ALERT For Strong SW Winds Overnight Into Friday With Snow & Mixed Precip Developing.  Caution For Hazardous Surfaces Due To Recent Bitter Air.

Strong SW winds will continue to generate low wind chill values, especially at mid-upper elevations, as a warm front passes across the mountains.

The most favored zone for accumulating snow in this type of air flow setting is from the High Knob Massif-Tennessee Valley Divide southwest (i.e., from Norton and Wise southwest into Lee County).  However, there remains a question as to how much moisture will be available for locations southwest of Wise.

So, be aware of this potential and otherwise expect the potential for hazardous surface conditions across the area where any precipitation falls due to a prolonged period of very cold temperatures.  Caution is advised.

Former Alerts

ALERT For Bitterly Cold Temperatures Continues Today Into Thursday 

Bitterly cold air will grip the mountain landscape today into Thursday with dangerously low wind chills and temperatures for anyone not prepared.

ALERT For Brief Morning Burst Of Snow Impacting Parts Of The Mountain Area

A brief burst of heavy snow will be possible this morning along an Arctic cold front.  Given bitterly cold conditions and already frozen surfaces it will take very little snow to cause hazardous conditions. Accumulations of a dusting up to 1″ is expected.

Mountain Area Forecast ( Jan 30-31 )

Overnight Into Mid-Morning Wednesday

Becoming cloudy & bitterly cold.  Chance of flurries and snow showers by morning.  A brief, heavy snow burst possible.  Windy.  SW-W winds 10-25 mph with gusts over 40 mph.  Temperatures varying from the single digits to 10s (coldest highest elevations). Wind chills 10 above to -3 below zero in elevations below 2700 feet.  Wind Chills of 0 to -20 degrees below at elevations above 2700 feet.

Wednesday Afternoon

Sunny & bitterly cold.  Windy.  W-NW winds 10-20 mph with higher gusts.  Temperatures near steady or slowly falling in the 10s at middle-lower elevations and in the single digits at upper elevations along and northwest-north of the High Knob Massif-Tennessee Valley Divide.  Somewhat milder to the southeast into river valleys of the Clinch, Powell and Holston.  Wind chills mainly in the single digits above and below zero, except -10 to -25 below zero at highest elevations.

Wednesday Night Into Thursday Morning

Increasing mid-level clouds.  Bitter.  WSW-WNW winds decreasing to 5-10 mph with higher gusts on mid-upper elevation mountain ridges.  Temps from 8 degrees above zero to -8 degrees below zero, except locally colder if mid-level clouds dissipate or do not develop in locations with snow cover.

Updated_New Forecast

Overnight Into Mid-Morning Friday

Cloudy.  A chance of flurries or snow showers by morning.  Windy across mountain ridges and exposed plateaus.  SW to WSW winds 10-25 mph, with higher gusts.  Temperatures near steady or slowly rising within the 20s to lower 30s.  Wind chills in the 10s and 20s, except single digits at highest elevations.

Mid-Morning Friday Into The Afternoon

Cloudy with a chance of snow & mixed precipitation.  Accumulations from a dusting up to 2″ . Windy. SW winds 10-25 mph, with higher gusts, then decreasing by late in the afternoon.  Temperatures varying from upper 20s to lower 30s to the upper 30s to lower 40s, warmest in downslope locations of northern Wise and Dickenson counties and coldest in upslope areas of the High Knob Massif. 

Weather Discussion (Bitter_Little Snow)

Although a snow burst could catch you off-guard this morning if not prepared, the big story with this event will be bitter temperatures today and Thursday.

Joe & Darlene Fields measured only 1″ of snow in High Chaparral of the High Knob Massif during January 29, as the bulk of this system weakened and trended to the far south and southeast.

While a bit more snow depth is observed in portions of the highest elevations, lingering from previous snow, it is generally not more than 1-3″ when not counting drifts.  Puny for this massif, at this time of year.

Although the snow season still has a potentially long way to go, it has been down along the typically snow favored windward slopes with season-to-date totals varying from 63″ at Snowshoe to 54″ on High Knob.  The major missing ingredient, Great Lake moisture!

A period of rather dense, freezing fog which occurred after light snow was probably the most exciting and hazardous aspect in Wise during January 29.

However, given upstream air flow trajectories from mid-continent, without any Great Lake moisture tap, even this was limited in duration.

Running a backward air flow trajectory analysis into Wise County (above), it is easy to see why snow was limited with this system.  The source region was from the dry Canadian and Midwestern provinces.

Shift that trajectory east-northeast 300-350 miles and it would have been a different world, and the upslope locations could have been literally buried with snow from capture of Great Lake moisture.

Previous Discussion

The most brutal cold will hold along and north of the Ohio River, with the upper trough not being quite as deep as forecast last week.  Still air will be bitter and the potential for sub-zero temps remains likely for highest elevations and possible to likely across the area with clearing over snow cover.

Wind chill values will make it feel below zero across the area, with life threatening conditions if you are not prepared.  Extreme Caution is Advised.

Snowfall Forecast_Tuesday Thru Wednesday

A general 1″ to 2″ with locally higher amounts

Target snowfall 1.5″ for the elevation of Norton-Wise (+/-) 0.5″ error to suggest a 1″ to 2″ snowfall potential.  Locally higher amounts will be possible, especially at mid-upper elevations along the High Knob Massif-Tennessee Valley Divide and the Tennessee-North Carolina border.

Model trends through the weekend into Monday were to decrease snowfall amounts with this system.

More of a focus has been toward Mississippi-Alabama and as the front may slow a bit toward the union of borders with Virginia-Tennessee-North Carolina.

Clearly, the biggest impact will be with bitter air and low wind chill values Tuesday-Wednesday, with some of the lowest temperatures by late Wednesday into Thursday morning as winds decrease.

Weather Headlines ( January 26-31 )

Severe Winter Weather Conditions Are Expected With A Major Arctic Outbreak During January 29-31

Accumulating snow and arctic air will combine to generate below zero temperature readings, with a chance to approach those felt in February 2015.

Conditions are likely to be significantly worse than the recent arctic blast of January 21, with much lower temperatures over fresh snow cover.

Temperatures remained at or below freezing once again during Friday, following the recent light snow fall that produced a general 0.5″ to 1.0″ in the area.

Friday afternoon temperatures varied from around  20 degrees at the top of the mountains to around 30 degrees at the elevation of Wise to 32 degrees at the elevation of Clintwood.  Balmy versus next week!

The coldest temperatures observed so far during the 2018-19 winter season have generally varied between 4 degrees above zero to -7 to -10 degrees below zero. 

The coldest wind chills being -20 to -30 below zero at highest elevations on Black Mountain and in the High Knob Massif, and around -15 degrees below in Wise.

A cross-polar flow will transport air from the most bitter portions of the arctic into this region to set the stage for a brutally cold ending to January and opening of February 2019.

Temperatures will be increasingly bitter from southwest to northeast along the Appalachians during the January 29 to February 3 period, with temperature means at 850 MB during this 5-day period predicted to vary from 25 degrees over extreme northern Georgia to 0 degrees near the Pennsylvania-West Virginia state line.  This is brutally cold for a 5-day ensemble MEAN temperature, with much lower specific MINS.

A low pressure wave developing along an arctic front plunging into the Deep South will spread snow across the mountains Tuesday.

Although too early to determine actual amounts, the European group has been consistent in predicting a general 4″ to 8″ spread along the mountains.

If current timing holds, county school systems should consider canceling classes Tuesday, especially within counties along and west of the Virginia-Kentucky state line where snow and falling temperatures will occur earliest ( stay tuned for timing updates ).

Mountain Area Forecast

ALERT For Rain Changing To Snow During The Predawn-Morning Hours Of Thursday ( Jan 24 )

Rain will change to snow as colder air pours into the western slopes of the Appalachians early Thursday with a period of moderate to heavy snow, especially at elevations near and above 2200 feet in locations along and northwest of the High Knob Massif and Tennessee Valley Divide.

Snowfall Forecast_Thursday ( January 24 )

0.5″ to 1.5″ at elevations below 2500 feet

1.5″ to 3.0″ at elevations above 2500 feet

Target snowfall of 1.5″ at the elevation of Wise (+/-) 1″ error potential, implying 0.5″ to 2.5″ of possible snowfall.  Winter wonderland conditions will be likely where rain changes to sticking wet snow, caution is advised!

Overnight Into Mid-Morning Thursday

Rain.  Areas of fog, widespread at upper elevations.  Rain changing to snow during the predawn-morning from top to bottom.  Period of moderate-heavy snow possible, especially at mid-upper elevations.  S-SW winds shifting WNW-NW at 5-15 mph with higher gusts.  Temperatures dropping into the upper 10s to upper 20s-low 30s ( coldest at highest elevations ).  Wind chills dropping into 10s & 20s, except single digits at highest elevations.  Riming developing at upper elevations.

Updated_Thursday PM to Mostly Cloudy.

Mid-Morning Thursday Through The Afternoon

Snow tapering to snow showers & flurries before ending.  Mostly cloudy.  Winds WSW-WNW at 5-15 mph with some higher gusts.  Temps near steady or slowly falling in the 20s to around 30 degrees at low-middle elevations and in the 10s to near 20 degrees at upper elevations ( milder to the south and southeast into the Great Valley ).  Wind chills in the 10s to lower 20s, except single digits at upper elevations above 3000 to 3300 feet.

An Arctic Cold Front Will Create A Snow Burst Potential Friday Morning.  Expect Low Visibility During A Brief Period With Hazardous Roads In Locations Having A Whiteout Burst Of Snow.

Thursday Night Into Mid-Morning Friday

Mostly cloudy with snow showers and flurries developing by morning.  A burst of snow possible.  WNW winds 5-15 mph with higher gusts.  Temps dropping into mid-upper 10s to around 20 degrees, except single digits highest elevations.  Wind chill factors in the single digits & 10s low-mid elevations and 0 to -15 degrees below at upper elevations by morning hours.

A major outbreak of arctic air is being monitored to arrive during the January 29-31 period with snow and extremely cold conditions, marking the beginning of a harsh stretch of winter.

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.

The extended 6-10 day period continues to show an intensification of winter, with a gradual southward trend in the mean storm track and baroclinic zone as snow cover persists and expands to the north.

This suggests that it will only be a matter of time before a major fall of snow impacts the Mountain Empire.  Stay tuned for later updates.

Current Weather ALERTS

ALERT For Strong SSE-SSW Winds Developing Saturday With 30 to 50+ MPH Gusts

A strong pressure gradient in advance of a deepening Low and arctic cold front will drive strong SSE to SSW winds across the mountains Saturday.

ALERT For Heavy Rainfall Saturday With Strong Stream Level Rises Becoming Possible By Saturday Evening Into Early Hours Of Sunday

Heavy rainfall is expected to develop Saturday, with orographic enhancement along and SSE-SW of the High Knob Massif & Tennessee Valley Divide.

Due to very wet antecedent conditions and partially frozen ground ( especially at upper elevations where light snow cover persists ), strong rises will become possible to likely on streams by late Saturday. 

ALERT For A FLASH FREEZE By Predawn To Morning Hours Of Sunday, From Northwest To Southeast Across The Mountain Area.  Do NOT Drive.

Driving During This Time Period Is Discouraged. While Snow Accumulation Is Expected, The Main Concern Will Be Rapid Freeze-Up With A Layer Of Ice Forming Beneath Accumulating Snow.

A potent temperature plunge will quickly drop air temperatures below freezing by the predawn to morning hours of Sunday as snow begins to stick.

Since rain will fall up until the rain to snow change any VDOT pre-treatment will be washed away. 

Ground temperatures will also be near freezing on northern slopes and in complex terrain where very limited sunshine has been observed during the past five days or longer.

ALERT For Bitterly Cold Temperatures And Dangerous Wind Chills During Sunday Into Monday Morning

Cold, with a Flash Freeze, and NOT snow will be the component of this storm system with greatest impact on the local mountains.

Air temperatures in the 20s around sunrise Sunday will fall into and through the 10s at middle to lower elevations during the day.

Air temperatures in the 10s around sunrise Sunday at upper elevations will fall through the 10s into single digits during the day.

Wind chill factors will be much colder and will drop below zero at nearly all locations along and north to northwest of the High Knob Massif.

Mountain Area Forecast ( Jan 19-21 )

Overnight Into Saturday Morning

Mostly cloudy.  Becoming windy at higher elevations. SSE winds increasing to 8-18 mph, with higher gusts, on mountain ridges-exposed plateaus below 2700 feet. SSE-SSW winds increasing to 15-25 mph with higher gusts on mountain ridges above 2700 feet. 

Temperatures varying from low 30s to low 40s, tending to rise overnight into morning.  Low clouds with dense fog at highest elevations.  Wind chills in the 20s & 30s ( coldest at highest elevations ).

Saturday Morning Through The Afternoon

Cloudy with rain developing.  Rain will be heavy at times during the afternoon.  Chance of lightning and thunder.  Windy. SSE-S winds increasing to 15-25 mph, with higher gusts, below 2700 feet.  S-SW winds 20-35 mph, with higher gusts, above 2700 feet. 

Temperatures widespread in the 40s to around 50 degrees.  Low clouds with widespread dense fog at upper elevations.  Wind chills in the 30s to lower 40s, except 20s possible in strong gusts on high peaks.

Saturday Night Into Sunday Morning

Windy with rain changing to snow.  A rapid predawn temperature drop with FLASH Freezing and period of ROARING winds.  Winds shifting NW-N at 15-25 mph with gusts 40-50+ mph.  Temperatures plunging into lower-mid 10s to low-mid 20s in locations along and northwest-north of the High Knob Massif-Tennessee Valley Divide ( milder toward the southeast-south ).

Wind chills plunging into the single digits and 10s, except 0 to -10 degrees Fahrenheit below zero at highest elevations, into morning.  Low clouds with freezing fog at upper elevations, and possible into middle elevations.

   Sunday Morning Through The Afternoon

Snow showers and flurries.  Windy and bitterly cold. NW-N winds 10-20 mph, with higher gusts.  Temps falling into the 10s at middle-lower elevations along and northwest to north of the High Knob Massif and Tennessee Valley Divide, and through 10s into single digits at upper elevations.  Wind chills 0 to 10 degrees below 2700 feet and 0 to -15 degrees below zero above 2700-3000 feet.  Freezing fog with riming at the high elevations.  Dangerous wind chills higher elevations.

Sunday Night Into Monday Morning

Mostly cloudy with snow showers & flurries.  Bitterly cold ( Dangerous wind chills at higher elevations ).  Winds NW-N at 5-15 mph with higher gusts. 

Temperatures falling into single digits above and below zero.  Wind chills 0 to -10 degrees below zero at elevations under 2700 feet, and -10 to -25 degrees F below zero at elevations above 2700-3000 feet.

Snowfall Forecast_Sunday-Monday AM

A general 1″ to 3″ of snow is expected, with the following break-down being favored:

1″ to 2″ at elevations below 2500 feet

2″ to 4″ at elevations above 2500 feet

Target snowfall 2″ in Norton-Wise (+/-) 1″ error potential, suggesting 1″ to 3″ of snowfall will be possible.

Locally heavier amounts will be possible, with lesser amounts expected in downslope locations into river valleys of the Clinch, Powell and Holston basins.

Forecast Discussion ( Winter Begins )

While the southern Appalachians have already experienced a good bit of wintry conditions, I will predict that a look back at the 2018-19 season will show the true winter beginning this weekend.

Reference These Sections of The High Knob Landform

The reason will NOT be because of just the first big blast of arctic cold this weekend, but because of the hemispheric pattern that is taking shape.

The upcoming 6-10 day period on the MEAN of the 51-member European ensemble group is simply showing an outrageous setting, which if verified would set up some of the most severe winter conditions observed since at least February 2015.

As I have highlighted for a long time, recent major sudden stratospheric warming + Modoki ENSO + low Solar supports this type of pattern developing in the eastern USA.

To quickly see why it will be turning severe, one needs only to look at where the Polar Vortex lobe since the major stratospheric warming event has established itself over North America, and also understand that coupling has now occurred between the stratosphere and underlying troposphere.

Northern Hemisphere 10 MB Flow Field

In the short-term, the upcoming storm brings many concerns the first of which being heavy rainfall that will have local orographic enhancement not being fully depicted by the above model graphic.

A general 1.00″ to 2.00″ of rainfall is likely along the Cumberland Mountains.  Those living and driving in low-lying, flood prone locations, as well as creeks, should remain alert for water level rises.

Any thunderstorms which might form, or training lines of heavy rain, could generate more serious problems Saturday afternoon-evening.

Due to such a large pressure change, winds are going to be a notable factor during this event.  I expect at least one period of especially notable wind along and just behind the initial cold front which will mark a temperature plummet; although, many hours will experience strong winds, especially higher terrain locations in mid-upper elevations.

The temperature plunges from 46 to 22 degrees at the Wise gridpoint in just 5-hours, most of that occurring in 4 hours or less.  This is a major concern for FLASH or rapid freezing of anything covered by water.

So, please plan not to drive into Sunday Morning and be very careful about decks, porches, walks, etc…as an icy layer forms beneath snow ( and even in places where little snow falls ).

I have a couple problems with model forecasts.

The European Model group has consistently been colder than the American models at 850 MB, to suggest temperature drops will be stronger than have been predicted.  I have selected the high-resolution NAM which is closest to the surface reflection of what such temperatures would produce even though it does not predict 850 MB temperatures as cold as the European.

NOTE that the coldest air with this initial outbreak will be centered around 875-850 MB, with milder air above that level.  This continues a trend observed during the past 5-days, at least, with a notable low-level inversion layer centered around 875 MB. 

Low-level NW-N winds climatologically favors the strongest cooling to develop along and northward of the High Knob Massif, with a large temp difference developing between Clintwood-Norton-Wise versus the Tri-Cities into early afternoon Sunday ( larger than predicted by the above graphic ) due to the influences of orographics ( terrain changes ).

Another problem often observed is that bitter cold air coming off a snowpack to the north will have limited bare ground over which to modify, prior to reaching the mountains, as enough snow falls to cover the ground into the western slopes of the mountains.

Rain & Snow Will Develop Today ( Jan 17 ) With Amounts Varying From Little To None Up to 1-3″

I have expanded my accumulations to now include more of the area, with snow accumulating at temperatures above freezing northward to Clintwood.

A fast moving weather system will spread a mix of rain and snow across the mountain area Thursday, with cooling on upslope winds expected to favor locations along and south of the High Knob Massif for greatest snowfall amounts.

A Major Weather Change Is Expected This Weekend With Strong Winds & Rain Saturday Giving Way To Plunging Temperatures & Wind Chills Sunday

Temperature are expected to fall through the 10s at lower-middle elevations, and through the single digits at upper elevations, during Sunday, with colder wind chills.

Former Alerts Ending Late Evening_January 16

ALERT For Low Cloud Bases On Northerly Upslope Flow With Dense Fog Changing To Freezing Fog At Middle-Upper Elevations Along & Northwest-North  Of The High Knob Massif-Tennessee Valley Divide.

Drizzle to freezing drizzle & light snow will also be possible. Any snow accumulations are expected to be light.  

Caution Is Advised For Low Visibility & Icing On Above Ground Objects.  Icy Patches On Roadways, Especially Secondary Routes At Higher Elevations, Will Be Possible.  Dense Fog Will Be Most Consistent And Widespread Above 2500-3000 Feet.

Rime deposition with freezing fog ( clouds ) began at the summit level of the High Knob Massif around 8:00 PM on January 13.  

Freezing levels had dropped downward to higher portions of the Wise Plateau at 11:00 PM on Sunday, and will continue dropping into Monday AM.

Temperatures will remain below freezing at upper elevations through a prolonged period and will also struggle to rise above low-mid 30s, beneath an 875 MB centered inversion, to maintain raw, cold and damp conditions at middle to lower elevations.

Update – Monday Afternoon_January 14, 2019

My alert will continue tonight as freezing fog has become widespread at elevations above 2500 feet, locally dropping to around 2000 feet, in locations on upslope flow along and north of the High Knob Massif and Tennessee Valley Divide.  Be safe and slow down.

Weather Headlines ( January 14-21 )

A short break, with partial mixing out of an inversion centered around 875 MB, on Tuesday PM gave way to more low clouds and renewed riming at the upper elevations where amounts were already significant.

So I left my alert for fog and low clouds through the daylight hours of Wednesday ( riming continues at highest elevations as of 1 AM Thursday ). 

Following another nasty system today ( Jan 17 ) focus will shift to a major event this weekend which will bring the first of what likely will be numerous blasts of arctic air into the Appalachians.

Previous Headlines

Nasty conditions brought by a Miller B style winter storm during the weekend will finally improve on Tuesday as sunshine returns.

Conditions will begin to deteriorate later this week with strong winds and rain developing well in advance of a major arctic outbreak.

Rising heights with building High pressure at high latitudes and lowering heights at middle latitudes will begin driving bitterly cold, arctic air southward later this week into the January 20-21 weekend.

Although specific details remain to be worked out from this distance, and changes are certain to occur from current projections, a threat for severe winter conditions is great enough to begin highlighting it now ( given this could be life threatening for those caught unprepared for such conditions ).

Given a major Sudden Stratospheric Warming that already has occurred, this increases the odds for a major intrusion of bitterly cold air.  This has now been on the table for weeks, so it should not be a surprise that middle latitude weather is poised to turn severe.  In fact, timing is nearly ideal, based upon past climatology for such events.

This major mid-winter warming event ( SSW or Sudden Stratospheric Warming ) at high altitudes above the arctic became official at beginning of the new year on January 1.

This resulted in a splitting of the Polar Vortex, with two major centers currently dominating the 10 MB flow field within the stratosphere.

10 MB Flow Field_Stratosphere

Although temperatures are cooling again in the arctic stratosphere, winds continue to be reversed and are predicted to remain easterly through the next 10 days as the impacts of this major SSW are working downward into the troposphere.

Major teleconnections on both the European and GFS ensembles are trending in the direction conducive for severe winter conditions in the eastern USA.

-AO ( Arctic Oscillation )
-NAO ( North Atlantic Oscillation )
+/-PNA ( Pacific-NA Oscillation )
-EPO ( Eastern Pacific Oscillation )
-WPO ( Western Pacific Oscillation )

A +ENSO ( Modoki type ) is currently running.

A small negative trend in the PNA being offset by a much larger negative trend in the EPO.  A point of notable inflection in these indices, centered on the January 20-21 weekend, is often indicative of major cyclogenesis; otherwise, the longer-term tendency being toward bad-severe winter conditions with or without major cyclogenesis by this weekend.

Since I consider this upcoming pattern to be so important, I have inserted a preliminary look at my weekly weather column, to be officially published on January 16, for those interested in a more plainly worded description of what is expected ( * ).

It should be stressed that the most important aspect that I am trying to get across is not whether a major arctic blast hits exactly on January 20-21, but rather that a hemispheric pattern change forced by changes already observed in the stratosphere will be setting the stage for severe winter conditions during weeks encompassing the second half of winter and possibly into Spring 2019.

*This marks 26 years that I have written weather columns.

January 1985 Arctic Outbreak

The core of this upcoming air mass will have temps at or below -25 degrees Celsius.  Many factors yet to be determined will dictate if that type of air mass can reach the Mountain Empire, with snow cover, both locally and to our north, being critical to how cold temperatures ultimately get in the short-term.

A major winter storm, likely with more than one wave, will be impacting the eastern USA within the baroclinic zone ( temp contrast ) that forms and intensifies ahead of incoming bitter air.

Stay tuned for later updates and details.

Mountain Area Weather Alerts

While Rain Is Expected To Dominate Saturday Night Into Sunday In Most Locations, Prior To A Change To Light Snow, Freezing Rain Remains A Possibility At Upper Elevations Within The High Knob Massif.

Update_10:30 PM Saturday

A major ice storm in mid-November 2018 caused extensive tree damage at highest elevations in the High Knob Massif, blocking roads and severely damaging some trees.  

While I do not expect this event to be nearly that severe, it only takes a little bit of ice to cause trouble.

Caution is advised for travelers into high elevations  of the High Knob Massif where icing has occurred this evening ( January 12 ) at upper elevations, mainly at elevations above 3300 feet, along State Route 619 and adjoining roadways.

A complicated, messy winter storm of the Miller B type is expected to begin impacting mountain area conditions by early Saturday ( January 12 ).

Cold air in place will initially support all snow before a layer of above freezing air aloft moves over the Tennessee Valley and southern Appalachians to force a change in precipitation type to a cold, nasty rain for most ( freezing rain remaining possible at upper elevations within the  High Knob Massif ).

Cloud bases will drop and precipitation will change back to snow by later Sunday into Monday morning with a rather prolonged period of freezing fog ( riming ) possible at the upper elevations along and north of the High Knob Massif-Tennessee Valley Divide ( mid-elevations above 2500 feet could also be impacted ).

Cloud Bases Are Expected To Lower On Northerly Upslope Flow With Dense Fog Changing To Freezing Fog And Becoming Widespread At Upper Elevations Sunday Into Monday.  Snow amounts will be light.

Former Alerts

A Period Of Snow Will Develop During The Predawn-Morning Hours Of Saturday Before A Break Develops In Advance Of Another Wave Of Moisture With Mixed Precipitation By Later Saturday.  Due To The Current Arctic Air Mass Hazardous Road Conditions Will Be Likely Early Saturday.  Caution Is Advised.

Mountain Area Forecast ( Jan 11-14 )

Friday Night Into Saturday Morning

Becoming cloudy with snow developing from high to low elevations into the predawn-morning as the air saturates from the top downward.  Light winds, then SSE-SW at 5-10 mph, with higher gusts, on mid-upper elevation mountain ridges toward morning.  Temps dropping into the 20s to around 30 degrees, with lower wind chills on higher ridges by morning.

Saturday Morning Through The Afternoon

Snow becoming mixed with or changing to sleet, rain or freezing rain.  Winds SE to SSW at 5-10 mph, with higher gusts, on middle-upper elevation mountain ridges and exposed plateaus.  Damp and raw with temperatures in the mid-upper 30s.

Saturday Night Into Sunday Morning

Mainly rain.  Freezing rain remaining possible in upslope locations at upper elevations in the High Knob Massif.  SE to S winds 5-15 mph, with higher  gusts, below 2500 to 3000 feet.  SSE-S winds 10-20 mph and gusty at upper elevations.  Temperatures widespread in the 30s.  Areas of fog and low clouds, especially at upper elevations.  Wind chills in the 20s to lower 30s, except 10s in gusts on higher peaks.

Sunday Afternoon-Early Evening

Rain or freezing rain changing back to snow at upper elevations first, then within middle-lower elevations by late in this period.

Dropping cloud bases with fog becoming dense at middle to upper elevations along and north of the High Knob Massif-Tennessee Valley Divide.  Light winds shifting NW-N at mainly 10 mph or less.

Temperatures dropping into upper 20s to mid 30s.

Sunday Night Into Monday Morning

Light snow and snow showers.  Freezing fog at mid-upper elevations along and north of the High Knob Massif-Tennessee Valley Divide.  NW winds mostly less than 10 mph.  Temperatures dropping into the middle-upper 20s, varying from low 20s at highest elevations in the High Knob Massif to lower 30s in downslope locations toward the south.

*Snowfall Forecast – Saturday To Monday

Up to 1″ at elevations below 2500 feet

Up to 2″ at elevations above 3000 feet

Target Snowfall of 0.5″ to 1″ in Norton-Wise area (+/-) 0.5″ error potential, suggesting a dusting to 1″ possible during entire event.  This is a relatively low confidence forecast.

Snowfall totals are for locations along and northwest to northeast of the High Knob Massif-Tennessee Valley Divide, with lesser amounts expected to generally fall toward the south within downslope locations of the Clinch, Powell, and Holston valleys.

*Stay tuned for later adjustments depending upon how the system evolves into Sunday.

Weather Discussion ( Miller B = Nasty )

Saturday Afternoon Update

Following a light coating of snow into Saturday AM across northern parts of Wise, Dickenson & Buchanan counties the day has featured a break and widespread temperatures hovering in the 30s to near 40.

While snow began falling on High Knob between 1-2 AM Saturday, subsequent precipitation evaporated as dewpoints tanked ( going sub-zero ) to suggest that sinking air aloft was being generated and completely missed by forecast models which predicted saturation from top to bottom over time.

 Based upon new model runs today I have greatly reduced snow amounts into Monday; however, this continues to be a low confidence forecast setting.

Using past climatology of Miller B systems, rain should dominate from this point forward westward of the cold air damming wedge, with a transition back to snow as winds shift northerly in direction late Sunday into Monday.  Since this system will not deepen into a Nor’easter,  snow amounts should remain light and limited in backside upslope flow.

A notable exception to the above being a continued threat of icing at upper elevations in the High Knob Massif where air temps-dewpoints remain supportive of freezing rain, which I have left in my forecast for upper elevations.

Outside of freezing rain, there is nothing worse and more nasty than a cold rain during winter with air temperatures in the 30s.  NASTY! 

Previous January 11 Discussion

The upcoming winter storm is forecast by models to take on characteristics of a Miller B system.  My past climatology of such storms can be summarized by a single word.  NASTY.

Miller B storms tend to throw everything but the proverbial kitchen sink down on the mountain area, and this event will be no different if it does indeed conform to this type of winter storm.

By nature, Miller B events tend to be among the most difficult to forecast with respect to specific amounts of any given precipitation type.

Some Miller B storm systems become Nor’easters.

Some Miller B storms ( like this one ) take a trajectory which carries them outward into the Atlantic Ocean and do not turn up the coast toward New England.

A large difference in snowfall amounts between the NAM 12 KM and its high-resolution 3 KM sibling can be used to illustrate the forecast difficulties.

The 12z run of the operational European Model and many ensembles are closer to the NAM 12 KM locally, but more like the NAM 3 KM toward the south where it transports more above freezing air aloft across the Tennessee Valley and southern Appalachians.

The European Model group and the NAM 3 KM are predicting a setting for  significant icing across much of North Carolina versus the GFS-FV3 and NAM 12 KM . 

The new GFS-FV3 looks too heavy over the Carolinas and more on target for the Greenbrier Valley region of southeastern West Virginia where past climo on Miller B storms shows a maximum in snow.

Totals of frozen precipitation types within upper elevations of the High Knob Massif also tend to be greater than generally indicated by models in this type of Miller B storm setting.

Government Shut-Down & USA Models

Is the current government shut-down impacting daily forecasts in the USA?

The  National Weather Service Is Open BUT

It should not in theory, but since high-resolution USA models use the GFS domain it is problematic.  It is not surprising that the GFS has generally struggled with rather significant inconsistencies and it is scheduled for a replacement upgrade to a new dynamical core being called the FV3 for Finite Volume Cubed-Sphere.

While the GFS-FV3 has been in testing mode, it is not yet the official USA model domain for running of the high-resolution terrain models.

The ECMWF and its ensemble mean has been my favored medium range model since I first began using it during the early 1990’s; however, being global in nature it is not designed for detailed topographic resolution.

No model ever generates a totally perfect forecast, especially in complex terrain settings, and all must be adjusted to best fit local terrain and climatology. 

Yet, the better a model performs the better any forecast can theoretically become.

A mostly unspoken factor, but extremely valid, is stress-strain this is putting upon employees of the National Weather Service and their families.  This entire aspect is simply wrong.

Members of the NWS are professionals and while they typically carry onward this is not their fault and they should not be penalized for their public service which, unfortunately, they typically do not receive the credit they deserve even without a shut-down.

Cold Blast of January 10-11

Temperatures plunged into the single digits and 10s with this first major cold blast of January 2019, not including wind chills, with a large vertical spread developing this morning ( Friday Jan 11 ) between rising readings into 20s on high mountain ridges versus temps dropping toward 0 degrees in high valleys ( hovering near 10 degrees in Clintwood ).

MAX temperatures January 10 did not rise above lower-mid 10s at highest elevations in the massif, versus mid-upper 20s around Wise and Clintwood.

This was the first cold frontal passage in months, if not longer, to transport limited moisture.

A dusting up to 1″, with most of the area only having a dusting of snow, was observed as the bulk of Great Lake moisture remained northeast of the area.

While I generally expected this, and noted it on my previous forecast page, moisture was a little slower to arrive on Wednesday and slower to leave upslope sides of the mountains on Thursday.

The local mountains were on the southwest edge of the moisture field into Thursday afternoon, with clouds banking up against the Wise County side of the High Knob Massif ( Scott-Lee Counties cleared ) versus clouds which extended farther southeast as air toward the northeast of the massif was not being lifted as efficiently ( allowing solid clouds to reach southeast to the Brumley-Garden mountain area )  nor sinking leeward as vigorously on NNW-NNE winds.

Weather Headlines ( January 7-13 )

ALERT For Accumulating Snowfall Beginning Wednesday Afternoon Into Thursday Morning Within NW Flow Upslope Zones Along And Northwest Of The High Knob Massif & Tennessee Valley Divide

Flurries and snow showers will begin developing during Wednesday afternoon and continue into the mid-morning hours of Thursday.  Caution for slick sections on roadways, with accumulations varying from a dusting up to 2″+ .

ALERT For Strong WNW to NW Winds And Bitter Wind Chills Wednesday Into Thursday – Especially Middle To Upper Elevations.  Caution is advised. 

Strong SSE-SW winds will develop Monday into Monday Night well in advance of a strong cold front.  Wind gusts of 25-40+ mph will be common in upper elevations & exposed mid elevation ridges-plateaus.

A strong and steady temperature decline will begin Tuesday Night and continue into Thursday Morning, with steady to falling temperatures expected during Wednesday as low-level moisture begins increasing.  Strong & gusty WNW-NW winds will make conditions feel much colder with dropping wind chill values.

ALERT for a blast of bitter cold with temperatures falling slowly through the 20s Wednesday at the middle to lower elevations along and northwest of the High Knob Massif, through the lower 20s into the 10s at upper elevations.

Expect much colder wind chill values.

NW flow snow showers and flurries are expected by Wednesday PM into Thursday AM on upslope flow.  Accumulations are expected to be light, with greater Great Lake moisture transport farther northeast in central-northern West Virginia into Pennsylvania.

The potential for a more widespread and significant winter storm system is being monitored for January 12-13.  Stay tuned for later updates.

Mountain Area Forecast ( Jan 9-11 )

Tuesday Night Into Wednesday Morning

Partly-mostly cloudy.  Windy and colder.  Winds W-NW at 10-25 mph with higher gusts.  Temperatures dropping into the lower 20s to the lower 30s, coldest at highest elevations.  Wind chills falling into the 20s and 10s, except single digits at highest elevations.

Wednesday Mid-Day Through The Afternoon

Mostly cloudy.  Windy & cold.  Flurries and snow showers developing.  Temperatures falling slowly through the 20s at middle-lower elevations, and 10s  at upper elevations, along and northwest of the High Knob Massif & Tennessee Valley Divide.  Milder in the downslope locations toward the south.  Wind chill factors in the 10s to lower 20s at elevations below 3000 feet and in single digits to 10s above 3000 feet.  Wind chills dropping below zero highest elevations. Riming at highest elevations.

Wednesday Evening to Mid-Morning Thursday

Snow showers, with a snow burst possible, tapering to flurries.  Windy and bitterly cold.  NW-NNW winds at 10-20 mph with higher gusts.  Temperatures varying from single digits at highest elevations to the mid-upper 10s.  Wind chills 0 to 15 degrees at low-middle elevations and 0 to -15 below at upper elevations.  Riming at highest elevations.

Mid-Morning Thursday Through The Afternoon

Clouds and any flurries giving way to partly sunny skies ( mid-high clouds ).  Unseasonably cold.  NW winds 5-15 mph with higher gusts.  Temperatures varying from mid-upper 10s to middle-upper 20s.  Wind chills varying from single digits to low 20s, except below zero in gusts on highest peaks.

Thursday Night Into Friday Morning

     Partly-mostly clear.  Winds shifting N at 5-10 mph, with some higher gusts, on middle to upper elevation mountain ridges.  Temperatures falling into the single digits & 10s, except locally colder in coldest mountain valleys at upper elevations.

Mountain Area Forecast ( Jan 2-5 )

Rain will change to snow at highest elevations late Friday night into Saturday morning.  Caution for a few slick patches, mainly above 3300 feet, into the early morning hours of Saturday ( Jan 5 ).  

Wednesday Night Into Thursday Morning

Evening showers and areas of drizzle giving way to soaking rain.  Breezing to gusty S-SW winds shifting W-NW and decreasing to 5-10 mph with some higher gusts.  Temperatures dropping into the 30s to lower 40s ( coolest at highest elevations ).  Low clouds with areas of fog, becoming widespread upper elevations. 

Wind chill factors in the 20s to lower 30s at upper elevations and the 30s to low 40s at middle to lower elevations ( mainly along mountain ridges and exposed plateaus ).

Thursday Morning Through The Afternoon

Morning rain and low clouds giving way to mid-high clouds.  Light NW-N winds becoming westerly at high elevations.  Temperatures in the 30s to middle 40s.

Thursday Night Into Friday Morning

Mostly cloudy ( mainly mid-high altitude clouds ) evening skies giving way to lowering cloud bases with rain developing into the predawn-morning.  Winds becoming SE-S and increasing to 5-15 mph, with higher gusts, mid-upper elevation mountain ridges. 

Temperatures in the 30s to lower 40s, steady or rising overnight into morning.  Areas of low clouds and fog developing ( especially at high elevations ).

Friday Morning Through The Afternoon

Morning rain giving way to showers.  Breaks in clouds during the afternoon, especially west to north of the High Knob Massif.  Unseasonably mild.  Winds SE-S at 10 to 20 mph, with higher gusts, at elevations below 2700 feet.  Winds SSE-SSW at 15-25 mph with higher gusts above 2700-3000 feet.  Temps in the 40s to mid-upper 50s.  Low clouds-fog at highest elevations.

Friday Night Into Saturday Morning

Windy & turning colder.  Evening rain showers changing to snow at upper elevations, becoming mixed with or changing to snow showers or mix at middle elevations and becoming mixed with snow or sleet at lower elevations.  Winds shifting SW to WNW at 10-25 mph, with higher gusts, on mountain ridges and exposed plateaus.  Temperatures dropping to around 30 degrees at highest elevations to the mid 30s to around 40 degrees.  Wind chills dropping into the 20s to lower 30s, except 10s in gusts highest peaks.

Snow accumulations of a dusting up to 1-2″ will be possible, mainly at elevations above 3300 feet.

Saturday Morning Through The Afternoon

Morning clouds giving way to mostly sunny skies.  Gusty and seasonally cool.  Winds W-NW at 10-20 mph with higher gusts.  Temperatures mainly in the 40s, with 30s at highest elevations during much of day.  Wind chill factors in the 20s and 30s. 

 An increasingly cold weather pattern is being monitored for the extended 6-10+ day period.  Stay tuned for later updates on a return of wintry conditions.

Weather Discussion ( Winter Not Dead )

Lovers of snow and cold weather should not despair despite a mild, wet beginning to 2019.  In fact, severe winter conditions remain likely to develop in coming weeks across the eastern USA.

Reference Wetness Of 2018 for a few highlights of 2018.

New Year Day 2019 marked not only the beginning of another year but the official designation of a major sudden stratospheric warming above high latitudes within the Northern Hemisphere.

Winds at 10 mb and 60 degrees North must change from westerly to easterly ( blue color above ) and the temperature gradient must become positive in order to meet the technical criteria adopted by the World Meteorological Organization for a Major Mid-Winter Warming or SSW ( Sudden Stratospheric Warming ) event to be designated.

This is an exciting development for meteorologists in the research fields, and a look back at last winter can illustrate why this is so important.

SSW = Sudden Stratospheric Warming

During the 2017-18 winter ( red line above ) a minor stratospheric warming aided an arctic blast which started 2018 as the Polar Vortex temporarily became weaker and the polar jet developed high amplitude.

The Polar Vortex then became stronger in January 2018 with a significant increase in zonal mean wind speeds ( upward spike in red line above ).  A mild and record wet February followed locally as changes at high latitudes generated a major SSW event and the Polar Vortex weakened in February with reversal of winds to easterly ( red line dips below zero above ).

Locally, March into April turned wintry and conditions during March 2018 were colder than February.

Major warming of the stratosphere came late in the winter season last year, with impacts locally being felt during March-April after they propagated down from the stratosphere to impact weather conditions within the troposphere.

This winter a record-level heat flux associated with current major SSW has occurred early in the winter season, with upcoming changes having the potential to be much more significant in terms of tapping air that is much colder ( forming amid darkness at high latitudes and being yet unmodified by rising solar angles ) in nature and transporting it southward.

Every SSW event tends to be different with varied results for middle latitudes, yet it must be recognized that these events tend to increase odds of conditions turning bad in mid-latitudes.  This can result in late season wintry conditions which are bad for the time of year or severe conditions that can occasionally result in extreme events like happened later in January 1985 following a major SSW.

Reference Great Arctic Cold Wave of Jan 1985