Weather Headlines
Update at 10 PM Saturday (January 11)
ALERT For Strong SW-W Winds Continues Into The Overnight With Diminishing Winds By Sunday Morning
Widespread 40-50 mph wind gusts will continue into the overnight. Locally higher gusts will occur. Wind speeds are expected to decrease by the predawn-sunrise period.
Interactive AEP Power Outage Map
Strong rises are occurring on steep creeks draining the High Knob Massif and these rises will continue overnight before beginning to drop Sunday.
A general 1.50″ to 2.00″ of rainfall have caused strong rises on creeks draining the high country surrounding High Knob. Caution is advised. Another period of downpours will occur along a cold front.
Previous ALERTS
ALERT For Strong SSE-SSW Winds Late Thursday Into Friday And Late Friday Through Saturday (January 9-11)
Although recent days have already been windy, with 40-50 mph gusts common at high elevations into morning hours of January 8 (local gusts to 92 mph in the Swinging Bridge Gap on Grandfather Mountain), a more widespread and prolonged period of wind is upcoming for the mountain region.
850 MB Wind Streamlines_North America
*WIND will be a big weather factor in coming days as the pressure gradient tightens up across the eastern USA with amplification of a ridge-trough-ridge pattern.
Showers and thunderstorms, with the potential for high winds and downpours of heavy rain, will impact the mountain area Saturday evening. Remain alert to NOAA Weather Radio and your favorite media sources for possible watches or warnings.
500 MB Wind Streamlines_North America
The movement of air, commonly called wind, is a very interesting atmospheric phenomenon. You can feel and smell it (due to natural and artificial chemicals) but can not see it unless something moves or rising motion causes moisture in the air to undergo condensation.
*A potentially major outbreak of severe thunderstorms and tornadoes will impact the Deep South during Friday into Saturday (January 10-11). A squall line of strong to severe thunderstorms will approach the Appalachians from the west-southwest by later Saturday.
An increasing temperature gradient across the North America continent, between the northern Rockies and eastern USA, will drive not only wind but anomalous temperatures and warmth for deep convection.
While snow has been melting, some slick areas on roads remain at highest elevations in the High Knob Massif.
Snow will become a memory into this weekend as anomalous warmth spreads across the Appalachians.
Detailed Mountain Area Forecast
Tonight Into Thursday Morning
Mostly clear and seasonally cold. Some increasing high clouds toward morning. Increasingly large vertical temp spread between frosty valleys and milder ridges. Calm valley winds with breezy-gusty W-NW winds 5-15 mph, with higher gusts on mountain ridges-exposed plateaus, decreasing overnight. Minimum temperatures varying from 10s in colder valleys at upper elevations to the 20s, except rising through the 30s on exposed middle-upper elevation mountain ridges (following initial drops).
A change from neutral to warm advection (as visually indicated aloft by increasing high altitude clouds) will allow temperatures on exposed mountain ridges to rise toward the morning hours of Thursday despite a temporary weakening of the pressure gradient.
Thursday Afternoon
Thickening high clouds. Becoming windy. SSE-S winds increasing to 10-25 mph, with higher gusts, below 2700 feet. S-SW winds increasing to 15-30 mph, with higher gusts, above 2700 feet. Max temperatures varying from 40s at upper elevations to the low-middle 50s. Wind chill factors in the 30s to lower 40s, except locally colder in gusts on highest peaks.
Warm advection increases aloft Thursday and the thickening of high clouds at this low sun angle time of year will be a factor to monitor regarding afternoon air temperatures. Ideally, they would be cooler than given above but I have allowed for downslope compression and warming leeward of the windward slopes and mountain barriers to offset the cooling due to decreased insolation through thickening clouds. High, thin clouds contribute more to the natural Greenhouse Effect and tend not to hinder warming until their optical thickness increases as forecast by high resolution models for Thursday afternoon within the 475-225 MB layer of the troposphere. Upslope locations, by contrast, in the High Knob Massif will remain chilly with increasing wind chills combining with decreasing insolation.
Thursday Night Into Friday Morning
High clouds. Windy. SSE-S winds 15-30 mph, with higher gusts, on mountain ridges and exposed plateaus below 2700 feet. S-SSW winds 25-40 mph, with higher gusts, on mountain ridges above 2700-3000 feet. Temperatures in the 30s and 40s, except locally colder in the most highly sheltered valleys (where air temps may fall toward freezing or below then quickly rise with mixing).
If the gradient increases enough by early evening it will hinder PBL decoupling of valleys, with the ones I am allowing for possible, not certain, initial drops being those embedded within the Russell Fork-Levisa Fork basins where lower elevations beneath the Tennessee Valley Divide tend to be more sheltered than valleys embedded within dissected terrain at upper elevations (where the gradient will be stronger and decoupling less likely to nearly impossible due to strong turbulent mixing). This scenario can be applied to other complex terrain locations across the Mountain Empire, but tends to be more widespread in terrain along and just northwest of the Cumberland-Allegheny Front due to its geomorphology.
Friday Morning-Early Hours Of Sunday
While showers will become possible by later Friday and Friday night (likely along eastern slopes of Blue Ridge by earlier Friday), rain with a chance of thunderstorms will become most likely by later Saturday into early hours of Sunday along the western slopes of the Appalachians. A squall line of strong-severe thunderstorms will approach from the west-southwest and will need to be monitored.
Strong pressure gradient winds will be complicated by local mountain wave winds in favored breaking zones along the northwest-north sides of the major mountain barriers (e.g., Powell Valley and Pine Mountain of Wise County to the Clinch River Valley of Russell-Tazewell counties into the leeward zones of eastern Tennessee.
Second Storm Brings Heavy Rainfall Potential
A second storm system will spread rain back across the mountains by later Monday into Tuesday, with a heavy rainfall potential.
Much Colder Pattern In Extended Range
A much colder pattern returns during the week of January 19-25, with potential for conditions to turn extreme in opposition to current anomalous warmth.