ALERT For Strong & Gusty SSW to SW Winds Across Middle-Upper Elevation Mountain Ridge & Plateaus Into Tuesday Morning
*Light freezing rain may be possible in sheltered mountain valleys by the predawn-morning hours of Tuesday, as well as on cold road surfaces running along northern slopes. Caution Is Advised.
Fog Will Become Possible Above Cold Snow Surfaces
*Drizzle will change to freezing drizzle Tuesday Night into Wednesday Morning. The Freezing Level will drop from the summit level of the High Knob Massif Tuesday evening to elevations of Norton-Wise by around 10 PM-Midnight.
Overnight Into Mid-Morning
Mostly cloudy. A chance of light showers by morning. Possibly freezing in sheltered valleys and on northern slope roads. Windy or becoming windy on exposed mid to upper elevation mountain ridges & plateaus. SSW-SW winds 10-25 mph, with higher gusts, along ridges-plateaus at middle elevations. SSW-SW winds 20-30 mph, with gusts of 40 to 50 mph, on upper elevation mountain ridges. Large vertical temperature spread varying from lower to mid 20s in colder mountain valleys ( tending to rise overnight ) to 30s-lower 40s on exposed ridges & plateaus. Wind chill factors in the 10s and 20s ( coldest at highest elevations ).
Mid-Morning Through This Afternoon
Rain showers, with a period of rain, likely. Chilly & raw with fog possible. Winds SSW-SW shifting W-NW around or after sunset at 5-15 mph below 2700 feet. SW to WNW winds 10-20 mph, with higher gusts, on ridges above 2700 feet. Temperatures mainly in the upper 30s to lower 40s. Wind chills in 20s and 30s ( coldest at highest elevations ).
Tonight Into Wednesday Morning
Low clouds & areas of fog. Turning colder ( inversion developing ). Light rain & drizzle to freezing drizzle late. Freezing fog along some middle to upper elevation ridges. WNW-NW winds 5-15 mph. Temperatures falling through the 30s into 20s, with upper 10s at highest elevations by morning. Wind chills falling into 10s to low 20s overnight into morning, with single digits & 10s at highest elevations.
Weather Discussion ( January 25-26 )
My Afternoon Update
Just as I had in my forecast, it has been a chilly, raw day with widespread areas of fog ( especially in valleys ) over the cold snowpack with temps in upper 30s to lower 40s.
At least wind gusts of 20 to 40+ mph, which dominated the overnight along many mid-upper elevation mountain ridges, decreased this afternoon ( it remains gusty atop High Knob ).
The official day-time ( since Midnight ) MAX temperature in Clintwood has been 38.6 degrees, with 37 degrees at 4:00 PM beneath low clouds and shallow areas of fog above snow.
The fog over snow has been widespread as the milder air runs across its cold surface. Shallow in comparison to the orographic clouds ( fog ) obscuring upper elevations amid the High Knob Massif where snow remains much deeper.
While the air temperature of 37 degrees on Eagle Knob is about the same as down in Clintwood, the difference is 20-30 mph SW wind gusts which are making it feel like 20s atop the massif ( and along some of our middle elevation mountain ridges like Sandy Ridge ).
My Overnight Discussion
Strong SW winds began increasing at highest elevations during Monday afternoon, with 30-40+ mph gusts common, to set the stage for nice orographic waves around sunset.
It would be rare to have air flowing across the High Knob Massif that is this strong, with moisture present, and not form waves.
Note the nice lenticular shape of these wave clouds.
A battle between strong cooling over the snowpack and the pressure gradient allowed for a drop in wind speeds after sunset into early evening, as cooling prevailed initially.
The general evening trend has featured progressively stronger wind gusts dropping downward onto middle elevation ridges amid an increasing pressure gradient.
This has begun to influence the elevation of Wise.
The strongest winds will lift northeast along the Cumberland range overnight into Tuesday morning.
Many mountain valleys have, by contrast, dropped into the 20s with drainage flow and calm-light winds. Temp rises are expected with increased clouds and increased vertical mixing. The chance of a little light rain and some valleys remaining at or below freezing must be respected into morning; although, this does not look widespread.
As noted previously, ground-road surfaces are cold, especially those on northern slopes which receive little to no sunshine. This increases the chance that icing could occur on contact in places.
As this beautiful photograph by my friend Rodney Parsons illustrates, snow cover remains widespread and as this air mass saturates today there will be potential for fog to form as its cold surface comes into contact with a new air mass from the Deep South bringing rain ( while this will be most likely across upper elevations, it could occur into portions of our lower-middle elevations along the Cumberlands ).
As air turns colder tonight behind the passage of an evening cold front moisture becomes shallow and trapped beneath a developing inversion. This tends to support low clouds-fog and drizzle that could change into freezing drizzle from top down through this evening into the overnight.
The freezing level will begin at the High Knob Massif summit level and drop downward over time to the elevations of Norton-Wise by around 10 PM-Midnight, then into lower elevations during the overnight period into Wednesday morning.
If the inversion holds, as the high-resolution NAM Model shows, low clouds will be hard to shake on Wednesday…especially along and north to northwest of the High Knob Massif-Tennessee Valley Divide on NW-N air flow. Stay tuned for updates.