).
Nora 4 SSE – Official NWS Observation Site ( Elevation 2650 feet )
Temperatures which spiked to 40 degrees amid the “break” into mid-day have now quickly dropped below freezing at all elevations above 2000 feet along and north of the High Knob Massif ( low 20s atop High Knob, with NW wind gusts to 30 mph generating WCFs down to around 5 degrees above zero at 4:00 PM amid riming ).
Regional Doppler At 4:18 PM on Monday – February 8, 2016
Focus now shifts to new convective bursts developing beneath bitterly cold air aloft to the west, with conditions expected to become extremely bad across the mountain area this evening into the overnight period in advance of a very compact vorticity max and excellent divergence ( diffluence of isobaric contours ) aloft ( the echoes across middle KY & middle TN will tend to intensify along the Cumberlands ).
NAM Model 500 MB Vorticity Forecast – 1:00 AM Tuesday ( February 9, 2016 )
Low-level temperatures will be dropping to enhance the bad conditions expected tonight into Tuesday morning. Caution is advised for anyone planning to travel during this time.
High Knob Massif Webcam – University Of Virginia’s College At Wise
Orographic pilatus clouds capping the high country of the High Knob Massif is a signal for enhanced snowfall ahead, via riming of snowflakes and increased volume of snow reaching the ground.
My Overnight Discussion
The main focus of this weather discussion is on a prolonged period of snowfall and increasingly cold air, starting today and continuing through this week into the weekend as a harsh period of winter settles into the Appalachians.
If my preliminary snowfall forecast numbers are not reached by Thursday morning, it is an excellent bet that they will be reached by Saturday afternoon ( February 13 ) as a strong reinforcing arctic blast brings more snow. In fact, this preliminary snowfall forecast may certainly be too low by the time all is said and done. Time will tell more and updates made as the actual weather pattern develops and new model data arrives in coming days. Stay tuned.
*The latest European 16 KM Model is forecasting a general 6″ to 16″ of snowfall ( at 10:1 density ) along upslope sides of the mountains between this morning and Saturday afternoon ( February 13 ).
NAM 4 KM Model Total Snowfall Forecast Next 60-Hours
Due to very cold air aloft, the high-resolution NAM Model continues to repeatedly show very heavy local amounts as the atmosphere becomes absolutely unstable by this PM into Tuesday. Placement of MAX amounts being varied on any given run, with the signal being most important to indicate intense bursts of snow ( whiteouts in blinding squalls ).
GFS Model Total Snowfall Forecast Next 84-Hours
The GFS Model forecasts a general 2″ to 11″ of snow along the upslope side of the Appalachians between this morning and Thursday morning ( again, at 10:1 snow density ).
GFS Model 5-DAY Snowfall Forecast
The GFS 5-day snowfall forecast is a general 6″ to 12″ along the upslope side of the Appalachians.
Regardless of how much snow falls, bitter cold air is going to become a major force in coming days with two distinct surges of arctic air into the Appalachians centered on the late Tuesday-Thursday period ( February 9-11 ) and the weekend ( Saturday-Sunday period of February 13-14 ).
The coldest temperatures will likely go sub-zero at some point during this period, and in the worst case scenario it would be possible that MAX temperatures in Norton-Wise will struggle to break above 0 degrees on the coldest day. This is the potential which the pattern possesses, and only a notice for what could occur. While this is not yet in my forecast, it has enough merit, given factors in my extended outlook and new model data, that it should be noted now to warn EMS personnel and residents well in advance. If this does not happen, then we have dodged a very bitter bullet.
European Ensembles 850 MB Forecast – 7 AM Saturday ( Feb 13 )
While the big picture of the pattern is relatively clear, details on any given day will be hard for models to fully resolve given the very cold air aloft and instability that develops vertically during the next few days.
