Partly to mostly clear. Winds shifting to NW and decreasing to generally less than 10 mph along mountain ridges-exposed plateaus ( with some higher gusts along the highest ridges ). Temps varying from 20 to 25 degrees in colder valleys at upper elevations to the 30s by morning on exposed middle elevation ridges & plateaus. A period of rime formation possible along highest NW facing crests.
Tuesday Afternoon
Mostly sunny and seasonally chilly. Light & variable winds. Temperatures varying from upper 30s to lower 40s within upper elevations to the low-middle 50s ( warmer southward into the Great Valley ).
Tuesday Night Into Wednesday Morning
Mostly clear during the evening, then increasing clouds overnight into morning. A rapid evening temp drop in mountain valleys. SSE-SW winds 5-15 mph, with higher gusts along mid-upper elevation mountain ridges and exposed plateaus. Temperatures varying from the 20s-lower 30s in colder mountain valleys to the mid-upper 40s. Temps rising into the overnight in valleys that recouple to the boundary layer wind field. Wind chills in the 30s along high mountain crest lines.
Wednesday Afternoon
Mostly cloudy. Chance of rain showers, especially near and west of the Virginia-Kentucky stateline. Winds S to SW at 5-15 mph, with higher gusts. Temperatures varying from upper 40s to lower 50s in upper elevations to the upper 50s to low 60s. Wind chills in 30s-low 40s at highest elevations.
Wednesday Night Into Thursday Morning
Partly-mostly cloudy. Chance of rain showers. Gusty across ridges. Winds SSE-S at 5-15 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet. SSW-SW winds 10-20 mph, with higher gusts, along mountain ridges above 2700 feet. Temperatures in the 40s and 50s ( coolest within mountain valleys sheltered from wind ).
Weather Discussion ( Wintry Recap )
The first real wintry blast of the season generated some nice scenes across the mountain area, mainly at mid-upper elevations, where nearly all accumulations occurred.
Long Ridge of Sandy Ridge – Elevation 2650 Feet
As I expected, the greatest amount of frozen precipitation and snow occurred along the Cumberland-Allegheny Front corridor, where air is initially lifted into upper elevations of the Appalachians on NW-N upslope flow. Snow amounts became less leeward of these front ranges, which included a notable decrease east of the spine of the Great Smokies into western North Carolina. The greatest snow depth reported reached 8″ at Canaan Mountain in northern West Virginia.
Storm Event Reports
Tri-Cities, TN NWS: 0″ ( 0.89″ Storm Total Precip )
Clintwood 1 W NWS: Trace ( 1.28″ Storm Total Precip )
*City of Norton WP: 1.0″ ( 1.54″ Storm Total Precip )
**Eagle Knob of High Knob Massif: 3.0″ ( 0.56″+ of Frozen Precipitation )
Mount LeConte, TN: 3.0″ ( 1.70″ Storm Total Precip )
Canaan Mountain, WV: 8.4″ ( 2.41″ Storm Total Precip )
Beech Mountain, NC: 1.0″ ( 2.21″ Storm Total Precip )
Mount Mitchell, NC: 0.5″ ( 3.61″ Storm Total Precip )
*Mean depth at the City of Norton Water Plant, at the northern base of the High Knob Massif ( elevation 2342 feet ), reached 0.5″ with around 1.0″ ( 0.10″ water equivalent ) of total snowfall.
Eagle Knob of High Knob Massif At 3:37 AM Monday – October 30, 2017
**Freezing rain initially generated icing before a change to snow at the summit level. More than 0.56″ fell in frozen form, with more than 0.30″ as snow water equivalent. The greatest depth of snow developed between sunset Sunday and the early hours of Monday with additional snow showers that recovered roads. This event produced the first single digit wind chills in the high country.
European Model 850 MB Temp Anomalies At 8 AM Monday – October 30, 2017
It was a cold start to the work week with Monday AM temperatures varying from upper 10s to upper 20s within the Norton-Wise and High Knob Massif area ( including in Clintwood with a MIN of 28 degrees over bare ground ).
European 51-Member Ensemble Mean Temp Anomalies Forecast: 8 AM Nov 2
Chilly conditions begin diminishing during late week into next week as the large eastern USA upper air trough does a retrograde movement into western North America.
European 51-Member Ensemble Mean 500 MB Height Anomalies: 7 AM Nov 6
The main uncertainty in the forecast during coming days will be how far east do waves of rain get, and that will be dependent in part upon where an upper ridge axis becomes aligned as noted above at 7 AM Monday ( 7 AM since time will have fallen back 1-hour to yield earlier model runs ).
A wet, stormy pattern will develop within the baroclinic zone between the Rockies and Appalachians, with details regarding the placement of this zone to be better resolved by models in coming days. Stay tuned for later updates.
ALERT For Freezing Fog-Rain At High Elevations Saturday Evening Prior To A Change Over Into Snow During The Overnight Into Sunday Morning
Air temperatures reached 32 degrees at the summit level of the High Knob Massif prior to sunset Saturday. Caution Is Advised for those traveling State Route 619, Routes 238, 237, and other high country roads, at elevations above 3500 feet, through Saturday evening due to dense fog and sub-freezing temperatures.
ALERT For Snow Accumulations of 1-3″ Above 3000 Feet Elevation, With Locally Higher Amounts, Into Sunday-Sunday Night ( With Riming ). Snow Depths Of 1″ or Less Are Expected At Elevations Below 3000 Feet. Unseasonably Cold Conditions, With Temps Remaining Below Freezing Through Sunday At The Upper Elevations Will Combine With Gusty NW-N Winds To Generate Low Wind Chill Values.
Rain will change to snow overnight into Sunday morning as a low pressure system develops east of the mountains to increase NW-N upslope flow into the windward side of the Cumberland-Allegheny and Blue Ridge ranges. Greatest snow accumulations will occur in upper elevations, above 3000 to 3500 feet, with lesser amounts in middle elevations between 2000-3000 feet ( especially along the Cumberland-Allegheny mountain ranges where sticking snow levels will be the lowest ). While the woods, grass, and above ground objects will tend to accumulate the most snow, some roadways at high elevations will also become snow covered.
Saturday Night Into Sunday Morning
Cold & blustery with rain showers changing to snow showers and flurries ( evening freezing rain & fog at the highest elevations ). NW-NNW winds 5-15 mph, with higher gusts, along middle to upper elevation mountain ridges and plateaus. Temperatures dropping into the low 20s to lower 30s ( coldest at highest elevations ). Milder south into river valleys of the Clinch, Powell, Holston ( Great Valley ) . Wind chills in the 10s & 20s, except dropping to around 10 degrees or lower on peaks above 3600 feet. Rime formation in the upper elevations above 3300 feet.
Sunday Morning Through The Afternoon
Gusty & unseasonably cold. Snow showers & flurries, especially along the upslope side of the mountains. NW-N winds at 10-20 mph, with higher gusts, on middle to upper elevation mountain ridges-plateaus. Temperatures varying from the 20s in upper elevations to the mid-upper 30s. Low cloud bases with riming at high elevations. Winds chills in the 10s and 20s to lower 30s, except single digits in gusts on high peaks above 3600 feet.
Sunday Night Into Monday Morning
Mostly cloudy with a chance of snow showers & flurries. WNW to NW winds 5-15 mph, with higher gusts. Temps widespread in the 20s, except 10s possible on highest crest lines of the High Knob Massif ( and in colder high valleys if any predawn-sunrise clearing occurs ). Wind chill factors in the 10s & 20s along mountain ridges, except locally lower on highest peaks.
Monday Afternoon
Mostly sunny. Gusty. SSW-SW winds 10-20 mph, with higher gusts ( especially along mountain ridges-plateaus ). Temperatures warming into the lower 40s to lower 50s. Winds chills in 20s and 30s ( coldest highest elevations ).
Weather Discussion ( Wintry Blast )
Sunday Afternoon Update
A wintry day has featured widespread sticking snow at elevations above 2000 to 2500 feet across Wise-Dickenson counties into northern Scott County, with some fairly large snow flakes falling in the more vigorous showers.
Snow Falling At The University Of Virginia’s College At Wise
My friend Wayne Riner submits a great shot showing snow on the pumpkin, at a fitting time of the year too!
Snow On The Pumpkin – Long Ridge of Sandy Ridge – Elevation 2650 Feet
A combination of snow-sleet has been falling in Clintwood with only brief sticking at 1560 feet elevation. The sticking snow has been mainly above 2000 feet.
Eagle Knob of High Knob Massif At 4:09 PM on October 29, 2017
The greatest snowfall amounts reported so far have been around 2″ at upper elevations in the high country.
Snow has even covered the road and graveled areas up on Eagle Knob, where the air temperature has been hovering around 25 degrees all day at top of the high country. The best sticking, as figured, being in woods and over grass.
Expect some more sticking at mid-upper elevations through Sunday evening, with the possibility that the lower limit of sticking ( at least on above ground objects ) may slip just under 2000 feet across the upslope zone before moisture wanes in the low-level flow overnight into Monday AM.
Previous Discussion
The beauty of a mid-autumn sunset was forgotten into Saturday as conditions turned simply NASTY within the mountains, with low cloud bases, rain, and falling temps.
Beautiful Sunset In Flag Rock Recreation Area – October 27, 2017
Air temperatures reached 0 degrees Celsius ( 32 F ) at the summit level of the High Knob Massif prior to sunset Saturday, as rain and dense fog engulfed the high country. Cooling on upsloping NW-N winds taking air temps down quicker than aloft, where readings remained above freezing. Rainfall totals topped 1.50″ along the high country into Saturday evening.
European Model 500 MB Analysis At 8:00 AM Saturday – October 27, 2017
A deep air upper trough ( above ) digging southward into the eastern USA is trying to capture newly named Tropical Storm Philippe, and IF the timing had been only a little bit different a much bigger impact could result; however, such a setting as Superstorm Sandy is rare.
As it is, low pressure will develop east of the Appalachians and help pull cold air aloft over the mountains as a strong low-level NW-N upslope flow develops into Sunday.
European Model 850 MB Analysis At 8:00 AM Saturday – October 28, 2017
While cold air flooded into the mountains Saturday PM into Saturday Night, generating simply NASTY conditions as was expected, forecast models show that temps aloft do not cool enough to support snow until overnight into the morning hours of Sunday along the Cumberland-Allegheny fronts.
NAM 3 KM Model Forecast Snowfall Pattern
Forecast models struggle with amounts and almost always under-estimate snowfall within the High Knob Massif at the expense of very often over-estimating amounts modeled to fit the Eastern Continental Divide, as climatology-research well documents. The general pattern of NW-N upslope flow is correct; however, with leeward depletion.
Snowfall totals of more than 6″ will likely occur on some peaks, being most widespread and heaviest along the backbone of the Allegheny Front in central-northern West Virginia. Early in the snow season highest snow amounts are typically biased toward highest elevations and favored upslope zones to an even greater extent than they are during the winter months. Except for rare events, like Superstorm Sandy, early season snows during October are typically upper elevation favored ( average snowfall during October being just over 2″ at top of the High Knob high country ).
In this case, unseasonable cold will be the major factor for all locations ( from top to bottom ) through Sunday.
European Model 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 6-10
While cold air really grips much of Canada, the ensemble mean is showing a big warming trend with periods of wet conditions developing across the central-eastern USA during the first week of November.
ALERT For Strong Winds Developing Friday Night Into Saturday Morning At Mid-Upper Elevations Along The Cumberland Mountains
An increasing pressure gradient in advance of a strong cold front and the coldest air mass of this season will cause the development of strong winds at higher elevations in the Cumberland Mountains during Friday Night into Saturday. Caution is advised.
Potential For Accumulating Snow Increasing
A strong cold front and upper air trough is expected to transport unseasonably cold air southward into the mountains this weekend into the beginning of next week as bombogenesis occurs over the New England states. NW-N upslope flow will bring sticking snow into the eastern highlands of West Virginia, with the potential now increasing for accumulating snow farther south along the mountains to the High Knob Massif, Mount Rogers, Roan-Hump Mountain, into the top of the Great Smokies.
Overnight Into Friday Morning
Mostly clear ( a few high clouds ). SSW-SW winds 5-15 mph, with higher gusts, on mountain ridges & exposed plateaus below 2700 feet. SSW-SW winds 10-20 mph, with higher gusts, on upper elevation mountain ridges. Temps varying from upper 20s to mid 30s in valleys to 40s along exposed ridges & plateaus. Wind chills in the low-mid 30s along higher mountain ridges.
Friday Afternoon
Mostly sunny. Blue skies. Gusty winds. SSE-SSW winds at 5 to 15 mph, with higher gusts on mountain ridges. Temps varying from 50s at upper elevations to the mid-upper 60s.
Friday Night Into Saturday Morning
Increasing clouds with rain developing by morning. Windy. SSE-SSW winds increasing to 10-20 mph, with higher gusts, at elevations below 2700 feet. SSE to SW winds 20-30 mph, with higher gusts, along mid-upper elevation mountain ridges. Temperatures falling into the 40s to lower 50s by morning. Wind chill factors in the 30s to lower 40s at upper elevations.
Saturday Morning Through The Afternoon
Rain. Local downpours. Turning colder. Winds shifting NW at 5 to 15 mph, with higher gusts, by mid to late afternoon. Temperatures dropping into the 30s to middle 40s ( coldest at higher elevations ). Low cloud bases with widespread dense fog across upper elevations. Nasty!
*The potential of the first accumulating snow is increasing for middle-upper elevations ( above 2000-3000+ feet ).
Saturday Night Into Sunday Morning
Cold & blustery with rain showers changing to snow showers and flurries. NW-NNW winds 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges and plateaus. Temperatures varying from the lower 20s to lower 30s ( coldest at highest elevations ). Milder south into river valleys of the Clinch, Powell, Holston drainages. Wind chills in the 10s & 20s, except dropping to around 10 degrees or lower on peaks above 3600 feet. Rime formation in the upper elevations above 3300 feet.
NOTE – A widespread freeze occurred into Thursday morning so I will no longer be highlighting any alerts related to frost-freezing conditions.
Weather Discussion ( Wintry Blast )
A drastic change in the weather is expected between a very nice TGIF ( outside of high country wind chills ) and a nasty Saturday into Sunday period.
Black Mountain Mesonet – 1 Hour Observations Ending At 12:20 AM Friday ( Oct 27 )
Changes related to this big weather shift are already being felt in upper elevations tonight, via gusty winds, with an initial sharp temperature drop in high valleys now being replaced by temp rises with recoupling of all but the most sheltered valley boundary layers.
European Model 850 MB-Surface Analysis At 8 AM Thursday – October 26, 2017
The first snowflakes of the season fell in the high country of the High Knob Massif during October 25 as the first of two cold pushes crossed the mountains ( the next one just emerging upstream near the Canadian border, above, will certainly be the most vigorous ).
Clearing skies into Thursday Morning ( October 26 ) allowed temps to drop into the 20s in many mountain valleys, with a hard freeze being observed in Clintwood, Norton, Tacoma-Coeburn and many other places ( coldest temps were recorded in high valleys above 3000 feet in the high country of the High Knob Massif ).
European 51-Member Ensemble Mean 500 MB Height Anomalies – 8 AM Oct 29
Details of the upcoming pattern are still being worked out by the models, but it is clear that a deep upper trough and disturbance will dig into the eastern USA into Sunday.
The first snow accumulations of the season look nearly certain now for higher elevations in the eastern highlands of central & northern West Virginia, with the only question being how far south along the Appalachians will this extend into Sunday.
Regardless of the snow potential, conditions will become increasingly NASTY as Saturday passes into Saturday Night and Sunday Morning with true winter temperatures and wind chills to impact the mountain region. Get Ready!
ALERT For Ponding Of Water Along Roadways And For Swift Water On Creeks Draining The High Country Of The High Knob Massif Into Monday Night
A general 2.50″ to 3.00″+ of rain has fallen from the City of Norton across the High Knob Massif, as well as into adjacent locations in the Clinch & Powell river valleys.
A Blast Of Cold Air Will Be Felt Tuesday Into Thursday AM With The Coldest Temperatures Of This Autumn At Highest Elevations ( Especially ).
Low wind chill values for this time of year are expected at upper elevations in the high country during Tuesday into Wednesday. Coldest valley temperatures may occur by Thursday AM, but will depend upon the timing of the next digging trough. Stay tuned.
Overnight Into Monday Morning
Increasing clouds. Chance of a shower by sunrise. Windy across middle-upper elevation mountain ridges-plateaus. SSE to S winds 10-20 mph, with higher gusts, along ridges-plateaus below 2700 feet. SSE to S winds 15-25 mph, with 30-50+ mph gusts, along mountain ridges above 2700 feet. Mild with temperatures widespread in the 50s to low 60s.
Monday Morning Through Monday Afternoon
Rain developing with a chance of thunderstorms. Downpours likely. Locally heavy rainfall totals, especially within upslope locations across the High Knob Massif and Tennessee Valley Divide. Windy. SSE winds shifting SW at 10-20 mph, with higher gusts, below 2700 feet. SSE to SW winds 20-30 mph, with higher gusts, above 2700 feet. Low cloud bases with dense fog across upper elevations. Temps dropping into the 50s lower-middle elevations, and into the 40s upper elevations, by mid-late afternoon.
Monday Night Into Tuesday Morning
Rain tapering to light rain. Partial clearing possible by morning. Chilly. SSW to SW winds at 10-20 mph, with higher gusts, along mid-upper elevation mountain ridges. Temperatures varying from the mid 30s to lower 40s. Wind chill factors in the 20s highest elevations.
Tuesday Afternoon
Partly to mostly cloudy. Chance of rain showers. Chilly. SW-WSW winds 5-15 mph, with higher gusts. Temperatures varying from the low-mid 40s to the low-mid 50s ( coldest in upper elevations ), dropping by late afternoon. Wind chills in the 30s & 40s, except locally colder on highest peaks.
Tuesday Night Into Wednesday Morning
Partly cloudy. Cold. SW-W winds 5-10 mph, with higher gusts along mid-upper elevation mountain ridges. Temps varying from the mid-upper 20s to the lower-middle 30s, coldest in the upper elevations. Wind chills in the 20s and 30s, except dropping into the 10s at high elevations in the High Knob high country above 3300-3500 feet.
With blocking at high latitudes another deep upper air trough is expected to dig into the region by late week into this weekend of October 27-30. The will be monitored for the potential of the first accumulating snow in the mountains. Stay tuned for updates and changes that may diminish or enhance this potential.
Weather Discussion ( Colder Pattern )
A trend toward a much colder weather pattern is taking shape for the coming week. This transition will feature strong winds into Monday, with general strong speeds at upper elevations and local mountain wave winds in the favored breaking zones lee of the larger mountains.
Big Cherry Wetland Valley – October 21, 2017
An average nightly MIN of 28.2 degrees was recorded at Big Cherry Valley 4 in the High Knob Massif during October 17-21, with a total of 39.2 hours now being observed below freezing in October. Many trees on, and along, the high valley floor are now bare of leaves.
The potential for heavy rainfall, with at least a period featuring torrential downpours, along and ahead of a strong cold frontal zone of convergence, will be possible everywhere into mid-day to early afternoon Monday.
HRRR Model Future Doppler Forecast At 11:00 AM Monday – October 23, 2017
The heaviest rainfall, and highest totals in general, are expected in favored upslope zones where strong winds will help enhance orographics. This includes the eastern slopes of the Blue Ridge, as well as the High Knob Massif – Black Mountain corridor within the Cumberland Mountains.
HRRR Model Future Doppler Forecast At 1:00 PM Monday – October 23, 2017
Chilly air pours into the mountain region into Tuesday and Wednesday, with rather significant wind chills for this time of year within the high country of the High Knob Massif on gusty SSW-WSW winds.
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 1-5
This will mark the beginning of a much different pattern than experienced during most of October 2017, with much colder conditions ( in the mean ) expected throughout the next 10 days to close October and open November 2017.
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 6-10
While temperatures trend below average in the next few days, it is the extended 6-10 day period that has a notable potential to turn down-right wintry in the eastern USA.
European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 1-5
Could this include the first accumulating snow of the season, at least in upper elevations ( if not lower ) on upsloping NW winds as a coastal storm develops?
European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 6-10
It remains too early to know for certain; however, the trend and upper air pattern is supportive. Check back later as the details of this evolving pattern become more clear.
Mostly clear. Light winds ( mostly less than 10 mph on mid-upper elevation ridges ). Large vertical temperature spread between cold mountain valleys and milder, exposed ridges & plateaus. Temperatures varying from 20s to lower 30s in the colder valleys to the mid 40s to low 50s on exposed ridges and plateaus. Areas of river valley-lake fog.
Friday Afternoon
Mostly sunny ( some high clouds ) and mild. Light winds. Temperatures varying from middle-upper 60s in upper elevations to the lower-middle 70s.
Friday Night Into Saturday Morning
Mostly clear ( some high clouds ). Winds SSE-SSW at 5-10 mph, with some higher gusts, along mid-upper elevation mountain ridges. Large vertical temp spread between the colder valleys and exposed ridges-plateaus. Temperatures varying from 30s in mountain valleys to the low-mid 50s on exposed ridges & plateaus ( around or below freezing in the coldest valleys at upper elevations ). Areas of river valley fog near lakes and mainstem rivers.
Saturday Afternoon
Partly sunny ( high clouds ). Mild. SSE winds mostly less than 10 mph. Temperatures varying from 60s in upper elevations to the mid-upper 70s.
Saturday Night Into Sunday Morning
Partly cloudy ( high clouds ). Winds SSE-SSW at 10-20 mph, with some higher gusts, on mid-upper elevation mountain ridges & exposed plateaus. Temperatures varying from 30s to lower 40s in colder valleys, decoupled from any wind, to the 50s across exposed ridges-plateaus.
Sunday Afternoon
Partly sunny ( high clouds ). Winds SSE at 5-15 mph, with some higher gusts. Temperatures varying from 60s in the upper elevations to the low-mid 70s.
Soaking rain followed by a blast of cold air is expected by the early to middle portions of next week. The first flakes of snow will also be possible at highest elevations. Locations which have not yet dropped to freezing or below, will likely do so next week.
Weather Discussion ( Nice Pattern )
A nice weather pattern, dominated by High pressure, will rule the mountain landscape through this weekend before major changes occur next week.
Rugged Stone-Pickem Mountain of High Knob Massif – October 18, 2017
Hold out Northern Red Oaks ( variation borealis ) in parts of the upper elevations will be changing to join a more muted array of color ( with more brownish tones ) where trees are not already bare. Meanwhile, lower elevations will have a chance to reach some sort of “peak” in a rather disjointed color season across the eastern USA.
Black Mountain Mesonet Observations – Ending At 12:15 AM Friday ( October 20 )
Although mountain ridges remain relatively mild, the bottom has been dropping out of the temperature in high valleys of the High Knob high country during recent nights with very dry air and light winds.
*Some middle elevation thermal belt sites, such as Nora 4 SSE on the Long Ridge of Sandy Ridge, have only dropped to 39 degrees during October to contrast with middle 20s in high valleys and a minimum of 31.6 degrees in Clintwood ( in the low elevations ).
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 6-10
A major pattern change across North America has been well forecast by the European ensembles to occur next week.
European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 6-10
This will include a wetter and colder transition as high latitude blocking develops near Greenland ( recurvature of a western Pacific typhoon will be beginning this process ).
Typhoon Lan In The Western Pacific at 0620z – October 20, 2017
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.
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.
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.
