A period of accumulating snow will be possible late Saturday into Sunday AM ( December 9-10 ), especially in locations along & north-northwest of the High Knob Massif and Tennessee Valley Divide, with a new surge of bitterly cold air.
Overnight Into Tuesday Morning
Becoming cloudy. Windy, especially along mid-upper elevation mountain ridges. Large vertical temp spread through early overnight between sheltered valleys and exposed ridges. SSE-SSW winds 10-20 mph, with higher gusts, below 2700 feet. S to SW winds 15-30 mph, with gusts over 40 mph, on mid-upper elevation ridges. Temps varying from 30s in colder valleys to the mid 40s to mid 50s along mountain ridges & exposed plateaus. Wind chills in the 30s along upper elevation mountain ridges.
Tuesday Morning Through The Afternoon
Cloudy & windy with rain developing. Local downpours. Winds SSW-WSW at 10-25 mph, with higher gusts. Turning cooler by late. Temperatures varying from low-mid 40s to the low-mid 50s. Low cloud bases with dense fog at upper elevations. Wind chills in the 30s along upper elevation mountain ridges.
Tuesday Night Into Wednesday Morning
Partly-mostly cloudy. A chance of flurries. Turning colder. Winds WNW to NW at 5-15 mph, with higher gusts. Temps from low-mid 20s to lower 30s. Wind chills in the 10s and 20s, except single digits in gusts at highest elevations.
Wednesday Afternoon
High clouds. Cold. Winds SW-W at 5-10 mph, with some higher gusts. Temperatures varying from upper 20s to lower 30s in upper elevations to upper 30s and lower 40s. Wind chills in the 20s to lower 30s on mountain ridges, except 10s in stronger gusts at highest elevations.
Wednesday Night Into Thursday Morning
Mostly cloudy ( high clouds ) and cold. Winds WSW-WNW at 5-15 mph, with higher gusts. Temperatures widespread in the 20s to around 30 degrees. Wind chills in the 10s & 20s, coldest at highest elevations.
Thursday Afternoon
Partly to mostly cloudy. Cold. Winds WSW-WNW at 5-10 mph, with some higher gusts. Temperatures varying from upper 20s to lower 30s in upper elevations to the upper 30s to lower 40s.
Thursday Night Into Friday Morning
Mostly cloudy. A chance of flurries. Cold. Winds WNW-NNW at 10 mph or less. Temperatures varying from the lower-middle 10s to the low-middle 20s.
A very cold pattern is taking shape for the eastern USA, with this initial push of cold air being only seasonably cold. Increasingly cold air, with potential for extreme cold, is being monitored for this weekend into the next 1-2 weeks in separated surges.
Weather Discussion ( Harsh Potential )
Late Tuesday Evening Update
Only a few changes to this update, including the addition of a word of caution for everyone to be watchful of icy patches on any above ground or outdoor surfaces that remain wet as temperatures continue to drop overnight.
As of Midnight temps had fallen into the middle 20s at highest elevations, in clouds, with wind chills dropping to around or below 10 degrees in gusts ( temps at the summit of High Knob tend to run a couple degrees colder than this live data from the Black Mountain mesonet ).
Rainfall with Tuesday’s cold frontal boundary averaged 0.75″ to 1.25″ over the High Knob Massif, and along higher portions of the Tennessee Valley Divide, with lesser amounts elsewhere.
The main change to Wednesday is to increase cloudiness, as it looks like it may be difficult to shake the high clouds as tonight’s frontal system stalls far to the south. This will make it a chore for many places to get out of the 30s in upslope locations along and west to southwest of the Tennessee Valley Divide and High Knob Massif.
Previous Discussion
Although only seasonable cold is expected to arrive this week, the upper air flow pattern taking shape across North America during the next 1-2+ weeks has serious potential to turn harsh, with December 1989 being a top analog for this point in time ( differences may; however, result in a varied outcome by January 2018 versus January 1990 ).
A majestic sunset graced December 4, with strong S-SW winds at mid-upper elevations being the only negative factor to signal changes upcoming.
These strong winds were putting a chill into the air at high elevations, in the High Knob high country and atop adjacent Black Mountain, where temperatures were in the 40s.
Strong winds will continue overnight into Tuesday ahead of a powerful cold front with a band of rain. Winds will tend to mix downward through middle into the lower elevations over time as the front gets closer, with rises in temps being possible in sheltered valleys that decoupled late Monday.
A band of rain, with local downpours, will arrive Tuesday with orographic enhancement of rain being possible from the High Knob Massif and Tennessee Valley Divide south and southwest ( downslope reduction in leeside zones ).
I see a progressively colder and more wintry pattern taking shape during the next week to 10 days, with any snow that may eventually fall and accumulate helping to enhance the potential for harsh conditions.
The upper air pattern taking shape during the next week to ten days is simply classic for increasing cold, with a series of progressively colder air masses likely to impact the region and eastern USA during the next 1-2+ weeks.
The upcoming pattern is analogous to that observed during December 1989, which featured a 60 degree MAX temp in Clintwood on December 6 prior to the bottom dropping out.
No two seasons are exactly alike, but certainly some do make better analogs than others and December 1989 is a top analog for this current point in time.
The mean of the European ensemble group has been strongly suggesting that this pattern locks in with a progressively colder nature during the next 1-2 weeks.
Although lovers of snow may be disappointed initially, the pattern and ensemble MEAN are also suggesting that snow chances will increase through next week. If snow cover is established then there is NO DOUBT that a pattern like this will turn harsh. Stay tuned for updates.
Clear. Cold. Large vertical temperature spread developing between cold valleys and “milder” ridges-exposed plateaus. NW winds 5 to 10 mph, with higher gusts, along mid-upper elevation mountain ridges. Temperatures dropping into the 10s to lower 20s in valleys versus upper 20s to lower 30s on exposed mountain ridges-plateaus ( 10-15 degrees in coldest valleys of upper elevations ). Wind chills in the 10s to lower 20s on highest mountain ridges. A smoky smell to the air in portions of the area from SE Kentucky wild fires.
Monday Afternoon
Sunny. Light winds. Temperatures varying from 40s to around 50 degrees in upper elevations to the mid-upper 50s to around 60 degrees.
Monday Night Into Tuesday Morning
Clear. Rapid evening temperature drops in mountain valleys with a large vertical difference developing between cold valleys and milder mountain ridges-exposed plateaus. Winds SSE to S at 5-10 mph, with higher gusts, on middle to upper elevation mountain ridges. Temperatures varying from upper 10s to upper 20s in mountain valleys to the upper 30s to lower 40s on exposed ridges & plateaus.
Tuesday Afternoon
Mostly sunny. Winds S-SSW at 5-10 mph, with some higher gusts. Temperatures varying from 50s in upper elevations to the upper 50s to lower 60s.
Tuesday Night Into Wednesday Morning
Mostly clear. Rapid evening temperature drops in mountain valleys with a large vertical difference developing between cold valleys and milder mountain ridges-exposed plateaus. Winds SW-W at 5-15 mph, with some higher gusts, along middle-upper elevation mountain ridges. Temperatures varying from 20 to 25 degrees in sheltered valleys to the lower-mid 40s on exposed ridges-plateaus.
Wednesday Afternoon
Mostly sunny. Light winds. Seasonally mild. Temperatures varying from lower 50s in upper elevations to the low-mid 60s at middle-lower elevations.
Wednesday Night Into Thursday Morning
Mostly clear to partly cloudy. Rapid evening temperature drops in mountain valleys with a large vertical difference developing between cold valleys and milder ridges. Winds SSE-SW at 5-10 mph, with some higher gusts, on mid-upper elevation mountain ridges. Temperatures varying from 20s in colder valleys to the low 40s on ridges-exposed plateaus.
Thursday Morning Through The Afternoon
Increasing clouds with a chance of rain showers developing by mid-late afternoon. Winds SSW-WSW at 5-15 mph, with some higher gusts. Temperatures varying from 40s to mid 50s ( coolest in upper elevations ).
Confidence of a Major Hemispheric Pattern Change Across North America is increasing for mid-late portions of next week, centered on December 6-9, with a shift to colder, wetter conditions. Potential for extreme cold is also being followed.
Weather Discussion ( Dry & Chilly )
Overnight Wednesday Update
This current weather pattern continues to feature cold nights in valleys and seasonally cool to mild days. I have to say seasonally cool since days are now so short that by the time deep valleys warm from such cold nights the amount of time for “mild” conditions is now very limited before local sunset ( defined as when the sun slips beneath the mountain horizon ) causes temp drops to begin again!
I show Lonesome Pine Airport obs above since it should be pointed out that all is not as it may appear when it comes to the Wise Plateau, with large temp variations many nights on the plateau itself.
Monday evening, as an example, had similar temperatures reported at the Airport but when I left UVA-Wise around 9:15 PM the temperature was in the 30s ( only 1.5 air miles from Lonesome Pine Airport ) and cold enough for frost to begin forming in places near the old J.J. Kelly High School in Wise ( 2.1 air miles from the Airport ). This is typical unless winds are gusty, such that the Airport temp is often most reflective of highly exposed locations in Wise ( this is why I frequently use the wording of “exposed plateaus” in my forecasts since this also applies to the Sandy Ridge area ).
SW winds have been more gusty, especially at mid-upper elevations, Tuesday evening into this early overnight of Wednesday such that sheltered valleys are now generally coldest ( 26 degrees in Clintwood at 2:50 AM Wednesday ).
Rainfall amounts continue to look generally light with the Thursday afternoon-night weather system. Clearly a main focus remains on next week for a major pattern change that is already taking shape.
The big bulls-eye height anomaly over the Aleutians which had been positive through most of Autumn 2017 has now been replaced by a negative anomaly ( above ), as positive heights with Greenland Blocking continue to mature.
A shift of the Stratospheric Polar Vortex into Eurasia by the start of Week 2 in December is signaling that a cross-polar flow could form, with potential for extreme cold to come into play to radically change the weather pattern across eastern North America. Winter is just around the corner!
Previous Discussion
This view illustrates the pattern currently embracing the mountain landscape, dry and mostly clear with cold nights and seasonally cool days.
The first week or so of November was unseasonably mild, and dominated by a positive phase of the Arctic Oscillation, +AO, as noted above on the top graph of observed conditions traced by the black line. Observe also that a shift into a -AO phase occurred shortly after that, and since November 10 the local pattern also changed into the current regime of cold nights, seasonably cool days, and drier than average conditions across the Mountain Empire.
The -AO as well as a -NAO have been largely acting to counter the impacts of a -PNA Oscillation which would typically generate unseasonably mild conditions.
Instead, the month of November has trended to near or below average in temps from this region northward.
Observe above that the Pacific North American ( PNA ) oscillation has been well down into negative territory throughout November. That is about ready to change.
The 51-Member European Ensembles, The GFS Ensembles, The Canadian ( GEM ) Ensembles, and the Japanese Model are all in rather striking agreement that -AO and -NAO phases will be joined by both +PNA and +EPO ( Eastern Pacific Oscillation ) by the middle to end of next week.
If these teleconnection forecasts hold
through coming days this week, the BIG NEWS
will be the shift into WINTER across the eastern USA
by the middle to end of next week.
At this point in time individual model runs will be chaotic, but Ensemble MEANS are more stable and should be used most for guidance since the significance of this upcoming change is not yet being fully resolved by models.
The -AO and -NAO phases are looking very likely to continue such that the key player will be the Pacific Ocean and the phases of the PNA and EPO.
Stay tuned for later updates as this pattern evolution is tracked through coming days.
Upslope clouds giving way to clearing skies. Cold. NW-W winds diminishing to 5-10 mph, with some higher gusts, on middle-upper elevation mountain ridges. Temps dropping into the low-mid 10s to low-mid 20s, except locally colder in high elevation valleys with adjacent snow cover in the high country of the High Knob Massif. Wind chills in the single digits and 10s along high mountain ridges.
Monday Afternoon
Mostly sunny ( some increasing high altitude ice crystal clouds ). Winds becoming SSE-SW at 5-15 mph, with some higher gusts along mountain ridges. Temperatures varying from the mid-upper 30s to the upper 40s to low 50s ( coldest at highest elevations ). Wind chills in the 20s to lower 30s in upper elevations.
Monday Night Into Tuesday Morning
Partly cloudy ( high clouds ). Large vertical temperature spread developing between gusty ridges and the sheltered mountain valleys. Winds SSE-SSW at 5-15 mph, with some higher gusts, on mountain ridges-exposed plateaus below 2700 feet. Winds SSW-SW 10-20 mph, with higher gusts, on mountain ridges above 2700 feet. Temperatures varying from 20s within colder valleys to upper 30s to lower 40s on gusty mountain ridges. Wind chills in the 20s to lower 30s.
Tuesday Afternoon
Becoming mostly cloudy by mid-late afternoon. Windy. SSW to SW winds 10-20 mph, with higher gusts. Temps varying low-mid 40s to the lower-middle 50s ( coldest in upper elevations ). Wind chills in the 20s and 30s at upper elevations, and in the upper 30s to mid 40s along middle elevation mountain ridges-plateaus.
Tuesday Night Into Wednesday Morning
Cloudy with a chance of rain showers or sprinkles. Flurries possible at highest elevations by morning. Turning colder. SW winds shifting NW at 5-15 mph, with higher gusts, on middle-upper elevation mountain ridges. Temperatures falling into the upper 20s to lower 30s highest elevations to the upper 30s to lower 40s. Wind Chills in the 10s and 20s at upper elevations.
Wednesday Morning Into Wednesday Afternoon
Low morning clouds, with a chance of flurries, giving way to afternoon clearing. Colder. Winds N at 5-10 mph, with some higher gusts. Temperatures holding steady or slowly falling in the 30s to lower 40s, except in upper elevations where temperatures will remain around or below freezing and fall during mid-late afternoon.
Wednesday Night Into Thanksgiving Morning
Clear & unseasonably cold. Light winds. Large vertical temperature spread developing between frigid mountain valleys and ridges. Temperatures varying from the 10s in mountain valleys to the 20s on mountain ridges, except single digits possible in coldest valleys at upper elevations versus temperatures rising to around freezing along the highest mountain ridges.
Thanksgiving Afternoon
Partly cloudy ( increasing mid-high altitude clouds ). Chilly. Winds SSW-WSW at 5-10 mph, with some higher gusts on highest mountain ridges. Temperatures varying from the 30s to around 40 degrees in upper elevations to the 40s to around 50 degrees in middle-lower elevations. Warmer south into the Great Valley.
Weather Discussion ( Cold Turkey Day )
Wednesday Night Update
The most favorable cooling conditions of this early cold season to date have developed over the mountains this evening with current dewpoints below zero ( F ) in upper elevations of the High Knob Massif and Black Mountain.
As of 11:00 to 11:30 PM air temperatures as cold as the 10s to lower 20s are already occurring from the High Knob Massif south to Shady Valley in northeastern Tennessee ( in valleys with much milder conditions along ridges as a large vertical temperature spread continues to develop ).
The entire atmospheric column ( above ) will be bone dry through morning, with light winds, before some high to mid-level moisture begins to increase by later during Thanksgiving Day. Have a great Holiday.
Tuesday Afternoon Update
It has been a windy Tuesday across the mountain landscape, with higher speeds than I predicted in some places. Temps have varied from middle 40s atop the High Knob Massif on brisk upslope flow to lower 60s in Clintwood on downslope.
Factor in the strong winds and conditions have felt like the 30s all day ( even 20s in stronger gusts ) in the high country, which has been a factor, indeed, for hunters in the woods.
Snow has now melted except for upper north slopes where some lingers in the woods at heads of the High Knob Lake and Big Cherry Lake basins.
Temperatures reached mid-upper 50s in the Wise area, but again never felt that warm due to these gusty SW winds.
My updated forecast into Thanksgiving has few changes, with increasing clouds and the chance of a sprinkle or high elevation flurry tonight as the next cold front passes. This will introduce colder air Wednesday and, after low clouds dissipate, will set the stage for a very cold night into the morning of Thanksgiving as conditions become prime for radiational cooling and cold air drainage.
For hunters in the high country expect a large vertical temp change to develop into Thanksgiving Morn, between frigid valleys and temperatures that rise toward freezing along highest mountain ridges as a westerly breeze develops ( * ).
*Anyone camping in high valleys should be prepared for temps that drop into the 10s, with coldest valleys making a run at the single digits on Thanksgiving Morning. Bundle Up for certain!
Previous Discussion
Following a dynamic system that brought wind damage and power outages to the mountain area, and sticking snow above 3000 feet in the High Knob Massif, a quieter pattern is taking shape into Thanksgiving Day. Another cold front, with building High Pressure, will set the stage for a very cold Thanksgiving Morning.
Reference Orographic Forcing Season on the High Knob Landform for information on how orographics have been generating some interesting and varied weather conditions during November.
Roaring wind gusts Saturday topped 50 mph in places, with numerous power outages into Saturday Night-early Sunday from the Cumberland Mountains west across Kentucky.
Clintwood 1 W NWS was out of electricity for 16 hours, with some locations out longer in Dickenson and Wise counties.
Rain turned to snow overnight into Sunday morning, with sticking mainly at elevations above 3000 feet where locally 1″ to 2″ fell at highest elevations above 3500 feet. A total of 0.90″ of precipitation was measured at the City of Norton Water Plant up to 9 AM Sunday, with a trace of snow.
Temperatures held in the 20s all day Sunday atop the high country, where a light coating of snow continues to cover the ground at present. Upslope clouds have been slow to break, but dry air transport should overcome clouds that are currently being generated by forced lifting of air.
A colder than average temperature pattern is looking to rule the next week to 10 days, but no big storms are being currently shown. A large system, that could be a potential big deal storm for the eastern USA is shown developing far to the south over the Gulf of Mexico and Florida, but this is expected to lift out far enough east to have limited impacts on the mountain region. Stay tuned should this change by Black Friday into the upcoming weekend.
Building High Pressure, with very low dewpoint air of true arctic origin, will set the stage for a very cold night heading into Thanksgiving Morning as skies clear and winds calm.
ALERT For Freezing Fog At Upper Elevations Above 3000 to 3300 Feet Through Mid-Morning Tuesday
Cloud bases generally remained near to just above the Wise and Sandy Ridge plateaus Monday Night into this morning, with fog and freezing fog at elevations above 3000 to 3300 feet in elevation ( temps in the 20s at highest elevations ) within locations along and north of the High Knob Massif and Black Mountains.
The low cloud deck, which has now kept highest elevations in the High Knob high country within dense fog for nearly 48 consecutive hours, will finally begin to break up later Tuesday. If mixing is slow this will be a slow dissipation versus if vertical mixing and orographic waves develop.
Partly to mostly clear, then becoming cloudy ( low, upslope clouds and areas of dense fog ). Winds NW-N at 5-15 mph, with some higher gusts, on mid-upper elevation mountain ridges & exposed plateaus. Turning colder. Temperatures varying from 20 to 25 degrees at highest elevations to the middle 30s. Wind chills in the 10s & 20s across mid-upper elevation mountain ridges-exposed plateaus ( single digits and 10s along high mountain crest lines ).
Friday Afternoon
Partly to mostly sunny. Cold. N-NE winds 5-10 mph, with some higher gusts. Temperatures varying from the 20s in upper elevations to the middle 30s to around 40 degrees. Milder south into the Great Valley.
Friday Night Into Saturday Morning
Mostly clear ( high clouds possible ) and unseasonably cold. Increasingly large vertical temperature spread developing between cold valleys and milder mountain ridges. Light & variable winds becoming southerly at 5-10 mph along mid-upper elevation mountain ridges. Temps varying from the upper 10s to mid-upper 20s, except as cold as 10-15 degrees in colder upper elevation valleys versus temps rising to near or above freezing along high mountain crest lines.
Saturday Afternoon
Sunshine & high altitude ice crystal clouds. Winds SSE-SSW at generally less than 10 mph. Temperatures varying from the upper 30s to lower 40s in upper elevations to the upper 40s to lower 50s.
Saturday Night Into Sunday Morning
Partly cloudy ( high altitude ice crystal clouds ). Large vertical temperature spread between cold valleys and milder mountain ridges. Winds SSW-SW at 5-10 mph, with higher gusts, along mid-upper elevation mountain ridges. Temperatures varying from upper 10s to lower 20s in the colder valleys to the 30s to around 40 degrees on exposed mid-upper elevation mountain ridges-plateaus.
A changing upper air pattern across North America and the Northern Hemisphere will increase the potential for a shift into wintry conditions by Thanksgiving week. Stay tuned for updates on this evolving hemispheric pattern.
Weather Discussion ( Arctic Brush )
A brush with true arctic air is featured during this forecast period in wake of some 36+ hours with dense fog at middle to upper elevations along & north of the High Knob Massif and Tennessee Valley Divide.
Check out the HUGE difference in conditions experienced from Wednesday at 5:48 PM ( above ) to Thursday at 5:20 PM ( below ). Another period with development and drop of low cloud bases is expected into Friday morning as an arctic cold front pushes across the mountains.
A few snow flurries will even be possible in favored upslope locations; although, I have left this out of my forecast above since there will be only a brief period where this could occur with bone dry arctic air surging in behind the arctic front.
Although the main push of coldest air will remain to the northeast of the southern Appalachians, this area will get into true arctic air with dewpoints by Saturday morning plunging into 10s at the surface, and as low as -10 degrees Fahrenheit at the summit level of the High Knob Massif.
Under ideal conditions the coldest high valleys could drop into single digits; however, conditions may not be quite ideal with potential for high altitude ice crystal clouds aloft and mixing within the PBL being yet to be determined. Still the possibility exists for some very cold temps in favored frost pockets with readings dropping under 10 degrees.
The upper air pattern does not seem compatible with all the coldness expected in coming days; however, this illustrates that not only do we not live at 500 MB ( around 18,000 feet ) but that the arctic is charging up with bitter air.
This is important since upper air blocking will be changing at high latitudes during the next week to 10 days, such that by the weekend before Thanksgiving, and the week of the holiday, the stage will be set for much colder conditions to develop across the eastern USA.
If this trend is real, it will become more evident in forecasts at 6-10 day time frames as we progress through next week.
A key feature above being bitterly cold air across western Canada and portions of Alaska.
I do not know what the upcoming winter will bring when all is said and done ( by next April-May ), but do have increasing confidence that the pattern starting to develop now, and within the next 1-2 weeks, could represent a big-time shift into winter for at least the latter portion of November into December.
My initial feeling is that the potential exists for more winter to occur between now and January 1 than was experienced during the anemic 2016-17 season. This remains, of course, to be seen and will become more clear as the current pattern changes during the next one to two weeks across the eastern USA.
**UPDATE…ALERT For Dense Fog Continues Into Wednesday Night For Middle & Upper Elevations Along-North Of The High Knob Massif-Tennessee Valley Divide
ALERT For Dense Fog At Mid-Upper Elevations Along And North Of The High Knob Massif-Tennessee Valley Divide From Late Tuesday Afternoon Into Wednesday
*A prolonged period of dense fog ( low clouds ) will develop as colder air invades the front range of the mountains from late Tuesday into Wednesday on upsloping northerly winds. A cold, damp & raw feeling day is expected Wednesday when air temps will struggle in the 30s to lower 40s in locations along and north of the High Knob Massif & Tennessee Valley Divide, with milder conditions leeward of the mountains into river valleys of the Clinch, Holston and Great Valley.
Overnight Into Wednesday Morning
Colder. Rain developing during the predawn-morning. Dense fog at mid-upper elevations along and north of the High Knob Massif and Tennessee Valley Divide. NNW-NNE winds at 5-10 mph, with some higher gusts. Temps falling into the 30s to around 40 degrees. Wind chills dropping into the 20s to lower 30s at the highest elevations.
*The potential for some local freezing rain will exist along northern slopes-crest lines of the High Knob Massif with cooling on northerly upslope flow into the lower 30s.
Wednesday Morning Into The Afternoon
Rain tapering to showers-drizzle. Nasty & bone chilling. Low cloud bases with dense fog at mid-upper elevations along-north of the High Knob Massif & Tennessee Valley Divide. Winds N-NE at 5-10 mph. Temperatures varying from lower 30s to lower 40s. Some breaks in the overcast possible leeward of the High Knob Massif-Black Mountain by mid-late afternoon. Wind chills in the 20s to around 30 degrees at upper elevations.
Wednesday Night Into Thursday Morning
Low clouds ( widespread dense fog continuing at mid-upper elevations ). Chilly. A chance of light showers and drizzle. Light N-NE winds becoming variable in direction at upper elevations. Temperatures near steady or slowly rising in the 30s to lower 40s.
Thursday Morning Into The Afternoon
Becoming partly to mostly sunny. Winds WNW-NW at 5-10 mph, with some higher gusts. Temperatures varying from the lower 40s to the lower 50s.
Thursday Night Into Friday Morning
Partly to mostly clear ( a period of increased low clouds possible into the morning ). Winds NW-N at 5-15 mph, with some higher gusts, on mid-upper elevation mountain ridges and exposed plateaus. Temperatures varying from the low the middle 20s to the middle 30s. Wind chills in the 10s in upper elevations ( near 10 degrees highest peaks in gusts ).
Friday Afternoon
Partly to mostly sunny. Cold. N-NE winds 5-10 mph, with some higher gusts. Temperatures varying from the 20s in upper elevations to the middle 30s to around 40 degrees. Milder south into the Great Valley.
Friday Night Into Saturday Morning
Mostly clear ( some high clouds possible ) and unseasonably cold. Light and variable winds on mountain ridges. Temps varying from the upper 10s to mid-upper 20s, except as cold as 10-15 degrees in colder upper elevations valleys.
Weather Discussion ( Nasty & Cold )
Wednesday Afternoon Update
Dense fog has now covered hundreds of square miles for 24 consecutive hours across northern Scott County, southern-central Wise County & central-southern Dickenson County.
The National Weather Service’s recognition of this:
is NONE!
I typically never say anything on this site, but as you see and experience this, drive in this, and know how widespread it is for 24-hours then ask this question:
If this occurred in the Great Valley, from Morristown to the Tri-Cities, what would be the resulting action?
Likely – Official Recognition with a Dense Fog Advisory.
It is not just MRX, but also RLX; however, MRX has the largest population impacted by these events, even though every single person COUNTS and a small community is just AS IMPORTANT as a big city which is my bottom line.
A raw, damp chill has, of course, been the other big story. Check out today’s temperature trend from Nora 4 SSE on Long Ridge of Sandy Ridge, where dense fog has also been persistent all day long.
Temperatures at upper elevations in the High Knob Massif have been mainly in the mid-30s all day ( 33 to 38 degrees ).
Fog will continue through this evening, and it is looking more likely that it will continue into Thursday before the cloud bases finally lift.
Please slow down and be extremely careful as it has been difficult to see vehicles on the road, not to even mention other things like people or deer!
Previous Discussion
Widespread low clouds ( dense fog ) are about as thick as they get across mid-upper elevations along and north of the High Knob Massif & Tennessee Valley Divide as colder air is being lifted vertically over a moist mountain landscape.
I had this well forecast in advance, reference my 110617 Forecast for previous details on this nasty period of weather conditions.
Conditions will become colder and even more nasty as a round of rain develops overnight into Wednesday morning.
Temperatures along northern slopes and crest lines in the high country will be borderline, or very close to freezing, as rain redevelops overnight into Wednesday morning. Close enough that folks traveling along State Route 619, 160, and Routes 238, 237, as well as others above 3300 feet, should be alert for possible slick patches amid the pea-soup fog.
If low clouds ( fog ) hang tough in the upslope flow through the day Wednesday then temperatures in Norton-Wise will hover in the nasty 30s to around 40 degrees, with somewhat milder conditions at lower elevations and within locations downslope and leeward of the High Knob high country and Tennessee Valley Divide.
A low cloud deck and neutral to slight warm air advection may help hold temperatures near steady Wednesday Night into Thursday morning in advance of the next push of even colder air set to arrive by Friday.
If the warm advection can out-weigh the neutrality, then rises in cloud base levels may also occur during the period of Wednesday Night-Thursday AM with eventual break-up of the cloud deck expected during the day Thursday.
The mountain area will be on the fringe of a big blob of much below average temperatures ( seen above ) over the western portion of Canada by Friday, with the core of the very coldest air extending from northern West Virginia northeastward into the New England states.
This will set the stage for the coldest temperatures of this season, to date, heading into Friday Night & Saturday AM, with 10s and 20s widespread. Favored frost pockets will have the chance, at least, to plunge toward 10 degrees if skies are clear and winds decouple ( even colder readings will be possible, especially where 850 MB temps are colder toward the eastern-northern highlands in West Virginia; however, low clouds from Great Lake moisture could be a hindrance there, along with gustier 850 MB winds ).
Meanwhile,
Please use extreme caution in this very dense fog.
ALERT For Dense Fog At Mid-Upper Elevations Along And North Of The High Knob Massif-Tennessee Valley Divide From Late Tuesday Afternoon Into Wednesday
*A prolonged period of dense fog ( low clouds ) will develop as colder air invades the front range of the mountains from late Tuesday into Wednesday on upsloping northerly winds. A cold, damp & raw feeling day is expected Wednesday when air temps will struggle in the 30s to lower 40s in locations along and north of the High Knob Massif & Tennessee Valley Divide, with milder conditions leeward of the mountains into river valleys of the Clinch, Holston and Great Valley.
Monday Night Into Tuesday Morning
Low clouds. Turning cooler during the evening, especially along and north of the High Knob Massif-Tennessee Valley Divide. Then rain developing overnight, with a chance of thunder. Downpours likely. N-NE winds at 5-10 mph, with some higher gusts, into the early overnight shifting SSE at 5-15 mph, with higher gusts, by morning. Temperatures falling into the upper 40s to low-mid 50s.
Tuesday Morning Through The Afternoon
Rain, heavy at times, through the morning. Thunder possible. Rain tapering to showers into the afternoon. Winds SSE-SSW shifting to NW-N by mid-late afternoon below 3200 feet at generally less than 10 mph. SSE winds shifting W-WNW at 5-15 mph, with higher gusts, at upper elevations above 3200 feet. Temperatures in the 50s to around 60 degrees, turning chilly during mid-late afternoon ( milder south into the Great Valley ).
Tuesday Night Into Wednesday Morning
Low clouds. Light showers or drizzle. Turning colder. Another period of dense fog likely at mid-upper elevations along and north of the High Knob Massif-Tennessee Valley Divide. NNW-NNE winds at 5-10 mph, with some higher gusts. Temps falling into the 30s to around 40 degrees. Wind chills dropping into the 20s to lower 30s at the highest elevations.
Wednesday Morning Into The Afternoon
Low cloud bases with areas of dense fog at mid-upper elevations along & north of the High Knob Massif and Tennessee Valley Divide. Cold & damp. Drizzle possible. Winds N-NE at generally less than 10 mph. Temperatures varying from the lower 30s to lower 40s ( coldest at the highest elevations ). Some breaks in the overcast possible leeward of the High Knob Massif-Black Mountain. Wind chills in the 20s to around 30 degrees at high elevations.
Weather Discussion ( Wet & Colder )
A mild, wet beginning to November will transition into a wet and cold pattern into mid-week. Locally heavy rain amounts will be possible Tuesday during this transition.
Folks living along and north of the High Knob high country and adjacent Tennessee Valley Divide need to get use to this view as low cloud bases become a persistent feature by late Tuesday into Wednesday, on upsloping northerly air flow.
The interaction of abundant low-level moisture with colder air will combine with lifting on upslope flow to generate a widespread low cloud deck into Tuesday Night-Wednesday, especially in locations ( of course ) on the rising air side of the Cumberland-Allegheny Front range.
Forecast models have been struggling to pin down where heavier rains will fall through Tuesday, but amounts of more than 2.00″ ( when including Monday ) are certainly possible in some locations ( around 1.30″ fell on Eagle Knob of the High Knob Massif Monday ), especially in those zones which have been ( and are being now ) pre-conditioned by condensation on rising air ( e.g., the lifting zone of the High Knob Massif-Black Mountain corridor to include the City of Norton & Towns of Wise, Appalachia, Big Stone Gap etc…).
A wave of low pressure developing over Texas, as seen above at 7 AM Monday, will spread a new wave of rain across the mountain region into Tuesday morning.
This will mark the beginning of a colder trend; however, due to upper air blocking over the Aleutians-Bering Sea sector, the brunt of the cold will dive into New England later this week as general -PNA ( negative Pacific North American oscillation ) is maintained.
The current 6-10 day trend is for near to a little above average temperatures locally, with above average temps forecast across much of the nation between the Rockies and Appalachians ( below ) by the 51-member ensemble mean.
Statistically, and in theory, a 51-member MEAN forecast should be more accurate than any individual model forecast. While this is not always true, more often than not the use of the MEAN of a large group is best when doing longer-range outlooks.
A notable exception to the above being when atmospheric changes climatologically proven by history to alter a particular pattern can be picked out by a forecaster in advance of later model shifts. An example of what I mean by this will be cited below with respect to the potential for changes heading toward Thanksgiving Week and early December that are only being hinted at by the best models.
Beyond the 6-10 day period there are increasing signs that high latitude blocking will begin changing its orientation, with a cross-latitude bridge of positive height anomalies forming from Northern Europe into Eastern Siberia along with a notable and increasingly negative trend in both the AO and NAO teleconnections, which could signal a more important pattern shift down the road ( especially if the current -PNA dissipates, which is NOT yet being forecast ).
Building of bitter air across northwestern Canada and parts of Alaska during next week in combination with formation of blocking near Greenland, can be preliminary indicators of Arctic Outbreaks into the continental USA. Stay tuned for later updates on this evolving pattern.
Reference my 110417 Forecast for details about why blocking over the Aleutians-Bering Sea is important to SE USA conditions. Note that cold can occur given this mean pattern, with 0 degrees being observed in high valleys of the High Knob Massif as late as March 16 this year; however, the type of pattern observed during Winter 2016-17 was not favorable for sustained cold-snowy weather.
ALERT For Strong ( ROARING ) SW Winds At Mid-Upper Elevations Into Monday Morning In Advance Of A Line Of Showers-Thunderstorms. Caution Is Advised.
Strong SW winds will continue to blow into the overnight ahead of an approaching line of showers-thunderstorms. Expect wind gusts of 30-40+ mph to continue, and to also mix downward into some SW flow wave zones across the northern portions of Wise and Dickenson counties.
An outbreak of severe thunderstorms is looking likely by later this weekend over the Ohio Valley, with potential for one or more bowing squall lines. The eastward progress of this will need to be watched as it approaches the western side of the Appalachians by Monday.
ALERT For Areas Of Local To Widespread Dense Fog Into Saturday Morning
Overnight Into Saturday Morning
Cloudy. A chance of rain showers, especially by morning. Low clouds with dense fog at upper elevations, and local to widespread at other elevations. Light winds. Temperatures widespread in the 50s.
Saturday Morning Into The Afternoon
Cloudy. A chance of rain showers, especially along and southeast of the Tennessee Valley Divide and High Knob high country. Breaks in the overcast possible by mid-late afternoon, especially north of the high terrain. SSE-SSW winds 5-15 mph, with higher gusts, on mid-upper elevation mountain ridges & plateaus. Temperatures varying from 50s in upper elevations to the middle-upper 60s ( warmest at lower elevations in the Russell Fork-Levisa Fork basins ).
Saturday Night Into Sunday Morning
Partly-mostly cloudy in the evening, becoming cloudy overnight into the morning with a chance of drizzle or showers. SSE-SSW winds 5-15 mph, with higher gusts, on mountain ridges below 2700 feet. S-SW winds 10-20 mph, with higher gusts, on mountain ridges above 2700 feet. Mild for the season with temperatures mostly in the 50s. Area of dense fog possible, especially at high elevations along the High Knob Massif-Tennessee Valley Divide.
Sunday Afternoon Updated
Partly-mostly cloudy. Unseasonably warm & gusty. S-SW winds 10-20 mph, with higher gusts. Temperatures from the 50s to low 60s at upper elevations to the upper 60s to low 70s ( warmest at lower elevations in the Russell & Levisa Fork basins, as well as to the south into the Great Valley ).
Sunday Night Into Monday Morning
Partly-mostly cloudy & windy. A chance of showers and thunderstorms, especially overnight into Monday. Winds S-SSW 10-20 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet. Winds SW at 15-25 mph, with higher gusts, on mountain ridges above 2700 feet.
Transition into a colder weather pattern is expected next week, with temperatures trending back toward near to below average.
Weather Discussion ( Moist-Mild )
Sunday Evening Updated Discussion
Strong SW winds are roaring over mountain ridges-exposed plateaus in the Cumberland Mountains this evening and will continue into the overnight as a line of showers and thunderstorms approaches the Appalachians.
Caution is advised to be extra careful of breaking limbs or trees, especially in the mid-upper elevations, but also at some lower sites in climatologically favored zones where mountain waves on SW winds break downward, such as within the Pound-Clintwood corridor and locations lying downstream of the High Knob Massif – Black Mountains.
Previous Discussion
A moist & unseasonably mild November air mass will grip the mountain landscape throughout this weekend, with a notable increase in gusty S-SW winds expected by Sunday into early Monday in advance of a cold front.
A rather large region from the Ohio Valley and lower Great Lakes into the middle Mississippi Valley will come under the gun for potential severe thunderstorms by Sunday. While the strongest activity is currently expected to remain west of the mountains, any east-southeast moving squall lines will need to be monitored as they cross into Kentucky.
Storminess will be occurring in advance of a major transition in the upper air pattern during next week; however, still not the complete change upstairs ( as highlighted below ).
This change being forced to occur as the atmosphere fights to establish some type of balance, between a simply HUGE autumn temperature gradient across North America ( noted above in the region between the eastern front range of the northern Rockies and the southern Plains & Mexico ).
A shift from unseasonably mild to below average temperatures is currently forecast by the MEAN of European Ensembles.
However, before winter fans get carried away, it should be pointed out that anomalously strong 500 MB heights over the Aleutians and Bering Sea is present currently and is forecast to remain in place through the next 10 days.
*Observe how strikingly similar the current pattern ( above ) is to that observed ( in the mean ) during Winter 2016-17 ( below ).
If you do not understand why this is important, simply look back at the MEAN pattern observed during last winter and note that there is a strong correlation between positive 500 MB height anomalies with a Bulls-eye type of configuration over the Aleutians & Bering Sea and milder than average weather conditions in the eastern-southeastern USA.
If the positive 500 MB height anomaly pattern should lose its “bulls-eye” type of configuration, becoming elongated as observed above, during February 2015, then a completely different result would occur ( much different! ).
A negative trend in the Arctic & North Atlantic Oscillations is forecast to occur during the next 1-2 weeks; however, due to persistence of a “bulls-eye” type of 500 MB height anomaly centered over the Aleutians-Bering Sea a -PNA pattern will continue to fight against eastern USA troughing.
It remains early, with the high latitude winter pattern just now taking shape, such that current blocking does not mean that the outcome will be the same as last winter ( every winter season is different, so stay tuned for updates as mixed signals are being teleconnected from the Arctic region at present…some which favor a “bad” winter and some favoring another mild season ).
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.
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.
**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.
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 ).
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.
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.
My friend Wayne Riner submits a great shot showing snow on the pumpkin, at a fitting time of the year too!
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.
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.
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.
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.
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.
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.
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.