112017 Forecast

Mountain Area Forecast ( Nov 20-23 )

Overnight Into Monday Morning

Upslope clouds giving way to clearing skies.  Cold.  NW-W winds diminishing to 5-10 mph, with some higher gusts, on middle-upper elevation mountain ridges.  Temps dropping into the low-mid 10s to low-mid 20s, except locally colder in high elevation valleys with adjacent snow cover in the high country of the High Knob Massif.  Wind chills in the single digits and 10s along high mountain ridges.

Monday Afternoon

Mostly sunny ( some increasing high altitude ice crystal clouds ).  Winds becoming SSE-SW at 5-15 mph, with some higher gusts along mountain ridges.  Temperatures varying from the mid-upper 30s to the upper 40s to low 50s ( coldest at highest elevations ).  Wind chills in the 20s to lower 30s in upper elevations.

Monday Night Into Tuesday Morning

Partly cloudy ( high clouds ).  Large vertical temperature spread developing between gusty ridges and the sheltered mountain valleys.  Winds SSE-SSW at 5-15 mph, with some higher gusts, on mountain ridges-exposed plateaus below 2700 feet.  Winds SSW-SW 10-20 mph, with higher gusts, on mountain ridges above 2700 feet.  Temperatures varying from 20s within colder valleys to upper 30s to lower 40s on gusty mountain ridges.  Wind chills in the 20s to lower 30s.

Tuesday Afternoon

Becoming mostly cloudy by mid-late afternoon.  Windy.  SSW to SW winds 10-20 mph, with higher gusts.  Temps varying low-mid 40s to the lower-middle 50s ( coldest in upper elevations ).  Wind chills in the 20s and 30s at upper elevations, and in the upper 30s to mid 40s along middle elevation mountain ridges-plateaus.

Tuesday Night Into Wednesday Morning

Cloudy with a chance of rain showers or sprinkles.  Flurries possible at highest elevations by morning.  Turning colder.  SW winds shifting NW at 5-15 mph, with higher gusts, on middle-upper elevation mountain ridges.  Temperatures falling into the upper 20s to lower 30s highest elevations to the upper 30s to lower 40s.  Wind Chills in the 10s and 20s at upper elevations.

Wednesday Morning Into Wednesday Afternoon

Low morning clouds, with a chance of flurries, giving way to afternoon clearing.  Colder.  Winds N at 5-10 mph, with some higher gusts.  Temperatures holding steady or slowly falling in the 30s to lower 40s, except in upper elevations where temperatures will remain around  or below freezing and fall during mid-late afternoon.

Wednesday Night Into Thanksgiving Morning

Clear & unseasonably cold.  Light winds.  Large vertical temperature spread developing between frigid mountain valleys and ridges.  Temperatures varying from the 10s in mountain valleys to the 20s on mountain ridges, except single digits possible in coldest valleys at upper elevations versus temperatures rising to around freezing along the highest mountain ridges.

Thanksgiving Afternoon

Partly cloudy ( increasing mid-high altitude clouds ).  Chilly.  Winds SSW-WSW at 5-10 mph, with some higher gusts on highest mountain ridges.  Temperatures varying from the 30s to around 40 degrees in upper elevations to the 40s to around 50 degrees in middle-lower elevations. Warmer south into the Great Valley.


Weather Discussion ( Cold Turkey Day )

Wednesday Night Update

The most favorable cooling conditions of this early cold season to date have developed over the mountains this evening with current dewpoints below zero ( F ) in upper elevations of the High Knob Massif and Black Mountain.

Black Mountain Mesonet

As of 11:00 to 11:30 PM air temperatures as cold as the 10s to lower 20s are already occurring from the High Knob Massif south to Shady Valley in northeastern Tennessee ( in valleys with much milder conditions along ridges as a large vertical temperature spread continues to develop ).

NAM Model Forecast Sounding Above Wise at 7 AM Thanksgiving

The entire atmospheric column ( above ) will be bone dry through morning, with light winds, before some high to mid-level moisture begins to increase by later during Thanksgiving Day.  Have a great Holiday.


Tuesday Afternoon Update

High Knob Massif Webcam – University Of Virginia’s College At Wise

It has been a windy Tuesday across the mountain landscape, with higher speeds than I predicted in some places.  Temps have varied from middle 40s atop the High Knob Massif on brisk upslope flow to lower 60s in Clintwood on downslope.

Black Mountain Mesonet – Ending At 10:40 AM Tuesday

Factor in the strong winds and conditions have felt like the 30s all day ( even 20s in stronger gusts ) in the high country, which has been a factor, indeed, for hunters in the woods.

Snow has now melted except for upper north slopes where some lingers in the woods at heads of the High Knob Lake and Big Cherry Lake basins.

Black Mountain Mesonet – Ending At 1:40 PM Tuesday

Temperatures reached mid-upper 50s in the Wise area, but again never felt that warm due to these gusty SW winds.

Lonesome Pine Airport In Wise

My updated forecast into Thanksgiving has few changes, with increasing clouds and the chance of a sprinkle or high elevation flurry tonight as the next cold front passes.  This will introduce colder air Wednesday and, after low clouds dissipate, will set the stage for a very cold night into the morning of Thanksgiving as conditions become prime for radiational cooling and cold air drainage.

For hunters in the high country expect a large vertical temp change to develop into Thanksgiving Morn, between frigid valleys and temperatures that rise toward freezing along highest mountain ridges as a westerly breeze develops ( * ).

*Anyone camping in high valleys should be prepared for temps that drop into the 10s, with coldest valleys making a run at the single digits on Thanksgiving Morning.  Bundle Up for certain!


Previous Discussion

 Following a dynamic system that brought wind damage and power outages to the mountain area, and sticking snow above 3000 feet in the High Knob Massif, a quieter pattern is taking shape into Thanksgiving Day.  Another cold front, with building High Pressure, will set the stage for a very cold Thanksgiving Morning.

High Knob Massif Webcam – University Of Virginia’s College At Wise
Reference Orographic Forcing Season on the High Knob Landform for information on how orographics have been generating some interesting and varied weather conditions during November.

Roaring wind gusts Saturday topped 50 mph in places, with numerous power outages into Saturday Night-early Sunday from the Cumberland Mountains west across Kentucky.

Peak Gusts Courtesy Of Jackson, KY NWS Forecast Office

Clintwood 1 W NWS was out of electricity for 16 hours, with some locations out longer in Dickenson and Wise counties.

Sunday Morning ( Nov 19 ) Snow In High Chaparral of High Knob Massif

Rain turned to snow overnight into Sunday morning, with sticking mainly at elevations above 3000 feet where locally 1″ to 2″ fell at highest elevations above 3500 feet.  A total of 0.90″ of precipitation was measured at the City of Norton Water Plant up to 9 AM Sunday, with a trace of snow.

European Model 850 MB Analysis At 7 AM Sunday – November 19, 2017

Temperatures held in the 20s all day Sunday atop the high country, where a light coating of snow continues to cover the ground at present.  Upslope clouds have been slow to break, but dry air transport should overcome clouds that are currently being generated by forced lifting of air.

European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 1-5

A colder than average temperature pattern is looking to rule the next week to 10 days, but no big storms are being currently shown.  A large system, that could be a potential big deal storm for the eastern USA is shown developing far to the south over the Gulf of Mexico and Florida, but this is expected to lift out far enough east to have limited impacts on the mountain region.  Stay tuned should this change by Black Friday into the upcoming weekend.

European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 6-10

Building High Pressure, with very low dewpoint air of true arctic origin, will set the stage for a very cold night heading into Thanksgiving Morning as skies clear and winds calm.

Happy Thanksgiving To Everyone!