*Frosty cold conditions are expected, especially in mountain valleys, on Wednesday-Thursday mornings in advance of the first of two important weather systems.
*Winds become gusty Thursday night with rain developing into Friday morning. Low clouds, wet, chilly conditions are expected Friday at high elevations and across the area for much of this weekend into Monday.
*Unseasonably cold conditions with slowly dropping temps Saturday will mark the start of a period with much below average conditions which extends into early Tuesday. The days of October 27 and October 29 are looking coolest in the short-term, with October 29 expected to modify more by late in the day than previous model runs indicated.
*A warmer break is expected for Halloween ahead of huge, cold upper-air trough development over North America as Hurricane Yutu recurves and becomes absorbed into the Polar Jet Stream at higher latitudes. Stay tuned for later details on how this will impact local conditions.
Overnight Into Wednesday Morning
Clear & cold. Winds NNW-NNE at 5-10 mph, with some higher gusts, along mid-upper elevation mountain ridges. Temperatures varying from lower-middle 20s to the low-mid 30s ( coldest in upper elevation valleys ). Wind chill factors in the 20s & 30s ( coldest highest ridges ).
Wednesday Afternoon
Mostly sunny ( few high clouds possible ). Blue skies. Seasonally chilly. Light N to NE winds generally less than 10 mph. Temperatures varying from the low-mid 40s to the lower-middle 50s ( coolest at upper elevations ).
Wednesday Night Into Thursday Morning
Mostly clear, then increasing high clouds into morning. Large vertical temperature difference developing between colder mountain valleys & milder ridges-exposed plateaus. Light winds. Temperatures varying from the lower 20s to the lower-mid 40s on exposed ridges-plateaus ( 10s possible locally within high valleys from the High Knob Massif to Burkes Garden ).
Thursday Afternoon
Increasing and thickening high to mid-level clouds. Chilly. Generally light winds. Temperatures in the 40s to lower-mid 50s, coolest in upper elevations.
Thursday Night Into Friday Morning
Increasing & lower clouds with rain developing overnight into morning. Becoming gusty. Winds SE-SSE at 5-15 mph, with higher gusts, on mountain ridges-plateaus below 2700 feet. Winds SE-S at 10-20 mph, with higher gusts, mountain ridges above 2700 feet. Chilly with temperatures dropping into the upper 30s to middle 40s ( coolest high elevations ). Low clouds with dense fog at upper elevations. Wind chills in the 20s & 30s on mid-upper elevation ridges.
Friday Morning Through The Afternoon
Morning rain, tapering to showers or drizzle into the afternoon. Low clouds and areas of fog. Winds SE to S at 10-20 mph, with higher gusts in mountain wave zones of Powell Valley and the Clinch River Valley. Winds SSE-S at 20-30 mph, with higher gusts above 2700 feet (winds may gust over 40 mph at high elevations & in breaking waves ). Temperatures varying from low-mid 40s to low-mid 50s (coolest at upper elevations). Wind chills in the 20s & 30s at high elevations.
Circulation around the first Nor’easter of the season will be driving a W-NW upslope flow Saturday into Sunday morning across the mountains. Most places will see rain showers-drizzle, but some snow will be mixing in at high elevations. A small accumulation will be restricted to highest peaks, with riming also possible amid clouds.
Saturday Morning Through The Afternoon
Periods of showers & drizzle. Low clouds and dense fog at upper elevations. Showers may mix with or change to snow highest elevations. Winds W-NW at 10-20 mph with higher gusts on mid-upper elevation ridges. Temperatures steady to slowly falling through the 40s at low-middle elevations along and north of the High Knob Massif-Tennessee Valley Divide and through the 30s at upper elevations. Wind chills in the 30s and 20s on higher mountain ridges.
Saturday Night Into Sunday Morning
Periods of showers & drizzle. Snow showers-flurries at highest elevations. Low clouds with dense fog at upper elevations. Winds W-NW at 5-15 mph with higher gusts on middle-upper elevation ridges. Temperatures varying from lower 30s to lower 40s ( around 30 degrees highest peaks ). Wind chills in the 30s & 20s, except 10s in gusts on peaks above 3600 feet.
Weather Discussion ( Winter Pattern )
Although autumn color is peaking ( nearing or past ) at upper elevations in the High Knob Massif, a pattern more like winter will be developing in coming days.
Autumn Color On Northern Slopes of High Knob Massif
Conditions deteriorate into Friday as remnants of former Hurricane Willa get absorbed into the upper-level flow and a new low pressure lifts northeast out of the Gulf of Mexico.
Sunset From The High Knob Massif – October 18, 2018
Although the track of this Gulf low will be right for snow, temperatures will remain a little too warm; although, the conditions will be simply nasty and unseasonably chilly.
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 3-7
A deep, winter-like upper-level trough digs into the region in wake of this first nasty system, with really cold air, more showers and a chance for some snow ( especially at higher elevations ) as temperatures go sub-freezing.
*The first snowflakes of this 2018-19 cold season fell at the summit level of the High Knob Massif during early hours of October 21. The first riming also briefly developed. Wind gusts to around 50 mph blasted the high summits prior to arrival of the coldest air into predawn hours of Sunday.
European Model 850 MB Temperature Anomalies Forecast: Days 4-8
The European Model is forecasting mean temperatures to hover around freezing during the final days of October at the summit level of High Knob, which translates to some unseasonably cold conditions at middle-lower elevations.
Frost will become widespread across the area by overnight into Thursday morning.
Due to breezy-gusty northerly winds, sites exposed within middle elevations will have less frost than more sheltered locations (temperatures at high elevations will still reach freezing even with wind). Fog will be likely along major river valleys and lakes.
*ALERT For Freeze Within Mountain Valleys – Coldest Temperatures Expected During Thursday Night Into Friday Morning
Frost will be patchy to widespread in mountain valleys and limited to none across exposed mountain ridges as a notable temperature inversion develops. The coldest temperatures of this initial chilly shot will occur in mountain valleys during Thursday night into Friday morning.
Fog will be possible again along major river valleys, with latent heat of condensation offering protection from the colder air expected in valleys with little to no fog.
Colder mountain valleys will have a hard freeze, with the coldest air expected in upper elevation valleys from the High Knob Massif to Burkes Garden due to very low dewpoint air and drainage into high valleys.
*First Widespread Freeze This Weekend
The first true blast of winter-like air will arrive this weekend with falling temperatures Saturday and unseasonably cold air Sunday ( October 21 ).
This blast of air will support the first widespread freeze, with even milder river valleys likely to dip below freezing.
Temperatures are likely to remain below freezing all day Sunday at upper elevations, with temps struggling in the 30s at lower-middle elevations along and north of the High Knob Massif-Tennessee Valley Divide. Potential for the first sticking snow is also being monitored for Sunday Morning, especially at upper elevations. Stay tuned for updates.
Former Alerts
ALERT For Dropping Cloud Bases And Dense Fog On Upsloping Northerly Winds At Mid-Upper Elevations Along & North Of The High Knob Massif-Tennessee Valley Divide For Later Monday Night Into Tuesday
A wind shift behind a cold front will combine with lingering low-level moisture under a developing inversion to develop dense fog at mid-upper elevations along and north of the High Knob Massif-Tennessee Valley Divide later Monday evening into Tuesday. Caution is advised.
Weather Headlines
*Raw, damp & chilly conditions are expected Tuesday in advance of a dewpoint front that will scour out abundant low-level moisture by Wednesday.
*The first widespread frost and freeze of the season is expected to develop Wednesday Night into Thursday Morning, with temperatures dropping into the 20s to around 30 degrees in most locations. Protective fog will be possible along major river valleys-lakes.
Upper air ridging will be building over the western USA as a deep trough develops over the northeastern USA in coming days. Note a split flow pattern. A developing central-Pacific based +ENSO, also known as a Modoki El Nino, will be a significant player in weather conditions expected during Winter 2018-19.
*A below average temperature pattern is generally expected to dominate the remainder of October, with up-down swings during frequent frontal passages.
Monday Night Into Tuesday Morning
Rain showers. Turning cooler with dropping cloud bases and dense fog formation at elevations around and above 2500 feet ( along and north of the High Knob Massif and Tennessee Valley Divide ). Winds shifting NNW to NNE at 5-15 mph with higher gusts. Temperatures dropping into the 40s ( around 40 degrees at high elevations ). Wind chills falling into low 30s to low 40s ( coolest high elevations ).
Tuesday Morning Through The Afternoon
Low clouds & chilly. Chance of rain showers. Light winds becoming SW at 5 to 15 mph, with higher gusts, by late, on middle-upper elevation mountain ridges. Temperatures in the 40s to lower 50s. Wind chills in the 30s higher ridges.
Tuesday Night Into Wednesday Morning
Mostly cloudy (mid-high clouds following dissipation of low clouds). Chance of a shower or sprinkles early. Areas of fog possible in valleys. Winds W-NW at 5-15 mph, with higher gusts. Temperatures in the mid 30s to middle 40s. Wind chills dropping into the lower 30s to around 40 degrees.
Wednesday Afternoon
Mostly sunny, blue skies (some high clouds possible). Crisp and breezy to gusty. WNW to NW winds 10-20 mph with higher gusts ( especially mountain ridges ). Temperatures in the upper 40s to lower 60s, coolest at upper elevations.
Wednesday Night Into Thursday Morning
Clear & cold. Frost and sub-freezing conditions becoming patchy to widespread. Fog possible in major lake and river valleys. Breezy to gusty NNW-NNE winds diminishing to generally less than 10 mph into morning. Temperatures dropping into the mid 20s to the low-mid 30s ( coldest in high mountain valleys and on highest mountain ridges ).
Thursday Afternoon
Sunny. Blue skies. Light & variable winds. Temperatures varying from low-mid 40s to the low-mid 50s ( coolest in upper elevations ).
Thursday Night Into Friday Morning
Mostly clear. Frosty cold valleys. A large vertical temp spread developing between colder valleys and exposed plateaus-ridges. Light SSE-SW winds along mid-upper elevation mountain ridges. Fog along major river valleys.
Temps varying from the 10s to middle 20s in colder valleys to the middle-upper 30s on exposed portions of mountain ridges and plateaus.
*A chilly air mass will be felt through the next several days, with shocking temperatures ( especially when factoring in wind chills at higher elevations ) in comparison to the mean of recent months.
*Unsettled conditions will occur as the remnants of Michael race away into the Atlantic and a secondary cold front drops into the mountains Friday Night into early Saturday. The first pellets of sleet or flurries & light rime will be possible at highest elevations, with a chance of a few cold rain showers in other locations.
*The first temperatures at freezing will occur at highest elevations, with the first sub-freezing wind chills at upper elevations on both Friday & Saturday mornings. Runners in the Cloudsplitter 100 Race will need to be prepared for these conditions.
*A southerly flow redevelops during the second half of the weekend, with warm air advection and increasing clouds. Wind chills will continue to be a factor in the upper elevations ( especially along high ridges ).
Thursday Night Into Friday Morning
Mostly cloudy. Turning much colder. Low clouds-fog with a chance of drizzle or light riming (highest peaks). NW winds 5-15 mph with some higher gusts. Temperatures dropping into the 30s to lower 40s ( around 30 degrees at on highest peaks ). Wind chills dropping into the 20s and 30s ( coldest at highest elevations ).
Friday Morning Through The Afternoon
Becoming partly to mostly sunny ( blue skies ), then increasing high clouds by late. Light to occasionally breezy W-NW winds. Seasonably chilly with temperatures varying from upper 40s to lower 50s at upper elevations to the mid 50s to lower 60s. Wind chills in the 30s to lower 40s at the highest elevations.
Friday Night Into Saturday Morning
Becoming cloudy. Chance of rain showers. Flurries or sleet pellets possible at highest elevations. Winds WNW-NW 5-15 mph, with some higher gusts. Temperatures dropping into the 30s to lower 40s ( around 30 degrees on highest peaks ). Wind chills dropping into the 20s and 30s, except upper 10s to lower 20s on highest peaks.
Saturday Morning Through The Afternoon
Low clouds giving way to partly cloudy skies. Chilly. Light northerly winds. Temperatures varying from upper 30s to lower 40s at upper elevations to the upper 40s to low 50s.
Saturday Night Into Sunday Morning
Mostly cloudy. Becoming gusty along mountain ridges. Winds SSE to S at 5-15 mph, with some higher gusts, on mountains ridges below 2700 feet. Winds S-SW at 10-20 mph, with higher gusts, on mountain ridges above 2700 feet. Temperatures mainly in the 40s. Wind chills in the 30s to lower 40s ( coldest at upper elevations ).
Be sure to check out What Makes High Knob Special, the latest published series by Wally Smith and Wayne Browning which talks just a little bit about this great mountain mass (scroll down to article links).
Weather Discussion ( Chilly Air )
Friday Morning Update
A low cloud deck held through the night with dense fog and low clouds continuing to engulf highest elevations this AM.
High Knob Massif Webcam – University Of Virginia’s College At Wise
It is a wintry morning up top with 34 degrees and wind chills in the 20s, amid dense fog-low clouds. This is what conditions will be like into Saturday morning, only even more nasty for the 8:00 AM start of the Cloudsplitter 100.
Previous Discussion
Falling temperatures through Thursday afternoon are just the beginning of a chilly period of weather conditions as Autumn 2018 finally decides to arrive.
High Knob Massif Webcam – University Of Virginia’s College At Wise
As of late afternoon Thursday air temperatures had fallen into the 40s, and wind chills into the 30s, at the summit level of High Knob to mark the beginning of a chilly to cold period of conditions amid the high country. A radical change, indeed, for runners taking part in the Cloudsplitter 100 race through this weekend.
Thursday afternoon breaks in the overcast will close back up as northwest flow and cold air advection drop air temps significantly into Friday morning. Clouds bases engulfing the summit of High Knob will lower to cover more of the high country into the upcoming night ( the first light riming may occur toward Friday morning on peaks ).
Clouds will break and Friday skies will feature a classic autumn look, with cumulus hung amid deep, blueness.
Conditions then begin changing Friday night into early Saturday as low-level moisture increases again and cloud bases drop back over the high country. Although most places will have a chance of showers, the first frozen precipitation types will be possible at high elevations during the predawn to post-sunrise period Saturday.
*The first light accumulation, or dusting, of snow will be possible farther northeast in the northern mountains of West Virginia at the highest elevations. A sign of the season upcoming.
Sunshine returns Saturday, eventually, and then more changes occur as moisture begins streaming across the USA from remnants of Sergio ( moving from the eastern Pacific into the southwestern USA ).
The Bottom Line, a much cooler but changeable period of weather is expected through this weekend.
Unseasonably mild conditions will return to dominate the next 1-2 weeks, with another trend toward above average precipitation developing as well during this extended 5-10+ day range ( remember that October is climatologically the driest month of the year ).
The anomalous warmth of September is exemplified by a 68.5 degree average daily maximum on Eagle Knob of the High Knob Massif, which just beat the 68.4 degree average daily max observed during August!
How often are average September high temperatures warmer than August? A question to be researched, but a quick look through the Wise database from 1955 to 2012 reveals NONE. NADA. No year had a September with warmer mean highs than August!
Signs of a major pattern change are beginning to show up in the far extended range, by mid-late October into November as a late developing, central-Pacific based El Nino ( +ENSO ) continues to form and exerts more influence upon the synoptic-scale flow fields across the Northern Hemispere ( along with other factors ).
Overnight Into Monday Morning
Partly cloudy then increasing clouds toward morning. Areas of dense valley fog. Winds S-SW at 5-10 mph with higher gusts on mid-upper elevation mountain ridges. Temps varying from lower 50s to the low 60s ( coolest in mountain valleys at upper elevations ).
Monday Afternoon
Partly-mostly cloudy. Chance of hit-miss showers and thunderstorms. Light SSW to SW winds generally less than 10 mph. Temperatures varying from mid-upper 60s to the mid-upper 70s ( coolest in upper elevations ).
Monday Night Into Tuesday Morning
Mostly cloudy. Chance of a shower. SW-W winds 5-10 mph with some higher gusts on mid-upper elevation mountain ridges. Temperatures in the upper 50s to middle 60s. Areas of valley fog.
Tuesday Morning Through The Afternoon
Chance of showers & thunderstorms. SW-W winds 5-15 mph, with some higher gusts on mountain ridges. Temps varying from the 60s to the middle 70s ( coolest in upper elevations ).
Tuesday Night Into Wednesday Morning
Partly-mostly cloudy. Chance of a shower. Areas of dense fog. Winds WSW-WNW at 5-10 mph on mid-upper elevation mountain ridges. Temperatures varying from the middle 50s to the middle 60s.
Reference the High Knob Hellbender 10K section for a forecast specifically designed for this race in coming days ( my Cloudspitter 100 forecast will be featured during coming weeks in advance of this race ).
Weather Discussion ( More Of Same )
A brief cooling trend which came just in time for the 12th Annual High Knob Naturalist Rally will become a memory through coming days.
High Knob Lake Recreation Area – High Knob Naturalist Rally 2018
A buoy line can be seen across the lake in the far distance to keep kayaks and canoes safely away from the overflowing High Knob Lake Dam. Up to 3.50″ of rain were reported in the area immediately prior to the Naturalist Rally.
Temperatures in the 50s to lower 60s were observed during the time of this year’s High Knob Naturalist Rally ( 7:00 AM to 5:30 PM below ), with morning low clouds and fog slowly giving way to some welcomed afternoon sunshine.
Eagle Knob of High Knob Massif ( Time UTC )
Temperatures in the 50s during much of the rally were in rather dramatic contrast to 70s-lower 80s in the Tri-Cities, with some visitors seen shivering ( and talking about the chill ).
Beautiful Water Flowing Into High Knob Lake – 2018 Naturalist Rally
Mean averages during the next week to 10 days will be lower given decreasing sun angles, but nothing close to reality for this point in the year ( see graphics below ).
Approaching Sunset – Upper Norton Reservoir – September 29, 2018
While trees are changing again in spurts, the combination of atypical mildness + a lack of frost + anthracnose fungi impacts are making it slower and duller so far. The final result yet to be determined; however, clearly these ingredients are far from ideal and have already caused some significant leaf drop ( especially at the higher elevations above 3500 feet ).
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 1-5
A deepening western USA upper trough will turn flow more S-SW across the eastern USA over time, renewing the above average precipitation pattern.
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 6-10
While some signs of a major change are beginning to show up in the far extended range, the next 1-2 weeks are looking anomalously mild at this present time.
European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 1-5
Warm anomalies in the 6-10 day range ( below ) increase due to both a combination of deeper southerly flow from the tropics and to climatology, given temperatures should be declining ( in the mean ) moving through October.
European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 6-10
This could be setting the region up for a HUGE temperature crash once a change finally occurs, and this pattern flips from current upper air ridging into upper troughing.
