ALERT For Heavy Rain Changing To Wet Snow By The Predawn-Morning Hours Of Today – Remain Alert For Water Ponding Along Roads, Snow Clogged Drains And In Low-Lying Poor Drainage Locations.
Caution For Black Ice and Snow On Roadways As Temps Drop Back To Around And Below Freezing
Updated Risk Regions For A Change From Rain To Period Of Snow
The highest risk region on the above graphic is along and northwest of the BLUE Line, which I have along Pine Mountain, with a high-moderate risk for locations along and northwest of the RED Line for at least a period of rain to wet snow.
A change from rain to wet snow is expected during the period between 1:00 AM and 4:00 AM, with changes first toward the southwest and at highest elevations rapidly overspreading the Cumberland Mountains.
Reference my 021516 Forecast and Discussion for more details.
HRRR Model Snowfall Forecast Next 15-Hours
Highest resolution models available are giving out a signal that fits the climatology of past such cases. So I have posted the region where a risk of heavy wet snow will be greatest above. THIS DOES NOT MEAN IT WILL OCCUR in a manner that is disruptive, but gives everyone an advance warning that it will be possible ( the risk for a change to heavy snow is high, with accumulations for any given place being the main unknown factor ).
The general trend is for heaviest snow amounts to the west and northwest, with lesser amounts toward the south and southeast, with respect to the Cumberland Mountains ( e.g., eastern Kentucky has a higher chance for more significant accumulations than does most of northeastern Tennessee, as illustrated by the models ).
NAM 4 KM Model Total Snowfall Forecast – Next 12-Hours
When the 32 degree air moves back overhead there will be little lag time before it can begin to accumulate at lower elevations on the Virginia side of the stateline. In between, a milder zone in the middle elevations ( like at Wise ) will have to be overcome ( air is colder both below and above the elevation of Wise tonight ).
The temp at 1:00 AM is holding steady at 32 degrees in Clintwood, with a borderline rain-freezing rain event.
GFS Model Total Snowfall Forecast – Next 12-Hours
Overnight Into This Morning
Rain. Heavy at times. Rain changing to snow by the predawn ( especially along and west-northwest of the Cumberland Mountains ). S-SSE winds 10-20 mph, with higher gusts, below 2700 ft. SSE-SSW winds increasing to 15-25 mph, with higher gusts, on upper elevation mountain ridges. Predawn winds shifting WNW-NW at 10-20 mph, with higher gusts. Temperatures dropping during the predawn-morning back into the 20s to lower 30s. Wind chills in the 10s and 20s along mid-upper elevation mountain ridges ( coldest at highest elevations ).
A period of moderate-heavy snow remains possible, especially in upper elevations where moderate snow has recently been falling on High Knob ( since 3:00 AM ), but trends have been for the most signficant snow band to remain just west and northwest of the Virginia-Kentucky stateline ( northwest of Pine Mountain ).
This Morning Through This Afternoon
Any early snow giving way to flurries, then mostly cloudy skies. Winds becoming variable & light ( generally less than 10 mph ). Temperatures varying from the upper 20s to the upper 30s ( coldest at highest elevations ). Milder in lower elevations toward the Tri-Cities.
Tonight Into Wednesday Morning
Cloudy with snow showers developing. A period of moderate to heavy snow possible. Winds NW-N 5-10 mph, with higher gusts, along mid-upper elevation mountain ridges. Temperatures dropping into the 20s to lower 30s. Wind chills in the 10s & 20s along exposed mountain ridges.
A new disturbance will renew snow showers tonight, with light to perhaps moderate accumulations ( in favored upslope locations ) expected into Wednesday morning, especially for locations along and north of the High Knob Massif and Tennessee Valley Divide.
Weather Discussion ( February 15-16 )
I heard a friend of mine call this the Valentine’s Slop Storm, and that is likely as good of name as any for what has been a royal pain to deal with both underfoot and forecasting.
As of 2:00 AM, trends continued toward a change to wet snow but with the most significant accumulations more likely along and west to northwest of Pine Mountain, so that is where I have placed the highest risk for up to 4″ or more of snow. It will be interesting to see how it plays out.
Sandlick Elementary School in Birchleaf – Up To 2 AM on February 16, 2016
This has been a border-line freezing rain event throughout the mountain hollows of Dickenson County, and colder hollows in Wise County, with official temperatures in Clintwood holding steady at 32 degrees ( around 33 degrees in Birchleaf ).
Lonesome Pine Airport In Wise Up To 1:55 AM Tuesday ( February 16 )
Go up more than 1,000 vertical feet higher in elevation and temperatures have been in the 40s, even with the 2 degree or so warm bias at Lonesome Pine Airport, readings have been around 10 degrees or more warmer than adjacent mountain hollows.
Black Mountain MesoNET Up To 2:15 AM Tuesday ( February 16, 2016 )
Continue upward 1347 vertical feet above Wise and temperatures on Black Mountain have now dropped below freezing again after holding steady in the upper 30s for a good while.
Up on the High Knob Massif an initial transition from rain to freezing rain had turned to snow around 3:00 AM with a temperature of 29 degrees ( moderate to heavy snow was falling by 3:30 AM ).
Big Stony Creek – February Stream Level Graph To 2:15 AM on Tuesday
Well over 2.00″ of total precipitation had fallen, as of 2:15 AM on Tuesday, at Big Cherry Lake Dam but had not yet ( at least ) generated a strong rise on adjacent Big Stony Creek. This indicated that the deep snowpack has been absorbing and holding much of the rainfall ( with major shrinkage of the snow depth within orographic clouds and rainfall ).
Another round of snow develops tonight into early Wednesday with a clipper-like system.
