ALERT For Widespread Frost Across The Area, And A Hard Freeze In Mountain Valleys, Friday Night Into Saturday Morning ( Another Frost-Freeze Is Likely In Mountain Valleys Saturday Night-Sunday Morning ).
*Smoke From Forest Fires In Kentucky & Along The Cumberland Plateau In Tennessee Will Continue To Impact The Area Until Winds Shift N-NE .
Overnight Into Thursday Morning
Partly-mostly cloudy. Winds SW-W 5-15 mph, with some higher gusts, along mid-upper elevation mountain ridges. Temperatures varying from 40s to low 50s in cooler valleys to the upper 50s to mid 60s along exposed slopes-ridges.
Becoming cloudy with a chance for rain showers. SW winds shifting W to WNW at 10-20 mph, with some higher gusts. Temps varying from low-mid 60s in upper elevations to the upper 60s to lower-mid 70s.
Thursday Night Into Friday Morning
Rain showers & gusty winds in the evening. Partial clearing into the morning. WNW winds shifting N-NE at 10-20 mph, with higher gusts, decreasing during the morning. Temps dropping into the 40s to lower 50s.
Sunny. Seasonally cool. N-NNE winds 5-15 mph, with some higher gusts. Temperatures varying from 40s in the upper elevations to the mid-upper 50s.
Friday Night Into Saturday Morning
Clear & cold. Widespread frost. Hard freeze in mountain valleys. Localized fog possible over major lakes & rivers. Light winds. Temperatures varying from 17-23 degrees in the colder mountain valleys to upper 20s-lower 30s.
Sunny. Light WNW-NNW winds generally less than 10 mph. Temps varying from 40s to lower 50s in upper elevations to the upper 50s to lower 60s.
Weather Discussion ( Frost-Freeze )
A cold front will offer another chance for needed rainfall as it pushes over the Appalachians late Thursday & Thursday Night. Fingers crossed that amounts can at least locally over-achieve in a few places; otherwise, a widespread wetting of fallen and falling leaves can be hoped for.
Forecast models are varied in potential amounts, from less than 0.10″ to locally more than 1.00″ on the high-resolution NAM. The golden rule: “when in drought…doubt.” In other words, odds are on the lower numbers verifying until seen otherwise.
The MEAN of the 51-Member European Ensemble group is from 0.10″ to 0.50″ across the Mountain Empire ( about the same as forecast by the GFS Operational Model below ). The best rain coverage being along and west of the mountain chain, with a notable decrease along-lee of the Blue Ridge.
High Pressure builds in during Friday to generate nearly ideal radiational cooling, cold air drainage, and vertical temperature inversion development Friday Night into Saturday Morning beneath clear skies and light winds.
The center of high pressure will ideally be directly over top of southwestern Virginia into Saturday morning, with similar conditions currently forecast into Sunday morning. This is accompanied by LOW dewpoint air in the 950-850 MB layer.
The Bottom Line…Frosty COLD nights upcoming, especially in mountain valleys, with a general widespread frost being possible in nearly all locations Saturday morning ( and a HARD Freeze within many mountain valleys of the area ).
A similar set of conditions are expected Sunday morning within mountain valleys, with somewhat milder conditions in thermal belt locations ( i.e., along exposed slopes-ridges ).
Although frost and freezing conditions, with hard freezes, have already occurred in colder mountain valleys, many exposed mid-elevation ridges ( thermal belt locations ) and lower elevation river valleys have not yet recorded freezing temperatures.