Weather Headlines

ALERT For Accumulating Snow From Friday Afternoon Into Saturday Morning

Moisture transport from the Great Lakes will combine with WNW-NW-N upslope flow to generate snow showers, snow flurries, and locally heavy snow squalls Friday into Saturday morning. Accumulations are expected to begin at the highest elevations early Friday, with sticking snow levels dropping through middle into lower elevations during Friday afternoon and evening.

The best sticking and most widespread impacts to travel are expected along the upslope side of the Appalachians during Friday night into Saturday morning.

Update At 5:00 PM on Friday_6 March 2020

Wind blown snow showers covered roadways at highest elevations in the High Knob Massif Friday afternoon, with deteriorating conditions expected Friday evening into middle and some lower elevation locations along and north to northwest of the Tennessee Valley Divide and High Knob Massif.

Upslope snow showers will continue developing in Great Lake moisture transport as air temperatures drop.

ALERT For Much Colder Air Temperatures And Low Wind Chill Factors

*Expect air temperatures to fall into the 20s at middle elevations, and into the upper 10s at highest elevations, during Friday afternoon (with much colder wind chills).

Snowfall Forecast

A general 1″ to 2″ below 3000 feet

**A general 2″ to 4″ above 3000 feet

**Locally higher amounts possible on highest peaks, with deeper depths due to blowing and drifting snow, being in contrast to only a dusting within some lower elevation sites at elevations below 1200 feet.

Any accumulations are expected to be limited leeward of the mountains into the Clinch, Powell, and Holston river valleys on downsloping air flow trajectories.

The worst travel conditions are expected to develop Friday night into Saturday morning, with falling temperatures and wind driven snow showers.

This snowfall forecast is primarily for WNW-NW-N upslope flow locations along and northwest of the Cumberland-Allegheny Front and highest elevations of Clinch Mountain and the Blue Ridge.

*Clearing and seasonally cold conditions are expected Saturday afternoon into Sunday morning, with coldest conditions developing within mountain valleys.

High pressure and sinking air, along with light winds and mostly clear skies are expected to set the stage for good outgoing longwave radiation (OLR) and compensative turbulent heat flux divergence from overlying air heading into late Saturday afternoon-evening. This will support strong temperature falls along slopes and initial drainage into valleys and basins where radiative flux divergence will aid cooling. Any lingering snow cover will also help to support cooling, and this is primarily expected to be the case for upper elevation cold air collecting basins and draining valleys-hollows of the southern Appalachians (middle to upper elevations in the central Appalachians).

Cold air collecting basins in the central Appalachians will have higher wind speeds into the evening that may initially make decoupling more difficult into the overnight hours [e.g., the classic northern Canaan Valley, WV frost pocket site appears to have a reflection point centered near 14 mph (6.3 m/s or 12 knots), with decoupling when speeds are under this point and partial to no-decoupling of basin winds when mean speeds are above 14 mph on adjacent Cabin Mountain at Dolly Sods]. The reflection point varies for different locations depending upon topographic factors.

Persistence In Longer Term

As I recently noted, persistence is the main guide for the medium range forecast through next week with warming and wet conditions (surprising…NOT!) developing once again in wake of early weekend cold and snow.

Although not exactly the same pattern as observed during February, the trend of the ensemble means of different model groups (GFS, GEM, and ECMWF) is becoming increasingly more like the Feb pattern.

This would increase wetness through the second-third weeks of March, with unseasonable warmth raising a concern for more strong-severe thunderstorms and convective rains.

The European Model is looking especially anomalous in terms of warmth during the upcoming 5-10 day period.

This anomalously warm pattern continues through mid into late March on the latest ensemble mean of the GFS Model group (below).

Observed SSW mean 925-850 MB flow trajectories during February (near the long-term climatological mean flow trajectories) provided plenty of orographic forcing and convergence for enhanced precipitation amounts along the Cumberland Mountains, Cumberland Plateau and Tennessee Valley during the month.

Precipitation Totals – February 2020

Clintwood 1 W
9.20″

City of Norton WP
10.47″

Jonesville 3.1 WSW
10.49″

Hunter Valley
10.70″

Black Mountain Mesonet
12.39″

Big Cherry Lake Dam
13.01″

High Chaparral-Robinson Knob
13.32″

Eagle Knob of High Knob Massif
13.47″

Weather Headlines

*Showers and local downpours, with possible thunder, is being monitored for Monday Night into Tuesday.

*Although heaviest rain amounts are currently expected to fall over the Deep South, the potential for downpours and at least localized thunderstorms should be closely monitored through Monday night into Tuesday.

Dense fog (orographic pilatus clouds) and air temperatures in the 30s (wind chills in 20s) will continue through Monday afternoon at highest elevations in the High Knob Massif. Caution is advised along Routes 619, 238, 237, 704, and others, at upper elevations.

*A transition from rain to upslope snow is being watched from Thursday Night into early Saturday as a developing coastal storm moves out into the Atlantic.

Former Caution Statement

Snow covered roads and hazardous travel conditions will continue into Sunday at upper elevations in the High Knob Massif. Caution is advised, especially for large drifts which are making some routes (e.g., 237) impassible to vehicles without chains and a high profile.

One of the heavier snowfall events of this rather timid snow season of 2019-20 produced 6″ to 8″ of fresh snow at upper elevations in the High Knob Massif into early morning hours of leap day (29 February 2020).

Waves of wind driven snow squalls dropped visibility to tens of feet at times from Friday afternoon through the overnight hours of Saturday.

Snowfall totals during the 26-29 February period reached 9.5″ in High Chaparral (3300 feet elevation) and around 12.0″ at the summit level of the massif where depths varied from near bare ground to feet in drifts.

This final events caps off a super-wet February with a general 13.00″ to 14.00″ of water equivalent precip at upper elevations in the High Knob Massif (not including, of course, added fog drip and rime drop from trees with 22 days in the clouds, and 14 days of rime formation, observed on Eagle Knob during the month).

February 2018 remains the wettest on record, with a general 14.00″ to 15.00″ of observed precipitation (this February had more snowfall, with 16″ to 22″ above 3000 feet).

Nearly 2000 vertical feet beneath the summit, Joe Carter measured 5″ of Saturday morning snow depth at the City of Norton Water Plant (10.47″ of February precipitation).

Looking Into Meteorological Spring

Although every month and season is different, the third consecutively WET February at least demands that the Northern Hemispheric pattern be reviewed.

The 2017-18 winter pattern (above) was followed by this spring pattern (below). In words, March & April turned colder and snowier than average in 2018.

The 2018-19 winter pattern (above) was followed by this spring pattern (below). March & April were collectively warmer than average in 2019 (below average snow).

Both May 2018 and May 2019 were much warmer than average (and also wetter than average).

While the pattern this winter is more like 2018-19 versus 2017-18 across the continental USA, especially the SE USA, global patterns were somewhat different.

The most striking difference is the very strong polar vortex this winter, with a couple of reflective events allowing wintry conditions to invade the region during late January and late February (following lag-time).

The polar vortex remains very strong and consolidated.

Final warming of the vortex associated with annual spring break-up will eventually occur, but until that actually happens persistence remains favored, with more of the same upcoming.

The development of showers and thunderstorms is therefore the next weather concern, with placement of main bands yet to be determined but certainly critical to the flood potential during this first week of March 2020.

Weather Headlines

ALERT For Snow Squalls

A region of bitterly cold air aloft moving across the mountain area Friday and Friday night will trigger snow squall development. Intense bursts of snow are expected to begin developing Friday afternoon into Friday evening. Embedded thundersnow will also become possible, along with visibility that may drop to near zero at times (for brief periods).

Hazardous Travel Conditions Are Expected To Develop, Especially Late Friday Into Friday Night

Although poor travel conditions may develop prior to late afternoon, the most widespread hazardous travel conditions are expected late Friday into Friday night and Saturday morning.

While the weather pattern has recently turned wintry, more like February should be climatologically, it is a transition back to unseasonable warmth and deep, tropical moisture transport that is most worrisome heading into early March.

**A heavy to excessive rainfall potential is increasing for next week as the pattern reverts back to that observed during much of February.

Former Alert

*ALERT For Accumulating Snow Beginning Wednesday Afternoon At Highest Elevations And Expanding To Include Middle & Lower Elevations Wednesday Night Into Thursday AM

*Locations along and north-northwest of the High Knob Massif and Tennessee Valley Divide are expected to have the greatest impacts (as well as locations on windward slopes from Mount Rogers southwest to the Smokies).

**The potential for hazardous road conditions will be greatest after sunset on Wednesday night with upslope snow showers and snow squalls on WNW-NW flow and Great Lake moisture transport.

**The exception will be at highest elevations, where all snow is expected to fall at the summit level of the High Knob Massif. This could impact travel on upper elevation routes Wednesday afternoon (e.g., State Route 619, 238, 237), including State Route 160 across Black Mountain between Appalachia and Cumberland.

*Air turns bitterly cold during Wednesday night into Thursday morning and again, with a second surge, during Friday night into Saturday morning.

Low wind chills will accompany both surges of arctic air during Wednesday night into Thursday and Friday night into Saturday. Caution is advised for outdoor activities.

*A snow burst potential will exist, especially during the late Friday into early Saturday period, with whiteout snow squalls becoming possible.

Huge Weather Swings In Early March

The first week of Meteorological Spring will feature a huge swing in weather conditions, from arctic cold to unseasonably mild temperatures.

This occurs as a upper trough over the eastern USA reverts back to a ridge-trough-ridge pattern which dominated the month of February.

The result will be a swing from much below average to much above average temperatures during next week.

A heavy to excessive rainfall potential is being monitored for next week into the second week of March, and will be in part dependent upon the longevity of this pattern that features a ridge-trough-ridge regime (similar to observed during February 2018, 2019, and 2020).

Many ensemble members, including those of the favored 51-member European Model group (which I can not show on this site), are predicting a return of heavy to excessive rain amounts next week into the second week of March.

While placement and intensity of the heaviest bands of rain remain to be work out, the pattern (as observed in February 2018, 2019, 2020 should now be well known to anyone following these wet months in the SE USA).

The pattern in February 2020 has added to the legacy of February 2018 and February 2019, with more than a foot of total precipitation now observed at upper elevations in the High Knob Massif during each of these months.

Big Cherry Lake Dam

February 2018: 14.37″

February 2019: 12.50″

*1-24 February 2020: 12.09″

*12.46″ on Eagle Knob and 12.52″ in High Chaparral-Robinson Knob

Weather Headlines

*Evaporative cooling amid lingering dry air will generate a period of wet snow Monday morning, especially at mid-upper elevations. Accumulations of a dusting up to 1″ will be possible (locally more on highest peaks) before precipitation changes to rain.

*A cold rain with areas of fog, widespread and dense at upper elevations, will be observed from late Monday into Tuesday. This will mark another prolonged period of clouds obscuring upper elevations.

A total of 16 out of the first 20 days of February were in clouds at upper elevations of the High Knob Massif and Black Mountain, including 9 days with riming on High Knob.

*Another system will bring a chance of accumulating snow late Wednesday into Thursday, with a snow burst potential as air turns bitterly cold aloft.

Recent Weather

It seems the mountain region can not buy a “good” snow during this 2019-20 winter season, yet at least, as there remains plenty of time for a break in this snow drought.

A general 2″ to 3″ of snow covered the ground from the High Chaparral community to Eagle Knob into Thursday afternoon, with riming at highest elevations.

At lower elevations the official NWS snowfall total reached 1.1″ in Clintwood, with melting on grass and most of the accumulation on trees, leaves, and above ground objects such as the snowboard!

Although snow has been limited, the February 1-21 period produced impressive amounts of precipitation.

Clintwood 1 W: 8.17″

City of Norton WP: 8.89″

Jonesville 3.1 WSW: 9.30″

**Big Cherry Lake Dam: 11.25″

**Eagle Knob of High Knob Massif: 11.58″

**High Chaparral-Robinson Knob: 11.64″

**The third consecutive February with double digit precipitation amounts.

Looking Toward Meteorological Spring

A colder than normal pattern currently looks to dominate final days of February into early March and the beginning of Meteorological Spring.

This will bring at least a couple more opportunities for snow next week, with a large region of below average temperatures across much of the continental USA.

Unfortunately, toward the end of the first week of March the current ensemble mean is predicting a return to the warmer and wetter than average pattern observed during much of February.

That is a long way out into the model future, so there is plenty of time for changes to occur in this forecast.

ALERT For The Development Of Accumulating Snow Thursday

A wave of low pressure moving along a stalled boundary in the Deep South will spread snow across the Mountain Empire Thursday. This is expected to be a fast hitting and short-lived event, with the bulk of snow falling between 8:00 AM and 4:00 PM. Some upslope snow showers will continue into evening.

Update At 1:30 AM_Thursday_20 February 2020

ALERT For Hazardous Travel Conditions Developing Thursday Morning Into Early Afternoon

Cold temperatures, with widespread 20s in valley locations along and north of the High Knob Massif, will set the stage for hazardous conditions Thursday as a combination of initial evaporative cooling and snowfall rates work to cover roadways.

Snowfall Forecast

1″ to 3″ along and southeast of Pine Mountain across southwestern Virginia and extreme southeastern Kentucky

3″ to 5″ at higher elevations of the High Knob Massif and Black Mountains, with locally higher amounts possible

Target snowfall: 2.5″ at 2500 feet (+/-) 1.0″ error potential, suggesting 1.5″ to 3.5″ of snow will be possible in the Norton-Wise area.

The error potential has been reduced by increasing confidence in a developing snowband impacting all locations along and southeast of Pine Mountain on upsloping, northerly low-level air flow.

Cold air will be interacting with moisture along the northwestern and northern side of this snow band to create lower snow density and higher snow-to-water ratios than farther south.

A sharp cut-off is expected to the northwest and southeast of a band of snow that will develop Thursday over the southern Appalachians and Tennessee Valley. Heaviest snow amounts are currently expected at highest elevations along the Eastern Continental Divide (from Roan Mountain to the crestline of the Great Smokies).

Weather Headlines: 17 February 2020

*Strong SSE-SW winds develop tonight into Tuesday at middle to upper elevations (especially). Wind gusts to over 40 mph will be possible at highest elevations.

*Rain overspreads the mountain area Tuesday. Moderate to locally heavy rainfall will be possible through Tuesday night, especially from favored upslope locations in the High Knob Massif-Black Mountain corridor southward.

*Rain may end as snow during the predawn-morning hours of Wednesday, with any accumulation likely restricted to elevations above 3000-3500 feet.

*A secondary wave of low pressure moving along a stalling boundary to the south will need to be closely monitored for potential development of a heavy, wet band of snow Thursday, with positioning of this band remaining uncertain. Stay tuned for updates.

The position and intensity of a potential snow band remains to be worked out, but many models (especially when including ensemble members) are beginning to see a potential that has now been shown on and off in the modeling for about a week.

Upcoming Pattern

Snow can not fall without cold temperatures, so at the least a colder regime is shown to rebuild in the mean during the short-term (following current warming).

Following a period of warming next week, the European ensemble mean is forecasting colder air to return in the first week of March and the beginning of Meteorological Spring. A trend to follow as the polar vortex remains at strong to near record-strong levels (one of the drivers of this mild winter of 2019-20 in the eastern USA).

Weather Headlines

An unseasonably cold air mass dominates the mountain region through Saturday. It then warms to seasonal cold by Sunday and to unseasonably mild once again by early to middle portions of next week.

The good news. Dry weather will finally give the soggy landscape a break until unseasonably warm air returns (of course). Well, mostly, as there will be a chance for some light showers Monday.

Reference Mid-Winter 2020_High Knob Massif for updated precipitation, with February 2020 marking the third consecutive one to reach double digit precipitation at upper elevations in the High Knob Massif.

Warmer air brings more rain. The potential for more significant rain exists, but it is too early to determine amounts. A trend toward colder air is currently being predicted for the final week of February.

Frigid Saturday Morning In Mountain Valleys

Conditions ideal for radiational cooling and the collection of cold air in mountain basins and valleys have been limited during the wet pattern of Winter 2019-20.

Air will be bone dry in the 900-800 MB zone, centered around 850 MB, which will favor the coldest conditions developing in upper elevation valleys.

Winds will remain light through Friday evening, allowing for nocturnal inversion formation. Speeds at 850 MB are then predicted to increase by Saturday AM, but deeper valleys and basins (in particular) should be able to remain decoupled from mean flow.

This should set the stage for the coldest minimums since 22 January when classic frost pockets in upper elevation basins dropped to within a few degrees of zero (a little below to a little above the goose egg). An exception was Burkes Garden, which was not able to fully decouple, with a minimum of only 9 degrees.

Update_7:00 AM_Thursday_13 February 2020

Headwater Creeks Will Continue Rising This Morning Into Mid-Day Thursday. Please Be Careful Around Swift Water, And Watch For Ponding Along Roads.

ALERT For Heavy Rain Developing Late Wednesday Into Thursday Morning

Due to recent flooding, and saturated soils, residents will need to remain alert for the potential of rapid water level rises as well as mud-rock slides. In addition, a gush of strong winds along the passing cold front will pose a tree damage danger (especially over super-saturated soils).

The downpour potential will be greater with this system than during Monday-Tuesday, raising concern for rapid water level rises. The ground is so saturated presently that a single downpour of significant intensity or duration could trigger flash flooding.

Updated_6:30 AM_12 February 2020

A surprising omission of Wise County (and Scott County) from the Flash Flood Watch by the MRX NWSFO is difficult to understand, so I reference them to their own research:

Precipitation And Flash Flood Climatology

What county during that study period had the most flash floods, the most flash flood deaths, and the only event to cost more than half a million dollars in damages within southwestern Virginia? Wise County!

Most recently, and most important to this current event, what county in southwestern Virginia has stations which have received around 9.00″ of total precipitation so far during the month of February? Wise County!

Wise, Scott, and Lee counties are all impacted by run-off from the High Knob Massif-Black Mountain corridor, the wettest long-term corridor in both Virginia and Kentucky.

Rainfall totals during Monday-Tuesday reached 1.42″ in Clintwood (6.58″ February) and 1.63″ at Big Cherry Lake Dam (8.86″ February) of the High Knob Massif. Streams are running swift and the ground is supersaturated, with areas of standing water common across the area.

ALERT For Strong SSE-SW Winds Developing Wednesday Afternoon Into The Overnight Hours Of Thursday AM

Strong SW winds will develop at upper elevations Wednesday afternoon, with downward mixing into middle elevations late Wednesday into the overnight hours of Thursday. Winds gusts of 50-60+ mph will be possible at upper elevations, with 30-50+ mph gusts at middle elevations and locally in the lower elevations.

Former Alerts And Statements

ALERT For Strong SSW-SW Winds At Middle-Upper Elevations Tonight Into Monday And Also Lower Elevations Of Northern Wise & Dickenson Counties

Strong SSW-SW winds will develop tonight into Monday as the pressure gradient strengthens in advance of the next waves of heavy rainfall. Wind gusts of 40-60+ mph will become likely along higher mountain ridges.

Strong gusts will also develop within wake zones of the High Knob Massif and Black Mountain corridor, into lower elevations of northern Wise and Dickenson counties, with breaking mountain waves.

Update_5:00 AM_A temperature jump from 31 to 45 degrees recently occurred at the official NWS station in Clintwood as strong wind gusts are mixing out the nocturnal valley temperature inversion on this Monday morning.

Recent Weather And Future Trend

Interactive Doppler Radar

Graupel has been observed with snow bursts Friday, indicating that they have a convective nature amid upward vertical motion in bitter air aloft.

The High Chaparral-Robinson Knob communities were in the core of heaviest rains with this recent flooding event, with 7.51″ of total rainfall (not including this snow)*.

*The only good news for them, water mostly runs downhill from there. Norton-Tacoma-Coeburn corridor flooding on the Wise County side, and Clinch River Valley flooding on the Scott County side, was unfortunately enhanced.

My snowfall forecast below includes the Saturday system. Amounts have already verified in many locations and it is possible that local totals could exceed what is predicted. As of 5:00 PM total snowfall had reached 1.7″ in Clintwood, with 3″ to 5″+ at upper elevations in the High Knob Massif.

Snowfall Forecast
(Friday-Saturday)

1″ to 4″ below 3000 feet

4″ to 8″ above 3000 feet

Target snowfall of 3.0″ (+/-) 1″ error potential for Norton-Wise, suggesting that 2″ to 4″ of snow will be possible. Greatest depths are expected on elevated surfaces and grass in the lower-middle elevations. Large snow depth variations are expected with blowing and local drifting at upper elevations.

In Wake Of Flooding

Extreme caution is advised around all streams as high velocity flows continue. While headwater creeks are dropping, main-stem rivers will remain elevated.

Reference my 013020 Forecast for stream links and a look at the Big Picture of this current turbulent weather pattern.

Southwestern Virginia Month-to-Date

Precipitation Totals
(1-9 February 2020)

*Robinson Knob: 7.83″

*Eagle Knob: 7.34″

*Big Cherry Lake Dam: 7.23″

Black Mountain Mesonet: 6.68″

Jonesville 3.1 WSW: 5.60″

City of Norton Water Plant: 5.47″

Clintwood 1 W: 5.16″

Saltville 1 N: 4.89″

Gate City 6.2 NNE: 4.79″

Tazewell 2.9 WNW: 4.69″

Lebanon 3.1 NNE: 4.44″

Abingdon 3 S: 4.41″

Nora 4 SSE: 4.33″

Richlands: 4.22″

Burkes Garden: 4.13″

Lebanon: 4.06″

Grundy: 3.96″

Wytheville: 3.61″

Blacksburg: 3.46″

Bluefield (WV): 3.08″

Roanoke: 2.63″

*Upper elevation locations in the High Knob Massif. Reference Mid-Winter 2020_High Knob Massif for a listing of monthly totals from Big Cherry Lake Dam.

I have not had time to even begin to go through the 1500+ photographs submitted to Chimein on WCYB’s weather page.

I selected a few amazing scenes from this flood event.

Little Stony Creek drains 16.4 square miles and heads near the High Chaparral-Robinson Knob communities of the High Knob Massif, where rainfall totals exceeded 7.00″ .

Water gushing out of the High Knob high country, and from the northeastern end of Black Mountain (Indian Mountain) caused flooding from Norton-Ramsey to Tacoma-Coeburn.

Impressive flooding along the North Fork of Clinch River which heads along the Wise-Lee county border in the High Knob Massif.

Big Stony Creek is often highlighted on this website, as a guide to steep creeks draining the high country, with Stock Creek heading in the high country southwest of Thunderstruck Knob of Powell Mountain (infamous for it’s carving of the great Natural Tunnel).

Although Big Cherry Dam holds back a huge amount of water, not including beaver dams upstream in high wetland valleys, rainfall was so heavy that the spillway overflow reached around 18″ .

While North Fork of Pound Reservoir is an unbelievable blessing to Pound, other streams such as Indian Creek and Bold Camp go into flood during these big events.

Not like 1957 and 1977, but close enough to bring back those horrid memories for residents around Haysi and Sandlick.

Terrible News For Saturated Landscape

If anyone doubts this, then merely review the Big Picture section I posted on 30 January at the link above. I knew then, based upon the combined composites of February 2018 and February 2019, that last week was going to be trouble and there is, unfortunately, no reason to doubt that this week will bring more of the same.

The really scary and frustrating aspect for myself, is that the 51-member ensemble MEAN of the European Model group has come into an even more dangerous alignment for next week, featuring a pattern that is repetitive with one wave after another of mostly rain. I expected this, as noted by what I wrote on 30 January, but at that time the period toward mid-February was showing some changes. That is no longer the case, with blocking high pressure now predicted to remain anchored over the eastern Pacific Ocean (just off the coast of North America).

Observe how similar the predicted 5-10 day anomalies (above) are to the composite mean of February 2018 + February 2019 (below). Rather amazing.

A setting like shown above is conducive to both Pacific Ocean and Gulf of Mexico moisture transport into the region next week, just like last week, with a positively tilted trough in a ridge-trough-ridge pattern.

Forecasters should remember that, like in February 2018 and February 2019, and most recently, of course, last week, a positively tilted 500 MB upper trough with westerly flow components tends to favor locations along and west of the Appalachians for heaviest rainfall amounts. The present negative tilt did not develop until after the bulk of heavy rainfall had shifted east into the Piedmont with rain changing to snow in the mountains on 7 February.

The flooding threat typically tends to be greatest along and west of the Cumberland Front, Cumberland Plateau, and Tennessee Valley with positively tilted troughs versus along the Blue Ridge with negatively tilted troughs.

Development of a negative tilt to the upper air (500-250 MB levels) trough this week was a little late to maximize rainfall along the Blue Ridge, and pre-flood forecasts that focused on the Blue Ridge were in error due to moisture and upslope forcing that were only partially in sync. Rainfall amounts were substantial along the Blue Ridge, especially within SW North Carolina where both westerly and easterly component flows are maximized, but notably less farther northeast along the mountain chain.

Despite cold air and snow at the moment, the pattern becomes unseasonably warm and moist once again next week to add support for more heavy-excessive rainfall.

The first wave producing significant rainfall Monday into early Tuesday (10-11 February) will also have snow melt from upper elevations to increase run-off into streams.

This will be followed by more worrisome waves during the middle to end of next week.

The Bottom Line: Heavy to excessive rainfall is expected next week, with the potential for serious, life-threatening flooding. Although it remains too soon to know exactly what locations will be impacted, the pattern will again favor locations along and west of the Appalachians.

Note: I had to begin the process of evacuating my house on 6 February. I was lucky and water ended up not entering the house, but I understand from personal experiences like this how scary it is for many folks who live near mountain streams. It is heart-breaking for those who must suffer through flooding, and beyond imagination for those losing loved ones to flooding. Personal property can be repaired or replaced. Precious lives can not.

A Potentially Serious Flash Flood And Flooding Situation Is Expected To Continue Developing Into Mid-Day

As of 5:00 AM Thursday, more than 5.00″ of total rain have fallen at upper elevations in the High Knob Massif from Powell Mountain across Big Cherry Basin to the Robinson Knob community. Creeks are now near or above flood stage in many locations downstream of these upper elevations along the high border area of Wise-Scott-Lee and Wise-Harlan counties.

Additional locations will likely experience flooding before rainfall diminishes later today. The main-stem rivers will likely rise through tonight. Please monitor the latest levels and forecasts for these rivers.

USGS Stream Data for Virginia

Levisa Fork River at Big Rock

Russell Fork River at Haysi

Guest River at Coeburn

Big Stony Creek (upstream Fort Blackmore)

Powell River at Big Stone Gap

Powell River at Big Stone Gap (Gage Height)

Powell River near Jonesville

Clinch River at Cleveland

Clinch River at Speers Ferry

**When Big Stony Creek is above flood stage it generally is an excellent indicator for all the steep creeks draining the High Knob Massif, with analogous levels on South Fork of Powell, Little Stony Creek, Stock Creek, Cove Creek, Clear Creek, and many others that drain the high country along the Wise-Scott-Lee border area.

Big Stony Creek in northern Scott County, VA, was 2.2 feet (27 inches) above official flood stage at 2:15 AM on Thursday, 6 Feb 2002

Residents living along South Fork of Powell River, downstream of Big Cherry Lake Dam, on the Wise County side of the High Knob Massif will need to remain alert for potential of significant flooding with a large overflow ongoing over the Dam

A large plume of rainfall downstream will be lifting northeast across the mountain area overnight into the daylight hours of Thursday.

*As of 5:00 AM on 6 February, the rainfall total had reached 5.07″ at Big Cherry Lake Dam (2008-2019 February average precipitation was 6.87″).

*More than 0.50″ of rain recently accumulated within less than 30 minutes to trigger the current spike in water levels.

Due to antecedent wetness, with 12.22″ since the beginning of January and 20.74″ since the start of December, the concern for flash flooding through Thursday is well above average. This also includes the possibility of mud and rock slides.

ALERT For Heavy To Excessive Rainfall Amounts During The Period From Late Tuesday Through Late Thursday (February 4-6)

Waves of rain, moderate to heavy at times, are expected throughout the next several days within an anomalously mild, moist atmosphere for this time of year. Folks living and driving along streams and in low-lying, flood prone locations will need to remain alert for water level rises and ponding of water.

**Stay tuned to NOAA Weather Radio and your favorite media sources for possible warnings.

Locations with greatest impacts will depend upon where the heaviest run-off develops, as waves of rain continue to move across the mountain landscape.

Although the greatest current flood potential is in the Clinch, Powell, and Cumberland river basins, where the greatest precipitation amounts have accumulated in the past 36-hours, flooding within adjoining basins (e.g., Russell Fork, Levisa Fork, Holston, etc.) will also become possible.

While orographic forcing will increase amounts within the High Knob Massif-Black Mountain corridor, as a low-level jet forms into Thursday, increasing upslope flow, the possibility of convection superimposed upon the general rainfall pattern will complicate as well as enhance the flash flooding potential in locations impacted by thunderstorms.

Weather Headlines

*Colder air is being monitored for possible significant snowfall accumulations by Friday into this weekend (centered on 7-8 February) as additional waves move east of the Appalachians prior to warming once again next week to anomalous levels. This would add to any flood potential next week.

Interactive Doppler Radar

*A pattern conducive to additional heavy to excessive rainfall is being monitored for next week, through the middle of February (reference updated charts below).

Big Picture Pattern

In the big picture, the upper air flow regime makes all the difference regarding how much precipitation falls as rain versus snow, and how much falls in total. This regime is dictated by ocean and land temperature contrasts which generate pressure differences that develop and drive weather systems across planet Earth.

Reference Mid-Winter 2020_High Knob Massif for updated precipitation amounts from the City of Norton into the high country of the High Knob Massif.

This big picture regime is then modulated by orographics within three-dimensional, complex terrain as exists here amid the majestic Appalachians.

With February knocking on the door, it is time to review the past two years when February produced excessive precipitation amounts (mostly rain, very little snow).

The past two Februaries had very similar upper air patterns, especially across the central-eastern USA.

Adding the two patterns together produces the above, featuring a notable SW upper air flow into the eastern USA with transport of both Pacific and Gulf of Mexico-Atlantic moisture. This flow regime included westerly component atmospheric trajectories.

Precipitation totals at Big Cherry Lake Dam reached 14.37″ in February 2018 and 12.50″ during February 2019, with locally higher amounts in the high country. Could February 2020 produce a trifecta?

The pattern ahead through the first week of February 2020 becomes eerily similar to that of the past two Februaries, so that means wetness increases!

Current Interactive 500 MB Flow Field_North America

Many ensemble members of both the European and GFS model groups are predicting heavy-excessive rains to fall in waves through the middle of February. This trend has only increased in recent days, as anomalous warmth for February returns next week to set the stage for more waves of heavy-excessive rainfall.

Consecutive model runs see the flood potential that is analogous to February 2018 and February 2019 in the upper air flow regime (as outlined above).

The Monday evening runs of both the European and GFS models are similar with prediction of significant snowfall during Saturday (8 February). Expect both timing and amounts to vary on future model runs.

If the mean upper trough axis remains positively tilted, as shown in the composite of the past two Februaries, it will push heaviest precipitation into western slopes of the Appalachians where orographic forcing will act to enhance amounts.

If the mean upper trough axis becomes negatively tilted it would favor heaviest amounts into the eastern slopes of the Appalachians, and locally along the southeastern side of major mountains like the High Knob Massif.

A comparison between daily accumulated precipitation observed in Big Stone Gap (VA) and Boone (NC) during February 2018 and February 2019 illustrates this very well, with the two months producing a total of 25.39″ under westerly component (upslope) flow in Big Stone Gap, VA versus 9.07″ in Boone, NC under downsloping.

Lovers of snow, of course, do not want to see this type of pattern. Instead, patterns like observed during 2010 and 2015 are the ones desired for deep snowpack formation.

Such patterns can easily produce between 50″ to 100″ of snow within a single month in favored upslope locations along the Cumberland-Allegheny Front.

To contrast with the patterns of 2017, 2018, 2019 and 2011 when the southern Appalachians were robbed of February snow. The current snow drought being very impressive from the perspective of recent decades.

If you are a student of weather, then learn how to read these maps and what they mean as you can see what an impact they equate to regarding sensible conditions.

Regressing the February snowfall trend during the past 6 decades, using the Burkes Garden NWS Cooperative site, finds a notable decrease (the 1897-Present trend shows an increase, but are early years as accurate?).

Measuring precipitation accurately can be difficult, especially snowfall at higher elevations, with many factors potentially acting to skew reported amounts away from reality. A topic for another day!

Developing light snow and lower elevation mix will generate less than ideal travel conditions later tonight into Thursday. Accumulations of snow are expected to remain light and mainly at elevations above 1500-2000 feet. Exercise caution when driving overnight into morning.

Update at 1:00 AM Thursday_The sticking snow level will drop to between 1500 and 2000 feet in locations along and north of the High Knob Massif and Tennessee Valley Divide.

Accumulations are expected to vary from a dusting to 1″, with locally higher amounts possible (mainly above 2500-3000 ft).

Low cloud bases, with riming, will occur at the highest elevations. Areas of fog will become possible at middle-lower elevations.

Former Caution Statement

Caution for snow covered roads and slick conditions at highest elevations in the High Knob Massif into Tuesday.

A 2019-20 winter season trend of snow being biased toward the highest elevations continued into the beginning of this new work week on Monday.

A general 1.0″ to 2.5″ of snow stuck at elevations above 3000 feet on the windward side of the High Knob Massif, from the crest of Powell Mountain across Big Cherry Lake Basin to the peak of High Knob. This included locations such as Thunderstruck Knob, Camp Rock Meadow, Little Mountain Knob, Bowman Mountain, Eagle Knob and the High Knob Lookout. Although snow tended to melt or to partially melt at elevations in the 3000-3500 foot zone, it remained all day, along with rime, at highest elevations.

Weather Headlines

*A weakening upper air wave will generate high elevation snow and lower elevation mix-rain Wednesday night into Thursday. Accumulations of generally a dusting to 1″ are expected, mainly at elevations above 2500-3000 feet.

Air only marginally cold enough for snow will continue to bias accumulations toward the highest elevations. In addition, shearing of upper air waves continue to weaken them which limits their strength.

*Moisture with a upper wave in the southern jet stream is being monitored for Friday night-Saturday. At this time the bulk of moisture is expected to pass southeast of the mountains with this southern wave. A clipper system to the north, in the polar jet stream, is also being watched.

Due to marginally cold air, accumulations will continue to be biased toward the highest elevations and at this time are generally expected to be light (some heavier snow at higher elevations can not yet be ruled completely out).

Although the February pattern is looking stormy, there is not yet a definitive focus on a major snowstorm. A survey of 70 ensemble members of the European-GFS model groups from the 1200 UTC model run of 29 January found only 20 to 30% showing significant snow accumulations between 29 January and 13 February.

*A milder period is expected through the beginning of February before a change to colder conditions becomes possible later in the first week or early second week of the new month. A wet pattern is likely to redevelop.

A general SW upper-level flow favors the continuation of a wet pattern in February, and at this time much more rain than snow through the first week of the month as mean temperatures will be well above average.

Reference Mid-Winter 2020_High Knob Massif for updated precipitation amounts from the City of Norton into the high country of the High Knob Massif.

Stay tuned for updates.

ALERT For Accumulating Snow And Hazardous Travel At Upper Elevations Between Midnight And Noon Monday

Snow is expected to develop later tonight into Monday at upper elevations, with a general 2″ to 4″ expected above 3000 feet in the High Knob Massif-Black Mountain area. Locally higher amounts will be possible, especially in the 4000 to 6000+ foot elevation zone from Mount Rogers and Whitetop southwest to Roan and the Great Smokies.

What appeared to be snow falling, during a period of Sunday afternoon sunshine, was rime crystals dropping off trees and towers on Eagle Knob where around 1″ of snow initially stuck and covered roads into early Saturday.

This forecast temperature time series off the high-resolution NAM 3 KM Model is predicting an elevation snow event, with the summit-level of High Knob in freezing air versus above freezing air in Wise. What the model can not typically do is properly resolve the local terrain and orographics, such that orographically force rising will cool the air and allow snow to fall at a lower elevation than suggested. The forecast dilemma being how low will the sticking snow level get? Ideally, if rising was coupled vertically it would reach all the way to the floor of Powell Valley and the Powell River Valley, however, as I discuss below, models are not currently showing a coupled unidirectional flow and instead predict too much cross-terrain flow above the surface SW flow (with sinking over mountain ridges working against upslope and up-valley cooling on the surface).

For those who got excited at the possibility of a SW Upslope Flow snow impacting Powell Valley and the Powell River Valley, I can not officially pull the trigger due to predicted model air flow trajectories which currently do not match my composite of SW Flow snowfall events observed in the past.

Although low-level winds will be SW, there is too much cross-terrain flow above the surface to match past events. This does not mean it could not happen, it only means that unless the flow above the surface is more SSW-WSW than currently predicted by models there looks to be too much terrain induced cross-isobaric ageostrophic flow for a coupled SW Flow snowfall event. In other words, too much sinking across mountain ridges into the valley to counter up-valley and up-slope flow adiabatic cooling, and air temperatures will not cool enough to allow sticking to the valley floor. On the other hand, if deeper SSW-WSW flow actually forms then snow falling above will be able to work down to the surface.

A coating of snow covered high elevations throughout the weekend, as visible across northern slopes of the High Knob Massif along the horizon (above). A trend that more often than not has dominated the 2019-20 winter season up to this point in time.

Weather Headlines

*Colder air will dominate the weekend with intervals of light snow, flurries and snow showers into early Sunday. Low cloud bases will generate riming (freezing fog) at the upper elevations. Any sticking of snow will be light and mainly at upper elevations, with generally a dusting up to 1″ expected (locally more possible on highest peaks).

A break in activity is expected Sunday afternoon in between the current system and the next upper air disturbance arriving into early Monday.

*A upper air disturbance and Great Lake moisture will offer a better chance for more widespread accumulations Monday into Tuesday. Locations typically experiencing upsloping on SW to NW flow will be most favored. The potential for 1″ to 4″ of snow is a preliminary estimate for these upslope locations (heaviest upper elevations).

School schedule changes will be likely for Monday and Tuesday (January 27-28).

While upslope cooling on SSW-WSW flow and snow in the corridor from Wise southwest through Powell Valley and Big Stone Gap into Lee County can not be ruled out, the current pre-event air flow predictions do not look as favorable for middle-lower elevations.

The level of sticking snow remains to be seen, with upper elevations around and above 3000 feet currently being most favored for accumulations. A vertical shift of 500 vertical feet or more could easily occur in the eventual level of sticking snow depending upon actual air flow trajectories and cooling-warming with rising-sinking along the High Knob Landform corridor.

Short-Term Forecast

Friday Night Into Saturday Morning

Lowering clouds with rain showers redeveloping and becoming mixed with or changing to snow at middle-lower elevations. Changing to snow upper elevations. Turning colder. Winds SW to W at 5-15 mph with higher gusts. Temperatures dropping into the mid-upper 20s at upper elevations and the 30s at middle-lower elevations. Wind chills falling into the 10s and 20s, except single digits in gusts toward morning on highest ridges. Accumulations up to 1″ above 3000 feet. Riming developing at elevations above 3000-3300 feet.

Saturday Morning Through The Afternoon

Cloudy and cold. Intervals of light snow, flurries and heavier local snow showers. Winds SW to W at 5-15 mph, with higher gusts. Temperatures holding nearly steady, in the 20s at upper elevations and 30s to near 40 degrees at middle-lower elevations. Low cloud bases with riming at highest elevations. Wind chills varying from 10s at the upper elevations to the 20s to lower 30s.

The best sticking potential for snow, outside of upper elevations, will exist Saturday evening into Sunday morning for locations below 2500 feet. That is, temperatures will tend to be above freezing at elevations below 2500 feet prior to Saturday night. Moisture will be limited and accumulations, if any at lower elevations, are expected to be light.

Saturday Night Into Mid-Morning Sunday

Cloudy and seasonally cold. Intervals of light snow and flurries. Heavier local snow showers possible. Winds SW to W at 5-15 mph, with higher gusts. Temps varying from upper 10s to upper 20s to around 30 degrees. Low cloud bases with riming at upper elevations. Wind chills from single digits at highest elevations to the 10s & 20s.

Sunday Afternoon

Low clouds breaking to increasing mid-level clouds. Winds SW-W at 5-15 mph, with some higher gusts. Temps varying from upper 20s to lower 30s to the upper 30s to lower 40s. Wind chills varying from 10s and 20s to 30s, coldest at highest elevations.

The potential for a light SW upslope flow snow is being monitored for Sunday Night into Monday on SSW-WSW flow. Locations along and southwest of the Tennessee Valley Divide and High Knob Massif will be most favored for sticking snow at lower-middle elevations (through the defined High Knob Landform corridor of Lee County into Powell Valley) in comparison to lower-middle elevations under downslope flow across northern Wise and much of Dickenson-Buchanan counties.

Sunday Night Through Mid-Morning Monday

Lowering cloud bases with snow developing at upper elevations. Mixed snow-rain at lower elevations. Winds SW-WSW 5-15 mph, with higher gusts, below 2700 feet. WSW-WNW winds 10-20 mph, with higher gusts, along mountain ridges above 2700 feet. Temperatures varying from 20s at highest elevations to the 30s (warmest in the downslope locations of northern Wise and Dickenson-Buchanan counties). Riming at high elevations. Wind chills varying from 10s to low 20s at upper elevations to the 20s & 30s at middle-lower elevations.

Following a likely break Monday afternoon, a shift to NW air flow will change the locations receiving the best potential for more snow to stick during Monday night into Tuesday to typical NW flow locations.

*The potential for a major winter storm system is still being monitored for the end of January-early February period, however, the setting is looking less favorable at the current time (26 January) for a major event across the southern Appalachians. There remains plenty of time for changes (which will occur in the modeling) so stay tuned for later updates.

Will the snow drought starting in early 2019 ever end? Reference my 012120 Extended Discussion.