ALERT For Dropping Cloud Bases And A Period Of Dense Fog On Northerly Upslope Flow Along And North Of The High Knob Massif-Tennessee Valley Divide Monday Evening Into Early Tuesday

Developing rain, with a chance of thunder, will give way to an influx of colder air by Monday evening into early hours of Tuesday with dropping cloud bases.

Northerly upslope flow will lower cloud bases to generate dense fog at elevations around and above the elevation of the Town of Wise.  Caution is advised for reduced visibility from late Monday into early hours of Tuesday.

Please use extreme caution for greatly reduced visibility through this morning (Tuesday).

Freezing fog, with riming, is expected at elevations above 3000-3300 feet. 

A changeable spring weather pattern is featured for the final days of March into early April, with a huge temperature fluctuation expected from unseasonable warmth to unseasonably cold air.

The late March-early April setting will bear close watching with high latitude blocking.  This will generate the potential for a large storm system.

Stay tuned for later updates.

ALERT For High Elevation Snow-Wind

Wind driven snow will impact high elevations into tonight, with caution advised for travelers crossing the High Knob Massif on Route 619 and connecting roads above 3300 feet.

Gusty NW winds and falling snow will combine with orographic clouds to cause greatly reduced visibility. Accumulations of 1-3″ are expected to be widespread on ground surfaces, with much less on roads during the day.  Greatest sticking on roads is expected to occur after sunset.

Little to no accumulation is expected at elevations below 2700-3000 feet, with sticking at these lower elevations expected tonight in snow showers.

Weather Headlines ( March 14-18 )

ALERT For Strong S-SW Winds Through Today And The Potential Of Strong To Severe Thunderstorms By Late Today And Tonight (March 14)

A powerful low pressure system lifting into the upper Great Lake will continue to generate strong and gusty S-SW winds across the mountains.

The Storm Prediction Center Has A Marginal To Slight Risk Predicted For Counties Along The VA-KY Border

Strong-severe thunderstorms will also be developing by Thursday afternoon west of the Appalachians and will need to be monitored by late today into tonight as they approach from the west and southwest.

Due to significant wind shear, thunderstorms which can become severe will have a tornado potential.

While the main risk will be across central Tennessee and Kentucky, these thunderstorms will need to be closely monitored as they approach the VA-KY stateline by Thursday evening.

Conditions for strong-severe thunderstorms become most favorable by tonight into the early overnight of early Friday ( 55% probability of a supercell using the SPC composite forecast sounding above for Wise ).

Storms are moving so fast that conditions will begin to rapidly change after 8:00 PM this evening.  The current HRRR Model is predicting a broken line of supercells, or strong-severe thunderstorms, to be just west of the mountains by 11:00 PM.

High shear but limited instability will be competing    to spin-up supercell storms, with numerous other parameters favorable for strong to severe storms.

The severe thunderstorm potential rapidly diminishes between 2 AM and 8 AM Friday.

Stay tuned to NOAA Weather Radio and your favorite media sources for updates and any possible watches and warnings which may be needed.

ALERT For Strong SSE-SSW Winds Developing Saturday Afternoon Into Saturday Night

A strong pressure gradient will develop generally strong winds across the mountain region during Saturday afternoon into Saturday night, with developing rain showers and the chance for thunderstorms.

Strongest general winds are expected in upper elevations at 30-50+ mph speeds, with locally higher gusts, and in mountain wave breaking zones where local gusts to hurricane force will be possible.

Previous Alerts

Wintry conditions dominated the first 8 days of March, with 3-4″+ of snowfall observed from the elevation of the High Chaparral and Robinson Knob communities upward in elevation within the High Knob Massif (1.4″ Clintwood ).  Still much more rain than snow, a trend that will continue.

ALERT For Hazardous Conditions Friday AM

A period of moderate to heavy snow will impact the mountain area Friday morning.  Accumulations of 1″ to 3″ are expected at mid-upper elevations, with up to 1″ at lower elevations, prior to changing to mix-rain, within locations along and north of the High Knob Massif-Tennessee Valley Divide.

Most of the past four days have been below freezing  (and remain below freezing at highest elevations), such that ground surfaces are cold.

Snow will be developing during the predawn-early morning  before surfaces have a chance to warm.  Caution is advised.

Weather Headlines ( March 4-11 )

A gorgeous array of rime covers a huge area along the common borders of Wise-Scott and Lee-Harlan counties, with a little even decorating the Wise-Sandy Ridge plateaus.

A cold pattern is currently gripping the mountain landscape, with Monday featuring daytime temps in the 10s across upper elevations and the 20s in places at lower-middle elevations along and north of the High Knob Massif and Tennessee Valley Divide.

Looking ahead the pattern will be reverting back to what dominated most of February 2019.

This means more concerns for high water events are upcoming as a series of waves move across the Pacific Ocean and the continental USA.

While a composite of 9 historic flood events reveals a somewhat sharper wave amplitude, and slight eastward displacement, it is otherwise strikingly similar to the February 2019 pattern. 

The similarity of the February 2019 pattern and a composite of 9 past flood events is rather striking.

A common denominator of the composite of past flood events is Gulf of Mexico, Atlantic and Pacific ocean moisture sources feeding heavy-excessive precipitation amounts.

This is a positive mountain torque pattern with inflow and orographics favoring locations along and west of the Eastern Continental Divide.

So, it really should not be surprising to see where the heaviest precipitation has fallen in this pattern given what past climatology illustrates.

It should also be no surprise, that real concern exists for the upcoming pattern if the first graphic in this section, and this 6-10 day graphic (below), verifies.

More severe storms and flooding will occur in such a pattern, so stay tuned for future updates by late this week into early next week.

Flooding-High Water Levels

Many creeks and mainstem rivers are near or above flood stage on this Sunday morning, with extensive local flooding in impacted locations.

Big Stony Creek was nearly 2 feet above flood stage in northern Scott County, as of 5:30 AM, with flooding on the Wise County side of the High Knob Massif along and on tributaries of South Fork of Powell River and the Guest River.  Extreme caution is advised.

Torrents of water gushing out of the High Knob Massif have quickly skewed the Clinch River well above its forecast trajectory (above), as of 6:15 AM Sunday, with strong current rises.

The Guest River at Coeburn has established a new record daily flow, and was still rising as of 5:45 AM.

Please do not drive into flooded locations and allow water time to recede.

The Bottom Line_Minor to locally moderate flooding is impacting some locations, while all other streams are elevated.  Expect levels on headwater creeks to begin dropping into mid-day, while mainstem river levels will continue to rise.  Stay tuned to NOAA weather radio and local authorities for updates.

Saturday Evening Concerns

A early Saturday evening update is to highlight the main concerns upcoming through the next 24-hours.

*Downpours Into The Overnight – The atmosphere is becoming unstable in advance of a upper air trough axis and its associated cold front.  While strong-to-severe thunderstorms west of the Appalachians will be weakening, they will be producing downpours.

The HRRR Model seems to have a descent handle on the evolution of current storms, with a general 0.50 -1.00″ of additional rain expected ( locally higher amounts will be possible ).  These amounts are also supported by new runs of the European Model and NAM Model.

This could trigger flash flooding and otherwise act to enhance ongoing high water levels and issues.  More mud-rock slides will also be possible.  This is a high concern given this activity will be occurring at night when it is more difficult to monitor conditions.

Given so many creeks currently around flood stage this should be considered a life-threatening situation and any possible precautions should be taken now.

*ROARING Winds Sunday – While a gush of strong wind will mark the passage of a cold front prior to sunrise, a particular concern is after sunrise Sunday when return of sunshine will help aid the downward transfer of high momentum air aloft to the ground.

A unidirectional SW-W flow will support this high wind setting.  Given flooded and saturated soils this increases the chance for wind damage.  Extra caution will need to be taken around trees through Sunday as any ongoing flood clean-up continues, in addition to those who homes are surrounded by trees.

Enhanced Flood Risk Into Sunday

An enhanced risk of flooding is being extended into Sunday with more significant rounds of moderate to heavy rainfall expected Friday into this weekend.

I consider this to be one of the most threatening flood settings in years, and if we can get to Sunday without major problems due to flooding then we all will be blessed and very thankful.

If the European Model forecast of 3.00″ to 4.00″ of additional rainfall is realized, a flood emergency will need to be declared in some locations during the next rounds of rainfall (Friday-Saturday) given continued high water levels and super-saturated conditions.

Friday Evening ( February 22 ) Update

Steady rains during the past 24-hours have kept the mountain area water logged and primed for trouble with heavier rainfall totals to come.

The only change in this update is to push the heavier rain threat throughout Saturday, and I think all NWS Forecast Offices serving this area will need to push the end time for the Flood Watches into Sunday AM.

I have to say that I am more concerned tonight than last night, given a model trend toward concentration of heaviest rains into a time-frame that will feature more of a convective nature + a potential that rains will also be areally concentrated within a band.

The main difference tonight between the NAM and European Model group is that the high-resolution    NAM 3 KM also includes eastern Tennessee, while the European and NAM 12 KM is more focused upon far southwest Virginia and southeast Kentucky.

The other main difference, of course, for those who are closely following these models, is that the NAM group wants to also concentrate the areal coverage of heaviest rainfall across the Mountain Empire versus the European group which is more areally spread.

From a meteorology perspective, positive feedback tends to be more often associated with the warmer months of the year; however, given this anomalous wetness in place it is a real factor to consider now.

This means that support for heavy rain will be even higher as the upper dynamics arrive to lift air ahead of a potent upper-wave and storm system.

The Bottom Line…A dangerous flood and mud-rock slide threat continues through Sunday AM with the most recent model runs tending to concentrate the heaviest new rainfall totals into the period between Midnight Saturday and the predawn of Sunday.

Although I have hesitated to post this, not wanting to take any focus away from this flood setting, a strong wind setup will develop Sunday as an intense surface low lifts across the Great Lakes.

A 978 MB low will cause strong winds, with a nearly unidirectional flow in a dry slot enhancing the down-ward transport of high momentum air.  While skies will turn sunny, the high wind gusts will combine with flooded and/or saturated ground to increase     the risk for uprooted trees and power outages.

The Currently Expected Scenario

Rain showers and rain will once again overspread the mountain landscape Thursday night into Friday AM.

It does not require a meteorologist to see the concern upcoming, with a deep tropical connection (what is called an atmospheric river) tapping moisture which extends thousands of miles into the Pacific Ocean in advance of a powerful upper wave (number 3 and the final one, thankfully, in this current wave series).

If the European group scenario is correct, and it has been the best model forecasting the synoptic-scale setting, the main period of concern will begin during Friday afternoon and continue into mid-morning to early afternoon of Saturday.  A break follows ahead of strong-severe thunderstorms developing along a cold front to the west of the Appalachians, which impacts the local mountains into early Sunday with downpours (low chance of damaging winds).

The latest run of the NAM 12 KM Model is coming into agreement with the European group, as has been the trend observed this week.

Given current stream levels and ground moisture this scenario would cause significant flooding.  This being prior to any additional downpours that might occur into early hours of Sunday (below).

Mud-rock slides and power outages may complicate this already dangerous situation.

The main local concern will not be severe storms but downpours, which could add to any ongoing flooding or trigger new flooding.

The European Model predicts around 0.50″ of basin-average rain during the passage of a squall-line and front, suggesting locally higher and lower amounts and that much of this will fall with downpours into early hours of Sunday (before sunrise).

The NAM Model has unfortunately come in with a forecast that is very close to the European Model group, featuring a final round of heavy downpours into early hours of Sunday along a weakening line of thunderstorms (which may spawn tornadoes west of the Appalachians on Saturday).

Headwater creeks draining the High Knob Massif are continuing to run (roar) at high levels on Thursday.

This includes the South Fork of Powell draining the Big Cherry Lake basin into the East Stone Gap area of Wise County, as well as Big Stony Creek draining into the Fort Blackmore area of Scott County ( plus many more steep creeks draining the upper elevations ).

The Clinch River peaked at 18.04 feet during this recent event at Speer’s Ferry.  While the river is forecast to reach 19.5 feet near 8 PM Saturday, I believe it will be significantly higher.

Clinch River At Speer’s Ferry At 7:15 PM Thursday_February 21, 2019

This is based on rainfall amounts forecast by the European group versus the observed differences between what has recently been predicted by the European group and actual rain amounts.

The Powell River peaked at 15.98 feet during this recent event near Jonesville, Va., in Lee County.

Powell River near Jonesville At 7:45 PM on Thursday_February 21, 2019

Originally published during February 13, 2019 ( following sections ) and updated on February 21.

Serious Flash Flood & Flood Pattern

A serious flood threat is upcoming for the Mountain Empire as a series of upper air waves moving across the nation periodically lift unseasonably moist air.

All EMS Departments need to prepare now for the real potential of flood emergencies and evacuations, if any preparations and planning need be done.

I seldom make statements like this in advance of an event, but the amazing consistency of this pattern across forecast models in combination with observed past climatology of flood events, and antecedent wet conditions during this past year, demands that extra effort be put into stressing this in advance.

Mean Upper Air Flow During The April 1977, March 2002, February 2018 Floods

It takes very little research to understand the threat presented by the upcoming pattern.  I have plotted 3 upper air flow patterns for past floods, ranging from the benchmark river flood event of April 1977 to the significant March 2002 flood to a much less serious but still important flood in February 2018.

These past events all possessed a notable orographic component, with the most severe flooding west of the Blue Ridge across the western Appalachians.

European 51-Member Ensemble Mean 500 MB Height Anomalies Forecast_Days 1-5

It is simply amazing, scary, and no mistake that past upper air flow regimes match this upcoming pattern predicted by the European Ensemble Mean.

Although every weather system is different, there is great value and strength in past climatology when it is used in a proper way to aid recognition of patterns which have inflicted pain and suffering.

European 51-Member Ensemble Mean 500 MB Height Anomalies Forecast_Days 4-8

There is no real change in this pattern until after the February 26 time period, with latest ensemble trends suggesting a shift to colder conditions by the end of February into early March.

European 51-Member Ensemble Mean 500 MB Height Anomalies Forecast_Day 10

An eastward shift in upper air troughing by the end of February into early March is predicted to occur, with a colder weather pattern.

Water Logged Mountain Landscape

The mountain landscape is water logged.  That is not breaking news.  Streams are running high following recent rains and antecedent wetness extending back through the past year of 2018.

Big Stony Creek of High Knob Massif_February 2019 Stream Levels

A general 2.00″ to 3.00″ of total precipitation during the February 10-12 period pushed mountain creeks to around flood stage within the High Knob Massif area.

Creeks crested around a foot below flood stage during the recent precipitation event, during February 15-17, when a general 1.50″ to 2.00″ were observed.

While NWS maps show the general areas which have had the most rainfall, they struggle to resolve local conditions such as the general 8.00″ to 10.00″+ totals which have occurred within the City of Norton and High Knob Massif-Black Mountain corridor.

This is partly due to local terrain blocking that causes the Doppler radar out of Morristown, Tn., to display a void zone along a radial that expands outward with distance across the High Knob Massif.  This is evident during live precipitation events when looking at this Doppler (it is not a factor on JKL Doppler but since the image above is from a composite of Doppler’s it is still reflected in this final estimation product).

A real-time example from this recent storm event reveals the radial void which is factored into the composite analysis to cause under-estimations.

February 1-21, 2019
City of Norton Water Plant
Daily Hand-Measured Precip
( 9:00 AM / 24-Hour Daily)

02/05    0.03″
02/06    0.06″
02/07    2.14″
02/08    0.63″

02/11    0.58″
02/12    0.37″
02/13    1.01″

02/16    0.38″
02/17    0.14″
02/18    0.95″

02/20    1.09″
02/21    1.19″

February Total: 8.57″

January Total: 5.44″

2019 Total: 14.01″

December 1-February 20: 21.95″

Precipitation totals have already reached 16.00″ or more at upper elevations in the High Knob Massif and Black Mountain during 2019, with 24.00″+ during the December-February period of this winter (*).

*Remember this does NOT include addition of moisture by addition of fog drip and rime deposition on trees at upper elevations, nor does it include often significant rain gauge under-catches caused by strong winds, such that effective total moisture input has been much greater in orographic locations (especially at elevations above 3000 feet).

February 2018_Virginia Record

One year ago the area established new marks for February wetness in Virginia, with locally more than 14.00″ of total precipitation.  There has been little respite since then with respect to general wetness.

Black Mountain Mesonet

January Total: 6.49″

2019 Total: 16.05″

December 1-February 12: 24.44″

Climate Prediction Center soil moisture maps do not fully capture the picture, given under-estimating of amounts which have fallen in the orographic zones including communities such as Appalachia, Big Stone Gap and the City of Norton, as well as Duffield, Fort Blackmore and Dungannon ( to note a few ).

Palmer Hydrological Conditions

While the southwestern mountain climate zone in Virginia is only rated as very moist, there is no doubt that counties along the VA-KY border are actually in the extremely moist category.

Eastern portions of southwestern Virginia, which have more official weather stations, have been much drier than far southwestern Virginia to skew the climate zone drier than local reality.

A perfect example being Blacksburg, where the February precipitation total has been 3.53″ and the 2019 year-to-date tally has been 6.29″ ( less than the City of Norton has measured just during February ). 

Norton has measured 11.21″ more precipitation than Blacksburg since December 1 ( only 48.9% as much precipitation has fallen in Blacksburg this winter ).

Differences are even greater between Norton and Bluefield, Wv., with 11.81″ less in Bluefield since the beginning of meteorological winter.

Generalized Average Run-off Anomalies_February 2019

The big concern moving forward is a pattern that will be favorable for excessive precipitation, as generally agreed upon by all major model groups.

GFS 21-Member Ensemble Mean Total Precipitation Forecast_Next 2 Weeks

The 51-Member European group is similar and has been more consistent than the GFS in predicting excessive precipitation amounts next week.

250 MB Jet Stream_Northern Hemisphere

Due to such a powerful jet stream flow coming off Asia into the Pacific Ocean the concern is very real from an energetics perspective, but placement of heaviest precipitation axes will be dictated by each individual wave.  It is simply not yet possible to tell where flooding will occur very far in advance.

European 51-Member Ensemble Mean 500 MB Height Anomalies_Days 6-10

Another disturbance impacting the Polar Vortex may attempt to turn conditions colder down the road, but that is not yet showing up in modeling with the mean of the 51-members of the European group continuing to show a pattern very conducive for heavy-excessive precipitation through the 6-10 day range.  Atlantic, Gulf and Pacific moisture feeds are being predicted.

The Bottom Line…a serious Flash Flood and Flood potential exists through the next week to 10 days and is being enhanced by both very wet current and past conditions plus a highly energetic jet stream flowing into the USA from upstream to interact with multiple moisture sources.  Stay tuned for updates.

Updated: A total of 1.1″ of snow were officially measured in Clintwood into morning hours of Saturday, February 16, with icing to the south.

Former Alerts Issued February 15

ALERT For Icing – Snow To North

Icing which is ongoing at high elevations within the High Knob Massif-Black Mountain will be dropping with the freezing level into the overnight-predawn hours to elevations of Norton-Wise.

Black Mountain Mesonet

A general 1″ to 3″ of snow is currently expected from Pound-Clintwood northward to Pikeville, Ky., during a fast predawn-morning period of snowfall.

Mixed precipitation, with mainly less than 1″ of snow is expected to the south where sleet and icing will be more common.  Significant icing will be possible at upper elevations in the High Knob Massif.

Caution for walking and traveling on above ground objects is advised overnight into Saturday morning.

A change to snow, which could limit icing, will be dependent upon the vertical temperature profile.

While the European Model group has consistently been forecasting a change to snow, with 2-3″ in the Wise area, higher resolution models maintain a layer of above freezing air near and above 850 MB to keep precipitation in the form of freezing rain and sleet, with the best chance of snow to the north.

Previous Outlook

Locations along and north of the High Knob Massif and Clinch Mountain in southwestern Virginia will need to monitor the potential for icing and snow developing during the predawn-morning hours of Saturday.

NAM 3 KM Model_Freezing Rain Forecast

Latest model trends are supportive of icing, especially at elevations above 2300 feet, with potentially significant icing and freezing fog development at upper elevations in the High Knob Massif from the predawn hours of Saturday into early evening ( prior to rising temperatures ).

NAM 3 KM Model_Forecast Vertical Sounding 

Updated: February 19

ALERT For Snow To Sleet Then Rain

Tuesday Evening Update – Precipitation began as snow and changed to sleet-freezing rain on High Knob and began as sleet in Clintwood, followed by mixing of rain and sleet (11:00 PM).

Freezing Rain on Eagle Knob of High Knob Massif

Around 0.40″ of rain has fallen, most in freezing form at the highest elevations.  A similar setting generated major icing which caused severe damage in November 2018.  With luck, warmer air will win this upslope cooling battle soon to help prevent more damage (but that is not yet known, so caution for possible downed trees and limbs is advised for travelers within the upper elevations).

Enough sticking has occurred to cause slippery conditions with the moderate-heavy initial fall of sleet, but melting will occur through the evening outside of upper elevations (where temperatures remain below freezing at high elevations).

Mesoscale Discussion

Warm air advection (transport) will begin during Tuesday evening around the 700 MB level and deepen over time in the vertical.  Any snow developing with evaporative cooling will change to sleet, then mainly to rain as the warm air deepens vertically.

Local exceptions could be a period of freezing rain within upslope zones of the High Knob Massif where orographically forced adiabatic cooling may offset warm air advection at the surface for a period of    time prior to being overwhelmed by warming air.

A gusty E-SE flow will prevent frozen accumulation within the downslope corridor lee of the High Knob Massif, from Powell Valley toward Big Stone Gap     into adjacent locations.

The same type of precipitation transition is expected along the  Blue Ridge, at high elevations, in western North Carolina to the peaks of Mount Rogers and Whitetop Mountain in southwestern Virginia.

Mountain peaks will go from snow to sleet to rain, versus locations at lower elevations within a wedge of cold air banking up against the eastern slopes.

A transition into widespread freezing rain-sleet will occur beneath mountain peaks, where warm air aloft will flow over a cold air damming wedge (i.e., worst conditions will be developing beneath high mountain crest-lines which stand above the CAD wedge) into the predawn-morning hours of Wednesday across western North Carolina into the Blue Ridge-western Piedmont provinces of Virginia.

ALERT For High Winds Wednesday_Especially From The Overnight Through The Day In Mountain Wave Zones And At Mid-Upper Elevations_Possible Power Outages Due To Downed Trees & Limbs

Black Mountain Mesonet At 5:25 AM_February 20, 2019

A strong pressure gradient and developing inversion around 875-850 MB will allow high winds and waves to develop Wednesday.  Winds of 30-50+ mph will be possible at upper elevations and in local mountain wave zones, with gusts to hurricane force likely.

Weather Headlines ( February 11-18 )

Caution For High Water Levels Tuesday Evening Into The Overnight Hours

A general 1.50″ to 2.00″ of rain in the High Knob Massif-Black Mountain area has resulted in creeks rising to near flood stage.  High levels are currently being observed along South Fork of Powell River and Big Stony Creek, among other creeks.  Caution is advised through tonight.

ALERT For Strong Winds And Cold Wind Chills

Strong westerly winds will produce increasingly cold wind chills into Wednesday morning as temperatures drop into the upper 10s ( highest elevations ) to the upper 20s.  Caution is advised.

ALERT For Moderate-Heavy Rain Tuesday With A Chance For Embedded Thunderstorms During The Afternoon-Early Evening

A Flash Flood Watch is officially in effect.

Due to saturated ground the potential for mud and rock slides will also need to be respected.  Remain alert for ponding of water in low-lying areas and strong rises on streams.

A change to snow is expected Tuesday evening.  Only light accumulations will be possible, mainly at the highest elevations ( dusting up to 1″ ).

Reference Winter 2019_High Knob Massif for more scenes

While whitewater looked pretty during the weekend, the volume was still elevated and water gushingly loud to indicate (like any proof is needed) that the mountain landscape is super-saturated.

Part of the reason extends back to February 2018 when a new record was established for wetness in Virginia, with 12.00″ to 14.00″+ falling across the High Knob Massif area.  Wetness has ruled the past 13 months.

The recent trend has featured heaviest precipitation amounts along and west of the Appalachians, with parts of central North Carolina not measuring any February precipitation.

Amazingly, or ominously, the upcoming pattern will become even more favorable for heavy to excessive precipitation during the next 1-2 weeks.

A deeper mean trough, and Gulf of Mexico+Pacific Ocean moisture connection, will generate an even better atmospheric setting for heavy to excessive amounts of precipitation in the 5-10+ day period.

The European, Canadian, Japanese and GFS model groups are all in basic agreement in this hyper-wet setting, with only details with individual waves varying with respect to timing and placement.

500 MB_Pacific Ocean Wave Train

A series of waves embedded in the flow regime can be seen when looking upstream, from the direction that weather systems are coming, across the Pacific.

250 MB_Jet Streaks Embedded In Strong Flow

Due to jet streaks, areas of enhanced upper-level wind speeds, forecast details will be evolving with any of these systems with respect to axes of heaviest precip…but the hyper-active nature can clearly be resolved.

While it is possible that some of the upcoming precip could be in frozen forms, the setting is one which will be favorable for heavy-excessive precipitation during mid-late February.

This is not breaking news, but it should be made plain that multiple threats for too much precipitation are increasingly likely during the next 1-2 weeks.

The amount of rain and run-off needed to generate flash flooding and flooding will be trending even lower in this type of atmospheric setting (antecedent conditions being partly responsible for recent flooding and numerous mud and rocks slides ).

Weather Headlines ( February 6-9 )

ALERT For Periods Of Rain With Possible Thunderstorms During Wednesday-Friday

Heavy To Excessive Amounts Are Possible

Forecast model trends are shifting the focus for moderate-heavy rain southward, with heaviest amounts now expected in locations along and westward of the Cumberland Mountains.

Expect periods of rain, with possible thunderstorms, during Wednesday into early Thursday followed by a break with record to near record warmth.  Additional rounds of rain are expected by late Thursday or early Friday.  Remain alert for ponding of water along roadways and for possible strong rises on streams.

Although the model trend has clearly been to shift heavier rains southeast, the signal is for heavy to excessive amounts in bands which are yet to be determined.  Past climatology with SW flow and strong low-level winds, as being forecast, suggests that the Cumberland Mountains will be within the heavy-excessive rainfall potential with orographic forcing becoming a factor in total amounts.

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

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

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

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

Former Alerts

ALERT For Bitterly Cold Temperatures Continues Today Into Thursday 

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

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

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

Mountain Area Forecast ( Jan 30-31 )

Overnight Into Mid-Morning Wednesday

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

Wednesday Afternoon

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

Wednesday Night Into Thursday Morning

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

Updated_New Forecast

Overnight Into Mid-Morning Friday

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

Mid-Morning Friday Into The Afternoon

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

   

Weather Discussion (Bitter_Little Snow)

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

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

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

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

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

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

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

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

Previous Discussion

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

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

Snowfall Forecast_Tuesday Thru Wednesday

A general 1″ to 2″ with locally higher amounts

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

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

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

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

Weather Headlines ( January 26-31 )

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

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

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

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

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

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

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

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

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

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

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

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

Mountain Area Forecast

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

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

Snowfall Forecast_Thursday ( January 24 )

0.5″ to 1.5″ at elevations below 2500 feet

1.5″ to 3.0″ at elevations above 2500 feet

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

Overnight Into Mid-Morning Thursday

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

Updated_Thursday PM to Mostly Cloudy.

Mid-Morning Thursday Through The Afternoon

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

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

Thursday Night Into Mid-Morning Friday

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

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