Mountain Area Headlines ( April 23-25 )

ALERT For Strong SE-SSE Winds Monday Into Tuesday Morning – Especially At Upper Elevations And Within Mountain Wave Zones Lee Of The High Knob Massif, Pine Mountain & Clinch Mountain

Strong SE-SSE winds are expected to continue and increase in strength through the remainder of the overnight into the daylight hours of Monday.  Strongest winds are expected at upper elevations and within mountain wave zones such as the Clinch River Valley of Tazewell-Russell counties, Powell Valley in Wise County, and locations along & just lee of the Pine Mountain ridge near the Virginia-Kentucky stateline.

A wet pattern features the heaviest rain amounts along the eastern slopes of the Blue Ridge, and locally within upslope locations of the High Knob Massif-Cumberland Mountains.

850 MB Streamline Flow

Although Monday will feature a chance of thunderstorms, the better chance arises on Tuesday with locally heavy rain amounts expected.

A cooler than average temperature pattern will continue this week, but signs for a shift to above average temps is now increasing as the month of May arrives.

Reference Explosive Spring Rebirth Period Delayed

Early spring conditions in the high country remain on display in wake of a cold April 1-21 period.

Numerous days with temperatures dropping into the 10s to lower 20s have been recorded, including up to 9.0 inches of snowfall at the highest elevations during the month.

Mountain Area Forecast ( April 21-23 )

Overnight Into Saturday Morning

Mostly clear ( high clouds ) and cold.  Large vertical temperature difference between colder mountain valleys & exposed middle-upper elevation mountain ridges-plateaus.  Variable winds generally less than 10 mph on ridges.  Calm valley winds.  Temperatures varying from low-mid 20s in the colder valleys to the mid-upper 30s to near 40 degrees on exposed mountain ridges.

Saturday Afternoon

Partly-mostly sunny with high clouds.  Light winds.  Temps varying from the upper 50s to low 60s at upper elevations to the upper 60s to lower 70s.

Saturday Night Into Sunday Morning

High clouds.  Large vertical temperature spread developing between sheltered valleys and exposed mountain ridges and plateaus.  Winds SSE-SSW at 5-10 mph, with higher gusts, on exposed mid-upper elevation mountain ridges-plateaus.  Temperatures varying from upper 20s to mid 30s in valleys to the mid-upper 40s on exposed mountain ridges.

Sunday Afternoon

Becoming mostly cloudy.  Small chance of a rain shower.  Seasonally cool.  SE-S winds 5-15 mph with some higher gusts on mountain ridges.  Temperatures varying from the lower 50s to the lower-mid 60s ( coolest highest elevations.

Sunday Night Into Monday Morning

Cloudy & windy.  Chance of rain showers by morning.  SE-SSE winds 10-25 mph, with higher gusts.  Temperatures mainly in the 40s to around 50 degrees ( falling to near 40 degrees at highest elevations ).

Weather Discussion ( Chilly Pattern )

Frosty cold conditions were developing in mountain valleys late Friday night into the early hours of Saturday as a chilly pattern continues for this time of year.

Although large temperature swings have occurred during the past week, the general pattern continues to be cooler than average for mid-spring.

Upcoming days will continue to feature near to below average conditions through the end of April, with a trend on the European Ensembles toward cooler conditions in the final days of this month ( it would not be impossible that more April snowflakes fly, at least at  high elevations ).

Coolest conditions in the next few days will occur along the eastern slopes of the Appalachian chain, on SE flow, before a shift back to the western side of the Appalachians occurs with a return of westerly to northwesterly flow.  This period will also feature periods of rain and showers.

Mountain Area Headlines

ALERT For Strong To Roaring SW Winds Overnight Through Friday PM In The Cumberland Mountains

A strong pressure gradient in advance of the next storm system developing over the central United States will generated strong ( roaring ) SW winds through April 13.

Winds will be especially strong at mid-upper elevations and within mountain wave breaking locations along and north to northeast of the High Knob Massif and Black Mountain in northern portions of Wise-Dickenson counties ( in surges ).

Mountain Area Forecast ( April 8-11 )

Previous ALERTS

ALERT For Accumulating Snow Mainly At Mid-Upper Elevations Through Early Monday Morning – Locally  At Elevations As Low As 1500 Feet Along & North Of The High Knob Massif

Update At 5:30 AM Monday – Snow is falling heavy enough to begin sticking with temps above freezing in Clintwood, with roadways now covered at upper elevations within the High Knob Massif where temperatures are in the 20s.

Some slick travel will be possible on higher elevation roads, especially those that cross through terrain above 3000 feet, but due to the snowfall rates some brief slushy travel will also be likely at elevations below 3000 feet.

A upper air disturbance will be crossing the mountains into Monday with another round of snow.  Most significant amounts are expected at elevations above 3000 feet, with lesser totals in middle elevations between 2000-3000 feet.  Limited sticking is expected below 2000 feet.  Due to the timing of heaviest snow, snowfall rates could be highest around-before AM commutes.

Snowfall Forecast – Monday AM ( April 9 )

1″ or less at elevations below 3000 feet

1″ to 2″ at elevations above 3000-3500 feet

Locally higher amounts are possible at highest elevations where air temperatures have been coldest ( generally near or below freezing during the weekend ).

Sunday Night Into Monday Morning

Lowering and thickening clouds with a rain-snow mix and snow developing during the predawn-morning.  A period of moderate to heavy snow will be possible, especially at mid to upper elevations.  Light NE surface winds to breezy SW winds highest elevations.  Temps varying from the 20s to low-mid 30s.

Monday Morning Through The Afternoon

Morning snow giving way to a chance of light rain showers.  SW winds shifting NW by late at generally 10 mph or less.  Temps varying from 30s in upper elevations to the mid-upper 40s ( milder to the south into the Great Valley ).  Orographic clouds ( dense fog ) at highest elevations.

Monday Night Through Tuesday Morning

Mostly cloudy.  Chance of flurries, especially at upper elevations in the High Knob Massif, then becoming partly cloudy into morning.  NW-N winds 5-10 mph with some higher gusts.  Temperatures in the 20s to low-mid 30s, coldest at upper elevations.  Wind chills in the 20s to low 30s, except 10s at highest elevations.

Tuesday Afternoon

Partly cloudy.  Seasonably chilly.  NW winds 5-10 mph.  Temperatures varying from upper 30s to low 40s in upper elevations to the upper 40s to low-mid 50s ( milder south into the Great Valley ).

Tuesday Night Into Wednesday Morning

Mostly cloudy, then becoming partly to mostly clear by morning.  Light WNW-NW winds.  Temperatures varying from low-mid 20s in mountain valleys to the low-mid 30s, locally colder within high valleys of the High Knob Massif.

A warmer and more active spring rain-thunderstorm pattern is being monitored for late this coming week into RACE Weekend at Bristol.  Stay tuned for later updates.

Weather Discussion ( Winter Lingers )

Monday Evening Update

A wintry morning in April greeted your Monday as snow fell briskly from the predawn through the post-sunrise period.

The greatest snow amounts occurred in upper elevations of the high country, with up to 0.28″ of water equivalent reported at  both Big Cherry Lake Dam and on Eagle Knob ( 2-3″ of snow ). 

To the east, Joe Fields measured 1″ of snow on the ground in the High Chaparral community at 8:30 AM.  Amounts were generally less than 1″ at elevations below 3000 feet ( 0.5″ depth Clintwood ) with 0.6″ ( 0.06″ water equivalent ) reported by Wayne & Genevie Riner on Long Ridge of Sandy Ridge up to observation time.

I think humans and ALL Creatures Great & Small will certainly welcome true Spring when it finally arrives to stay this year, as the Ole Man Of Winter is beginning to ”wear out his welcome.”

Snow melted away relatively fast in Wise but lingered throughout the day, beneath some nice mountain waves, along northern slopes at upper elevations.

*This latest event brings the days with 1″ or more of snow depth to 11 weeks for the 2017-18 winter season on northern slopes at the upper elevations in the High Knob Massif ( High Knob Lake Basin ).

While a few snow flurries are falling on High Knob tonight, the main focus through Wednesday will just be cold temps with mountain valleys experiencing another hard freeze during Tuesday Night into Wednesday AM. 

Previous Discussion

Winter conditions will linger for a few more days before a major pattern change introduces a warmer spring-storm regime by late in the upcoming week-next weekend.

An unseasonably cold Sunday morning for April greeted the mountain landscape with temperatures varying from 10s at upper elevations to the 20s ( 22 degrees in Clintwood ).

 Sunday remained so cold that extensive rime covering the high country of the High Knob Massif was actually able to linger throughout the daylight hours at highest elevations   ( with snow on northern slopes ).

Quite a feat, indeed, for early April given that the Noon Solar Angle over the High Knob peak is now 61.1 degrees.

A solar angle of 61.1 degrees above the horizon at noon means that insolation ( incoming solar radiation ) is being spread across 1.14 units of surface area to generate a solar intensity of 87.5 percent of what it would be if the sun were directly overhead ( * ).

*The sun is NEVER directly overhead outside the tropics ( 23.5 degrees N to 23.5 degrees S ) and reaches a maximum over the High Knob peak during the Summer Solstice when the noon solar angle is 77.0 degrees ( June 21 ).

At that time insolation is spread across 1.026 units of surface area to generate a solar intensity of 97.4% of what if would be if the sun were directly overhead.  Although MAX solar intensity occurs in June, due to seasonal lag-time forced by the slower accumulation of heat by surfaces the MAX in mean annual temperature typically does not occur until July.  Interestingly, in the High Knob Massif, highest annual temps sometimes occur during Spring, prior to full leaf maturation, as clouds become so abundant during Summer that insolation is increasingly blocked.

The Sunday morning 850 MB temperature analysis from the European Model certainly showed this unseasonable April cold, and the anomalies ( below ) associated with it.

Looking ahead this eastern USA trough will be replaced, at least for a short time, by ridging forming in advance of an upper wave that is looking increasingly potent on forecast charts by late this coming week into the weekend.

The focus in coming days will be on this wave and whether or not it does intensify to develop a negative tilt or if the wave maintains a positive tilt ( the former = a much more potent system ).  Significant rain and thunderstorms could result amid an increasingly large temperature gradient if the wave undergoes significant amplification ( since cold air will remain abundant to the north across Canada ).

More cold air, and perhaps even more snow, will be possible if this upcoming wave amplifies significantly by around the April 15-16 period ( way out in time and merely speculation at this point, so check back for updates ).

Mountain Area Forecast ( April 6-8 )

Unseasonably Cold Conditions Will Continue Through Sunday In Wake Of A Wintry Saturday

Although a little snow stuck to roads at highest elevations, and the graveled lots, most of the 1″ to 2″ of accumulation was in the woods, on grass and above ground objects ( with rime formation on trees ).

A snowfall total of 1.2″ was officially measured in Clintwood during this late season event ( 1″ being the maximum depth ).

Former Alert

ALERT For Significant Snowfall Developing During The Predawn-Morning Hours Of Saturday ( April 7 )

A wave of low pressure following what is a climatologically favored track for significant snowfall will be developing by late Friday into Saturday, with rain changing to heavy, wet snow.  While the most significant accumulations are likely at mid-upper elevations, the combination of recent cold and fast falling snow is expected to present a hazard across the area, especially in locations beneath upslope flow on NW-N air flow trajectories along & north of the High Knob Massif and Tennessee Valley Divide.

Snowfall Forecast – Saturday Into Saturday Evening

General 1″ to 3″ at elevations below 3000 feet in locations along and north of the High Knob Massif-TN Valley Divide

Target Snowfall of 2″ ( +/- ) 1″ for Norton-Wise.  This implies the potential for 1-3″ of snowfall within the 2000-3000 foot zone.

Locally higher amounts possible above 3000 feet.

There is currently a low-moderate chance that snowfall could be heavy enough to cause power outages, so please check back for a update as the storm track and intensity becomes more certain.

Overnight Into Friday Morning

Partly cloudy ( high clouds ).  Windy across ridges.  SW winds 5-15 mph, with higher gusts, along mountain ridges and plateaus below 2700 feet.  SW winds 10-20 mph, with higher gusts, on mountain ridges above 2700 feet.  Temps varying from 20s to low 30s in sheltered valleys to the low-mid 40s on exposed middle elevation ridges-plateaus.

Friday Afternoon

Becoming cloudy with a chance of rain showers by late.  SW winds 10-20 mph with higher gusts.  Temperatures varying from low-mid 40s in upper elevations to the mid-upper 50s to around 60 degrees ( downslope locations ).

Friday Night Into Saturday Morning

Rain, heavy at times.  Turning colder.  Rain changing to a mix or snow into the predawn-morning.  SW winds shifting NNW-NNE at 10-20 mph with higher gusts.  Temperatures dropping into the 20s to lower 30s, especially in locations along and north of the High Knob Massif-Tennessee Valley Divide.  Wind chills dropping into the 10s and 20s, except colder at highest elevations.

Saturday Morning Through The Afternoon

Cold & gusty with snow showers and snow, especially in the mid-late afternoon.  Winds N-NNE at 5-15 mph with higher gusts.  Temps varying from the lower 20s to the lower 30s in locations along & north of the High Knob Massif-Tennessee Valley Divide.  Milder to the south into the Great Valley.  Low clouds with riming at the highest elevations.

Saturday Night Into Sunday Morning

Evening snow showers & flurries giving way to clearing skies and diminishing valley winds.  Unseasonably cold.  Winds NW-N at 5 to 10 mph, with higher gusts, along the middle-upper elevation mountain ridges.  Temps dropping into the low 10s to low-mid 20s ( coldest upper elevations ).  Wind chills in the single digits and 10s, except colder in gusts at highest elevations.

Sunday Afternoon

Increasing mid-high altitude clouds.  Light NW-NE winds.  Temperatures varying from 30s at upper elevations to the 40s at lower-middle elevations ( especially along-north of the High Knob Massif-Tennessee Valley Divide ).

A major pattern change into Spring is being tracked for next week, with an increasing threat for strong-severe thunderstorms by late next week-weekend ( possible squall line ahead of a negatively tilted upper-air trough ).  Stay tuned for later updates.

Weather Discussion ( Heavy Snow? )

Early Overnight ( Saturday ) Update

Forecast models continue to struggle with this system, with the European Model group solution being followed since it has been most consistent during the past couple days.

If the European Model solution holds, a low pressure will track south of the area and be over South Carolina by 8:00 PM Saturday, placing the Cumberland Mountains in northerly upslope flow and generating the best conditions for snowfall during the mid-late afternoon into the evening prior to clearing skies into Sunday.

Previous Discussion

Although forecast models have struggled to pinpoint this system, a clear southward trend has occurred during the past 24-36 hours with a mean track that now is fitting past climatology of heavy snow producing systems within the High Knob Massif area.  Will this trend hold?  Check back  for an update into Friday night.

*Winter Storm Watches to the north may need to be moved south, as the heaviest snowfall is looking more likely across the higher terrain of the southern-central Appalachians.

Bloodroot, with a distinctive leaf ready to curl around it’s lovely bloom, has been covered many times in spring by snowfall in the mountains ( it is now blooming at low-middle elevations along & north of the High Knob Massif, and has been blooming, or even past bloom, in milder locations toward the southwest & south ).

Ideal cooling conditions beneath High pressure allowed temperatures to drop into the 10s amid high valleys and along highest mountain ridges in the High Knob Massif during morning hours of April 5.  An official minimum of 24.6 degrees was recorded in Clintwood ( the air temp had dropped back to a frosty 30 degrees at 3:50 AM Friday ).

Models clearly have some work to do yet before they come into agreement, with the European Model and the mean of its cluster currently being closer to the GFS Model than to the NAM Model ( the 00z April 6 run ).

So the BEST option at this present time is to look at the storm track versus past climatology and to use that as a strong bias, the result suggesting that the NAM will be increasing its output of snow in coming runs to fit what similar tracks in the past have generated ( thus, potential exists that total snowfall may be heavier than currently suggested and this will need to be updated late today into tonight ).

Mountain Area Forecast ( April 3-5 )

Strong-Severe Wind Gusts Recorded With Squall Line

A severe 70 mph wind gust was recorded just prior to 2:00 AM on April 4 by the Flatwoods Mountain Mesonet, adjacent to Pine Mountain, in extreme southeastern Pike County, Ky., near the Pike-Dickenson County border.

A 52 mph gust, with many gusts at or above 40 mph, was recorded by the Black Mountain Mesonet in Harlan County, Ky., adjacent to the Wise-Harlan line on the VA-KY border.

An array of AEP System Power Outages have occurred.

Former Alerts

Severe Thunderstorm Watch Number 34 Is In Effect

ALERT For Strong SW Winds Developing Late Tuesday Into Tuesday Night Well In Advance Of A Squall Line

A strengthening pressure gradient will increase winds across the mountain area Tuesday afternoon into Tuesday night in advance of a developing line of strong to severe thunderstorms forming west of the Appalachians.

Locally strong to severe wind gusts will also be possible along the squall line that should be in a weakening mode as it crosses the mountains after midnight Wednesday, with a sharp temperature drop expected into Wednesday morning.

Frosty cold conditions are expected into Thursday morning.

Overnight Into Tuesday Morning

Cloudy.  Areas of dense fog.  A chance of scattered rain showers.  SW winds 10  to 20 mph, with higher gusts, along mid-upper elevation mountain ridges.  Temperatures in the 40s to lower 50s.

Tuesday Afternoon

Partly to mostly cloudy.  Chance of hit-miss showers and thunderstorms.  Windy.  SSW-SW winds 10-20 mph with higher gusts.  Temperatures varying from low-mid 60s to low-mid 70s ( coolest at upper elevations ).

Tuesday Night Into Wednesday Morning

Showers & thunderstorms becoming likely, especially overnight.  Windy.  SSW-SW winds 15-25 mph, with higher gusts, shifting WNW by morning.  Turing sharply colder by morning.  Evening temperatures in the 50s and 60s, then plunging rapidly into the 30s to low 40s by morning…with upper 20s to around 30 degrees at highest elevations.  Wind chills dropping into the 20s & 30s by morning, with 10s in gusts at highest elevations.

Wednesday Morning Through The Afternoon

Morning clouds giving way to partly-mostly cloudy skies.  Windy & seasonally cold.  WNW-NW winds 10-20 mph with higher gusts.  Temperatures varying from 30s in the upper elevations to the 40s at low-middle elevations ( milder lee of the Cumberland-Allegheny Front ).

Wednesday Night Into Thursday Morning

Becoming mostly clear with decreasing NW-N winds.  Frosty cold.  A hard freeze within mountain valleys.  Temperatures falling into the 20s to near 30 degrees, except 10s in colder mountain valleys at upper elevations.

A colder than average weather pattern for this time of year is expected to continue into next week.  A system with the potential to produce significant snow is being monitored for this weekend.

Weather Discussion ( Active Pattern )

An active spring weather pattern will continue through coming days, with a notable trend toward colder-than-average conditions for this time of year.

Temperatures held in seasonally chilly 40s to lower 50s through Monday in locations along and north of the High Knob Massif and Tennessee Valley Divide.  By Wednesday temperatures will be even colder despite a developing mix of sunshine and clouds.

Although early spring wildflowers are beginning to bloom, especially at lower-middle elevations, a up-and-down temp pattern is typical for this time of year…as is snow.

While beginning to show signs, very little is currently blooming at upper elevations in the High Knob Massif where the colder valleys recently dropped into low-mid 10s during March 22 and the lower-middle 20s during March 31 ( the last 0 degree reading occurred in early February ).  Another morning with MIN temperatures into the 10s is upcoming into April 5.

This forecast period ( April 2-5 ) 31 years ago featured a historic snowstorm during 1987, with a general 2 to 4 FEET of snow depth along and north of the High Knob Massif.

Carl Henderson, electrical engineer for the Blue Ridge PBS transmitter station on Eagle Knob reported a general 2 to 6 feet of snow depth by the conclusion of this great storm.

Nearly 2000 vertical feet below, in the City of Norton, a snow depth of 3 feet was reported by Gary Hampton at the Norton Water Plant this week in April 1987.

Reference the Turbulent Spring Pattern In 2018 for a replay of reanalysis charts detailing the great April 1987 winter storm.

The short-term forecast will focus on increasingly strong winds and the potential of wind damage, locally in pressure gradient driven flow late Tuesday into Tuesday night, then along a squall line of showers-thunderstorms into the over-night and predawn hours of Wednesday.

While the short-term will focus on a windy, warm surge of air Tuesday ( March 3 ) that will support formation of severe thunderstorms west of the Appalachians by the afternoon, medium range attention quickly shifts to a colder than average pattern that has the chance to generate some significant snowfall by this weekend.

A mean 850 MB temperature around 32 degrees F ( 0 C ) is being forecast by the European Model Ensemble MEAN in the upcoming 4-8 day period during April 6-10.  This chilly period begins, as noted in the forecast, by Wednesday AM and features frosty cold 20s by Thursday AM ( with 10s in colder valleys of the High Knob high country ).

While there are signs the pattern may trend milder during the second half of April, up-down temperature fluctuations are likely to continue into May ( as climatology shows ).