Widespread Frost And Freezing Conditions Are Expected Tuesday And Wednesday Mornings In Mountain Valleys And Other Typical Cold Pockets Upon The Wise & Sandy Ridge Plateaus
Widespread frost, as well as areas of below freezing conditions, are expected Tuesday and Wednesday mornings across Dickenson, Wise, and adjoining counties toward Tazewell. Major river valleys prone to fog, and a few mid-elevation thermal belt sites, may be able to remain above freezing but precautions should still be made to protect any cold-sensitive late season plants.
Hard freezes are expected in typically cold mountain valleys on multiple nights throughout this week, with coldest valleys from the High Knob Massif to Burkes Garden dropping into the 20 to 25 degree range on colder nights. Tuesday Night into Wednesday AM is looking to have the best cooling conditions in high valleys. The growing season ended in these locations during early October.
*October 17 NOTE – Let me make it crystal clear about the extent of frost which was WIDESPREAD and NOT patchy in mountain valleys on the morning of October 17.
Route 83 – Morning frost was continuously visible from Clintwood into Pound, except for the rise through Red Onion Mountain Gap.
Frost was visible from Pound to the foot of Wise Mountain, along U.S. 23, then absent from the mountain. Frost was visible in Wise, except for exposed portions like Lonesome Pine Airport. Frost was then continuous from Norton to Coeburn along Alt. 58.
When you can drive for MILES and see frost that = widespread in valleys. When you see frost in a valley, then have to drive for a mile, or miles, before seeing anymore then that = patchy.
AM Mins on October 17 were in the upper 20s to lower 30s in most valleys, except even colder in favored high valleys of the High Knob Massif. More of the same will be seen into morning hours of October 18, with even drier air in the vertical profile ( some high clouds will decorate skies overnight into Wednesday AM ).
Overnight Into Sunday Morning
Mostly clear to partly cloudy, except low clouds with dense fog ( orographic clouds ) at upper elevations within the high country of the High Knob Massif and along high elevations in the Black mountains. Winds S to SSW at 5-15 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet. Winds SSW-SW at 10-20 mph, with higher gusts, on middle-upper elevation mountain ridges above 2700 feet. Temperatures varying from upper 40s to low 50s in valleys protected from winds, to the lower 60s.
Sunday Afternoon
Low clouds in upslope areas ( becoming cloudy in downslope locations ). Windy in higher elevations. Showers becoming likely by late, with a chance of thunder. Temperatures from 60s in upslope locations ( Norton-Wise ) to the lower-middle 70s in downslope sites ( Pound-Clintwood-Haysi ).
Sunday Night Into Monday Morning
Evening rain likely, with a chance of thunder. Downpours. Rain diminishing to drizzle overnight. Turning much colder with dropping cloud bases on NNW-N winds ( bases possibly dropping to elevations of the Wise & Sandy Ridge plateaus ). Temperatures dropping into the 40s, except 30s in upper elevations ( to around freezing on highest peaks ). Wind chills dropping into 20s to low 30s at highest elevations.
Monday Afternoon
Becoming partly to mostly sunny. Chilly. N winds 5-15 mph with some higher gusts. Temperatures varying from low-mid 40s in upper elevations to the low-middle 50s ( milder south into the Great Valley ).
Monday Night Into Tuesday Morning
Mostly clear. Cold. NE-ENE winds 5-10 mph, with some higher gusts, along mid-upper elevation mountain ridges. Temperatures varying from 20s in colder valleys at upper elevations to the low-middle 30s.
Tuesday Afternoon
Mostly sunny. Deep blue skies. Light NNE-E winds. Temps varying from low-mid 50s in upper elevations to the lower to middle 60s.
Tuesday Night Into Wednesday Morning
Mostly clear ( some high clouds overnight ). Cold. Light winds. Frosty cold in mountain valleys with a large vertical temperature spread between valleys and ridges. Temps varying from upper 20s to lower 30s in valleys, except 20 to 25 degrees in coldest valleys of the High Knob high country and Burkes Garden, to upper 30s-middle 40s along exposed mid-upper elevation mountains ridges and plateaus.
Reference My History Of Autumn Color 2017 for an update on color changes & recorded temperatures in the High Knob high country.
Weather Discussion ( Colder Air )
Sunday Afternoon Update
It has been an interesting Sunday along the Cumberland Mountains, as often is the case in this type of setting.
NASA Visible Satellite Image At 8:30 AM Sunday – October 15, 2017
Low clouds and dense fog ( orographic cap clouds ) obscured high elevations in the High Knob Massif overnight into Sunday. Note clear skies, by contrast, in the downslope sector across northern Wise County and most of Dickenson-Buchanan counties where SSW air flow was sinking ( above view ).
Black Mountain Mesonet Observations – Ending At 7:35 AM Sunday – October 15
This was a windy, chilly feeling air flow atop the high country versus calm winds down in lower elevations ( where the AM MIN reached 50.7 degrees at Clintwood 1 W amid calm conditions ).
Low clouds banked up along the High Knob Massif – Black Mountain corridor held temperatures in the 50s atop the high country of the massif until early afternoon, while abundant sunshine to the north allowed readings to rise upward into the 70s in Clintwood.
NASA Visible Satellite Image At 12:00 PM Sunday – October 15, 2017
As rising air with convergence along a strong front to the west propagated closer to the mountains, enough sinking air finally helped to dissipate clouds along all but the high crest lines into late afternoon.
High Knob Massif Webcam – University Of Virginia’s College At Wise
Sunday afternoon MAX temps varied from low 60s atop the High Knob Massif to 78 degrees in Clintwood ( following the morning low of 50.7 degrees ). Temps also rose into the 70s in Norton-Wise with increasing sunshine by 2:00 PM.
Previous Discussion
The coldest air mass of the autumn season, to date, will be pushing into the mountains by Monday. Showers, with a chance of thunder, will become likely by late Sunday into Sunday evening. Locally heavy rain, with orographic cap clouds, will be possible in favored upslope locations.
Although not resolved exactly as it should be, a signal for locally heavy rain is being picked up on by terrain models ( below ). This has added support by the early formation of orographic cap clouds in upper elevations of the High Knob high country. Rainfall totals may reach 1.00″ in favored upslope zones, with lesser amounts in other locations ( the western side of the Appalachians being most favored for heavier rain amounts in this type of setting ). Any thunderstorms that form could skew the rainfall pattern.
NAM 12 KM Model Total Rainfall Forecast
Orographic clouds, with dense fog at highest elevations, began developing with upslope SW flow into the High Knob Massif and Black mountains by late Saturday Night into the early overnight of Sunday.
Black Mountain Mesonet Ending At 1:55 AM Sunday – October 15, 2017
This is well in advance of a strong front that will be reaching the Cumberland Mountains by late Sunday.
Black Mountain Mesonet Ending At 12:05 AM Sunday – October 15, 2017
Convergence along the cold front, which is shown vividly below, will be just west of the mountains by 8 PM Sunday if the NAM Model timing is correct. Regardless, convergence is the important feature that will combine with relatively narrow but rich moisture to develop downpours as the boundary pushes into the mountains. Any storms that develop could skew the rainfall pattern, as noted above.
NAM Model Forecast Surface Wind Speed-Streamlines at 8 PM Sunday
A shift to northerly upslope flow, combined with a band of lingering moisture behind the frontal boundary, will likely drop cloud bases lower ( into the middle elevations ) by late Sunday Night into overnight-predawn hours of Monday amid significant cold air transport.
NAM 12 KM Model MSL-Precipitable Water At 8:00 AM Tuesday – October 17, 2017
The focus then shifts to building High Pressure and very dry air that will set the stage for widespread frost and freezing conditions across the mountains into Tuesday morning.
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.
The Potential For The First Widespread Frost-Freeze Of The Season Is Being Monitored For Next Week With An Autumn Air Mass Pushing Into The Appalachians
Although numerous frosty mornings have already been observed in mountain valleys, with local sub-freezing temperatures as well, no widespread frost-freeze has yet been experienced. River valleys that fog up, and a few favored mid-elevation thermal belts, might still be able to remain above freezing. This may be progressive and not long-lived, with above average temperatures returning by late next week into the following week by day. Nights look to continue to be cold, especially in valleys, with large diurnal temp ranges.
Reference My History Of Autumn Color 2017 for an update on color changes & recorded temperatures in the High Knob high country.
Overnight Into Thursday Morning
Areas of dense fog developing in lower-middle elevations. Becoming mostly clear in the upper elevations. Light winds, except W-NW at 5-10 mph, with some higher gusts, on upper elevation mountain ridges. Temperatures varying from 30s to mid 40s in colder valleys at upper elevations in the high country of the High Knob Massif to the lower-middle 50s.
*NOTE – Temperatures Thursday will be cooler than currently in my forecast if a low-level cloud deck develops and does not mix out as currently expected. That remains a small possibility to be noted, especially in locations along & west-northwest of the Tennessee Valley Divide and High Knob Massif.
Thursday Afternoon
Partly to mostly sunny. Deep blue skies above any clouds. Generally light winds. Temperatures varying from low-mid 60s in upper elevations to the low-mid 70s ( warmer in river valleys, especially southward into eastern Tennessee ).
Thursday Night Into Friday Morning
Partly to mostly clear. Areas of dense valley fog. Light valley winds. Winds SE-S at 5-15 mph, with higher gusts, along middle-upper elevation mountain ridges. Large temp spread between cooler valleys and milder mountain ridges, varying from 40s to lower 50s in cooler valleys to the lower-middle 60s on exposed ridges-plateaus.
Friday Afternoon
Partly cloudy. Winds SSE-SSW at 5-10 mph with some higher gusts. Temperatures varying from 60s in upper elevations to the mid-upper 70s.
Friday Night Into Saturday Morning
Partly to mostly clear. Areas of dense valley fog. Light valley winds. Winds S-SW at 5-10 mph, with some higher gusts, along mid-upper elevation mountain ridges. Large vertical temperature spread between cooler valleys and exposed ridges-plateaus. Temperatures varying from the 40s in colder mountain valleys to the upper 50s to low 60s.
Weather Discussion ( Air Mass Changes )
An unseasonably humid air mass following remnants of Nate have been ruling the mountain landscape during recent days. This is going to change, with one transition into Thursday and a much bigger change into next week.
High Knob Massif Webcam – University Of Virginia’s College At Wise
Wednesday afternoon maximums varied from upper 60s in the High Knob Massif to the upper 70s ( 79 degrees in Clintwood ) to around 80 degrees.
Nora 4 SSE on Long Ridge of Sandy Ridge – October 11, 2017
October 1-10 Rainfall
Nora 4 SSE 1.48″
Clintwood 1 W 2.06″
*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.
Recent rainfall was welcomed, despite bad timing for the final leg of the Cloudsplitter 100 Mile race, with current totals being nearly as great or greater than observed in September ( Norton measured 2.86″ of September rain ).
European 51-Member Ensemble Mean 500 MB Height Anomalies – Days 6-10
Although a notable cool push of air will be felt next week, the ensemble mean of the European Model group currently suggests it will be progressive with a trend back toward above average temperatures by later next week. The main difference versus this recent pattern being a continuation of cold nights, especially in mountain valleys, with large vertical and diurnal temperature spreads.
European 51-Member Ensemble Mean 850 MB Temp Forecast – Days 6-10
ALERT For Strong Winds & Heavy Rainfall Developing Sunday Into Monday Morning With Remnants of Nate
Strong Rises On Mountain Streams Will Become Possible By Sunday Night Into Monday Morning
Remnants of Hurricane Nate will begin impacting the mountain region Saturday Night into Sunday Morning with developing rain. Rainfall will become heavy during Sunday into Monday Morning, especially along windward slopes & crestlines of major orographic features like the High Knob Massif.
Reference My October 7-8 Race Forecast For More Detailed Information On The High Knob Hellbender 10K and The Cloudsplitter 100 Races.
Overnight Into Saturday Morning
Partly-mostly clear ( some high clouds ). Becoming gusty higher elevations. SSE-SSW winds increasing to 10-20 mph, with higher gusts, on middle to upper elevation mountain ridges. Temps varying from 40s in cooler mountain valleys ( sheltered from winds ) to middle-upper 50s to around 60 degrees on exposed mountain ridges and plateaus.
Saturday Afternoon
Becoming partly to mostly cloudy & more humid. Winds SSE-SSW at 10-20 mph, with higher gusts. Temperatures varying from upper 60s to lower 70s ( 18 to 22 Celsius ) in upper elevations, above 3000 feet, to middle-upper 70s ( 24-26 Celsius ) at elevations below 3000 feet. Warmest at low elevations in the Hanging Rock Recreation Area where temperatures could rise above 80 degrees ( 27 Celsius ).
Saturday Night Into Sunday Morning
Becoming cloudy with light rain developing overnight into morning. Cloud bases lowering to near or below the summit level of the High Knob Massif. SSE-S winds 5-15 mph below 2700 feet. Winds S-SW 10-25 mph, with higher gusts, above 2700 feet ( especially on mountain ridges ). Temperatures falling into the 60s ( 16-18 Celsius ).
Sunday Morning Through The Afternoon
Increasing rain, with a chance for thunderstorms. Locally heavy rainfall likely, especially along windward slopes and crestlines of the High Knob Massif. Lesser rain amounts in downslope locales in central-northern Wise and Dickenson-Buchanan counties.
Winds SE-SSE at 10-25 mph, with higher gusts in upper elevations ( lighter winds at lower elevations in hollows-valleys ). Temps near steady in low-mid 60s ( 16-18 Celsius ) at high elevations and in the upper 60s to middle 70s ( 20-22 Celsius ) at lower elevations ( below 2000 feet ).
Sunday Night Into Monday Morning
Rain becoming heavy. A chance of thunderstorms. Windy. Dense fog ( orographic clouds ) across upper elevations in the High Knob Massif. SE-S winds 15-25 mph, with higher gusts below 2700 feet. SSE to SSW winds 25-35 mph, with gusts over 50 mph, at elevations above 2700 feet. Temps widespread in the 60s ( low-mid 60s in upper elevations ).
Weather Discussion ( Nate & Races )
The recent streak of dry conditions will be ending this weekend, perhaps in a big way for some locations. The timing will favor the High Knob Hellbender 10K Race and the first day of the Cloudsplitter 100 races; however, the second day of the Cloudspitter will be a different story featuring deteriorating conditions.
Autumn Beauty In Upper Elevations of High Knob Massif – October 5, 2017
Increasing wind and rain with Nate will not greatly impact trees at the summit level, where many trees are now bare around High Knob Lookout ( for example ), but color that is now approaching peak in other places of the high country could be hurt ( dulled and many downed ) by this system.
Autumn Reflections on Upper Norton Reservoir – October 5, 2017
As of the early overnight period of Saturday, Nate is under-going expansion and increasing organization. Meanwhile, a cold frontal zone to the west has triggered a squall line to form from Texas across Oklahoma into Kansas.
NASA Infrared GOES-16 Image At 1:07 AM Saturday – October 7, 2017
Local conditions are already beginning to change, with a notable increase in both wind speeds and moisture levels across high elevations to strengthen a nocturnal temp inversion ( with cooler valleys & milder mountain ridges ).
Black Mountain Mesonet at 1:40 AM Saturday – October 7, 2017
An increase in wind speeds and rise in dewpoints have occurred at highest elevations between 9:40 PM Friday and 1:40 AM Saturday.
Black Mountain Mesonet At 9:40 PM Friday – October 6, 2017
This will set the stage for a more humid, mild Saturday with nocturnal mountain valley inversions mixing out following sunrise. If the above trend continues, then some low clouds could begin developing above the mountain summits prior to Saturday afternoon ( when my forecast is calling for the conditions to become partly-mostly cloudy ).
Nate Becomes A Hurricane As of The 2 AM Advisory Saturday – October 7, 2017
Since Nate has now become a hurricane ( as of 2:00 AM ) the next 12-18 hours will be critical as to how strong he can get before landfall. A stronger Nate = a likely stronger system post-landfall which will be important to impacts across the southern-central Appalachians. Stay tuned for updates.
Main changes in this update include a slight shift west in the National Hurricane Center track for Nate, with a little faster arrival of the worst conditions. This is not good news for final hours of the Cloudsplitter.
ALERT For Strong Winds & Heavy Rainfall Developing Sunday Into Monday Morning With Remnants of Nate
Strong Rises On Mountain Streams Will Become Possible By Later Sunday Into Monday Morning
*Later Portions of the Cloudspitter 100 race will have to endure increasingly bad conditions. Due to the speed of Nate there is increasing concern that some of the worst weather conditions may now arrive before the finish or ending time of the Cloudsplitter 100. Runners will need be prepared for increasingly bad conditions Sunday afternoon into Sunday evening, with ROARING winds developing over the high country of the massif. This could generate dangerous conditions for final hours of this race.
Strong rises on creeks will become possible by later Sunday into Sunday evening and Monday morning.
Autumn Reflection at Upper Norton Reservoir – October 5, 2017
Saturday will feature relatively warm & gusty conditions for the High Knob Hellbender 10K Race and the first day of the Cloudsplitter. Conditions will then begin to deteriorate into Sunday and the second day of the Cloudsplitter, with precise conditions dependent upon the track and intensity of Nate into the central-southern Appalachians.
Conditions in the high country of the High Knob Massif will become much worse than at low elevations if this current National Hurricane Center track forecast verifies.
Nate became a hurricane by 2:00 AM Saturday.
Nate Becomes A Hurricane As of The 2 AM Advisory Saturday – October 7, 2017
A slight westward shift in the track of Nate is important since worst conditions will be along and east of the track.
National Hurricane Center Track Forecast As Of 11:00 PM Saturday
Note – I will show graphics from the high-resolution NAM 3 KM Model for this forecast period. Although this model struggles to resolve local terrain, its high resolution allows for better modeling than courser model solutions. I will fill in the gaps with my own information based upon local climatology.
Friday Night Into Saturday Morning
Partly-mostly clear ( high clouds possible ). Becoming gusty higher elevations. SSE-SSW winds increasing to 10-20 mph, with higher gusts, into the overnight-morning on middle to upper elevation mountain ridges. Temps varying from 40s in cooler mountain valleys ( sheltered from winds ) to mid-upper 50s to around 60 degrees on exposed middle-upper elevation mountain ridges and plateaus.
NAM 3 KM Model Temperature Forecast At 8:00 AM Saturday – October 7, 2017
A morning temperature inversion is likely on the floor of the valley in the City of Norton, with upper 40s to lower 50s ( 9 to 11 degrees Celsius ) during the sunrise period.
Racers beginning early will encounter the inversion layer upon climbing upward toward Benges Rock and the turn to Flag Rock Recreation Area ( warmer temperatures in this zone than down in the City of Norton ), with temperatures warming into the lower-middle 60s ( 18 Celsius ).
NAM 3 KM Model Temperature Forecast At 10:00 AM Saturday – October 7, 2017
Climbing higher, above Flag Rock-Upper Norton Reservoir, the temperature will begin to decline back into the lower 60s ( 16 Celsius ) as wind speeds increase out of the SSW to SW at 10 to 20 mph, with higher gusts ( especially along the high crest lines ), to make it feel somewhat cooler than air temperatures suggest. While humidity levels will be higher than in recent days, conditions should in general be fine for the High Knob Hellbender 10K and the first day of racing in the Cloudsplitter.
NAM 3 KM Model Temperature Forecast At 12 Noon Saturday – October 7, 2017
Saturday Afternoon
Becoming partly to mostly cloudy & more humid. Winds SSE-SSW at 10-20 mph, with higher gusts. Temperatures varying from upper 60s to lower 70s ( 18 to 22 Celsius ) in upper elevations, above 3000 feet, to middle-upper 70s ( 24-26 Celsius ) at elevations below 3000 feet. Warmest at low elevations in the Hanging Rock Recreation Area where temperatures could rise above 80 degrees ( 27 Celsius ).
Note that microclimates in the High Knob Massif will impact conditions, with forest trails going along creeks and valleys ( which are cold air drainages ) tending to be cooler than more open sections during the day.
During this race period, of October 7-8, higher elevations will tend to be cooler by both day and night given enhanced mixing by winds and increasing moisture levels. The main exception being at the race beginning when temperatures in the City of Norton will be cooler than higher up until the nocturnal inversion mixes out into mid-morning Saturday.
NAM 3 KM Model Forecast Temperature At 2:00 PM Saturday – October 7, 2017
If winds are light enough, some hollows, valleys and stream drainages could see temperatures fall back through the 60s late Saturday afternoon into the early evening, but unlike recent days a increase in clouds and moisture will prevent rapid temperature drops and keep most locations at or above 60 degrees ( a few high valley drainages could drop into the 50s early Saturday afternoon prior to rising later into the night as clouds thicken and rain develops ).
NAM 3 KM Model Forecast Temperature At 8:00 PM Saturday – October 8, 2017
Saturday Night Into Sunday Morning
Becoming cloudy with light rain developing overnight into morning. Cloud bases lowering to below the summit level of the High Knob Massif. SSE-S winds 5-15 mph below 2700 feet. Winds S-SW 10-25 mph, with higher gusts, above 2700 feet ( especially on mountain ridges ). Temperatures falling into the 60s ( 16-18 Celsius ). Around 60 degrees ( 15-16 C ) at the summit level of the high country.
NAM 3 KM Model Forecast Temperature At 2:00 AM Sunday – October 8, 2017
Temperatures will not be varying much in the high country as moisture levels increase and cloud bases begin dropping to eventually engulf upper elevations ( above 3000-3500 feet ) in dense fog ( orographic, upslope clouds ).
Runners can expect temperatures in the low-mid 60s with 90-100% RH throughout most of Sunday at elevations above 3000 feet, with mid-upper 60s expected at lower elevations.
Because lower elevations on the Scott County side of the massif, such as at Hanging Rock Recreation Area and the Devil Fork Trail, will be on the windward side of the massif during this event, conditions through Sunday will tend to be somewhat cooler and wetter than at lower elevations on the Wise County side of the massif ( below 2500 feet ).
NAM 3 KM Model Forecast Temperature At 8:00 AM Sunday – October 8, 2017
Weather conditions are expected to become worse as Sunday continues, with increasing rain, wind, and the chance for thunderstorm development into afternoon-evening hours. Cloud bases are likely to drop into upper elevations of the high country to produce dense fog.
Sunday Morning Through The Afternoon
Increasing rain, with a chance for thunderstorms. Locally heavy rainfall likely, especially along windward slopes and crest lines of the High Knob Massif ( at elevations above 3000 feet & downward to bases in northern Scott County ). Cloud bases lowering to obscure upper elevations.
Winds SE to SSE increasing to 15-25 mph by later afternoon, with gusts over 40 mph in upper elevations ( lighter winds at lower elevations in hollows-valleys ). Temps near steady in low-mid 60s ( 16-18 Celsius ) at high elevations and in the upper 60s to middle 70s ( 20-22 Celsius ) at lower elevations ( below 2000 feet ).
NAM 3 KM Model Forecast Temperature At 2:00 PM Sunday – October 8, 2017
This is the period, Sunday afternoon into Sunday evening, when weather conditions are likely to begin to deteriorate as remnants of Nate begin approaching and the pressure gradient begins increasing. This will begin increasing lift and orographic forcing across the High Knob Massif, with increasing wetness and increasingly strong SSE-S winds.
NAM 3 KM Model Forecast Temperature At 8:00 PM Sunday – October 8, 2017
Although it is hoped that everyone will be finished with this race by the time wind speeds become dangerous, all runners should remain vigilant for possible falling limbs or trees as wind speeds increase into the 20-40+ mph range by Sunday afternoon into evening ( gusts of 50+ mph will be possible ).
Sunday Night Into Monday Morning
Rain becoming heavy. A chance of thunderstorms. Windy. Dense fog ( orographic clouds ) across upper elevations. SE-S winds 15-25 mph, with higher gusts below 2700 feet. SSE-SW winds 25-35 mph, with gusts over 50 mph, at elevations above 2700-3000 feet. Temps widespread in the 60s ( low-mid 60s in upper elevations ).
A general 2.00″ to 4.00″+ of rain is currently expected over the High Knob Massif area during Sunday into Monday AM, with locally higher amounts possible depending upon the track of Nate, his strength, and the positioning of a cold frontal boundary that is depicted above with a zone of enhanced rainfall amounts across central Kentucky.
Unseasonably warm and dry conditions will dominate the first day of racing on October 7, which will include all of the High Knob Hellbender 10K and the first day of Cloudsplitter races ( which extends through Sunday ).
Friday Night Into Saturday Morning
Partly-mostly clear ( high clouds possible ). Becoming gusty higher elevations. SSE-SSW winds increasing to 10-20 mph, with higher gusts, into the overnight-morning. Temps from 40s in cooler mountain valleys ( sheltered from winds ) to mid-upper 50s to around 60 degrees on exposed middle-upper elevation mountain ridges and plateaus.
The race period is only now ( Oct 4 ) coming into range of high resolution forecast models; therefore, I will begin to update this through coming days with more details that will extend through the entire race periods.
Currently it is clear that a surge of unseasonably warm air will be felt through Saturday in advance of another change back into unseasonably cool conditions by middle portions of next week.
What is uncertain, and will have to be updated, is how will a developing tropical system in the Caribbean-Gulf of Mexico impact the mountains by Day 2 of the Cloudsplitter. Stay tuned for updates as new data gets incorporated into forecast models during the next couple of days.
An Autumn Cold Front And Developing Tropical System Are Being Monitored For Possible Impacts Upon The Mountain Region By Later This Weekend Into Early Next Week ( October 8-10 )
Details on this setup are yet to be worked out, with the Tuesday night run of the operational European Model trending east to keep significant rains along and east of the mountains ( from the Blue Ridge east to southeast ). This is in contrast to the U.S. GFS Model, and most hurricane models, which track the tropical system much farther west. Timing of an approaching cold front and upper air trough will help determine where the tropical system goes and how any linkage between it and the frontal zone develops.
A shot of unseasonably cool air will likely follow whatever happens with this tropical system by the middle of next week. Stay tuned for updates.
Overnight Into Wednesday Morning
Mostly clear. Light winds, except SSE-SSW at 5-10 mph, with some higher gusts, on mid-upper elevation mountain ridges. Large vertical temperature spread between colder mountain valleys and milder ridges. Temperatures varying from upper 20s to middle 30s in colder valleys to the upper 40s to lower-middle 50s on exposed ridges-plateaus. Areas of fog along major rivers.
Wednesday Afternoon
Mostly sunny. Light winds. Temperatures varying from mid-upper 60s in upper elevations to the mid-upper 70s. Warmer south into the Great Valley and river valleys.
Wednesday Night Into Thursday Morning
Mostly clear. Light winds. Large vertical temperature spread between colder mountain valleys and exposed ridges and plateaus. Temps varying from 30s in the colder valleys to the lower-middle 50s on exposed ridges-plateaus. Areas of river valley fog.
Thursday Afternoon
Mostly sunny ( some high clouds ). Light northerly winds. Temperatures varying from 60s in upper elevations to the mid-upper 70s ( warmer south into the Great Valley ).
Thursday Night Into Friday Morning
Mostly clear. Light winds. Large vertical temperature spread between colder valleys and exposed mountain ridges and plateaus. Temperatures varying from 30s to lower 40s in colder mountain valleys to the low-mid 50s on exposed ridges and plateaus.
Friday Afternoon
Partly-mostly sunny ( high clouds ). Unseasonably warm. Light southerly winds. Temperatures varying from upper 60s to lower 70s in upper elevations to the upper 70s to lower 80s ( warmer south into the Great Valley ).
Friday Night Into Saturday Morning
Partly-mostly clear ( high clouds possible ). Becoming gusty higher elevations. SSE-SSW winds increasing to 10-20 mph, with higher gusts, into the overnight-morning. Temps from 40s in cooler mountain valleys ( sheltered from winds ) to mid-upper 50s to around 60 degrees on exposed middle-upper elevation mountain ridges and plateaus.
The first full moon closest to the Autumnal Equinox is always called the Harvest Moon, for times when farmers and Native Americans used moonlight to gather in late season crops. Although not quite full yet, the moon early on October 4 was getting close in the chilly air filling mountain valleys of the Cumberland Mountains.
Harvest Moon Above The Cumberland Mountains – October 4, 2017
While it is looking to be unseasonably warm and continued dry for the High Knob Hellbender 10K race on Saturday, the second day of the Cloudsplitter 100 is more uncertain and will depend upon what happens with a developing tropical system in the Gulf of Mexico.
Changing Seasons In The High Knob High Country
Ensembles of the GFS Model have been farther west than the mean of the 51-Member European Model group. Right now the bulk of hurricane models are also farther west.
Hurricane Spaghetti Model Track Forecast – 8 PM Tuesday Run ( Oct 3 )
I think the setting will become more clear once hurricane hunter data and other data being collected gets put into the models during the next couple of days. A track like above would tend to spread heavy rain across all of the southern-central Appalachians, while a track like the current run of the Operational European Model would keep heavier rains mainly along and east of the Blue Ridge.
An ALERT For Cold Night-time Conditions In Mountain Valleys Continues, With Large Vertical Temperature Spreads Between Ridges & Valleys
While foggy river valleys and exposed mountain ridges-plateaus will remain well above freezing, a very dry air mass will continue to support both large diurnal temperature spreads and also large vertical differences between ridges and mountain valleys.
Colder valleys will continue to drop into the 30s, with local below freezing conditions expected through mid-week ( Wednesday AM of October 4 ). Reference observed minimums reported along the Appalachians on Sunday AM of October 1 in my discussion below.
Overnight Into Monday Morning
Partly to mostly clear ( high clouds ). Breezy to gusty SE winds of 10-20 mph, with higher gusts, through early to mid-overnight on mid-upper elevation mountain ridges before decreasing during the predawn. Large vertical temp spread between colder valleys and milder ridges-exposed plateaus. Temps varying from 30s in colder valleys to the mid-upper 40s to around 50 degrees on exposed ridges and plateaus ( except for a rapid temperature drop to around or below freezing in high valleys during the predawn-early morning ). Local areas of dense river valley fog along major rivers. Wind chills in the upper 30s to lower 40s in gusts along high mountain crest lines.
Monday Afternoon
Partly sunny ( high clouds ). Light SE to SSE winds. Temperatures varying from low-mid 60s in upper elevations to the low-mid 70s.
Monday Night Into Tuesday Morning
Partly-mostly clear ( high clouds ). Light winds, except SSE-SSW at 5-10 mph on mid-upper elevation mountain ridges. Large vertical temperature spread between colder valleys and milder mountain ridges. Temperatures varying from upper 20s to upper 30s in mountain valleys to the upper 40s to lower 50s along mountain ridges-exposed plateaus. Fog along major river valleys.
Tuesday Afternoon
Mostly sunny ( some high clouds possible ). Generally light winds. Temperatures varying from low-mid 60s in upper elevations to the lower-middle 70s.
Tuesday Night Into Wednesday Morning
Mostly clear. Light winds, except SSE-SSW at 5-10 mph, with some higher gusts, on mid-upper elevation mountain ridges. Large vertical temperature spread between colder mountain valleys and milder ridges. Temperatures varying from 20s to middle 30s in colder valleys to the upper 40s to lower 50s on exposed ridges-plateaus. Areas of fog along major rivers.
Weather Discussion ( WxDiversity )
Autumn has arrived in the mountains. This combined with a recent streak of dryness will enhance diversity in weather conditions, both from day-to-night and also ( as typical of this time of year in the mountains ) between ridges-valleys.
Rugged Stone-Pickem Mountain of High Knob Massif – September 30, 2017
The following temperatures are mostly NWS Cooperative sites, with a few Weatherbugs added ( note Weatherbug sensors are typically mounted much higher than the standard 4-6 feet height of official thermometers ).
Western North Carolina Jefferson: 31 degrees Boone: 35 degrees Spruce Pine 4 ENE: 39 degrees
West Virginia Bartow: 29 degrees Hacker Valley: 31 degrees Frost 3 ENE: 32 degrees White Sulphur Springs: 32 degrees Lewisburg: 33 degrees Beckley: 34 degrees
Areas of valley frost were widespread across Wise and Dickenson counties, away from river valley fog, early October 1 and no doubt were also in many other places located within the mountains. Coldest high valley sites, outside of Burkes Garden, of Canaan Valley and the Big Cherry Basin in the High Knob Massif are not even yet included in this list ( that data yet to be collected ).
Valley frost is typically observed when air temperatures at standard NWS sensor height of around 5 feet reach the middle 30s since air temperatures right at ground level are generally colder. Frost occurred in the Clintwood area, for example, with a MIN air temperature of 34.8 degrees at the 5 foot sensor height.
Brilliant Color In Flag Rock Recreation Area – September 30, 2017
Another interesting feature is wind chills along the high mountain crest lines. This is being caused by a compression of thicknesses by night + a pressure gradient around a High currently centered over Pennsylvania.
If anyone doubts that nocturnal wind chills are a factor, then just drive up to the High Knob Lookout and that doubt will be quickly eradicated. Winds relax into the day as thicknesses increase.
NAM 12 KM Model Mean Sea Level Pressure-Streamlines at 8 PM October 1
This type of setting is not ideal for coldest conditions in the higher mountain valleys; however, a relaxation during pre-dawn and sunrise periods is enough to allow for rapid temp drops in the favored frost pockets ( where temps often drop below surface dewpoints reported at any given time ).
Black Mountain Mesonet at 12:55 AM Monday – October 2, 2017
Wind chills in the upper 30s to lower 40s are being observed along high mountain crest lines, especially in the frequent gusts. This low-level jet setting weakened into morning hours of October 1 and will likely weaken again into this morning ( October 2 ).
If the High center slides a little more southwest, allowing the nocturnal pressure gradient to weaken, conditions will actually become more favorable for cooling within the high mountain valleys into Tuesday and Wednesday mornings. Therefore, I have continued the alert for cold nights since no official advisories have been issued.
European Model 51-Member Ensemble Mean 500 MB Height Anomalies: Days 0-4
While there is little to no chance of rain this week, there are signs of important changes ahead that could break this dry streak out in the 5-10 day period ( below ) as eastern USA ridging ( above ) breaks down.
European Model 51-Member Ensemble Mean 500 MB Height Anomalies: Days 6-10
Meanwhile, it will be wise to avoid any outdoor burning.
ALERT For Cold Night-time Conditions In Mountain Valleys, With Frost And Local Freezing Conditions By Sunday & Monday Mornings ( October 1-2 ).
While foggy river valleys and exposed mountain ridges-plateaus will remain well above freezing, a very dry air mass + clear skies sets the stage for a large vertical temperature difference to form during coming days. Coldest valleys in higher elevations may dip into the 30s by Friday and/or Saturday mornings, but the coldest and most widespread chill is expected Sunday & Monday mornings when 30s will become widespread in mountain valleys ( with 20s in coldest valleys of the High Knob Massif-Burkes Garden areas ).
Overnight Into Thursday Morning
Becoming partly to mostly cloudy by morning. Cloud bases dropping onto highest mountain ridges. NNW-NNE winds at 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges. Areas of dense river valley fog. Temps varying from upper 40s to lower 50s in cooler mountain valleys to the low-mid 60s.
Thursday Morning Through The Afternoon
Mostly cloudy. Turning cooler. Small chance of showers or sprinkles. NNW to N winds 5 to 10 mph, with some higher gusts. Temps varying from lower 60s in upper elevations to the upper 60s to lower 70s, dropping by mid-late afternoon into the 50s at upper elevations and the lower-middle 60s at elevations of Norton-Wise.
Thursday Night Into Friday Morning
Becoming partly to mostly clear. N-NNE winds 5-10 mph, with some higher gusts, on mid-upper elevation mountain ridges. Chilly. Temperatures dropping into the lower 40s to lower 50s, except 30s in coldest mountain valleys ( above 2500-3000 feet ) in the Cumberland-Allegheny mountains.
Friday Afternoon
Partly to mostly sunny ( deep blue skies ). NNW-N winds at 5-10 mph, with some higher gusts. Temperatures varying from mid-upper 50s in upper elevations to the mid 60s to around 70 degrees ( warmer south into the Great Valley ).
Friday Night Into Saturday Morning
Partly cloudy. Chilly. NNW-NNE winds 5-10 mph, with higher gusts, on middle-upper elevation mountain ridges. Temperatures varying from 30s in colder mountain valleys to the lower 40s to around 50 degrees. Wind chills in the upper 30s to low 40s along high ridges.
Saturday Afternoon
Sunny. Deep blue skies. Cool. NNE-NE winds 5-10 mph, with some higher gusts. Temperatures varying from lower to middle 50s in upper elevations to the middle-upper 60s.
Saturday Night Into Sunday Morning
Clear. Cold. Winds becoming SE at 5-10 mph, with higher gusts, along mid-upper elevation mountain ridges. Temps varying from upper 20s to lower 30s in coldest mountain valleys to the mid-upper 40s on exposed ridges.
A frontal boundary will be crossing the mountains during Friday Night into Saturday Morning, with any initial clouds expected to give way to deep blue skies during Saturday.
High Knob Naturalist Rally Forecast – Updated Saturday – September 30
Partly cloudy to clear morning conditions are expected with NNE winds at 5-15 mph ( the higher wind speeds being at the High Knob Lookout ). Morning temperatures in the low-mid 40s will rise into the lower-middle 50s by afternoon.
9:00 AM at High Knob Lookout – Mostly Sunny. NNE to NE winds at 5-15 mph, with higher gusts. Temperatures in the middle 40s. Wind chills in the 30s to lower 40s.
3:00 PM at High Knob Lake – Sunny. Gorgeous blue skies. NNE winds 5-10 mph. Max temp 56-58 degrees at 2:30 to 3:00 PM, dropping quickly after 4:30 to 5:00 PM.
Weather Discussion ( Autumn Taste )
A true taste of autumn will be felt by Friday into Saturday, just in time for the 11th Annual High Knob Naturalist Rally.
Early Autumn at High Knob Lake Recreation Area – September 23, 2017
*As of September 29 autumn color was not as good as it was on September 23, with many early changing leaves having fallen. Chilly nights upcoming will have to stimulate a new wave of changes in an autumn that has been unusual with strong early color changes fading amid recent warm, dry days.
This photograph taken on September 16 illustrates the strong early color changes in the high country, looking across the lofty High Knob Lake Basin. Today ( September 29 ) nearly all the trees seen below with color are bare, with leaves having fallen.
Looking Across High Knob Lake Basin – September 16, 2017
Ten consecutive days, from September 19-28, featured MAX temperatures between 70 and 76 degrees at High Knob Lake. Nearly all the 3.50″ to 4.00″ of September rainfall fell during September 1-15 ( recent dryness also aiding the leaf drop ).
Afternoon maximum temperatures on September 29 felt like autumn, varying from around 60 degrees in cooler places of the High Knob Massif to 71 degrees in Clintwood.
An Alert For Frost And Freezing Temperatures Will Likely Be Needed For Parts Of The Mountain Area By This Weekend ( * ).
*River valleys and typically milder thermal belt ridges may be able to escape freezing temperatures, versus colder mountain valleys, but those with flowers and late season crops should stay tuned for later updates on this first major push of autumn air.
Meanwhile, Hurricane Marie will influence the mountain region with high clouds at times during the next few days. A general subsidence, or sinking air, regime will be a main influence that will continue to help support unseasonably warm conditions ( especially by day ). Air flow around her circulation field will also be a factor in wind directions.
Overnight Into Monday Morning
Partly cloudy ( high clouds streaming off Hurricane Marie ). Large vertical temperature spread between colder valleys and exposed mountain ridges-plateaus. SE winds 5-10 mph, with higher gusts, along mid-upper elevation ridges. Temps varying from 40s colder mountain valleys to low-mid 60s. Areas of dense river valley fog.
Monday Afternoon
Partly sunny ( high clouds may continue to stream off Marie into the region ). Unseasonably warm. Easterly winds less than 10 mph in most places. Temperatures varying from the lower 70s in upper elevations to the upper 70s to lower 80s ( warmer south into the Great Valley ).
Monday Night Into Tuesday Morning
Mostly clear. Light winds in valleys. Winds ESE-SSE at 5-10 mph, with higher gusts, on mid-upper elevation mountain ridges. Large vertical temperature spread between colder valleys and milder ridges-plateaus. Temperatures varying from 40s to lower 50s in the colder valleys to the lower-middle 60s. Areas of dense fog within main river valleys and around larger lakes.
Tuesday Afternoon
Partly-mostly cloudy. Light northerly winds generally less than 10 mph. Temperatures varying from lower 70s in the upper elevations to the lower 80s ( warmer south into the Great Valley and within lower elevations of river basins ).
Tuesday Night Into Wednesday Morning
Partly-mostly cloudy. Light northerly winds, except breezy along highest mountain ridges. Milder with temperatures generally in the 50s ( valleys ) and 60s ( ridges ).
Preliminary Outlook – High Knob Naturalist Rally
My initial outlook is forecasting clear skies and chilly conditions with a classic, deep blue afternoon sky above High Knob Lake on September 30. A northerly air flow is expected, especially for those who visit High Knob Lookout where conditions will mainly feel like 40s during the day.
Morning temperatures in the 30s to lower 40s will only rise into the low-mid 50s by 2:00 to 3:00 PM at High Knob Lake, then drop back into the 40s and 30s on Saturday evening. Generally an ideal forecast for those seeking a taste of the high country in early autumn. Hope to see you there!
Following morning lows in the 40s and 50s in mountain valleys, with low-mid 60s on ridges, another unseasonably warm day was observed. Monday afternoon maximums reached low 70s on High Knob and low 80s in Clintwood, with my official NWS max being 81.1 degrees.
My update this afternoon includes the first preliminary forecast for the 11th Annual High Knob Naturalist Rally. This forecast will become more detailed later in the week.
Meanwhile, a nice little group of stationary lenticular mountain wave clouds are featured at sunset on Monday ( September 25 ) as viewed from the High Knob Massif Webcam located on top of the Computer Science-Mathematics Building on campus.
High Knob Massif Webcam – University Of Virginia’s College At Wise
These clouds are being generated by east-northeast air flow streaming across the massif from the broad circulation field associated with Hurricane Marie.
NAM 12 KM Model 10-Meter Wind Field At 2:00 PM on September 25, 2017
A general subsidence regime is ruling, but orographic lifting along the High Knob Massif is taking advantage of just enough moisture to develop this group of stationary lenticular wave clouds.
Like Monday morning, when low temperatures reached the mid-upper 40s in cooler valleys, this will support another chilly night in typically cooler valleys of mid-upper elevations as the dry air allows for a large diurnal temperature spread in valleys.
NAM 12 KM Model 850 MB Wind Field At 2:00 PM Monday – September 25, 2017
Previous Discussion
Early Autumn at High Knob Lake Recreation Area – September 23, 2017
Although conditions vary significantly across the area, color continues to develop across the high country and is currently varying from green trees to bare trees!
Approaching Sunset At Upper Norton Reservoir – September 23, 2017
Big weather changes continue to look likely just in time for the 11th Annual High Knob Naturalist Rally, with 40s to mid 50s day-time temperatures ( at max heating ) currently in my forecast. A detailed forecast will be issued later.
Hurricane Marie – Overnight Of Monday – September 25, 2017
High clouds from Hurricane Marie are moving overhead tonight as she spins closer to the eastern coastline of the USA. Although chances for rainfall are looking to increase into the first week of October, the nearby presence of Marie will in part hinder precipitation development along and in advance of the first strong autumn cold front that sweeps into the region later this week ( pushing Marie away ).
National Hurricane Center Forecast Track
Tropical Storm Watches are in effect for eastern North Carolina.
Marie will impact our weather in a number of different ways, as already highlighted above, with winds along highest mountain crestlines being a little gustier even tonight due to a SE flow forced by the large wind field circulating around Marie. Winds will shift in direction through coming days as Marie changes her position.
