ALERT For Strong SSE-SSW Winds Developing During Tuesday Night Into Wednesday
A strong pressure gradient between retreating arctic High pressure and developing Low pressure will drive strong SSE-SSW winds across the mountains by late Tuesday through Wednesday.
Wind gusts of 40-50+ mph will generally be possible, with hurricane force gusts at highest elevations and within any breaking mountain waves. Caution for possible tree damage and power outages.
Mountain Area Forecast ( Jan 22-24 )
Overnight Into Tuesday Morning
Partly-mostly cloudy (high clouds). Large vertical temperature spread between warming ridges and bitter mountain valleys. Winds increasing to 5-15 mph, with higher gusts, on mountain ridges-exposed plateaus below 2700 feet. SSE-SSW winds 10-20 mph with higher gusts on mountain ridges above 2700 ft. Temperatures varying from single digits to low 10s within colder valleys to rising through the 20s on gusty mountain ridges. Wind chills in single digits and 10s along mountain ridges.
Tuesday Afternoon
Partly-mostly cloudy with filtered sunshine through high clouds. SSE-SSW winds 10-20 mph with higher gusts. Temperatures varying from low-mid 30s to low-mid 40s. Wind chills in the 20s and 30s, except 10s in gusts at highest elevations.
Tuesday Night Into Wednesday Morning
Mostly cloudy. Chance of sprinkles by morning. High winds developing over mid-upper elevation mountain ridges-plateaus overnight into morning. SSE to SSW winds increasing to 15-25 mph, with higher gusts, below 2700 feet. S to SW winds 20-40 mph, with higher gusts, above 2700 feet. Temperatures within the 30s to lower 40s, with any evening drops in valleys tending to rise later with strong mixing. Wind chill factors in the 20s & 30s, except colder in gusts on highest mountain ridges.
Wednesday Morning Through The Afternoon
Partly to mostly cloudy. Windy. Chance of rain showers. SSE-SSW winds 15-35 mph, with higher gusts. Temperatures varying from low-mid 40s at upper elevations to the lower-mid 50s. Low clouds developing at upper elevations within upslope areas along the High Knob Massif.
Wednesday Night To Mid-Morning Thursday
Rain. Heavy at times. Rain becoming mixed with and changing to snow by the predawn-morning. A period of heavy snow possible. SW winds shifting NW to N at 5 to 15 mph, with higher gusts. Temps crashing during the predawn-morning into mid-upper 10s to middle-upper 20s. Wind chills plunging into single digits and 10s, except below zero on highest peaks by morning. Riming at upper elevations.
Strong rises along creeks Wednesday night will be followed by a rapid temperature drop into Thursday morning. Alerts may be needed.
Accumulating snow will create hazardous travel conditions Thursday morning in locations along and west to northeast of the High Knob Massif-Tennessee Valley Divide.
A snow burst with an arctic cold front will be possible into Friday morning, with hazardous road conditions.
Previous ALERTS
ALERT For Bitterly Cold Temperatures & Dangerous Wind Chills Sunday Night Into Monday Morning
As of 5:00 to 6:00 PM on Sunday ( Jan 20 ) air temps had dropped into the single digits and 10s at middle to upper elevations along and northwest to north of the High Knob Massif-Tennessee Valley Divide.
ALERT For Icy Patches On Roads & Other Surfaces Through Monday Due To Bitter Cold Temperatures
Secondary roads continue to have icy patches or stretches with snow cover. Caution is advised.
A general 1″ to 3″ of snow accumulated across the upslope corridor of Wise & Dickenson counties.
Joe & Darlene Fields measured 2″ of snow depth at their home in High Chaparral, located 4.0 air miles east of the main crest zone at 3300 feet elevation.
Depths varied from wind swept bare ground to drifts of 6″ or more along the highest ridges of the massif, as noted above on Eagle Knob.
*Wind chill values are running dangerously cold at upper elevations, to -15 degrees ( F ) below zero or colder in gusts as of late Sunday afternoon. Extreme caution is advised.
For YEARS now I have said there is an error in temperatures at Lonesome Pine Airport. I will illustrate this for yet another year.
Compare the Lonesome Pine Airport temperatures to the closest site with live temp data that is part of the National Weather Service network, located on Long Ridge of Sandy Ridge just northeast of the Wise Plateau at an elevation nearly identical to LNP.
If we add in another site, the closest to LNP with live data from Pole Bridge Road of the Wise Plateau, and do a direct comparison of all three sites it looks like this.
This is a problem since Lonesome Pine Airport is used by main media sources ( like the Weather Channel ) and the National Weather Service to generate temp forecasts, for both air and wind chill values, and to issue advisories where temp is a critical factor.
During much of the year it goes unnoticed, but it has and continues to exist for whatever the reason might be and it is not the only AWOS to be reading warm in the United States versus true air temperatures.
Upcoming Weather ( January 21-26 )
An inversion centered around 900-875 MB is expected through Monday to hold bitter temperatures over the mountain landscape, with morning air temperatures varying from single digits above and below zero in many locations ( especially those with snow cover ).
An increase in high clouds into Monday afternoon will signal the next potent system poised to impact the mountains by later Tuesday into Wednesday.
Monday afternoon temps will vary from mid 10s at upper elevations to the middle 20s ( except somewhat warmer toward the south into the Tri-Cities ).
Both the European and WRF high-resolution models are forecasting a potent low-level jet of ROARING winds to develop Tuesday Night into Wednesday.
Current speeds of 60+ knots are being forecast at the summit level of the High Knob Massif, with a positive mountain torque setting developing in a tightening pressure gradient across the Appalachians.
*Analogous in some ways to the negative mountain torque setting that is currently driving strong NW winds across the mountains, producing highest speeds along the Blue Ridge versus this warm advection setting that will be producing highest wind speeds along the Cumberland Mountains by Tuesday Night into Wednesday Morning.
Another significant precipitation event is expected Wednesday into Thursday, with more heavy rain that will change to snow. Due to retreating arctic air the initial precipitation type near the surface may be an issue before a change to rain.
A low pressure wave developing along another potent cold front will need to be closely watched for possible formation of a snowband or enhancement of snow on westerly-northerly component flow by Wednesday night into Thursday morning.
