My Forecast For Today ( January 31 )

ALERT For Strong & Gusty SW Winds Across Mid-Upper Elevation Mountain Ridges & Plateaus Through Sunday

Overnight Into Sunday Morning

Mostly clear ( high clouds ).  Large vertical temperature spread between mountain valleys with calm winds & snow cover verses windy mid-upper elevation mountain ridges.  SSW to SW winds 10-25 mph, with higher gusts, on ridges-plateaus below 2700 feet.  SW winds 20-35 mph, with gusts to 40+ mph, on upper elevation mountain ridges.  Temps varying from 20s in colder valleys to 40s-lower 50s along exposed mid-upper elevation ridges & plateaus.  Wind chills in the 30s & 40s ( coldest at the highest elevations ).

*Rapid overnight temp rises ( chinook style ) are possible in any decoupled mountain hollows which couple back up with the very strong SW wind field above ( i.e., rapid 20+ degree temp jumps ).

This Afternoon

Sunshine to increasing mid-high clouds.  Windy.  SSW winds 10-20 mph, with higher gusts, along mid elevation ridges & plateaus below 2700 feet.  SSW-SW winds 20-30 mph, with gusts to 40+ mph, along upper elevation ridges.  Temperatures varying from low-mid 40s over deep snow on northern slopes in upper elevations of High Knob Massif to 55 to 60 degrees in downslope locations ( even milder south over bare ground into the Tennessee Valley ).  Wind chills in the 30s along upper elevation mountain ridges ( 40s on mid elevation ridges & plateaus ).

Tonight Into Monday Morning

Increasing low-mid clouds.  A chance of light rain-showers by morning.  Winds SSW-SW 10-20 mph, with higher gusts, along middle elevation ridges & plateaus below 2700 feet.  SSW-SW winds 20-30 mph, with higher gusts, along upper elevation mountain ridges.  Temperatures widespread in the 40s.  Wind chill factors in the 30s & 40s ( coldest at the highest elevations ).

Weather Discussion ( January 30-31 )

Saturday featured a large temperature spread in mountain valleys and a relatively small temperature spread over deep snow still across upper elevations of the High Knob Massif.

The official National Weather Service temperature in Clintwood began the day at 19 degrees and peaked at 52 degrees, before falling quickly back to 30 degrees by 10:00 PM.

*The temperature being reported for Clintwood on WCYB-TV is actually from a weather station located near Ramey Flats, not far from majestic Pine Mountain and north of the Pound River ( thus the large differences observed at times since the official Clintwood NWS site is in a valley ).

Temperatures along upper elevation crestlines varied from upper 20s Friday evening, at around 10 PM, to low-mid 40s Saturday PM, followed by a minor drop back to 42 degrees this evening before a small rise back up amid strong SW winds.

Feels-like conditions were, of course, much colder with 30s and even some 20s ( in stronger gusts ) atop the High Knob Massif and Black Mountain during the afternoon.  That is continuing tonight and is even making the 48-50 degrees reported at LNP in Wise feel chilly.

The air is very dry so any evaporation from melting snow acts as a cooling process to slow down it’s rate of decrease ( snow will melt much faster amid moist air ).  A general 1″ to 5″ of snow depth was measured at Clintwood 1 W this afternoon near sunset ( elevation of 1560 feet above mean sea level ).  Snow cover continues to be widespread across northern slopes and in deep hollows verses much less snow or bare ground on well exposed southern slopes.

This truly generated a huge contrast with places like the Tri-Cities where bare ground now rules and temps soared into the 60s during the afternoon ( no snow to melt so the insolation was able to be applied to maximum heating of the surfaces, which then heat the overlying air ).

While Sunday will remain dry, the start of this new work week is looking wet.  This will especially be true for places along and northwest of the Cumberland Mountains, as now forecast by both the NAM Model group and European Model.

Meanwhile, if it sounds like a jet airplane has landed near your house it is because winds are ROARING along the high mountain ridges ( if you live in a place to hear-feel them ).

Given the thermal structure of the atmosphere, some of these stronger winds are mixing downward to Norton-Wise overnight and ( of course ) into the many ridge communities across Dickenson-Wise counties.  Batten down the hatches!

Have a great Sunday.

My Forecast For Today ( January 30 )

ALERT For Strong SW Winds Across Mid-Upper Elevation Mountain Ridges & Plateaus From Late Saturday Through Sunday

*State Route 619 remains extremely icy.  Chains are recommended if traveling across the High Knob Massif from the City of Norton to Fort Blackmore.  Hazardous conditions remain on other routes in the area ( Route 237 remains impassible due to snow drifts ).

Overnight Into Saturday Morning

Mostly clear.  A large vertical temperature spread developing between colder valleys and milder mountain ridges into morning.  WNW winds shifting S-SW at 5-10 mph along mountain ridges-plateaus below 2700 feet. W-  WSW winds 10 to 20 mph, with higher gusts, along upper elevation mountain ridges ( especially by morning ).  Temps dropping into 10s in colder valleys with calm winds verses rising readings through the 20s into 30s along middle to upper elevation ridges & plateaus.  Wind chills in the 10s and 20s ( coldest at highest elevations ).

This Afternoon

Mostly sunny.  SSW winds 5-15 mph, with higher gusts, below 2700 feet.  SW winds 10-25 mph, with higher gusts, across upper elevation mountain ridges.  Temps widespread in the 40s, varying from upper 30s to around 40 degrees on northern slopes at upper elevations of the High Knob Massif to 50-55 degrees in downslope locations of the Russell Fork & Levisa Fork basins.  Wind chills in the 20s & 30s across upper elevation mountain ridges.

Tonight Into Sunday Morning

Mostly clear.  Large vertical temperature spread between mountain valleys with calm winds & snow cover verses windy mid-upper elevation mountain ridges.  SSW-SW winds 10-20 mph, with higher gusts, on ridges-plateaus below 2700 feet.  SW winds 20-30 mph, with gusts to 40+ mph, on upper elevation mountain ridges.  Temps varying from 20s in colder valleys to the 30s & 40s along exposed mid-upper elevation ridges & plateaus ( tending to rise along highest mountain ridges into morning ).

Weather Discussion ( January 29-30 )

Reference my 012916 Forecast discussion for a recap of my first missed snow forecast of this season, at least for the High Knob Massif & Norton-Wise area, with reasons behind the miss.  It is indeed refreshing to have a weather source that admits when a wrong forecast was made.  It is good to miss a forecast and to admit to it, as that promotes advancement in the science.

That last statement may sound insane in this world, but actually is part of the very foundation of the scientific method where “critical” thinking is and should always be promoted.  No human nor supercomputer will ever make consistently perfect forecasts.  Is a “perfect” forecast even possible?  If you think so, then maybe it is time to review some scientific principles!

A clear sky featured a beautiful close to TGIF as night fell upon snow cover that remains widespread across the area from the High Knob Massif north ( and no doubt, in some other directions too ).  A high water content pack of snow that will not magically disappear, especially on northern slopes where it will take some time to all melt away.

*That is why I keep the slick & hazardous road statement at the beginning of this forecast, as no one should think they can jump into their car and drive up to the High Knob Lookout on Saturday like during a late spring or summer day.

Unless State Route 619 has been worked ( Friday ) again, it remained extremely icy with chains required for safer travel between the City of Norton and Fort Blackmore during Jan 28.  Some roads, such as Route 237, remained blocked by drifts.

Focus now shifts to a January Thaw weekend with ideal conditions in comparison to a week ago.  However, as my friends who live along ridges in Wise, northern Scott, and Dickenson counties constantly remind me, there will be a factor ( WIND ) that will make this less than pleasant.

As is so often the case, it’s difficult to get “warm” in the mountains at this time of year without cranking up winds which act as a great transporter of warm air from southern latitudes ( wind being a direct response to an increasing north to south temperature gradient ).

The NAM Model group and European Model are predicting winds around the summit level of the High Knob Massif to increase into the 40-50 knot range during Saturday Night into Sunday Night, with speeds tending to increase today ahead of this low-level jet of stronger winds.  This will, of course, make conditions feel chillier than air temperatures show across middle-upper elevations ( especially ).

Winds have already made the SW turn up top and are generating chill factors tonight that are making high crestlines feel like the colder valleys down below where drainage flows continue.

Wind chills and the effect of them are essentially never mentioned in most forecasts outside of arctic outbreak periods.  As residents of the mountains know well; however, this effect is important in much more of the year than most would like and is a near constant factor throughout the cold season from mid-late autumn through the early-mid spring ( i.e., October-April ).

The SW air flow trajectories forecast through this weekend will correlate well to mean annual winds, such that affects of this type of flow are well documented in my climatology.

This shows a tendency for cooler conditions from the Tennessee Valley Divide and High Knob Massif southwest, on upslope flow and rising air, verses milder conditions to the northeast on downslope flow and sinking air.

MAX temperatures in Jonesville to Big Stone Gap and Norton-Wise tend to be cooler under this type of flow than communities such as Pound, Clintwood, Haysi, and Grundy.  Under these conditions it is not unusual for temps at the summit level of the High Knob Massif to be as cool as the highest peaks in the southern Appalachians.

Beyond this weekend an initial wave of rain will become possible Monday ( February 1 ) in advance of a major storm system that will be lifting northeast from the lee of the Rockies into the Upper Midwest and Great Lakes during Ground Hog Day-Wednesday of next week.

A strong pressure gradient associated with this major storm will crank winds back up across the mountains, with potential for a mountain wave event on S-SE flow ( precise flow trajectories and inversion levels aloft are yet to be determined ).

An outbreak of severe thunderstorms, with possible tornadoes, will need to be closely followed west of the Appalachians as it approaches the mountains late Tuesday into early Wednesday.

Reference my latest Extended Outlook for trends beyond this time as winter is likely to return with a vengeance by the second week of February ( with much going on in the Northern Hemisphere ).

Have a great Saturday.

My Forecast For Today ( January 29 )

ALERT For Snow Shower & Local Snow Squall Development Overnight Into This Morning

Visibility will be reduced in heavier snow showers and any snow squalls which develop.  Roads in affected locations could quickly become slick & hazardous.  Remain Alert.

*State Route 619 remains extremely icy.  Chains are recommended if traveling across the High Knob Massif from the City of Norton to Fort Blackmore.  Hazardous conditions remain on other routes.

Overnight Into Mid-Morning

Lowering cloud bases with flurries and snow showers developing overnight into morning.  Snowstreaks and snow squalls possible.  Winds SW to WNW-NW at 10-20 mph, with higher gusts on middle-upper elevation ridges and plateaus.  Temperatures dropping into the upper 10s to upper 20s by sunrise to mid-morning.  Wind chill factors in the single digits and teens ( coldest at highest elevations ).

Snowfall Forecast For Friday

Upslope Side of Mountains
0.5″ to 3.0″

Downslope Side of Mountains
Dusting to 0.5″

Target snowfall of 1.0″ at Wise, ( +/- ) 0.5″ Error Potential.  This implies 0.5-1.5″ possible in the Norton-Wise area.  Extremes of a dusting up to 2-3″ will be possible across the area, with greatest snow amounts expected along upslope side of mountains with respect to WNW-NW air flow trajectories ( i.e., least snow likely ESE-SE of the High Knob Massif and Tennessee Valley Divide ).

This Afternoon

Any snow showers & squalls tapering to flurries & ending.  Cloudy skies becoming mostly sunny.  Cold.  WNW winds 5-15 mph, with higher gusts.  Temperatures varying from 20s to low 30s high elevations to the middle-upper 30s.  Milder south into river valleys of the Clinch, Powell, Holston and Great Valley of the Tri-Cities. Wind chills 10s & 20s.

Tonight Into Saturday Morning

Becoming mostly clear to partly cloudy.  A large vertical temperature spread developing between colder valleys and milder mountain ridges.  WNW winds shifting S to SSW at  5-10 mph along mountain ridges-plateaus below 2700 feet. SW-WSW winds 10-20 mph, with higher gusts, along upper elevation mountain ridges ( especially by morning ).  Temps dropping into the 10s to low 20s in colder valleys with calm winds verses rising readings through the 30s along mid-upper elevation ridges ( mainly above 2700-3000 feet ).

*Strong SW winds of 10-20 mph, with 30-40+ mph gusts, will become possible Saturday into Saturday Night across mid-upper elevation mountain ridges as warmer air is transported into the Cumberland Mountains ( conditions will feel much cooler than generally forecast, especially at higher elevations ).

Weather Discussion ( January 28-29 )

My Afternoon Update

This afternoon update documents my first missed snow forecast of this winter season ( it will remain above and be saved for later reference ).  The only current change was to update afternoon temperatures since with more sun and less cloudiness they have trended a little higher.

Even though this was to be a very weak event, a dusting to 0.5″, at the very most, is all that occurred along the upslope side of the mountains.

I typically look at a dozen or more different parameters when forecasting NW Flow snowfall.  However, of them all moisture is perhaps most critical since regardless of how good other factors are you can simply not get snow without sufficient moisture.

Moisture along and upstream of the high north-northwest facing slopes and crestlines is especially important in the generation of orographic snow on NW flow.  At 10:00 AM above, as one point selected, the 87% RH value came in well below the 96% value predicted by the 7 AM run of the NAM model this morning ( the GFS Model being very similar ).

The air never did saturate completely with orographic pilatus being limited and of short-duration during the morning, which limited riming.  Riming is a very important factor in enhancement of snowfall across upper elevations in the High Knob Massif where it adds to snow volume, in addition to its deposition and growth upon trees and other exposed objects ( as a secondary source of moisture that is visible until its drop…the rime enhancement of snowfall is visible only via close analysis and inspection ).

A major reason, of course, for the lesser amount of low-level moisture is that a calculation of backward air flow trajectories into Wise up to 7:00 AM reveal a miss with incoming air from a continental source region instead of the Great Lakes ( the above plot set for 500 meters above ground level with a 100 meter plot streaming in from mid-continent to an even greater extent ).

Vigorous morning snow showers moved through the Charleston area of West Virginia.  From space the difference is small between Wise & Charleston; however, on the ground the difference this AM was large since air flow into Charleston crossed the Great Lakes upstream ( illustrating, as has been well known here for decades, how important the Great Lakes are to NW Flow ( upslope ) snow in absence of wrap-around and all other moisture sources ).

Moisture streams off the Great Lakes are notoriously narrow in nature along the Lakes, and can remain that way downstream.  Hitting any given point from 400 air miles away then becomes a challenge if flow across the Lakes is not strong and vigorous and cyclonic in nature.

My Overnight Discussion

A significant spread in temperatures were observed across the mountain area during Thursday, as past climatology has dictated, with PM MAXS varying from low-mid 30s over the snowpack atop the High Knob Massif to middle 40s on SW downslope flow at Clintwood and upper 40s in Grundy.

A period of afternoon clouds featured more nice waves visible above the High Knob Massif area, with gusty SW winds making conditions feel like winter ( for certain ) across the higher terrain.

MAX temperatures in the upper 30s to lower 40s were common in the Norton-Wise area, in contrast to mid-upper 40s from Pound and Clintwood to Grundy.

NW winds tonight have been gusting over 30 mph recently along our high mountain crestlines.

This has occurred as the temperature begins to drop and moisture begins to increase ( below ).

Focus now shifts to the final cold air push of January 2016 which has been a relatively cold month in the mountains, with increasing overnight moisture to bring a final snow.

The NAM Model now predicts that the 925-850 MB flow field will come into alignment to bring a period of Great Lake moisture into the High Knob Massif area during the predawn to mid-morning period of this TGIF ( flow now being predicted to come farther south into the area verses previous model runs ).

Snow showers and flurries will develop with potential now for local squall and snowstreak development given this increased moisture in low-levels amid the upslope lifting zone.

The GFS Model streamline forecast predicts the same basic flow, which will be short-lived but potentially productive during a 6 hour or so period from the predawn into mid-morning.

I increased my previous snowfall forecast only slightly for the area in general, leaving my target snow forecast for Wise alone given uncertainty associated with where squalls and any narrow snowstreaks may hit ( the upslope area having widespread snow, but with embedded heavier bursts which are impossible to pinpoint since they are yet to form on Doppler ).

Snow flakes began falling on Eagle Knob of the High Knob Massif during the 2:00 to 2:30 AM period as an upper air disturbance passed and the atmosphere began to moisten.  The best low-level moisture not arriving until the predawn to mid-morning period when Doppler will begin to show a more classic upslope development of echoes as air rises upon approaching the Virginia-Kentucky border area.

With widespread old snow remaining on the ground, the upcoming day will be cold so bundle up, as this fresh batch of cold air arrives.

For those wanting a warm up, the good news is that cold air will begin retreating as soon as this upcoming overnight-Saturday morning period along highest mountain ridges of the Cumbelands; but, the bad news, is with increasingly strong winds from the SW which will drop chill factors to effectively delay true sensible warming for our middle-upper elevations until the late weekend and/or Monday.

As long as snow cover remains widespread it is hard to get really warm.  A major storm system next week still looks to generate a potential for strong winds ( and mountain waves ) along with the chance of strong-severe thunderstorms as the warmest air arrives by Tuesday ( February 2 ).  Stay tuned for updates.

 Have a great TGIF.

My Forecast For Today ( January 28 )

Overnight Into This Morning

Partly cloudy ( some high clouds ).  Patchy fog possible along major rivers.  Winds becoming S-SW at generally less than 10 mph along mid elevation ridges and plateaus.  SW to WSW winds 10-20 mph, with higher gusts, along upper elevation mountain ridges.  Temperatures varying from the 10s to lower 20s in colder locations verses rising readings into upper 20s to lower 30s on exposed ridges at mid-upper elevations ( mostly above 2700 feet ).  Wind chills in the 10s and 20s ( coldest at highest elevations ).

This Afternoon

Partly to mostly sunny.  A period of mid-high altitude clouds.  SSW-SW winds at 5-15 mph, with higher gusts, below 2700 feet.  Winds SW-WSW 10-20 mph, with higher gusts, above 2700 feet.  Temps varying from the lower 30s to the lower 40s ( coldest at highest elevations ), with mid 40s possible in downslope sites ( e.g., Pound, Clintwood ).  Wind chills in 20s & 30s.

Tonight Into Friday Morning

Lowering cloud bases with flurries and snow showers developing overnight into morning.  Turning blustery.  Winds SW shifting WNW-NW at 10-20 mph, with higher gusts on middle to upper elevation ridges and plateaus.  Temperatures dropping into upper 10s to upper 20s by sunrise to mid-morning.  Wind chill factors in the single digits and teens ( coldest at highest elevations ).

Snowfall Forecast For Friday

Upslope Side of Mountains
0.5″ to 2.5″

Downslope Side of Mountains
Dusting to 0.5″

Target snowfall of 1.0″ at Wise, ( +/- ) 0.5″ Error Potential.  This implies 0.5-1.5″ possible in the Norton-Wise area.  Extremes of a dusting up to 2-3″ will be possible across the area, with greatest snow amounts expected along upslope side of mountains with respect to WNW-NW air flow ( i.e., least snowfall to the ESE-SE from the High Knob Massif and Tennessee Valley Divide ).

Weather Discussion ( January 27-28 )

Reference my 012616 Forecast discussion section for a look at some interesting mountain wave clouds observed Wednesday.

The day began amid low clouds and a coating of rime along middle-upper elevation mountain ridges & plateaus, with widespread riming across the High Knob Massif as shown via an iPhone shot by my friend Darlene Fields on her way to work ( school nurse at Appalachia Elementary ).

Wednesday ended with a gorgeous sunset featuring mountain wave clouds above the lingering snow.

Following a mix of sun and clouds today ( Thursday ) just enough moisture and lift will combine overnight into Friday morning for some snow to develop along the mountains.

Unless flow off Lake Michigan improves from what is being predicted by models now, limited moisture will only allow for light accumulations.  It is so close; however, that a shift south by 50 air miles or so would increase snowfall significantly into the High Knob Massif area via more moisture from Lake Michigan & Lake Superior on NW flow.

Flurries and snow showers will become possible late this evening into the early overnight of Friday as a upper air disturbance will be crossing the mountains.

 A January Thaw which opens February continues on tap as a major winter storm develops and lifts northeast across the central USA, putting the southern Appalachians in its warm sector initially as February opens.  Thunderstorms and strong gradient ( mountain wave ) winds are likely before cold air returns once again to shorten the thaw!

Reference my 012616 Extended Outlook for more details.

Have a great Thursday.

My Forecast For Today ( January 27 )

ALERT For Icy Walks-Decks-Above Ground Objects And Roadways Overnight Into Early Afternoon Wednesday

Drizzle & Fog Changing To Freezing Drizzle & Freezing Fog With Especially Dense Fog Amid Upslope Locations Along & North of the High Knob Massif and Tennessee Valley Divide Overnight Into Wednesday

This setting favors very dense fog for Wise and places of similar or higher elevation along and north of the High Knob Massif and the Tennessee Valley Divide overnight into Wednesday.  Please slow down and use extreme caution walking outside and/or driving. 

Overnight Into Wednesday Morning

Turning colder ( inversion developing ).  Freezing drizzle and freezing fog – worst at mid-upper elevations.  NW-N winds 5-15 mph.  Temperatures falling into the 20s, with upper 10s at highest elevations by morning.  Wind chills falling into 10s to low 20s overnight into morning, with single digits & 10s at highest elevations ( milder temps in river valleys of Clinch, Powell, Holston toward Tri-Cities ).

This Morning Through This Afternoon

Cloud bases lifting and becoming partly sunny.  Light N to NE winds generally less than 10 mph, becoming variable.  Temperatures mostly in the 20s to mid 30s ( milder south toward the Tri-Cities and river valleys of Clinch & Powell ).

Tonight Into Thursday Morning

Becoming clear.  Areas of fog possible.  Winds becoming SSW-WSW at 5-15 mph along mid-upper elevation ridges, with higher gusts by morning.  Temperatures varying from the 10s to low 20s in colder locations verses rising readings on exposed mountain ridges above 2700 feet.

Weather Discussion ( January 26-27 )

Afternoon Update

Cloud bases began lifting off of middle elevations this morning, with breaks for sunshine developing into early afternoon ( northern slopes of the High Knob Massif and portions of the Tennessee Valley Divide being slower to break for sun than locations lee of the mountains into portions of the Clinch River Valley ).

While some clouds still linger along northern sides of the High Knob Massif, the view is certainly better than 12-hours earlier when the area was engulfed amid freezing fog.

Temperatures are slowly beginning to rise with upper 20s to lower 30s from Norton-Wise to Clintwood at 2:00 PM, in wake of low temps which occurred at mid-morning.

A feature of note this afternoon is a nice, stationary orographic wave cloud which has now held in the same position for a couple hours or more.

Other waves are visible, but this orographic cloud has tended to be the biggest and most predominate seen from this CAM perspective.

Observe also miles of riming visible along the High Knob Massif from the prolonged freezing fog event of Tuesday Night into today.

It changes shape a little and color as light changes, but basically holds in the same place over time.  It is present in the first image above at 2:18 PM and remains in this latest image at 4:14 PM.

Looking downward from space ( above ) three such clouds are visible along the Wise-Scott border of the High Knob Massif, with the middle one being the cloud best seen in above CAM images.

Mountain waves ( above ) after sunset with more defined stacked lenticular forms in the same location as the long-lived afternoon wave that possessed more of a roll-type appearance.  Very nice!

Observe the “white light” above Eagle Knob which is the PBS Transmitter Tower at 4413 feet above sea level ( appears red to naked eye, as this is the infrared night mode of the High Knob Massif Webcam ).

My Overnight Discussion

A raw and nasty Tuesday was dominated by rain, gusty winds at higher elevations, and a general array of fog that formed over the cold snowpack as moist, milder air was transported across the area on southerly air flow.

That played a major role in my forecast last night, in which I greatly undercut model forecast temperatures for Tuesday ( reference my 012616 Forecast for more details ).

Now my ALERT for Freezing Drizzle & Freezing Fog should be taken seriously by everyone planning on being outside overnight into Wednesday.  Be careful walking-driving as any surface could be icy & slick.

The Norton-Wise temp being 30-32 degrees at 11:30 PM.

The setting from now through the overnight is all about cloud bases which are dropping on northerly upslope flow and temperatures that go sub-freezing to generate an array of icy conditions on above ground and ground surfaces.

Temperatures at 11:30 PM on January 26 included

Black Mountain: 28 degrees
( Elevation 4031 feet )

Lonesome Pine Airport: 32 degrees
( Elevation 2684 feet )

Clintwood 1 W: 33 degrees
( Elevation 1560 feet )

Jonesville Airport: 35.6 degrees
( Elevation 1411 feet )

While the entire area will be dropping below freezing into Wednesday morning, locations from Norton-Wise & Sandy Ridge are at or below freezing now and will fall into and through the 20s into the upcoming day ( reaching a MIN around mid-morning Wednesday, followed by steady or slow rises through the afternoon with small recoveries ).

The moisture profile appears to become too shallow to support any snow, with freezing fog and freezing drizzle being favored instead amid upslope locations along and north of the High Knob Massif and Tennessee Valley Divide ( given this thermal structure ).

The biggest unknown during this forecast cycle arises by late today when high-resolution models like the NAM show a shift in wind directions working downward from top of the inversion layer ( above High Knob summit level in the morning to below its level by late afternoon ).  Depending upon when this occurs, cloud bases will begin to lift and break up ( it may be during mid-late PM or after sunset ).

Climatology shows it could be BOTH.  Settings like this in the past have featured clearing across the high country of the High Knob Massif before it occurs from Wise northward to Pound-Clintwood as moisture thins from top to bottom.  Snow on the ground acts as a complicating factor; however, since it keeps low-levels cold and can enhance a vertical inversion ( warmer air over cold air ).  If the snow effect is strong enough then clouds may just hold right into Wednesday evening.

Regardless of how this plays out exactly, it will be another raw day and I have again undercut temperatures to make them colder than guidance suggests as many places along and north of the High Knob Massif and Tennessee Valley Divide will remain below freezing all day.  Keep warm!

Make it a safe Wednesday.

My Forecast For Today ( January 26 )

ALERT For Strong & Gusty SSW to SW Winds Across Middle-Upper Elevation Mountain Ridge & Plateaus Into Tuesday Morning

*Light freezing rain may be possible in sheltered mountain valleys by the predawn-morning hours of Tuesday, as well as on cold road surfaces running along northern slopes.  Caution Is Advised.

Fog Will Become Possible Above Cold Snow Surfaces

*Drizzle will change to freezing drizzle Tuesday Night into Wednesday Morning.  The Freezing Level will drop from the summit level of the High Knob Massif Tuesday evening to elevations of Norton-Wise by around 10 PM-Midnight.

Overnight Into Mid-Morning

Mostly cloudy.  A chance of light showers by morning.  Possibly freezing in sheltered valleys and on northern slope roads.  Windy or becoming windy on exposed mid to upper elevation mountain ridges & plateaus.  SSW-SW winds 10-25 mph, with higher gusts, along ridges-plateaus at middle elevations.  SSW-SW winds 20-30 mph, with gusts of 40 to 50 mph, on upper elevation mountain ridges.  Large vertical temperature spread varying from lower to mid 20s in colder mountain valleys ( tending to rise overnight ) to 30s-lower 40s on exposed ridges & plateaus.  Wind chill factors in the 10s and 20s ( coldest at highest elevations ).

Mid-Morning Through This Afternoon

Rain showers, with a period of rain, likely.  Chilly & raw with fog possible.   Winds SSW-SW shifting W-NW around or after sunset at 5-15 mph below 2700 feet.  SW to WNW winds 10-20 mph, with higher gusts, on ridges above 2700 feet.  Temperatures mainly in the upper 30s to lower 40s.  Wind chills in 20s and 30s ( coldest at highest elevations ).

Tonight Into Wednesday Morning

Low clouds & areas of fog.  Turning colder ( inversion developing ).  Light rain & drizzle to freezing drizzle late.  Freezing fog along some middle to upper elevation ridges.  WNW-NW winds 5-15 mph.  Temperatures falling through the 30s into 20s, with upper 10s at highest elevations by morning.  Wind chills falling into 10s to low 20s overnight into morning, with single digits & 10s at highest elevations.

Weather Discussion ( January 25-26 )

My Afternoon Update

Just as I had in my forecast, it has been a chilly, raw day with widespread areas of fog ( especially in valleys ) over the cold snowpack with temps in upper 30s to lower 40s.

At least wind gusts of 20 to 40+ mph, which dominated the overnight along many mid-upper elevation mountain ridges, decreased this afternoon ( it remains gusty atop High Knob ).

The official day-time ( since Midnight ) MAX temperature in Clintwood has been 38.6 degrees, with 37 degrees at 4:00 PM beneath low clouds and shallow areas of fog above snow.

The fog over snow has been widespread as the milder air runs across its cold surface.  Shallow in comparison to the orographic clouds ( fog ) obscuring upper elevations amid the High Knob Massif where snow remains much deeper.

While the air temperature of 37 degrees on Eagle Knob is about the same as down in Clintwood, the difference is 20-30 mph SW wind gusts which are making it feel like 20s atop the massif ( and along some of our middle elevation mountain ridges like Sandy Ridge ).

My Overnight Discussion

Strong SW winds began increasing at highest elevations during Monday afternoon, with 30-40+ mph gusts common, to set the stage for nice orographic waves around sunset.

It would be rare to have air flowing across the High Knob Massif that is this strong, with moisture present, and not form waves.

Note the nice lenticular shape of these wave clouds.

A battle between strong cooling over the snowpack and the pressure gradient allowed for a drop in wind speeds after sunset into early evening, as cooling prevailed initially.

The general evening trend has featured progressively stronger wind gusts dropping downward onto middle elevation ridges amid an increasing pressure gradient.

This has begun to influence the elevation of Wise.

The strongest winds will lift northeast along the Cumberland range overnight into Tuesday morning.

Many mountain valleys have, by contrast, dropped into the 20s with drainage flow and calm-light winds.  Temp rises are expected with increased clouds and increased vertical mixing.  The chance of a little light rain and some valleys remaining at or below freezing must be respected into morning; although, this does not look widespread.

As noted previously, ground-road surfaces are cold, especially those on northern slopes which receive little to no sunshine.  This increases the chance that icing could occur on contact in places.

As this beautiful photograph by my friend Rodney Parsons illustrates, snow cover remains widespread and as this air mass saturates today there will be potential for fog to form as its cold surface comes into contact with a new air mass from the Deep South bringing rain ( while this will be most likely across upper elevations, it could occur into portions of our lower-middle elevations along the Cumberlands ).

As air turns colder tonight behind the passage of an evening cold front moisture becomes shallow and trapped beneath a developing inversion.  This tends to support low clouds-fog and drizzle that could change into freezing drizzle from top down through this evening into the overnight.

The freezing level will begin at the High Knob Massif summit level and drop downward over time to the elevations of Norton-Wise by around 10 PM-Midnight, then into lower elevations during the overnight period into Wednesday morning.

If the inversion holds, as the high-resolution NAM Model shows, low clouds will be hard to shake on Wednesday…especially along and north to northwest of the High Knob Massif-Tennessee Valley Divide on NW-N air flow.  Stay tuned for updates.

Have a great Tuesday.

My Forecast For Today ( January 25 )

The ALERT For Strong Winds Has Begun For Upper Elevations ( 3:00 PM ) With Downward Mixing Into Middle Elevations Expected Tonight

Caution For Possible Icy Patches From Refreezing Of Water And The Continuation Of Hazardous Travel On Untreated Roadways

ALERT For Strong & Gusty SSW-SW Winds Developing Across Mid-Upper Elevation Mountain Ridge-Plateaus During Monday Night Into Tuesday Morning

*Light freezing rain may be possible in sheltered mountain valleys by the predawn-morning hours of Tuesday, as well as on cold road surfaces running along northern slopes.

Overnight Into Monday Morning

Cold with high clouds.  SSE-SSW winds at generally less than 10 mph below 2500 feet.  SW-WSW winds 10-20 mph, with higher gusts, along exposed upper elevation mountain ridges & plateaus.  Large vertical temp spread between snow covered mountain valleys with calm winds and exposed mid to upper elevation ridges.  Temps varying from single digits and 10s in colder valleys to mid 20s-lower 30s on exposed mountain ridges ( wind chills in the 10s to low 20s ).

This Afternoon

Sunshine & high altitude clouds.  S-SSW winds increasing to 10-20 mph on mountain ridges & plateaus below 2700 feet.  Winds SSW-SW 15-25 mph, with higher gusts, along ridges above 2700 feet.  Temperatures in the 30s to low-mid 40s.  Wind chills in the 20s & 30s ( coldest at high elevations ).

Tonight Into Tuesday Morning

Mostly clear skies giving way to clouds.  A chance of light rain or showers by morning.  Possibly freezing in sheltered valleys and on northern slope roads.  Windy across exposed mid-upper elevation mountain ridges & plateaus.  SSW-SW winds 15-30 mph, with higher gusts, on ridges-plateaus at elevations below 2700 feet.  SW winds 25 to 35 mph, with gusts to 40-50 mph, on upper elevation mountain ridges.  Temperatures varying from low-mid 20s in colder valleys to the 30s on exposed ridges & plateaus.  Wind chills in the 10s & 20s ( coldest at highest elevations ).

*Some blowing and drifting of snow will be possible at high elevations as wind speeds increase Monday Night, especially across northern slopes and shaded sides of crests where snow tends to be shaded from direct sunshine ( keeping recent low density top layer snow loose & able to blow more efficiently ).

Weather Discussion ( January 24-25 )

Afternoon Update

The ALERT for strong SW winds has now started with recent gusts to between 40 and 50 mph along the high crestlines of the High Knob Massif and Black Mountain.

 Although temperatures have risen into upper 30s to around 40 degrees, it feels like 20s along the high mountain ridges.

Following a MIN of 12 degrees at Clintwood 1 W the PM temp climbed to 44 degrees before dropping back to 38 degrees as of 5:00 PM.  Low-Mid 40s have also been reported in Norton-Wise and the adjacent ridge communities on increasingly gusty SW winds ( and warm air advection ).

A low-level jet and wind speed max will be moving up along the western side of the Appalachians tonight, with greatest impact across mid-upper elevations of the Cumberland Mountains.

My Overnight Discussion

Upslope snow finally ending into early hours of Sunday and low clouds began to break for some locations.  A real temp plunge took readings down to around 0 degrees or locally below in some places.

MIN Temperatures Sunday Morning

Burkes Garden
-2 below zero

Clintwood 1 W
1 degree

South Fork of Pound
5 degrees

Jonesville Airport
7 degrees

Upslope clouds held tough along and just north of the High Knob Massif to keep temps a bit “milder” into Norton-Wise, with upper single digits to lower 10s reported ( heatwave ).

The day featured beautiful blue skies and only scattered high altitude ice crystal clouds.  A nice day for NASA to capture Landsat Images of widespread snow cover.

Observe that flat or rolling terrain tends to show snow better than mountainous, convex topography

Unless you are really into climatology, an aspect that is never talked about on a day like Sunday is that snow glare causes thermometers to read too high, that is unless they are shaded completely ( e.g., on northern exposures ).

Even National Weather Service MMTS Thermometers can read too high with intense snow glare reflecting sunlight upward into radiation shields from the ground.

That is one reason I like to use Nora 4 SSE observations, at the official NWS station of Wayne & Genevie Riner, where the thermometers are on the north side of the house and protected from radiation and intense snow glare.

The MAX temperature of 30 degrees was more representative of what elevations such as Wise truly had, with the elevation of this station being only 34 feet lower than Lonesome Pine Airport where the reported MAX reached 37 degrees.

*Snow glare radiation caused many Weatherbug Stations to read absurdly high during Sunday ( roof + snow glare ).

As always it seems amid this complex terrain, interesting weather variations are on display once again tonight with colder valleys 10 to 15 degrees at 2:45 AM ( Jan 25 ) verses a temp trend that has been rising along high crestlines into the lower 30s on steady and gusty SW winds ( WCF 10s ).

Speaking of which, SW winds are going to really begin to CRANK along the Cumberland Mountains late Monday into Tuesday Morning as this next weather maker arrives.

This low-level inversion will be stronger than the NAM predicts since valley temperatures in many places will drop off fast during Monday evening above snow, before rising overnight into Tuesday morning for places that have enough turbulent, vertical mixing to overcome stratification ( warmer air above cold air ) and recouple calm valleys back up with strong flow along top of the boundary layer field ( the recoupling point being dependent upon the local terrain features and varying with location ).

An inversion will further enhance this setting by aiding channelization of air flow between the High Knob Massif and Black Mountain, as SW winds stream up through the High Knob Landform corridor tonight into Tuesday.

A possible freezing concern will be any valleys that remain decoupled, with light to calm winds, since precipitation will be developing by the predawn-sunrise period of Tuesday.  In addition, as past climatology shows, northern slope roads will also be a concern since surfaces will be very cold.

While precipitation amounts with this next system are yet to be fully resolved, the high-resolution NAM fits climatology with an axis of heaviest amounts extending northeast across the Cumberland range on strong SW flow.

*In particular, the upslope-downslope couplet being shown between the High Knob Massif-Black Mountain corridor and Russell Fork-Levisa Fork basins fits climatology of strong SW flow regimes well.

Although relatively close, the SW Upslope Flow snow potential with this system seems currently to be reduced by above freezing air forecast for the 825-775 MB layer.  However, should that layer cool then the threat would increase.  A trend to monitor today.

 Make it a great Monday.

My Forecast For Today ( January 24 )

ALERT For Bitter COLD Temperatures Into Sunday Morning With Hazardous Travel Conditions

Temperatures will plunge overnight if low clouds dissipate, with potential for readings to drop below 0 degrees in places that can clear several hours before sunrise over deep snow.  Meanwhile, readings will be “milder” if low clouds hold until sunrise.

Overnight Into Sunday Morning

Light snow & flurries into the overnight with partial clearing or clearing possible by predawn hours.  Up to 1″ of new snow possible along windward slopes of the High Knob Massif.  WNW-NW winds decreasing to generally 10 mph or less by morning.  Temps widespread in the single digits and 10s if low clouds can hold, but becoming bitter if skies clear with 5 above to -10 below zero readings possible amid mountain valleys having a deep snowpack.

Mid-Morning Through This Afternoon

Becoming sunny with only a few high clouds possible.  Winds SSW generally less than 10 mph below 2700 feet.  SW-W winds 5-15 mph along upper elevation mountain ridges.  Temperatures mostly in the 20s to lower 30s.

Tonight Into Monday Morning

Mostly clear through the evening.  Some mid-high clouds possible by morning.  SSE-SSW winds at generally less than 10 mph below 2500 feet.  SW-WSW winds 10-15 mph, with higher gusts, along exposed mid-upper elevation mountain ridges & plateaus.  Large vertical temp spread between snow covered mountain valleys with calm winds and exposed mid to upper elevation ridges.  Temps varying from single digits and 10s in colder valleys to the mid-upper 20s on exposed mountain ridges ( but wind chills in the 10s ).

Weather Discussion ( January 23-24 )

Tonight presents a more difficult forecast for me than the past winter storm, as temperatures are poised to TANK if low clouds dissipate over a fresh, deep snowpack.  With northerly upslope keeping the snow machine going along windward slopes of the High Knob Massif at 11:00 PM it might not seem very likely, but must be covered as past climatology dictates ( especially with clearing now just northwest of the Virginia-Kentucky stateline ).

Wes Ward measured an additional 1.0″ of new snow at the Norton Water Plant at 9:30 PM Saturday evening to bring the storm snowfall tally to 19.1″ at the base of the massif.

City of Norton Water Plant
Elevation 2342 feet

January 22 at 9:00 AM
4.0″

January 22 at 4:00 PM
1.8″

January 22 at 9:45 PM
6.0″

January 23 at 3:40 AM
2.0″

January 23 at 9:00 AM
2.8″

January 23 at 3:00 PM
1.5″

January 23 at 9:30 PM
1.0″

Snowfall Total: 19.1″

The 2-day water equivalent total ending at 9:00 AM Saturday was 2.26″ ( not counting what has fallen since then ).  Note that 13.3″ of snow fell between sunset Friday and 9:30 PM Saturday after winds shifted to northerly upslope.

*The only measurement that had to be partially estimated was the first one due to a tremendous amount of SLEET which tended to bounce off of the measuring surface.  After each measurement the surface is swept clean and made ready to collect what falls until the next 6-hour measurement.

It is not hard to figure what made snow along windward sides of the great High Knob Massif so deep ( from Bowman Mountain toward Big Cherry Lake ) when noting that 13.3″ of snowfall was measured at the City of Norton Water Plant after 4:00 PM Friday when winds shifted north ( snow was much deeper atop the High Knob Massif by 4 PM Friday than it was down in Norton, where heavy overnight precipitation into Friday AM had been dominated by sleet ).

Observe how black isobars above are close together along the Appalachians, with the coldest air in the entire storm having formed right over the southern Appalachians as orographic forcing and lifting worked to chill the air mass.  This combined with abundant moisture to keep the upslope snow machine cranking out the flakes ( especially since low clouds-riming existed within prime temperatures for dendritic crystals ).

Saturday was a raw, cold and snowy day with low-mid 10s and below zero wind chills combining with blowing snow to create the worst conditions of this winter so far atop the High Knob Massif, with not a whole lot of improvement down in Norton-Wise and across the adjacent ridge communities of Wise & Dickenson counties.

Tonight presents a real dilemma since moisture has decreased to a thin vertical layer with cloud bases now just below and above the summit level of the High Knob Massif, such that the question becomes one of to clear or NOT!

As the big East Coast storm continues to move away the gradient is weakening and low-level winds are forecast to shift more W-SW in lower levels overnight into Sunday Morning.  Given a fresh, deep pack of snow, past climatology clearly shows that any clearing can enhance radiational cooling and inversion formation to quickly decouple boundary layer winds and cause temps to TANK.

The NAM Model predicts lee side clearing through the TN Valley and along the eastern side of the Appalachians overnight, but the problem is that MUCH more clearing has already occurred west of the mountains than the model indicates.

So low temperatures into Sunday AM will be dependent upon clouds holding or folding, with a large spread possible across the region should upslope clouds hold & downslope locations clear out.  Time will tell what happens, and this is the reason my forecast includes clearing as a possibility.

Looking Ahead Through Jan 25-30

A couple of weather systems are being tracked for the upcoming week.  The first system is timed for Tuesday.

This system is currently forecast to CRANK SW winds along the Cumberland Mountains.  It will not be a simple forecast as the current, widespread snowpack will cause low-level temperatures to be chillier than the model is showing.

In addition, strong SW upslope ( if the above verifies ) will also keep temperatures cooler than predicted from Norton-Wise into Big Stone Gap and portions of Lee County.

The second and potentially stronger and much more important system is another wave that will dig into northern portions of the Gulf of Mexico by Thursday.

The European Ensembles show that this will be another system to closely monitor, with some members predicting Miller A cyclogenesis ( which could be another significant snow maker for the southern Appalachians ).

The ultimate track of the low pressure will be critical, with spread among the 51-Member ensemble group too large to have any real confidence in a solution at this point in time.  However, given it is ensembles and not a single model showing this, an immediate caution flag is raised.

Have a great Sunday.

My Forecast For Today ( January 23 )

ALERT For Snow & Bitter Wind Chills Through Saturday With Hazardous Travel Conditions

*Some high elevation roads in the High Knob Massif have become impassible.  Please use extreme caution when traveling in upper elevations through this weekend, and on all untreated roads.

Heavy Upslope Snow Will Remain Possible In Favored Locations Today Along With Blowing & Drifting Snow In Exposed Locations At Higher Elevations

Overnight Into This Morning

Snow & snow showers.  Heavy at times ( especially along upslope side of mountains ).  N winds 10-20 mph, with higher gusts, along mid-upper elevation mountain ridges-plateaus.  Temperatures varying from single digits at the highest elevations to the 10s ( milder in downslope sites ).  Wind chill factors from single digits & 10s below 2700 feet to as cold as 0 to -10 below at upper elevations.

This Morning Through This Afternoon

Periods of snow & snow showers.  Cold & gusty.  Blowing and drifting snow at exposed mid-upper elevations. N to NW winds 10-20 mph, with higher gusts.  Temperatures varying from low-mid 10s to low-mid 20s ( coldest at the highest elevations ).  Milder in downslope communities toward the Tri-Cities.  Wind chills from 0 to -10 below at highest elevations to the single digits and 10s.

  Tonight Into Sunday Morning

Snow showers & flurries ending into the overnight.  Cold.  WNW-NW winds decreasing to generally 10 mph or less by morning.  NW-N winds 10-15 mph, with higher gusts, along mountain ridges above 2700 feet.  Temps widespread in the single digits and 10s ( colder should any clearing occur ).

Weather Discussion ( January 22-23 )

My Afternoon Update

Snow, snow, and more snow.

Upslope snow has been steady, and locally heavy at times, throughout the daylight hours of Saturday.

My update this afternoon is not to change anything with the forecast, but rather to highlight what has been observed.

The City of Norton Water Plant had officially measured 18.1″ of snowfall as of 3:00 PM ( and it was still snowing ).

In specific, the fine measurements taken at the City of Norton Water Plant by Superintendent Andrew Greear and his staff ( Caleb Ramsey and Wes Ward during this event ) should be highlighted to illustrate the proper way to measure snowfall during any storm event.

City of Norton Water Plant
Elevation 2342 feet

January 22 at 9:00 AM
4.0″

January 22 at 4:00 PM
1.8″

January 22 at 9:45 PM
6.0″

January 23 at 3:40 AM
2.0″

January 23 at 9:00 AM
2.8″

January 23 at 3:00 PM
1.5″

January 23 at 9:30 PM
1.0″

Snowfall Total: 19.1″

The 2-day water equivalent total ending at 9:00 AM today was 2.26″ ( not counting what has fallen since then ).

*The only measurement that had to be partially estimated was the first one due to a tremendous amount of SLEET which tended to bounce off of the measuring surface.  After each measurement the surface is swept clean and made ready to collect what falls until the next 6-hour measurement.

Measuring every 6-hours ( or as close to that as possible ) is ideal for helping to minimize compression which occurs as snow accumulates.

Note that if snow falls and sticks, then melts and/or gets blown away in between the measurement times then it should be added to the total ( if not directly measured, then carefully estimated ).

*As always occurs on High Knob in big storms like this, ground depths tend to vary from wind blown bare ground ( or near bare ) to 4-5+ feet in drifts.

A preliminary estimate of total snowfall for Eagle Knob of the High Knob Massif is 26.0″ ( up to 3:00 PM on Saturday ).  A general 1-3 feet of depth is visible in the above image.

The hardest hit corridor was, as expected, between Bowman Mountain and Thunderstuck Knob of Powell Mountain, with resident Gregory Adams of the Little Mountain community reporting around 2 feet of snow depth at his home.

Cody Blankenbecler measured a settled snow depth of 14″ in Wise, with Andrew Greear & family measuring 15″ of depth at his home on Guest River above Norton.

As of 5:40 PM my official snowfall total for Clintwood had reached 11.0″ with steady, light snow still falling.

My Overnight Discussion

Reference my Afternoon 012216 Forecast Discussion section for more details on the period of heavy morning snow, sleet-ice.

Some of the most intense snow of this storm event, along with the coldest temps-wind chills observed, developed over the High Knob Massif into portions of Norton-Wise during Friday evening beneath the upper low & northerly upslope.

The center of the closing upper low was very close to the area, with Doppler suggesting a circulation right over the High Knob Massif.

Wes Ward of the City of Norton Water Plant measured 6″ of new snow at 9:45 PM ( it accumulated since 4 PM, but mostly after sunset ). This brought the ground depth to around 14″ with a 11.0″ storm snowfall total at the Water Plant.

*The Norton Water Plant had 1.60″ of water equivalent precip for the 24-hour period ending at 9 AM ( accumulated from 2-9 AM ), with only 3″ of new snow as enough warming with sinking air along the High Knob Massif changed snow into sleet along the mixed ( milder ) side of the TIM Circulation.  Most precipitation between Bowman Mountain & Big Cherry Lake fell as snow along the colder, upslope side of this mesoscale circulation.

Snow has also gotten deep at UVA-Wise.  Check out the car which is nearly buried by snow ( the car has been parked there for this entire event so far ) in this view ( below ).

Benches along the walk-way are now completely buried, with another unknown object ( is it too a car? ) appearing to be buried out at the entrance to the college along the main highway.  That may just be a big pile of snow which was pushed off the road.

Focus now is all about upslope snow on northerly flow that will be increasing today as the pressure gradient between this area and the intensifying Atlantic Low strengthens.

The flow has just begun to turn northerly, with a deep northerly flow predicted to develop overnight into today.

Observe wind vectors on the far right side above, and how the northerly flow extends upward through the atmosphere to the jet stream level around 300 MB.  Also note deep moisture present as the solid blue temperature line, and dashed blue dewpoint line, remain nearly together to around 500 MB.

Such a setting certainly supports upslope snow, heavy at times, into Saturday with a transition to more hit-miss snow showers by later Saturday into Saturday Night.

The increasing gradient along the mountains will not only be increasing higher elevation winds but also increasing orographic forcing.  Thus I expect significant snow is not yet over for upslope locations overnight into Saturday.

New snowfall will generally be much lighter for locations downslope of the mountains, with respect to NW-N air flow, toward the Great Valley & Clinch-Powell-Holston rivers.

Have A Warm & Safe Saturday.

My Forecast For Today ( January 22 )

A Crippling Fall of Very Heavy Snow, With Extreme Snowfall Rates, Is Likely For Friday ( Predawn Into Mid-Day )

*Even the downslope wake zone of the High Knob Massif may have very heavy snowfall during this time period

Please Do Not Travel If Possible

Many Roads May Become Impassible during the Friday Morning to Early Afternoon Period.  A Break In Activity Will Be Followed By NE-NW Upslope Flow Snow, With Blowing & Drifting, Dropping Temperatures & Low Wind Chills From Friday Night Into Saturday To Generate Additional Severe Conditions.  Travel Is Not Recommended During This Event.

Very strong LIFT ( Upward Vertical Motion ) will be moving across the region Friday.  This has an excellent chance of overwhelming downslope sinking-warming of air in wakes to generate very heavy snowfall during the Sunrise to Early Afternoon Period of Friday.

Wake = the zone of sinking air on the leeward side of major mountain barriers like the High Knob Massif.  In this case air will be sinking in locations to its northwest-west-southwest as air flow  streams across the massif from the SE-E-NE during this major event before shifting N-NW ( changing the lee wake zone to the south & southeast of the massif and Tennessee Valley Divide ).

Locations in the downstream wake of the High Knob Massif and the Tennessee-North Carolina border, on easterly air flow, will likely have a period of very heavy snow but do remain zones within NE TN and SW VA with the highest uncertainty.

Overnight Into The Predawn

Increasing clouds with snow or a mix developing at onset, changing to snow ( any mix lasting longest in the Powell Valley-Big Stone Gap corridor and adjacent locations in the downstream wake of the High Knob Massif ).  Winds becoming E-SE at 5-15 mph, with higher gusts, on ridges-plateaus below 2700 feet.  Winds ESE-SE 10-20 mph, with higher gusts, along mountain ridges above 2700 feet.  Temps varying from 10s in colder mountain valleys to lower-middle 30s on exposed upper elevation mountain ridges ( temps rising overnight in colder valleys and dropping on ridges following onset of precipitation ).

*The Predawn to Early Afternoon period remains the most uncertain for locations in the downslope wake of the High Knob Massif, with respect to precipitation type.  It is very difficult to get snow in Powell Valley on easterly air flow, but if dynamic lift aloft is strong enough and evaporative cooling sufficient it may be able to overcome warming with sinking air into the Valley corridor to generate heavy snow.

If a valley mix of precipitation types continues a TIM Circulation across the High Knob Massif will develop to generate even more extreme snowfall rates in the high country above 3000 feet.

Predawn To Early Afternoon

Snow becoming very heavy.  Extreme snowfall rates of 1-3″+ per hour possible during peak of intensity.  ESE winds 10-20 mph, with gusts 30-40+ mph at highest elevations.  Blowing & drifting snow upon exposed mid to upper elevation mountain ridges & plateaus.  Cold with temperatures from upper 10s to mid-upper 20s.  Wind chills in single digits & 10s, except below zero on high crestlines of the High Knob Massif ( in gusts ).

Mid-Late Afternoon

Heavy snow diminishing.  A break in activity possible before new snow & snow showers redevelop late.  ESE to SE winds becoming ENE at 5-15 mph, with higher gusts. Temperatures varying from upper 10s to upper 20s ( coldest at highest elevations ).

Tonight Into Saturday Morning

Snow.  Heavy at times.  Turning colder.  NE winds shifting NNW-NNE at 10-20 mph, with higher gusts, along mid-upper elevation mountain ridges-plateaus.  Cloud bases dropping ( possibly into mid elevations ).  Temperatures dropping into the 10s along upslope side of mountains, with upper single digits to around 10 degrees at summit level of High Knob Massif.  Wind chills dropping into the single digits to low 10s, except 0 to -10 below along upper elevation ridges.  Blowing and drifting snow along mid-upper elevation ridges.

*Additional fluffy snow accumulations are likely thru Saturday into Saturday Night and the overnight hours of Sunday along the upslope side of the mountains with respect to northerly air flow.  Cloud bases will be low through this period, with continuation of rime formation across upper elevations where heavy amounts are expected to bow small trees.

Weather Discussion ( January 21-22 )

Afternoon Update

It has been quite a day across the mountains.  As of mid-afternoon a general 5″ to 10″ of snow had accumulated from the High Knob Massif north & east, with MUCH LESS amid the downslope wake ( shadow zone ) of the massif where 1″ or so has been reported amid the Powell Valley to Big Stone Gap corridor ( with much mixed precipitation ).

Although not as great as past events ( with a TIM Circulation this time not associated with a pure rain-snow boundary but a snow-mixed boundary ), differences in snow depths and new snow were still very significant through this AM between Big Stone Gap and the High Knob Massif.

Reference TIM Circulation for more information.

The effect has been nicely illustrated this afternoon by some gorgeous views captured via the High Knob Massif Webcam at UVA-Wise, where a break in activity allowed downslope breaks leeward of the great massif in this easterly flow regime to become visible.

While only a tiny portion of the massif is actually visible, upon looking to the left of these views it is possible to see subsidence breaks ( caused by orographically forced sinking air on E winds ).

Following very heavy morning snow, with 1-2″+ or so per hour accumulation rates in parts of the area, the afternoon has featured bands of snow with on-and-off activity.

Afternoon bands have been manageable in comparison to the very heavy morning snow which made some roads in the area impassible or nearly so.

Snow began falling atop the High Knob Massif around 2 AM and quickly became heavy, with around 1″ falling in just 30 minutes or so.  A little mix may have occurred initially, but the bulk was snow above 3000 feet.  The heavy snow spread into Norton-Wise, with more mix-sleet in Norton vs more snow in Wise ( the difference…more sinking air off the mass into Norton on ESE air flow ).

Southwest of Norton, into the Powell Valley to Big Stone Gap corridor, sinking was significant enough to even beat out the very strong upward vertical motion that was developing aloft in the atmosphere.

Once again this illustrates how difficult it is to get just snow, and significant snow, on easterly air flow streaming across the High Knob Massif as I had indicated in my earlier discussions.  I should have left my preliminary snow forecast for this zone ( 6″ or Lee ) alone ( of course, this event is not yet over ).

My friend Chris Allgyer reported freezing rain, sleet, and snow all in Big Stone Gap that formed a slushy mess, as the new accumulation above can be seen on his sidewalk ( with lingering snow from the previous event beside the walk ).

My friend Sharon Daniels reported about the same amid the Head of Powell Valley ( around 1″ through the morning ).

This effect of sinking air adjacent to the High Knob Massif also impacted snow amounts in Norton, with more mix than in nearby Wise.  My friend Sandy Earls measured 4″ of depth at 12:43 PM.

A classic TIM Circulation reflectivity pattern, as viewed from the JKL Doppler, found highest echoes on the Wise County side of the massif that formed, and reformed, over time.

My friend Caleb Ramsey of the City of Norton Water Plant reported 3″ of new snow, with 6″ on the ground, at 9:00 AM after MUCH overnight mixed precip ( NWS 8″-diameter rain gauge total will be given later to illustrate how much mix occurred to contrast with mostly snow high atop the main crest zone of the High Knob Massif ).

As winds shift NE-NW this evening into Saturday snow will increase again across the mountain area with snow in all locations.  Snow will become very heavy once again in upslope locations northwest to northeast of the High Knob Massif and Tennessee Valley Divide ( widespread 6″ to 10″+ of additional snow in upslope locations verses 4″ or less in the downslope sites ( e.g., toward the Tri-Cities ).

My Overnight Discussion

An inversion over fresh snow cover in combination with upsloping air flow worked to keep temperatures along and north of the High Knob Massif much cooler during Jan 21 than locations to the south and southeast.

A PM MAX temperature of 28 degrees at the official NWS observation station in Clintwood fell to 15 degrees by 11 PM on January 21, beneath increasing mid-high clouds.

*The MAX temperature in Clintwood being the same as on High Knob during the afternoon, before evening temperature rose on High Knob in warm air advection ( creating a large vertical temp spread across the area between valley and peak ).

These colder temperatures look to play an important role in this storm event, with potential now high for a impressive period of heavy snowfall development into the predawn to mid-day period of this TGIF.

While deep convection over the Deep South can interfere with northward moisture transport, in this case it is not likely to disrupt what is already developing a structure featured in many great winter storms of the past.

My forecast suggests a general 1 to 2 feet of snow will fall across the area, and now has support of nearly all models, with the Friday Night to Saturday period having snow to water ratios ( density ) much lower than the 10:1 used by forecast models.  It will be surprising if snow totals do not top 2 feet in the High Knob Massif, with large to massive drifting possible in places along the main crest zone.

What you have on the ground by mid-day to late Friday afternoon will be added to Friday Night through Saturday Night ( with 6″ or MORE of additional snowfall likely for upslope locations on NE-NW air flow ( northerly ).

This snowfall will be low density, fluffy snow and be hard to keep track of as it will blow around over the harder, snow mass on the ground from earlier Friday.

 *Upslope locations including Norton-Wise, Pound, Clintwood, all communities along Sandy Ridge and others in Wise & Dickenson and, of course, the High Knob Massif of Wise-Scott-Lee.

While more snow now looks to fall amid wake zones of major mountain barriers like the High Knob Massif and TN-NC border ( in NE Tennessee ), these lee wakes will likely also have the highest probability of power outages due to higher density ( wetter ) snowfall.

Time will tell.  That was the trends being shown Thursday.  As already noted, it is very hard to get significant snow to accumulate in the Powell Valley to Big Stone Gap corridor when air flow has to cross the wide expanse of the High Knob Massif on easterly air flow trajectories.  It will only occur if atmospheric dynamics and thermodynamics can overcome the subsidence warming.  Timing and model lift forecast Thursday suggested it would be possible.

As of 2:00 AM snow had started to fall atop the High Knob Massif, so time will soon tell when winds shift easterly and increase if snow will continue to be able to overspread Powell Valley ( amid inverse orographic forcing for the Valley corridor…forced sinking ).

As of 2:30 AM around 1″ or a little more of snow had already accumulated on Eagle Knob of the High Knob Massif amid gusty easterly winds.

The NAM 4 KM Model predicts 11″ of snow in Wise by 7 PM Friday, most of that accumulating between Sunrise and early afternoon ( 9″ ).

The NAM 12 KM has a storm total of 18″ in Wise with a bulls-eye of highest totals centered on the High Knob Massif area with respect to southwestern Virginia.

The ECMWF ( European Model ) continued to replicate previous forcast’s with a snowfall total of 14″ for Wise.

As already noted, all models are under-estimating snowfall amounts amid the cold ( and dendritic ) NE-NW upslope flow during the Friday Night-Saturday Night period.

If the lights stay on, I will update later today.

Have A Safe TGIF.