A major weather pattern change is occurring just in time for the 2018 Cloudsplitter race, with a radically different air mass expected to be in place over the High Knob Massif versus last weekend.
Model Forecast Sounding At 8:00 AM Saturday – October 13, 2018
Unlike during the Hellbender Race, when even the summit of Mount Whitney would have failed to reach the freezing level, this weekend the freezing level will be low enough to intersect the summit of High Knob, especially on Saturday as the race begins.
High-Resolution Model Time-Height Cross Section During Friday-Saturday ( Oct 12-13)
Dry air will be abundant aloft, but low-level moisture is expected to increase and deepen vertically again in the Friday Night to mid-morning Saturday period as a reinforcing boundary passes and winds shift more strongly to the NW for a period of time.
Although most of this weekend will remain dry with respect to falling precipitation, surface conditions will be wet from recent rain. A chance for some light showers during the predawn to post-sunrise period Saturday and again on Sunday, as warmer air begins to push back over the region, will keep conditions somewhat unsettled and changeable.
*Weather conditions are always changeable with the large variations in elevation and terrain across the High Knob Massif area. These synoptic-scale ( or large-scale ) weather changes will add to this variability through the weekend.
Chilly air and low wind chills, versus recent mild conditions, will be a factor that runners will need to be prepared for, especially along ridges at the upper elevations ( 3000 to 4200 feet levels ).
Forecast Details…Temps in Degrees Fahrenheit
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.
Wintry Morning On Eagle Knob of High Knob Massif – Friday ( October 12, 2018 )
By the time first runners reach the summit level conditions could have a chance to improve, but I would not bet on much since I expect cloud bases to be slow to break Saturday.
Friday Night Into Saturday Morning
Becoming cloudy. Chance of rain showers. Flurries or sleet pellets possible at highest elevations. Light rime formation becoming possible on trees and vegetation in high gaps and on the peaks of Eagle Knob, High Knob, and Little Mountain Knob and Camp Rock Knob into Saturday AM.
Winds WNW-NW 5-15 mph, with some higher gusts. Temperatures dropping to around 30 degrees on the highest peaks, with widespread 30s above 3000 feet elevation. Wind chills dropping into the 20s above 3000 feet, with a period featuring 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 above 3300 feet, with mid-upper 40s to low 50s degrees at lower sections of the race course ( middle 50s at lowest elevations near Hanging Rock Recreation Area and the Devil Fork Loop ).
Saturday Night Into Sunday Morning
Mostly cloudy. Becoming gusty along mountain ridges at middle to upper elevations above 2700 feet. Winds S-SW at 10-20 mph, with higher gusts. Temperatures mainly in the 40s. Wind chills in the 30s to lower 40s. Calmer conditions, with less wind, is expected in hollows and deep gorges.
While the temperature trend will feature near steady to slowly rising readings on exposed mountain ridges, the possibility for temp drops into the 30s, especially during Saturday evening before clouds thicken, will need to be respected within mountain hollows and valleys more sheltered from wind and mixing.
Sunday Morning Through The Afternoon
Mostly cloudy with a chance of rain showers. S-SW winds 5-15 mph, with higher gusts ( especially on mountain ridges ). Temperatures in the 40s at upper elevations, above 3300 feet, with low-mid 50s at lower elevations of the course.
My forecast verified well with respect to temps, wind, and relative humidity levels in the High Knob Massif, with the main problem being related to a rapid break up and dissipation of fog over the Norton Valley.
GOES-16 High Resolution Visible Image At 9:42 AM on October 6, 2018
A solid deck of fog is visible in Powell Valley and along the Clinch River Valley at 9:42 AM, just prior to the beginning of Hellbender 2018, with fog along the Powell River from near Norton through Appalachia.
Fog remained in Powell Valley and the Clinch River Valley at 10:02 AM ( below ), but was dissipating fast outside these locations. I had forecast a fog strip to extend from Powell Valley to just above Norton, along and above the Benges Rock section of the route.
GOES-16 High Resolution Visible Image At 10:02 AM on October 6, 2018
Dry air aloft, which helped high valleys drop well down into the 50s, also aided fog dissipation more quickly over the Norton Valley and a faster rise in temperatures between 8 AM and 10 AM.
High Knob Massif Webcam – University Of Virginia’s College At Wise
Beautiful skies greeted race time in the view looking south from UVA-Wise ( fog in Powell Valley, of course, not being visible from this perspective ).
GOES-16 High Resolution Visible At 3:02 PM on October 6, 2018
The mid-day temperature reached 72 degrees on High Knob, with 70-80% relative humidity, which was also the max for the day as persistent cumulus cloud formation helped hold temperatures down during the afternoon.
Hellbender 10K Race Forecast – 2018
This is a detailed look at the atmosphere during this year’s race, which is highly anomalous for High Knob or any mountain at this latitude in early October.
*Reference my Bottom Line and forecast below to omit this more technical discussion, which some will find interesting for the meteorology-terrain interactions.
The forecast sounding ( below ) at race time Saturday is one featuring a freezing level which is around 14,760 feet above mean sea level or, to put that into better perspective, if the tallest peak in the continental USA ( Mount Whitney ) were standing here the peak would still be just shy of the 0 C or 32 F degree Freezing Level. Simply amazing!
NAM 3 KM Model Forecast Sounding At 10:00 AM Saturday – October 6, 2018
Drier air is forecast to advect over the area aloft, as lower level air remains moist = a good chance for fog formation into Friday night-Saturday morning even though this high resolution NAM 3 KM Model is not forecasting a complete saturation near the surface, one of several adjustments which must be made to such models to more accurately depict weather conditions in the mountains.
Observe that the RH ( relative humidity ) in the 300-850 MB layer is forecast to be in the 35-40% range, over top of air that is 100% saturated near the surface ( in reality, not quite on the model ).
NAM 3 KM Model Forecast Sounding At 11:00 AM Saturday – October 6, 2018
A conditionally unstable atmosphere will be in place, which means it will be stable while unsaturated and unstable if it becomes saturated. The lower right inset shows Theta-E or Equivalent Potential Temperature, which decreases with increasing height to indicate that any layer becoming saturated will develop convective instability.
This is one reason that hit-miss showers and thunderstorms must remain in the forecast; although, with luck any local development will not occur until after the race is completed. The European and other models are forecasting a chance of localized development between 8:00 AM and 2:00 PM.
A low-level boundary layer inversion is expected to form into the overnight-Saturday morning with a combination of radiational cooling and drainage of cooling air downward from higher elevations in the High Knob Massif into the Norton Valley and adjacent Powell Valley.
Warmer air over cooler air is stable in the valley fog layer, but there will be a considerable amount of mixing near the top of this layer. Runners beginning in downtown Norton by 10:00 AM may be just beneath a fog layer, and depending upon how fast it can mix out could be running upward into a corridor of fog before climbing above the fogginess with increasing elevation.
NAM 3 KM Model Forecast Sounding At 12:00 ( NOON ) Saturday – October 6, 2018
Due to vertical mixing, the relative humidity along higher sections of the race course is not expected to drop below 70 or 80%; although, it should feel notably better than near saturated to saturated conditions at lower levels.
A transition from mountain to valley air flow will be aiding this vertical mixing process during the post-sunrise to mid-day period ( centered on mid-morning ).
Bottom Line, Forecast & Race Timeline
High Knob Massif Webcam – University Of Virginia’s College At Wise
The early evening prior to race day ( above ) features a notable layer of haze beneath clear skies ( drier air aloft ) which will be increasing overnight into Saturday morning to help generate formation of fog in valleys. Fog will attempt to grow in depth vertically into the predawn-early morning hours Saturday.
Vertically tall clouds above, and some localized showers, arising from within the moist boundary layer. Such will also be the case during this weekend.
An unseasonably mild and humid atmosphere will be in place for Hellbender 2018, with light winds. This is relative to what is more typical for early October.
There will be humidity changes vertically along the race course, with near saturation to saturation at lower levels versus less humid air with mixing at higher levels of the course ( but still humid for this time of year ).
Cooler air will be featured in the morning near the base with fog, or layers of fog, expected in between downtown Norton and the Flag Rock & Upper Norton Reservoir junctions with State Route 619.
Fog will mix out over time, and although the timing of this is unknown it is expected that air will be humid and close to saturation ( if not saturated ) in lower portions of the race course.
While valleys will be cooler than the summit level in the morning, this will reverse during mid-morning into mid-day Saturday as the low-level inversion mixes out and warms to unseasonable levels.
Higher sections of the race course are expected to feature notably drier air, versus saturation below, and more pleasant conditions into mid-day with temperatures in the 60s to around 70 degrees.
*An overnight update features the addition of possible fog formation at the summit level into morning with 4 AM RH values near 100%. If this occurs and does not mix out then higher sections of the course will have more humid air. Drier air aloft may still be able to keep it mixed out?
Friday Night Into Saturday Morning
Chance of a localized evening shower or thunderstorm, then becoming partly-mostly clear. Dense fog developing during the evening-overnight, especially in mountain valleys such as Powell Valley and the City of Norton ( and Clinch-Powell river valleys ). The fog layer may build vertically to include the Wise Plateau ( a possibility that has to be noted ).
Light S-SW winds, except 5-10 mph with some higher gusts on upper elevation mountain ridges. Temperatures varying from middle 50s to lower-middle 60s ( coolest high valleys ).
Saturday Morning Into The Afternoon
Partly to mostly cloudy with a chance of hit-miss showers and thunderstorms, especially during the afternoon. Winds S-SW at generally less than 10 mph. Temperatures varying from the upper 60s to the low-mid 70s ( coolest at highest elevations ) in the High Knob Massif, with upper 70s to lower 80s in surrounding lower-middle elevations.
Race Timeline
8:00 AM: 59 degrees in City of Norton with fog or low cloud bases ( or a fog layer just above downtown ).
Low-mid 50s in cooler high valleys of the High Knob Massif.
60 to 62 degrees at the summit level of High Knob with breezy S-SW winds. Chance of low clouds & dense fog.
10:00 AM: 63 degrees in Downtown Norton with a fog layer or breaking low cloud base above the city.
63 to 65 degrees at summit level of High Knob with partly cloudy skies as fog layer begins breaking on light to breezy S-SW winds.
A mixing layer in between downtown Norton and the summit level will be marked by fog that is beginning to break up and dissipate. Air flow along the massif will be undergoing transition (change) from nocturnal mountain (downslope) to daytime valley (upslope) air flow with increased vertical mixing.
This period can sometimes result in rapid vertical cloud development over the massif, and trigger showers, but with some luck localized shower or thunderstorm development will hold off until after the race is over ( however, this has to be noted and kept in mind ).
12:00 NOON: 76-78 degrees in Norton with partly cloudy skies. Light S-SW winds.
68 to 70 degrees at summit level of High Knob with partly cloudy skies ( vertically building clouds ). Light to breezy S-SW winds.
Although perhaps hard to believe, unless being there, the first color changes actually began showing up within high valleys of the High Knob high country in August.
First Hints Of Autumn In Late Summer – Big Cherry Wetland Valley ( Aug 5, 2017 )
Recorded summer temperatures illustrate partly why.
Having high resolution and very accurate temperature data helps to illustrate why, since it certainly was not dryness in this area that triggered any early color changes ( perhaps a combination of cool temps and too much water on the wet-land valley floor that averages around 3200 feet ).
Early Autumn Color In Big Cherry Wetland Valley – September 16, 2017
Any doubts about early color changes being a figment of imagination were quickly erased as September arrived, with unseasonable chill stimulating changes across the high country of the High Knob Massif.
Big Cherry Wetland 2 September 1-16 of 2017 Elevation 3248 feet
The use of the Big Cherry 2 and 4 sites give a general range along the valley; although, it is unlikely that sensors are actually placed within the very coolest spots amid this large area.
Big Cherry Wetland 4 September 1-16 of 2017 Elevation 3186 feet
*A 9.0 degree average, per day, turn-around on Eagle Knob represented a huge change from the first half of September. This change was so great, in fact, that the average temp for the second half of September was the same as observed on Eagle Knob during the June-August period of summer!
Bare Trees On The High Knob Peak – September 23, 2017
By late in September early changing leaves at the highest elevations had either turned mostly brown or fallen as the focus of a new wave of color changes, with chill returning, shifted to northern slopes.
Big Cherry Wetland 2 September 2017 Elevation 3248 feet
Changing Seasons In The High Knob High Country – September 30, 2017
A chilly start to October, with frosty cold conditions in high valleys and a general chill across the high country, brought significant color changes. Temps dropped to freezing and just below in the colder locations.
Autumn Reflections on Upper Norton Reservoir – October 5, 2017
Majestic maples, ashes, birches and many other species had accelerated color changes in the upper elevations.
Majestic Color Changes On Northern Slopes – October 5, 2017
Average low temperatures as cold as 34 degrees were recorded in the Big Cherry Wetland Valley during the October 1-5 period. Although nights remained chilly through most of the first half of October, days again warmed to well above average.
Beautiful Maples In Upper Elevations of High Knob Massif – October 5, 2017
Big Cherry Wetland 2 October 1-13 of 2017 Elevation 3248 feet
Mean temperatures again went back to around 58 degrees during the October 1-13 period ( the same as in September ). This was 10.4 degrees cooler than down in the Tri-Cities, but still well above average for October ( a low of 45 degrees in the Big Cherry Valley on October 12 was 15 degrees cooler than in the Tri-Cities, but still way above average ).
Big Cherry Wetland Valley of High Knob Massif on October 13, 2017
Big Cherry Wetland 4 October 1-13 of 2017 Elevation 3186 feet
*Less than ideal radiational cooling, with shallow to at times partial decoupling at best, limited the low to 31.5 degrees at Big Cherry Wetland 4. Locally colder temps likely occurred. The growing season ended at 145 days.
Sugar Maple Along Floor of High Valleys in High Knob Massif – October 13, 2017
Although color could still be found, many trees along the high valleys and along the high crest lines were becoming bare of leaves as of October 13 ( in wake of heavy rains ). Nearly all the rain this month, of course, fell with Nate.
October 1-10 Rainfall
*City of Norton WP 2.74″
Big Cherry Dam 3.60″
Robinson Knob 4.69″
*Precipitation total of 50.56″ during 2017. Upper Elevations in the High Knob Massif have had a general 55.00″ to 60.00″+ this year.
As of mid-October, the peak at lower-middle elevations north of the High Knob Massif was yet to come, with color along Pine Mountain developing.
Developing Color Along Pine Mountain on October 12, 2017
Birch Knob of Pine Mountain, at 3149 feet elevation, is below many of the valley floors within the High Knob Massif, often making a big difference in conditions.
*Birch Knob is the highest peak in Dickenson County, Virginia. The above view is from the Adam Childress Family Farm along Rt. 611, with the actual peak of Birch Knob being to the right of this view. Pine Mountain is certainly on my list of favorite mountains!
Big Cherry Wetland Valley of High Knob Massif – October 13, 2017
Holly and Alder are among many wetland species that include an array of sedges, rushes, ferns ( many having now died back ) and distinctive trees such as Yellow Birch and Black Cherry.
It looks like you can almost reach up and touch the clouds on days when they form on upslope flow into the high country, as noted in this view above on SE flow ( that is, of course, when bases actually do not drop down to engulf the upper elevations ).
When you climb to the top of the Lookout Platform on Birch Knob it seems like you’re at the top of the world, but it is all about perspective as the area that is above 3000 feet along the entire 120 mile crest line of Pine Mountain is very small compared to the 50+ square miles that sit above 3000 feet in the High Knob Massif. Sitting on a sprawling crest, valleys in places like the High Knob Massif, Burkes Garden, and Canaan Valley are unique in being able to cool quickly.
Typical Temperature Drop In Big Cherry Valley
Autumn is a good time of year to illustrate what I mean, with the contrast between the valley of Big Cherry Lake versus the Tri-Cities, in the Great Valley, shown here.
Hourly Temperatures In The Tri-Cities For Comparison – October 3, 2017
The temperature at Noon on October 3 was not hugely different, varying from 63 degrees in the Big Cherry Valley to 68 degrees in the Tri-Cities. PM MAXS reached 72 degrees in Big Cherry Valley and 82 degrees down in the Tri-Cities. By 1750 hours ( 5:50 PM ) the temp difference varied from 63 degrees in the Big Cherry Valley to 81 degrees in the Tri-Cities. By 1950 hours ( 7:50 PM ) a 22 degree temperature difference had developed ( 72 degrees at TRI versus 50 degrees in the Big Cherry Lake Valley ). This difference held until the 2150 hour ( 9:50 PM ) observations when a 20 degree variation was reported ( 45 versus 65 degrees ). By about the midnight hour this difference diminished to 12 degrees.
Along Benges Branch Gorge of High Knob Massif – October 18, 2017
The focus of best color development clearly shifted into the gorges of the massif, and toward middle-lower elevations, by October 18 amid an array of frosty cold mornings which featured 20s in high valleys.
Benges Branch Gorge of High Knob Massif – October 18, 2017
The average low temperature observed during the period of October 17-21 was 28.2 degrees at the Big Cherry Wetland 4 site, with a total of 39.2 hours below freezing this month.
Below Freezing Period In Big Cherry Valley
Such a long below freezing period equaled to a hard freeze within colder portions of the high valleys in the High Knob high country.
Many Bare Trees In Big Cherry Wetland Valley – October 21, 2017
Afternoon maximums reached the 60s in upper elevations of the High Knob high country during October 21, following morning lows that dipped into low-mid 30s within coldest places.
Although some color remained on October 21, many bare trees were observed along the high crest-lines and high valleys in the High Knob high country, with best color development presently occurring throughout middle elevations toward the City of Norton.
What color remained looked very beautiful in the upper elevations, amid increasingly bare trees above 3000 feet, during late afternoon hours of October 21.
Moon Rise Over High Knob Lake – October 27, 2017
Temperatures did not go below freezing at High Knob Lake until the morning of October 17, some 12 days later than in Big Cherry Lake basin. This brings up an important point to be made. Regardless of whether a recording site is on an AM to AM recording format, or Midnight-Midnight format, too much emphasis is placed upon 2 single points in time ( i.e., the daily MAX and MIN which generate monthly and longer term climatological means ). What is truly most important, once you begin to understand the climate regimes of these places, is knowing WHAT the temperature is doing during all those other points in time + those two recorded values.
Air temps at 7:00 AM on the morning of October 18 varied from a relatively mild 53 degrees on Eagle Knob of the High Knob Massif to 34 degrees at High Knob Lake. At the same time, a temperature of 28 degrees was recorded at Big Cherry Wetland Valley 4 ( a 25 degree temperature difference in 1002 feet of vertical change ). This large difference was not restricted to a single point, the MIN recorded at 7:00 AM, but instead existed through extended time.
That is courtesy of decoupling, cold air drainage, and nocturnal temp inversion amid complex terrain. Differences of 30 degrees or more can occur at times ( nocturnal inversions of a few degrees to 10 degrees is more typical of rolling, lower elevation terrain ).
Autumn Color Along Benges Basin Gorge on October 27, 2017
Lingering color from Flag Rock Recreation Area downward toward the City of Norton would set the stage for a mix of autumn-winter beauty as the first accumulating snow of this season fell during October 29.
Beautiful Sunset In Flag Rock Recreation Area on October 27, 2017
This set the stage for the coldest temperatures of autumn with readings dropping down to around 20 degrees in the coldest high valleys in the high country.
Big Cherry Wetland Valley In The Clouds – November 4, 2017
The month of October ended wet, with 7.60″ of total precipitation measured in the official rain gauge at the Norton Water Plant, and 8.00″ or more across the high country of the High Knob Massif.
Big Cherry Lake of High Knob Massif – November 4, 2017
Microclimates were on full display into early November with conditions looking like winter in the high country versus still near peak conditions down within depths of South Fork of Powell River Gorge.
South Fork Gorge of High Knob Massif – November 4, 2017
The cliff-line at upper right marks the 3000 foot level, above which trees becoming increasingly bare of leaves as the high country sprawls outward for miles.
