Mountain Area Forecast ( Jan 21-24 )

An Alert For Development Of A Major Storm System, With Deep Low Pressure, Is Now In Effect From Late Sunday Into Tuesday Morning. 

A powerful low pressure will develop along the Appalachians by late Sunday into Monday.  Showers & thunderstorms Sunday will give way to the development of heavy rainfall Sunday Night into Monday, with significant rainfall amounts expected.

Strong rises on streams will be likely into Monday.  Folks living & driving through low-lying and flood prone locations will need to remain alert for changing conditions.

An increase in wind speeds and colder air will develop by late Monday into Tuesday, with a change from rain to accumulating snow at elevations above 3500 feet. 

Overnight Into Saturday Morning

Mostly cloudy ( high clouds ).  Areas of valley fog possible.  Winds SSW-SW at 5-15 mph, with higher gusts, on ridges & plateaus below 2700 feet.  SSW-SW winds 10-20 mph, with higher gusts, on upper elevation mountain ridges.  Temps varying from 30s to around 40 degrees in valleys to the upper 40s to low-mid 50s on gusty mountain ridges.

Saturday Afternoon

Increasing clouds with a chance for showers or steady rain by middle to late afternoon.  Unseasonably mild.  Light SE-S winds at mostly less than 10 mph.  Temperatures varying from upper 40s to lower 50s at highest elevations to the upper 50s to lower 60s.

Saturday Night Into Sunday Morning

Mostly cloudy.  Chance of showers.  SE-S winds increasing to 5-15 mph, with some higher gusts along mountain ridges by morning.  Temperatures in the 40s to lower 50s.  Areas of dense valley fog.

Sunday Afternoon

Mostly cloudy.  A chance of showers & thundershowers.  Mild.  ESE-SSE winds at 10-20 mph, with some higher gusts, especially across middle-upper elevation mountain ridges & plateaus.  Temperatures from the 40s to lower-middle 50s, coolest at the highest elevations.

Strong water level rises on streams will be possible into Monday.  Folks living and driving through low-lying, flood prone locations will need to remain alert to changing conditions.

Sunday Night Into Monday Morning

Rain developing.  Becoming windy.  Heavy rainfall totals.  Winds shifting from easterly to northerly into morning.  Wind speeds 10-20 mph, with higher gusts, on mid-upper elevation plateaus-ridges.  Dense fog ( orographic clouds ) at mid-upper elevations.  Temperatures dropping into the 40s.  Wind chills falling into the 30s in upper elevations.

Monday Afternoon

Rain & showers.  Low clouds with dense fog at elevations above 2500-3000 feet.  Patchy fog at lower elevations.  NW-N winds 10-25 mph with higher gusts.  Temperatures falling into the 30s to low-mid 40s ( coldest at highest elevations ). Wind chills dropping into the 20s & 30s.

A change from rain to snow is expected in upper elevations by late Monday into Tuesday AM.  Accumulations of 1-3″ are expected at elevations above 3500 feet, with 3-6″+ at elevations above 4000 to 5000+ feet in the southern Appalachians.  Slushy to hazardous driving conditions are expected at these high elevations.

Monday Night Into Tuesday Morning

Rain & showers.  Rain changing to snow at the highest elevations.  Winds NW-N at 10-25 mph, with higher gusts.  Dense fog at elevations above 2500-3000 feet, becoming freezing fog at elevations above 3400 feet.  Temperatures dropping into the upper 20s to mid-upper 30s ( coldest at highest elevations ).  Wind chills in the 10s and 20s ( again coldest at highest elevations ).

A storm system tracking across mid-continent will push milder air briefly back into the mountain region by the middle of next week,  before temperatures crash during late week to mark the start of a prolonged wave of cold conditions.

Weather Discussion ( Major Storm )

Saturday Night Update

The strongest low pressure of the winter season to date will be impacting the mountain region Sunday into Tuesday AM, with home barometers expected to plunge toward 29.00″ .

Any time pressure has reached that low in the past, strong winds develop as the center begins moving away with rapidly rising air pressures as air flow rushes across the mountains to fill the “void” of low pressure ( i.e., the atmosphere works to achieve balance ).

Although varying at the surface with details, models remain fairly consistent at upper levels.  Past climatology says that significant weather impacts will occur with this type of storm development, which will present an array of conditions varying from showers and possible downpours in thunderstorms Sunday to heavy rain Sunday Night into Monday.  Winds increase and air turns colder later Monday as barometric pressure begins rising rapidly as the storm center shifts east.  Rain turns to accumulating snow at upper elevations ( cold air is limited, so this will be a strongly elevation biased event with respect to snow accumulations ).

Previous Discussion

This is the “quiet” before major storm development occurs by late weekend into early next week over top of the great southern Appalachians.

The energy responsible for this major storm system is just entering the western USA, and will track eastward across the southern states this weekend.

Models are in excellent agreement with the wave developing a negatively tilted ( from NW to SE ) upper trough, with strong low pressure development from the surface upward to 500 MB by late Sunday into Monday.

A couple of different low pressure centers are currently forecast to give way to rapid development of a deep, strong low center over the southern Appalachians early Monday.  It will be important to check back as new model runs come out through the next 24-hours.

The Friday evening ( 00z ) run of the European Model has a 984 MB ( 29.06″ ) low near the Tri-Cities at 1:00 AM Monday.

Either scenario, by the NAM or European, would create a high impact upon the mountain area with strong winds and heavy to potentially excessive rainfall ( enhanced by orographic forcing along the Cumberland Mountains and TN-NC border area ).

Since the wavelength between major waves is relatively short, only a brief window of opportunity will exist from Monday afternoon into Tuesday morning for a possible transition to snow at mid-upper elevations ( forced by a combination of dynamic + upslope + advective cooling of the vertical column…before warm air advection aloft develops in advance of the next mid-continent system ).

The Bottom Line:

Major Storm Development is expected by late Sunday into Monday with deep low pressure forming over top of the southern Appalachians.  Heavy rain and strong water level rises on streams will be possible.

Folks living & driving through flood prone, low-lying areas will need to remain alert to changing conditions.  Strong winds will also develop, especially at middle-upper elevations.  In addition, a change to wet snow is being monitored for upper elevations by later Monday into early Tuesday ( with snow levels and any possible amounts yet to be determined ).

Mountain Area Forecast ( Jan 16-19 )

Several Significant To Major Storm Systems Will Be Impacting The Mountain Region During The Next Five To Ten Days, And Beyond In Time, With A Colder Trend Developing During The January 23-31 Period.

Strong rises on streams will begin to become more of a concern during this stormy pattern.  Folks living and driving through low-lying, poor drainage and flood prone locations will need to keep alert of changing weather conditions.  Stay tuned for updates.

ALERT For Dense Fog Continues Into Monday Morning

A very moist, saturated atmosphere will support widespread dense fog into Monday morning.  Visibility will drop to a quarter mile or less in the more dense areas of fog.  Caution is advised.

Overnight Into Mid-Morning Monday

Low clouds with widespread dense fog.  A chance for drizzle.  Winds SW to W at 5-10 mph, with some higher gusts, along middle-upper elevation mountain ridges.  Temperatures widespread in the 40s to around 50 degrees.

Monday Afternoon

Partly cloudy & unseasonably mild.  Winds SSW-SW at 5-10 mph, with higher gusts.  Temperatures varying from low to mid 50s in upper elevations to the lower-middle 60s.

Monday Night Into Tuesday Morning

Cloudy.  Becoming windy with a chance of showers and downpours overnight into morning.  Thunder possible.  Winds S-SW at 5-15 mph, with higher gusts, on mountain ridges & plateaus below 2700 feet.  Winds SW 15-25 mph, with higher gusts, on mountain ridges above 2700 feet.  Mild with temperatures in the upper 40s to low-mid 50s.  Dense fog redeveloping along upper elevation mountain ridges ( locally in other locations ).

Tuesday Afternoon

Low clouds.  Windy.  Showers redeveloping, with a chance of thunder ( especially by late ).  SW winds 10-20 mph with higher gusts.  Dense fog along upper elevation mountain ridges.  Temperatures from around 50 degrees at highest elevations in the High Knob Massif to the upper 50s to middle 60s ( warmest in lower elevations ).

Tuesday Night Into Mid-Morning Wednesday

Showers with a chance of thunder.  Downpours likely.  Gusty SW winds at 10-25 mph, with higher gusts, shifting WNW by morning and decreasing to 5-15 mph.  Mild through the overnight then turning colder during morning.  Temps widespread in the 50s, then dropping into the 40s and 30s during the predawn to mid-morning period ( coldest at the highest elevations ).  Areas of fog with widespread dense fog across the upper elevations.  Wind chills developing by morning with values dropping into the 20s and 30s.

Updated: Wednesday Afternoon

Partly to mostly cloudy ( cloudier toward the north and northwest of Wise ).  Chilly.  Winds WNW-NW at 5-10 mph, with higher gusts.  Temperatures varying from upper 30s to around 40 degrees at highest elevations to the mid-upper 40s to around 50 degrees ( warmer southward into valleys of the Clinch, Powell, Holston rivers ).

Wednesday Night Into Thursday Morning

Mostly clear during the evening, then increasing high altitude clouds overnight into morning.  Areas of fog possible, especially at lower-middle elevations.  A large vertical temperature spread developing between valleys & ridges.  Light & variable winds below 2700 feet.  Winds SW to WNW at 5-15 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures varying from low-mid 20s in high valleys to the 30s, except readings rising into 40s on higher elevation ridges by predawn-morning.

The return of a colder, wintry pattern is being monitored for the January 23-31 period.  This could begin with a major storm system, featuring high winds and a heavy rainfall to high elevation snow potential.  Stay tuned for later updates.

Weather Discussion ( Active Pattern )

Wednesday Morning Update

Low clouds are breaking up along the southeast edge of a large cloud shield, so I have updated my Wednesday PM forecast to account for this current trend.

If this trend continues, afternoon temperatures will be a little milder and sunshine more abundant.  A low cloud deck will likely remain very close by, near the Virginia-Kentucky stateline, such that conditions will vary significantly over short distances along the U.S. 23 corridor.

Turbulent mixing, enhanced by mountain waves, appears to have been able to mix out a relatively narrow inversion just above the summit level of the High Knob Massif to open up clouds.  To the northwest, by notable contrast, where mountain waves are lacking, a solid deck of clouds is continuing to hold.

Monday Evening Update

A stormy weather pattern is upcoming for the mountain region during the next 1-2+ weeks.  It is important to begin highlighting this now, as the first wave will start impacting the mountains overnight into Tuesday ( the weakest wave ).

The European Ensembles remain very consistent day after day in the upcoming forecast setting, with blocking taking shape near Hudson Bay and a storm train of waves moving across the USA from west to east beneath it.

As I have already noted, many days ago, the combination of Pacific Ocean moisture ( mid-upper levels ) & Gulf of Mexico moisture ( low-levels ) with orographic forcing will make upcoming systems productive precipitation producers.  Given all the wetness of the past 7 weeks, an increasing threat for too much water will have to be respected.

As the EPO trends negative by around January 23, it will join a +PNA to help a colder pattern to develop.  Until then rain will continue to be the major precipitation form.

Previous Discussion

A very moist atmosphere continues to grip the mountain area with widespread dense fog at middle-upper elevations across Wise and Dickenson counties at the present time.

The lower atmosphere has become saturated through a deep layer.

Fog has now been dense at high elevations in the High Knob Massif for the past 6 days  Only a minor break occurred when the highest elevations got briefly above the low cloud deck.  Another break, if lucky, could occur Monday afternoon with partly cloudy skies.

An unseasonably warm air mass for this time of year is widespread across the USA and western-central Canada.

The NWS HRAP Precipitation Estimate is too low for the City of Norton and High Knob Massif area ( above ), where totals during the November 28 to January 12 period have varied from 12.80″ in the City of Norton ( official NWS rain gauge ) to as much as 18.00″ in upper elevations of the High Knob Massif.

This is part of a wet winter season pattern that has produced a general 10.00″ to 15.00″+ of total precipitation in the High Knob Massif area ( including the City of Norton ) since the beginning of December 2016 ( several inches more if including the final couple of days in November ).

Several important weather systems will be impacting the mountain region through the next week to 10 days, with number one upcoming for late Tuesday into Wednesday when gusty showers & possible thunder will give way temporarily to a drop in temperatures.

As the wet pattern rolls onward this week, signals for a major-league storm system continue to show up in models for the final week of January ( beginning around the Jan 22-23 period based upon current timing ).  This occurs as high latitude blocking develops over Canada with falling 500 MB heights to the south.  Confidence in this is increased since major changes are also expected in the stratosphere and polar vortex positioning through the end of January.

A setting like this typically produces a series of storms, so a very active pattern is upcoming into the extended that will feature a notable trend back toward wintry conditions in the final week of January.

Stay tuned for updates.

Mountain Area Forecast ( Jan 13-15 )

ALERT For Dense Fog Development Into Friday AM For Locations Along and N-NE Of The High Knob Massif & Tennessee Valley Divide

A frontal boundary will drop into the Cumberland Mountains and stall, with fluctuations in its position expected throughout the up- coming weekend.  Dense fog will tend to be persistent across high elevations, with intervals of dense fog at middle-lower elevations.  Intervals of showers will also occur, continuing this wet pattern.

Overnight Into Mid-Morning Friday

Showers developing.  Gusty SW winds shifting NNW-NNE by morning at 5-15 mph, with higher gusts.  Dense fog possible, especially at mid-upper elevations along and north of the High Knob Massif-Tennessee Valley Divide.  Temperatures dropping into the 40s.

Friday Afternoon

Low clouds.  Chilly.  Chance of drizzle or light showers.  Light & variable winds.  Temperatures in the upper 30s to middle 40s in locations along and north of the High Knob Massif & Tennessee Valley Divide ( milder to the south ).

Friday Night Into Saturday Morning

 Light rain & showers redeveloping.  Areas of fog ( dense at high elevations ).  Winds shifting SSW to WSW at 5-15 mph, with higher gusts.  Temperatures steady or rising into the middle 40s to lower 50s.

Saturday Afternoon

Showers.  Gusty.  Areas of fog ( dense at high elevations ).  SSW-WSW winds 5-15 mph, with higher gusts, below 2700 feet.  Winds SW-WSW 10-20 mph, with higher gusts, along upper elevation mountain ridges.  Temperatures varying from upper 40s to upper 50s ( coolest highest elevations ).

Saturday Night Into Sunday Morning

Showers.  Area of fog ( dense across upper elevations ).  SW-W winds 5-15 mph, with higher gusts, possibly shifting N by morning.  Temperatures widespread in the 40s to lower 50s.

*A heavy rainfall potential continues to be monitored for next week.  Strong rises on streams could occur depending upon rain amounts.  Stay tuned for later updates.

**A major pattern change back to cold, wintry conditions is being monitored for the last week of January into the start of February.  Chances for a return to a cold, wintry pattern are increasing for the longer-term period.

Weather Discussion ( Wet Pattern )

A frontal boundary will be dropping into the mountains and stalling, with the boundary being south to north of the area throughout the upcoming weekend.  This means periods of showers and a predominance of low clouds, with dense fog being persistent and long-lived across high elevations.

As the front drops into the area by the predawn-morning of Friday the first concern becomes dropping cloud bases and the possibility of dense fog formation amid locations along and north of the High Knob Massif-Tennessee Valley Divide on upsloping northerly winds.

The high-resolution NAM Model forecast’s temperatures to drop to around 40 degrees in Wise by 10:00 AM Friday.  This would also be accompanied by dense fog.  Conditions which actually develop will be highly dependent upon the position of the frontal boundary.  The colder air will be shallow, and temperatures at middle-lower elevations north of the High Knob Massif could be cooler than at highest elevations.

Rainfall amounts from Friday through this weekend will also be dependent upon the frontal position.  A currently predicted area of heavier rains just north of the area could easily be across the Cumberland Mountains with only a tiny shift in the boundary from current model projections.

*Orographics will also be a factor, such that amounts within the High Knob Massif-Black Mountain corridor are likely to be greater than models are currently forecasting ( as recently observed ).

A continued mild, wet pattern is expected into next week with a combination of Pacific moisture ( at mid-high levels ) and Gulf of Mexico moisture ( at low levels ) setting up the potential for significant rainfall across the Ohio-Tennessee valleys & Appalachians.  Timing and details, of course, yet to be resolved ( but the pattern is relatively clear ).

Major changes in the stratosphere beyond this upcoming 6 to 10 day period signals an increasing chance for a return of colder, wintry conditions across eastern portions of the USA by the final week of January into early February.

*The shift of a developing warm pool of stratospheric air across to the North American side of the North Pole, and eastward shift of the Polar Vortex off the pole, initially suggests a change back toward more typical winter conditions.

If the European group is on target, additional changes in the flow field around the vortex will then set up the return of cross-polar flow back into the USA during early February.

**Although the stratosphere is also dynamic, with many wave influences and interactions, conditions tend to be much more stable than within the troposphere and forecast’s made outward in time also tend to be more reliable than those made within the troposphere.  By no means perfect; however, often a usable precursor for upcoming tropospheric changes.

Mountain Area Forecast ( Jan 10-12 )

An ALERT Continues For Strong SSW-SW Winds Into Thursday, With Strongest Winds Expected At Middle To Upper Elevations During Much Of This Period.

A prolonged period of very windy conditions, with high wind gusts, will be impacting the Cumberland Mountains during the Tuesday to Thursday period ( January 10-12 ).  Despite milder air working into the area, these strong winds will continue to make conditions feel cold Tuesday & chilly through Wednesday.  The strongest winds are expected to come in waves, centered on the daylight and evening hours of Tuesday as well as the Wednesday afternoon into Thursday time period.

**As moisture increases dense fog will become widespread at the highest elevations.  This will also need to be watched for at middle and lower elevations, especially within the SW Upslope Flow zone from Wise-Sandy Ridge plateaus southwest across the High Knob Massif into portions of Lee County ( and locally in other locations ) during the Wednesday-Thursday period.

Tuesday Night Into Wednesday Morning

Cloudy & windy.  A chance of evening showers, then rain developing into the overnight.  Wind driven across higher elevations.  Local downpours in the SW upslope zone.  SSW to SW winds 10-25 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet.  SSW-SW winds 20-35 mph, with higher gusts, along mountain ridges above 2700 feet.  A period of lower wind speeds into predawn hours ( then increasing again after sunrise ).  Temperatures mainly in the 30s to lower-middle 40s.  Wind chills in the 20s & 30s, except 10s highest ridges ( evening ).  Areas of dense fog developing into the overnight-morning.

*As milder, moist air comes into contact with cold, frozen ground the potential for dense fog formation will arise by the overnight-Wednesday period.  Dense fog formation is also more likely within the SW upslope flow zone where air is forced to naturally rise.  Caution Is Advised.

Wednesday Afternoon

 Windy with showers likely.  Downpours possible.  Areas of dense fog, especially in the SW air flow upslope zone.  S-SW winds 10-25 mph, with higher gusts, on mountain ridges and plateaus below 2700 feet.  Winds SW 20-35 mph, with higher gusts, on mountain ridges above 2700 feet.  Temps widespread in the lower 40s to low 50s ( warmest at the lower elevations in the downslope zone from Pound to Clintwood, Haysi & Grundy ).

Wednesday Night Into Thursday Morning

Chance of showers & drizzle.  Areas of dense fog.  Windy.  SSW-SW winds 10-25 mph, with higher gusts, on mountain ridges-plateaus below 2700 feet.  SW winds 20-35 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures widespread in the 40s.

A mild & wet pattern is expected during the next 5-10 days, with a heavy rainfall potential continuing to be monitored for next week.  Stay tuned for updates.

Weather Discussion ( Windy-Wet )

Wednesday Afternoon Update

Following a very windy Tuesday, with cold wind chills, a boundary that produced showers, local downpours, and light rain-fog changed wind directions and temporarily reduced wind speeds for a more pleasant Wednesday PM. Cloud bases even lifted briefly off all but highest peaks.

Cloud bases are lowering and winds are increasing once again as the sun is setting on this Wednesday.

Temperatures reached lower 50s at UVA-Wise through 4:00 PM, with low-middle 40s observed in upper elevations where a morning period featured wind speeds mostly under 25 mph.  This as the strongest winds are coming in waves, as predicted, with the next period of ROARING winds already underway at higher elevations.

*The warming nature of the atmosphere can be seen as temps at high elevations are just reaching their highest levels now, as the sun is setting ( the warmest temps observed since January 3 ).

Due to another period with a tightening pressure gradient I will keep my ALERT for strong S to SW winds into Thursday for middle-upper elevations of the Cumberland Mountains.  Many limbs have been blown out, so caution is advised. 

Previous Discussion

In my opinion it was a cold Tuesday. Even though temps are rising WIND was a major factor at middle-upper elevations amid the Cumberland Mountains, with 15-30 MPH sustained speeds from Wise upward in elevation ( gusts 40-50+ mph at higher elevations within the High Knob Massif, Black-Pine mountains ).  That made conditions feels like 20s-30s in Wise and 10s & 20s at upper elevations above 3000 feet.

Wind chills have consistently been in the 20s and 30s throughout Tuesday in Wise, even with Lonesome Pine Airport’s 1-2 degree F warm bias ( versus UVA-Wise and other local thermometers ).

Wind speeds only get stronger the higher in elevation you venture.

At 5:00 PM temperatures were the warmest of the day at highest elevations, and the warmest since last week, with low-mid 30s at upper elevations from the High Knob Massif to Black Mountain.

Snow remains solid, significant, and roads partially or completely covered in upper elevations of the High Knob Massif where winds sound like a JET taking off.  I still have some doubts if I will be able to take my Field Studies In Microclimatology class on a field trip into upper elevations by this weekend!  Time will tell.

Although a boundary with colder air will bear watching by Friday into this weekend ( first along western slopes of the Appalachians then down along the eastern slopes ) a much warmer pattern is clearly going to dominate most of the USA during the next 5-10 days.  This will also be a wetter pattern, with amounts needing to be monitored over time.

Periods of rain are expected, as many waves moves across the region amid fast flow aloft.  Due to the combination of both Pacific Ocean moisture ( at mid-high altitudes ) and Gulf of Mexico moisture ( at low-levels ) amounts over time could become significant.  This is what the synoptic pattern is saying versus any particular model.  Stay tuned.

The mean temperature during the next week to 10+ days will average well above “normal” for this time of year.

There are longer range signs, with expected changes within the stratosphere, that suggest a wintry pattern will return by late January into February.  More harsh weather ahead?  Time will tell amid a winter season that can not yet lock down into any given temperature regime, with wetness being the only consistent theme.

Mountain Area Forecast ( January 7-10 )

An Alert For ROARING SW Winds In Effect From The Overnight-Predawn Hours Of Tuesday Into Thursday, With Strongest Winds Expected At Middle To Upper Elevations During Much Of This Period.

**Blowing snow from the ground will be a factor overnight into Tuesday, especially at highest elevations.  Some roads will be covered in places which had previously been plowed.

A prolonged period of very windy conditions, with high wind gusts, will be impacting the Cumberland Mountains during the Tuesday to Thursday period ( January 10-12 ).  Despite milder air working into the area, these strong winds will continue to make conditions feel cold Tuesday & chilly through Wednesday.  The strongest winds are expected to come in waves, centered on the daylight and evening hours of Tuesday as well as the Wednesday afternoon into Thursday time period.  Stay tuned for updates.

Dense fog development, with wind driven rains, will also occur Tuesday Night into Wednesday, especially in locations along and southwest of the High Knob Massif & Tennessee Valley Divide.  Rain amounts of 0.50″ to 1.00″+ are expected in the SW upslope flow corridor of the High Knob Landform through Wednesday afternoon ( with added run-off from melting snow ).

*Due to frozen ground and melting snow fog development could become very dense in places and more widespread in coverage than just the upslope flow corridor ( i.e., the Sandy Ridge, Norton-Wise, High Knob Massif & Lee County zone ) as moisture increases by late Tuesday into Wednesday.

ALERT For Bitter Cold Air And Wind Chills Continues Into Sunday – Bitter Air Persisting Into Monday AM – Along With Hazardous Secondary Roads.

Bitter cold will grip the mountain landscape into Sunday.  Wind chills will continue to make bitter temperatures dangerously cold along middle to upper elevation mountain ridges, with 0 to -20+ degree below zero chill factors ( coldest along highest ridges ).

Sunday Night Into Monday Morning will offer the best conditions for extreme temperatures in mountain valleys, with diminishing evening winds.  Temperatures may again plunge to below zero in the colder mountain valleys.  I expect a large vertical temperature spread to develop into the overnight-Monday Morning as SSW-SW winds begin increasing again along higher mountain ridges ( with 20-30+ degree temperature differences between valleys and ridges becoming possible ).  The factor that may limit temperature falls being an increase in mid-high altitude clouds which may help off-set some of the radiational cooling & cold air drainage effects.

Updated: Overnight Into Sunday Morning

Increasing clouds.  Flurries and snow showers developing,  especially along and north to northwest of the High Knob Massif-Tennessee Valley Divide ( on the upslope side of the mountains ).  New snow accumulations of a dusting up to locally 0.5″ to 1.5″ .  Bitter Cold.  NW-N winds 5-15 mph, with higher gusts, on middle to upper elevation mountain ridges.  Temps varying from 5 degrees above zero to -5 below zero, except colder in any snow covered valleys that can develop calm winds.  Wind chill factors of 0 to -10 degrees below zero on middle elevation ridges, with -10 to -25 degree below zero wind chills upper elevation ridges.

Sunday Afternoon

Mostly sunny.  Some increasing high clouds possible late.  Bitter cold.  Light WNW-NW winds.  Temperatures varying from around 10 degrees at highest elevations to the upper 10s to around 20 degrees.  Wind chills below zero in gusts at the highest elevations.

Sunday Night Into Monday Morning

A rapid evening temperature drop, especially in mountain valleys.  Bitter.  Increasing high altitude clouds.  SSW-SW winds developing at 5-15 mph, with higher gusts, during the overnight-morning along higher mountain ridges. A large vertical temperature spread developing with variations from below zero in the colder mountain valleys to readings rising through the 10s into the lower 20s along exposed mountain ridges.

Monday Afternoon

Mid-high altitude clouds.  Becoming windy.  SSW-SW winds 10-20 mph, with higher gusts, below 2700 feet.  Winds SW-WSW 15-25 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures in the 20s to lower 30s, mildest in downslope locations from Pound to Grundy.

Monday Night Into Tuesday Morning

Mostly cloudy.  Windy.  SSW-SW winds 10-25 mph, with higher gusts, on mountain ridges-plateaus below 2700 feet.  Winds SW 20-30 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures varying from near 20 degrees to lower 30s.  Wind chills in the 10s to lower 20s, except single digits along high mountain ridges.

ROARING SW winds will continue and increase Tuesday, with a chance for rain showers developing.  Wind gusts of 30-50+ mph are expected in the Cumberland Mountains.

A wet and generally mild pattern, with a heavy rainfall potential, is being monitored for later next week into next weekend during the January 12-17 period.  Stay tuned for updates. 

Weather Discussion ( Bitter Cold )

Early Monday Update

Following a new dusting of snow ( up to 0.5″ on High Knob ) into early Sunday the second half of this weekend turned mostly sunny but remained very cold ( as expected ).

Sunday afternoon temperatures struggled toward 10 degrees atop the High Knob Massif and finally reached 19 degrees in Clintwood.  Better than Saturday MAXS, with Joe Carter of the City of Norton Water Plant recording a Saturday HIGH temp of just 14 degrees.  Maximums remained in single digits, of course, atop the massif.

High clouds late Sunday held off long enough to allow colder mountain valleys to plunge below 0 degrees into Sunday evening ( well below zero in high valleys ), with a “balmy” 1.7 degrees being the MIN at lower elevations in Clintwood prior to some rise with increasing clouds.

Winds will be increasing into Monday morning at high elevations, then mixing downward over time into middle and lower elevations.  By Monday Night, and especially Tuesday-Wednesday, SSW-SW winds are going to ROAR.  This will keep conditions feeling cold through Tuesday.

Previous Discussion

*Note: Due to current satellite trends and the latest model trajectories I have added redevelopment of clouds with a chance for flurries and snow showers into the overnight and Sunday morning.  New snow accumulations from a dusting up to locally 0.5″ to 1″ of fluffy snow will also be possible along the upslope side of the mountains, mainly over and north to northwest of the High Knob Massif and Tennessee Valley Divide.

Reference My 010617 Forecast for previous forecast details.

Reference My High Country Focus for information on 2016.

Reference The High Knob Landform for recent work & photos.

Bitterly cold conditions are the now the main weather factor, along with hazardous secondary roads, in wake of the first widespread winter storm impact of the season.

Storm Event Snowfall Reports For Jan 6-7
( Snow Depths On Morning of January 7 )

Clintwood NWS Station
4.6″ of Total Snowfall
( 4″ ground depth )

UVA-Wise NWS Station
4.7″ Of Total Snowfall
( 5″ ground depth )

City of Norton Water Plant
5.0″ of Total Snowfall
( 4-5″ ground depth )

Nora 4 SSE on Long Ridge
5.3″ of Total Snowfall
( 5″ ground depth )

High Chaparral of High Knob Massif
5.5″ of Total Snowfall
( 3″ to 6″+ depths )

Eagle Knob of High Knob Massif
6.5″ of Total Snowfall
( 4″ to 8″+ depths )

Wind did not become a factor in this event until the overnight-morning hours of Saturday, when increasingly gusty N winds developed across middle to upper elevations.  This helped reduce differences in total snow amounts between low-high elevations.

Temperatures tonight into Sunday Morning are very, very problematic, not due to the cold, but from a forecasting perspective since they are primed and ready to TANK.

Anyone watching me do this forecast live, during the past 1-2 hours can gather that this ( to me ) is the most difficult forecast setting there is ( outside of precip in marginal vertical columns ).  Enough high resolution data has now been collected during the High Knob Massif project at UVA-Wise, in combination with my decades of previous research in these mountains, to understand fully how delicate this setting is with UP and DOWN fluctuations in valley temperatures being typical as winds begin decoupling, then recouple and decouple, etc…it is amazing at times to both experience in person and to also follow with collected data.

*NOTE – Since I originally wrote this the forecast has been simplified by a trajectory from the Great Lakes which will allow for upslope clouds and flurries-snow showers to form into the overnight-Sunday Morning ( January 8 ).  Prior to this the trajectories were shown to just miss the area.  The best valley temp drops are now expected Sunday evening.

*With temperatures at 7:30 PM Saturday hovering around 0 degrees along high mountain ridges it does not take a rocket scientist to figure out that adjacent high valleys could tank if their winds diminish.  Especially given incoming dry air associated with High Pressure.  The key factor will be if the pressure gradient between High and Low pressure can relax by the predawn and morning hours of Sunday ( MINS could occur after sunrise  into mid-morning should that happen ).

Under these type of conditions it only takes a few hours for the literal bottom to drop out of temperatures, so I initially opened up the temperature range in my forecast to account for this.  Then I decided to just note it here, since so many factors are working against complete PBL decoupling in even deep valleys.

A check of the latest NAM Model shows that the local mountains will be close to Great Lake moisture advection  by overnight into Sunday AM, enough to reform upslope clouds, flurries and some snow showers along windward slopes.  So for these reasons, in combo with the pressure gradient, I have decided to hold temps in the 5 above to -5 below range  ( the potential for -10 to -15 below in mountain valleys is certainly there, but likely not to be realized on this night…another shot for it comes Sunday Night ).

While the wind field becomes very favorable for valleys to decouple by Sunday Night, an increase in mid-high clouds may then be the factor to keep the full cooling potential from being realized.  Stay tuned for later updates.

Mountain Area Forecast ( January 6-8 )

ALERT For Periods Of Snow Friday Into Saturday Morning With Widespread Hazardous Travel

ALERT For Bitterly Cold Conditions Friday Into Sunday

Overnight Into Friday Morning

Light snow & flurries.  Winds WNW-NNW at 5-15 mph, with higher gusts.  Temperatures dropping into 10s to around 20 degrees ( as cold as 10 degrees at highest elevations ).  Wind chills in the single digits and 10s, except below zero in gusts along upper elevation mountain ridges.  Rime formation in upper elevations.

Friday Afternoon

Periods of snow and flurries.  Bitterly cold.  Winds NW to N at 5-10 mph.  Temps  varying from lower-mid 10s in upper elevations to lower-middle 20s.  Wind chill factors in single digits & 10s ( coldest at highest elevations ).

Updated Snowfall Forecast: Friday Into Saturday

A general 1″ to 4″ of new snowfall is expected, with locally heavier totals in upper elevations of the High Knob Massif.  My target has been changed to the expected snow depth in the Norton-Wise area by Saturday, and has only been adjusted to account for new snowfall.

Target Snow Depth 5″ In Norton-Wise ( +/- ) 1″ Error Potential.  This suggests a possible range from 4″ to 6″ in Norton-Wise by Saturday ( this includes snow that fell through Thursday ).  Deeper depths will be possible in the High Knob Massif ( above 2700 feet ).

New snowfall Friday into Saturday will tend to be less toward the north, in places that received the most snow through Thursday, and greater toward the south from Norton-Wise into the High Knob Massif and adjacent Great Valley region.

Friday Night Into Saturday Morning

Periods of snow & snow showers.  Heavy at times.  Bitterly cold.  NNW-N winds 5-15 mph, with higher gusts on middle to upper elevation mountain ridges.  Temperatures varying from 0 to 12 degrees.  Wind chills from 5 above to -10 below, except -10 to -20 degrees below zero upper elevation ridges.

Saturday Afternoon

Snow showers and flurries ending.  Partial clearing possible by late PM.  Bitterly cold.  NW winds 5-15 mph, with higher gusts.  Temperatures varying from single digits within the upper elevations to 10s across lower-middle elevations.  Wind chills in the single digits above and below zero.

Saturday Night Into Sunday Morning

Mostly clear.  Bitter.  NW winds 5-15 mph along upper elevation mountain ridges.  Diminishing winds in valleys.  Temperatures varying from 5 above to -5 degrees below zero, except locally colder in mountain valleys.

Weather Discussion ( Harsh Weather )

Friday Afternoon Update

My only change is to ease the expected snow depth up a little from Norton-Wise southeast across the High Knob Massif as snowfall tonight becomes moderate to heavy before tapering to upslope snow showers & flurries.

I already had the coldest forecast of any sources, and if anything it may be even colder than I have predicted.

Around 2″ of snow is now on the ground across the Norton-Wise area, with 2-3″ in upper elevations of the High Knob Massif where significant rime has transformed the landscape into a winter wonderland amid bitter air.

A total of 2.1″ of snow was reported by Caleb Ramsey at the City of Norton Water Plant ( 2″ on the ground ) around 5:00 PM.

A total of 2.0″ has been measured in Clintwood, with locally more across northern Dickenson County ( mainly from Thursday ).

This air mass along the western side of the mountain chain is bitterly cold, with 4:30 to 5:00 PM temperatures varying from 10 degrees on Eagle Knob of the High Knob Massif and 11 degrees ( 10.6 ) on Black Mountain to 16 degrees on Sandy Ridge and 17 to 19 degrees in Norton-Wise.

Air will turned even colder into Saturday as temperatures plung toward 0 degrees at the top of the high country and to single digits to around 10 degrees at elevations of Norton-Wise and Sandy Ridge ( low-mid 10s at lower elevations ).

Temperatures during the day Saturday will remain in single digits at upper elevations and the 10s in Norton-Wise and in most of the Cumberland Mountains ( wind chills will make conditions feel even colder ).

The focus now turns to a final round of snow that is likely to become heaviest from the High Knob Massif area south and southeast.  This should push ground depths into my forecast range for Norton-Wise, and could exceed them if upslope on northerly flow becomes more of a factor with low density snowfall than models are currently indicating.

New snow accumulations tonight are likely up to along the VA-KY stateline, as past climatology of these events dictate, with a rapid diminishing of snowfall northwest of Pine Mountain and a notable gradient across the High Knob Massif area as upsloping N winds increase into the overnight and Saturday morning ( increasing amounts across the high country toward Norton-Wise ).

Travel tonight into Saturday is discouraged as bitterly cold air & snow will combine to generate widespread  hazardous travel conditions.

Previous Discussion

Reference My 010417 Forecast for previous details.

Air is turning bitter with more periods of snow upcoming into Saturday.  Places that received the most snow during Thursday, with 1-2″ in Clintwood and as much as 2″ to 5″ from John Flannagan Lake & Breaks Interstate Park into portions of Pike County, Ky., will tend to get the least.

Locations toward the south will get the most snow through Friday Night into Saturday, from Norton-Wise and the high country of the High Knob Massif southeast toward the TN-NC border and Great Valley ( where very little to no snow accumulated through Thursday Night ).

The track and moisture supply will be critical, with any shift northwest producing more snowfall across the entire area while a shift toward the southeast will restrict new snow to mainly locations toward the TN-NC border and Great Valley.  The Mountain Empire is on the fence.

*A composite of all models, including Ensembles, plus past climatology of systems embedded within this type of upper air setting suggests that accumulating snow with the main system will reach up to the Virginia-Kentucky border, then taper rapidly toward the northwest and north.  Amounts will increase toward the southeast of the VA-KY stateline, with the High Knob Massif being a local focus via upsloping northerly flow and very cold air to produce low density snowfall. 

Bitter cold is the other main story, with temperatures at just before 5:00 AM Friday varying from 12 degrees atop Eagle Knob of the High Knob Massif to 22 degrees in Clintwood ( a little milder SE toward the Great Valley ).

*Freezing drizzle has been reported into the Great Valley.

Stay tuned for later updates.

Mountain Area Forecast ( January 4-7 )

ALERT For Accumulating Snow & Hazardous Travel Developing Thursday Afternoon Into Friday Morning

Low dewpoint air moving into the Cumbeland Mountains will allow temperatures to drop significantly into Thursday Morning, followed by increasing clouds that keep temperatures cold during Thursday to set the stage for development of a moderate impact snowfall event by late Thursday into Friday.

Widespread hazardous travel conditions are expected to develop during Thursday PM-Evening into Friday Morning.  Bitter temps and wind chills will add to these hazardous conditions.

An ALERT For Accumulating Snow May Be Needed For Late Friday Into Saturday Morning As A Second Wave Impacts The Mountain Region

Overnight Into Thursday Morning

Mostly clear into the overnight then increasing high clouds.  Cold.  W-NW winds 5-15 mph, with higher gusts, becoming light.  Temps in the 10s to low-mid 20s, varying from 10-15 degrees in high valleys of the High Knob Massif to low-mid 20s along exposed middle elevation ridges.

Mid-Morning Thru Thursday Afternoon

Cloudy.  Cold.  Light winds.  Virga developing aloft, then flurries and light snow reaching the surface.  Temperatures generally varying from the 20s to the lower 30s.

Thursday Night Into Friday Morning

Snow.  Turning bitter.  Winds WNW-NNW at 5-15 mph, with higher gusts.  Temperatures dropping into 10s to around 20 degrees ( as cold as 10 degrees at highest elevations ).  Wind chills in the single digits and 10s, except below zero in gusts along upper elevation mountain ridges.  Rime formation in upper elevations.

Friday Afternoon

Morning snow tapering to flurries and snow showers.  Bitter cold.  Winds NW to N at 5-10 mph.  Temps  varying from lower-mid 10s in upper elevations to lower-middle 20s.  Wind chill factors in single digits & 10s ( coldest at highest elevations ).

Snowfall Forecast: Late Thursday to Late Friday

A general 1″ to 4″ of snowfall is expected in counties along the Virginia-Kentucky border, with locally higher amounts possible at upper elevations of the High Knob Massif ( least snowfall amounts are expected across central-western Lee County and portions of the Clinch & Holston river valleys ).

Target Snowfall 3″ In Norton-Wise ( +/- ) 1″ Error Potential.  This suggests a possible range from 2″ to 4″ in Norton-Wise during this period.  Snow Density will be lower than 10:1 in locations along & north to northwest of the High Knob Massif and Tennessee Valley Divide to generate more “fluff factor” than in locations farther to the southeast ( i.e., the snow to water ratio will be locally higher ).

Friday Night Into Saturday Morning

Periods of snow & snow showers.  Heavy at times.  Bitterly cold.  NNW-N winds 5-15 mph, with higher gusts on middle-upper elevation mountain ridges.  Temperatures varying from 0 to 12 degrees.  Wind chills from 5 above to -10 below, except -10 to -20 degrees below zero upper elevation ridges.

A second storm system lifting northeast out of the Gulf of Mexico is now forecast to impact the mountains late Friday into Saturday morning, with an update to the forecast noted above. 

Sunday & Monday morning’s ( January 8-9 ) will both feature bitterly cold temperatures, especially in mountain valleys, with single digits and sub-zero temperatures being possible.  Please stay tuned for later updates.

Weather Discussion ( Harsh Period )

Thursday Afternoon Update

An initial wave of snow dropped 0.5″ to 1″ of accumulation across portions of northern Wise and Dickenson counties into early afternoon Thursday, before waning.

I officially measured 0.5″ of snow in Clintwood, with heavier snow to the north and northeast toward Pine Mountain and Breaks Park.

Although flurries and light snow showers have occurred throughout Wise County, the lower atmosphere south of Pound has not yet been able to saturate with abundant amounts of low-level dry air.

A developing area near Middlesboro on Doppler radar is expected to be the beginning of saturation and sticking snow as it lifts northeast across Lee-Wise counties and northern portions of Scott County into this evening.

This system is coming in waves instead of one consolidated area of energy ( at least at this time ), with an initial wave impacting sites to the north while the current developing area of snow denotes a wave that will impact locations farther to the south ( e.g., Wise County which mostly missed sticking early afternoon snow ).

Conditions for snowfall will be improving into Thursday evening as a low-level wind shift to the NW-N increases upslope into the High Knob Massif area and temperatures begin to turn colder.

Meanwhile, the past several runs of the NAM Model group have become aggressive in spreading the heaviest snow across the Mountain Empire late Friday into Saturday.

The Morristown NWS Forecast Office has issued a Winter Storm Watch for later Friday into Saturday.  I will wait to this initial period passes tonight before updating my snow forecast for this second event.  There remains substantial model disagreement with respect to how much moisture reaches the area.  Stay tuned for later updates.

Previous Discussion

A harsh period of winter conditions will dominate the mountain landscape during upcoming days.  While no big winter storm is expected, the combination of bitter cold air and some snow will create the harsh conditions, especially in a season where this type of weather has been limited.

Rain showers changed to snow showers & flurries into early Wednesday with a little accumulation at high elevations in the High Knob Massif.  The most important aspect; however, was clearing skies with advection of much drier, lower dewpoint air into the mountains.  This will allow for cold conditions into the daylight hours of Thursday, as clouds increase, and set the stage for a Moderate Impact winter event late Thursday into Friday.

A huge mass of bitterly cold air will continue to move south and southeast into the mountains during the next few days. 

The NAM Model group has nearly all the snow falling with the first disturbance across the Cumberland Mountains, as the second and much bigger wave spreads snow across parts of the Deep South into the Carolina’s and the TN-NC border this weekend.  The latest European Model run ( 00z ) has cut back amounts across the board, except for the Deep South & Carolina’s ( a bulls-eye of 12″-15″ being centered mainly on the zone that got devastated by Hurricane Matthew flood waters in central-eastern North Carolina on the ECMWF ).

I always have some Error Potential factored into my snow forecast’s; however, if this reduction trend continues then totals may have to be cut back ( as it stands now, the NAM data would allow it to verify while the new European Run would make it a push to reach the lower end of the range ).

This remains true since models are forecasting at 10:1 density, and with very cold air in the vertical column + a period with moisture intersecting the prime dendritic crystal growth temperature zone the actual snow density will be significantly lower ( snow to water ratios will be higher than 10:1 ).

Regardless of snowfall amounts, conditions are going to be bitter Friday through this weekend with 0 to 10 degrees by Saturday Morning and the potential for even colder MINS, especially in mountain valleys, on Sunday & Monday AM’s.

Update: 1 AM Thursday NAM Model Run

In opposition to the last European Model run, the overnight NAM Model group has come in wetter and also now brings accumulating snow into the mountain area from the next wave tracking across the Deep South.

Clearly, the models are struggling to handle these waves embedded within fast flow aloft tracking across the USA against a huge arctic air mass to the north.

Stay tuned for more updates.

Mountain Area Forecast ( January 2-4 )

A Harsh Period Of Winter Weather Is Becoming Increasingly Likely For The January 5-10 Period

An ALERT For Accumulating Snowfall, Hazardous Travel And Increasingly Bitter Conditions Will Be Likely Issued For The Late Thursday Into Saturday Period ( With Bitter Cold Continuing Into Monday )

*I will issue a new forecast by later Wednesday.

Overnight Into Monday Morning

Cloudy.  Scattered showers.  Areas of drizzle & fog ( dense along upper elevation mountain ridges ).  Mild.  SSE-S winds 5 to 15 mph, with some higher gusts, along mountain ridges below 2700 feet.  Winds S-SW at 10-20 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures in the 40s to around 50 degrees.

Monday Afternoon

Cloudy.  Periods of showers.  Thunder possible.  Areas of fog ( dense along upper elevation mountain ridges ).  SSE-SSW winds 5-10 mph, with higher gusts, below 2700 feet.  Winds S-SW at 5-15 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures widespread in the 50s.

Monday Night Into Tuesday Morning

Periods of rain & showers. A chance of thunder.  Local downpours possible.  Areas of fog ( dense fog along upper elevation mountain ridges ).  Winds SSE-S at 5-15 mph, with higher gusts, on ridges & plateaus below 2700 feet.  Winds S-SW at 10-20 mph, with higher gusts, on mountain ridges above 2700 feet.  Temps in the upper 40s to low-mid 50s.

Tuesday Afternoon

A chance of showers, otherwise, partly-mostly cloudy.  Unseasonably mild.  SW winds 10-20 mph, with higher gusts.  Dense fog continuing along high elevation ridges.  Temperatures varying from upper 40s to lower 50s amid upper elevations to upper 50s to low-mid 60s ( warmest in downslope sites around Pound, Clintwood, Haysi, Grundy ).

Tuesday Night Into Mid-Morning Wednesday

Turning colder by morning.  Rain showers changing to snow by morning at mid-upper elevations before ending.  A light accumulation ( dusting ) possible at highest elevations.  SW winds shifting WNW-NW at 10-20 mph, with higher gusts, along middle to upper elevation mountain ridges-plateaus.  Temps dropping into the middle-upper 20s to mid-upper 30s by mid-morning ( coldest at the highest elevations ).  Wind chills dropping into the 10s and 20s.

*Air will turn bitterly cold by Friday into this upcoming weekend.  Snow accumulations look likely for the mountains, but amounts remain in question.  If substantial snow accumulates the potential for air temperatures to drop below zero will increase, especially in mountain valleys.  Sub-zero wind chill factors will be likely across exposed mountain ridges.  Stay tuned for updates as this winter weather episode gets closer.

Weather Discussion ( Mild-Nasty )

Reference My High Country Focus for a brief recap of 2016.  Additional details will be added later to this reveiw section.

A mild and generally nasty period of weather is on tap through early week as abundant low-level moisture will support periods of light rain, drizzle, areas of dense fog, and even some downpours ( with possible thunder ).

This current pattern is not new, as wet and mostly gloomy conditions have dominated the mountain landscape for the past 10 days with generally mild temperatures ( for this time of year, outside of the NW flow snowfall period ).

Some orographic enhancement of rain will be possible by Monday Night Into Tuesday, with heaviest amounts associated with strong to severe thunderstorms over the Deep South.  Time will tell how that may or may not impact rainfall across the Mountain Empire.

While there will be a chance of thunder, due mainly to elevated instability aloft, the risk for severe thunderstorms is currently expected to remain southwest and south of the mountains.

The air mass begins to change & turn colder by  Wednesday into Thursday, with a developing streak of light snow on the NAM Model ( above ) being a subject many are already interested in ( yet it remains too far out in time to know how much snow will fall across the mountains ).

*Note that I outlooked the potential for a HARSH period of winter conditions days ago, not because of any given model but due to the synoptic-scale pattern that is developing.  Bitter air will come and if snow accumulates this will make conditions much colder, that is true, but bitter air will make conditions harsh regardless of snow for at least a few days.

With respect to snowfall potential, past climatology of settings  like this says that two options are most favored:

A ).  The northern stream becomes dominant and forces snow generating energy far to the south, with the only moisture source available being the Great Lakes for upslope snow in locations that can get a fetch from the lakes.

B ).  Cold air arrives but does not dominate initially, with energy in the sub-tropical jet tracking far enough north to generate a band of potentially significant snowfall.  Upslope NW flow snow could then add to amounts along windward slopes in the mountains.

The next couple of days will help determine which scenario will verify, with the MEAN of the 51-Member European Model Group currently going with a snow band development.  It should be noted that if one looks at EACH MEMBER the variation forecast is from less than 1″ up to 6-12″+ .  The MEAN, which often is closer to true reality, is between these extremes.  So it is too soon for anyone to be making an actual forecast of snow amounts.  That will come.

Dual blocks will force cross-polar flow into the USA that will make the DAY 3-7 or DAY 4-8 period ( which ever one you wish to pick out ) very cold, with the local mountains being at the -10 C 850 MB isotherm ( that is a MEAN temp of 14 degrees near the High Knob summit for a 5 day period ).  That will be cold, of course, at all elevations.

So even if snow does not accumulate it will get cold.  If snow cover develops it will become MUCH colder.  Stay tuned for updates on this upcoming wintry period.

*Some moderation is currently being shown by next week, but the pattern is one that looks like it can reload.  So time will tell more as the setting across the eastern Pacific will be very complex.  The Pacific pattern has been forcing our weather, so with limited data points across this expanse it is not surprising that models will be struggling to pin down details of individual systems until they actually reach the North American continent.

Note I say the Pacific has been forcing our pattern, but that Pacific pattern has also been forced by other factors.  A key factor appears to have been a rapid and extensive development of snowpack across Siberia during this past autumn that altered the flow field across the northern Pacific and impacted the Polar Vortex.

Mountain Area Forecast ( Dec 31-Jan 2 )

ALERT For Strong SSW-SW Winds For New Year Eve’s Day ( Saturday ) Is Now In Effect.  ROARING SW Winds Will Develop At Upper Elevations First And Mix Down Into Middle & Lower Elevations Of The Cumberland Mountains During The Day Saturday.

*Following a decrease in winds Friday evening, the gradient tightens again by Saturday morning with another period of ROARING winds ( SW in direction this time ) throughout the daylight hours of New Year Eve’s Day.

A developing temperature inversion late Saturday into Sunday morning, with evaporative cooling, will then restrict strongest winds to highest elevations along top of the planetary boundary layer ( i.e., evaporative cooling will force decoupling as lower levels in the atmosphere cool relative to milder air aloft ).

*The Potential For Snow Or Frozen Precipitation Forms Needs To Be Monitored For New Year Eve’s Afternoon & Evening – Especially In The Southwest Upslope Flow Zone Of Wise, Scott, Lee Counties Along And SW Of The High Knob Massif – Tennessee Valley Divide.

Overnight Into Saturday Morning

Mostly clear.  Cold.  Winds becoming SSW-SW at 10-25 mph, with higher gusts, along middle-upper elevation mountain ridges.  Light valley winds.  Temperatures in the 10s & 20s, varying from single digits to around 10 degrees in sheltered upper elevation valleys to readings rising overnight into morning along mountain ridges ( to low-mid 30s on ridges within the 2000-3000 foot elevation zone ).  Wind chills from single digits & 10s on upper elevation ridges to the teens to lower 20s.

Mid-Morning Through Saturday Afternoon

Increasing clouds with lowering cloud bases over time.  Virga forming aloft with a chance for flurries to light snow developing, especially along and southwest from the High Knob Massif & Tennessee Valley Divide.  Windy & cold.  SSW-SW winds 15-25 mph, with higher gusts, at elevations below 2700 feet.  SW winds 20-30 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures varying from upper 20s-low 30s at highest elevations to upper 30s to middle 40s, dropping with the onset of precipitation.  Wind chills in the 10s and 20s.  Dense fog developing at highest elevations.

Saturday Evening Into Sunday Morning

Chance of evening snow ( especially along-southwest of the High Knob Massif-Tennessee Valley Divide ) or mix giving way to rain.  Frozen forms possible in the SW upslope zone.  SSW-WSW winds 10-20 mph, with higher gusts on middle-upper elevation ridges, decreasing into morning.  Temps mainly from the lower 30s to around 40 degrees.  Areas of dense fog.

Sunday Afternoon

Mostly cloudy.  Chance of light showers or drizzle.  Milder.  Winds SSE to SSW at 5-15 mph.  Temperatures in the 40s to around 50 degrees.  Areas of fog, especially at highest elevations along mountain ridges.

Sunday Night Into Monday Morning

Mostly cloudy.  Chance for a light shower or drizzle.  Mild.  Winds SSE-SSW 5-15 mph along mountain ridges-plateaus below 2700 feet.  Winds SSW-SW 10-20 mph, with higher gusts, along upper elevation mountain ridges.  Widespread temperatures in the 40s to around 50 degrees.  Dense fog at highest elevations.

**The potential for a prolonged, harsh period of winter conditions is being monitored for the January 4-6 period, and beyond in time, with formation of high latitude blocking and a cross-polar flow from Siberia into North America.  Stay tuned for updates on this major shift into significant winter conditions in January 2017.

Weather Discussion ( More Nasty )

Reference My High Country Focus for a brief recap of 2016.

Saturday Afternoon Update

Flurries and light snow showers have occurred throughout the afternoon of New Year’s Eve Day across the High Knob Massif area of Norton-Wise ( even at low elevations in the downslope zone to Clintwood ).

Conditions have varied from beautiful mountain waves being visible to a reduction in visibility in light snow-flurries ( below ).

The atmosphere has been saturating from the top down, with the summit levels of the High Knob Massif now being obscured in freezing fog ( clouds ) amid flurries-light snow. A small accumulation has recovered roads.  Travel should be avoided on State Route 619, Routes 237, 238, and others in the upper elevations into this evening as frozen precip will continue at times ( fog will become persistent and lower in elevation to below the main crest lines by late evening ).

Winds are simply wicked in upper elevations, with gusts of 40-50+ mph being common.  The 5:15 PM temperature is 29 degrees on Eagle Knob of the High Knob Massif, with 30 at a little lower elevation on adjacent Black Mountain.

Wind have also, of course, been strong in Wise with Lonesome Pine Airport displaying its typical temp bias:

versus adjacent stations at the same elevation:

Surface temperatures from just below to just above freezing will continue into this evening within the upslope flow zone of the High Knob Massif area.

At all locations outside the highest elevations there remains a small temperature-dewpoint depression for evaporative cooling.  Temperatures aloft, above the high summits, should continue to warm to strengthen a low-level temperature inversion.  Strong wind gusts at locations below the elevation of Wise should begin decreasing, while gusty to ROARING winds will continue through the night in upper elevations.  Have a Safe & Happy New Year. 

Previous Discussion

Reference my 123016 Forecast page for details on recent snow.

Reference The High Knob Landform for views of December 2016.

Given wind and chilly conditions with developing virga to surface precipitation through New Year’s Eve and Morning, I have updated my forecast page to clean it up for these next upcoming weather conditions.

Winds are beginning to increase again at upper elevations, and this will continue into Saturday with mixing of higher speeds downward into middle and lower elevations with time ( at least until evaporative cooling begins ).

My main concern for the short-term will be the potential for some snow and frozen precipitation to develop Saturday PM & Saturday Evening, especially in the High Knob Landform corridor where SW air flow rises 1000 to 3000 vertical feet as it streams northeast from Tennessee.  The wind max that is shown above, over the Nation’s Heartland, will be along the Appalachians by New Year Eve Afternoon-Evening.

*Low-level cooling will be greater than models suggest into Saturday Evening, even as temperatures continue to warm aloft, so this threat must be monitored until wind direction’s change.

It is easy to see from this sounding forecast ( above ), that if the surface temperature & dewpoint are just a little closer together at levels downward from the summit of the High Knob Massif ( where orographic lifting occurs ) that the column will be saturated and sub-freezing through a relatively deep layer.  So my concern is a no brainer unless the model is completely out of whack, which is not as likely given current low dewpoint air ( to support cooling ).

Mild air for this time of year will then rule the mountain region from Sunday into Tuesday, with periods of rain, before conditions turn cold once again.

As always, please stay tuned for updates and have a Safe and Happy New Year.