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My Forecast For Today

Mountain Area Forecast ( Dec 17-19 )

ALERT For Icy Conditions For Those Traveling Across The High Country of The High Knob Massif During Sunday Afternoon ( December 17 )

State Route 619 at Camp Rock During Afternoon of December 16, 2017
Although sections of State Route 619 remained snow covered and locally icy on Saturday, light precipitation ( some snow-mix-rain ) has combined with temperatures falling to around or below 32 F at highest elevations Sunday afternoon.  Caution is Advised.
High Knob Lake Recreation Area – Christmas Bird Count – December 16, 2017
Conditions were cold and gusty Saturday, but nothing like Sunday with low wind chills being generated by ROARING SSW-SW winds.
Black Mountain Mesonet For 1-Hour Period Ending At 2:35 PM December 17, 2017

121317 Forecast

Mountain Area Forecast ( Dec 13-14 )

ROARING SSW To SW Winds And Low Wind Chills Will Continue Into The Overnight And Predawn Hours Of Thursday Morning – Caution Is Advised

A fast moving clipper system passing north of the Mountain Empire will continue to generate ROARING winds across the mountain area through tonight into the overnight.

 Wednesday Night Into Thursday Morning

Partly cloudy during the evening, then becoming cloudy with a chance of flurries & snow showers by morning. Windy and cold.  Winds S to SW 15-25 mph, with higher gusts, below 2700 feet.  SSW-SW winds 25-35 mph, with higher gusts, along mountain ridges above 2700 feet.  Winds diminishing after sunrise.  Temperatures varying from upper 10s to lower 20s in upper elevations by morning to the mid-upper 20s to around 30 degrees.  Wind chills in the 10s to low 20s, with single digits high mountain ridges.

Thursday Afternoon

 Partly-mostly cloudy.  Cold.  NW winds generally less than 10 mph.  Temperatures varying from lower 20s in upper elevations to the lower-mid 30s.

Thursday Night Into Friday Morning

Partly-mostly cloudy.  Cold.  Light winds.  Temperatures varying from low-mid 10s in upper elevations to the low-middle 20s.

 

Weather Discussion ( Windy )

It does not take a meteorologist to tell winds are roaring across the mountains, especially in the High Knob Massif area where an array of beautiful lenticular ( mountain wave ) clouds are being highlighted by sunset.

High Knob Massif Webcam – University Of Virginia’s College At Wise

These strong winds are also continuing the low wind chills.

High Knob Massif Webcam – University Of Virginia’s College At Wise

Although we do not have the mesonet coverage as needed, there is enough data such that there is no excuse for leaving out the Cumberland Mountains in current Wind Advisories.

Black Mountain Mesonet

Note sustained speeds are over 30 miles per hour at high elevations.

Black Mountain Mesonet

These mesonets span the 2774 to 4031 foot elevation zone, in which thousands of people live across Wise, northern Scott, and southern Dickenson counties.

Flatwoods Mountain Mesonet

Drop through middle elevations, even into lower elevations below 2000 feet in parts of Wise & Dickenson counties, and these winds are still ROARING since SSW-SW flow is climatologically the windiest in this area.

Lonesome Pine Airport In Wise

Snow depths of 2″ to 3″+ occurred with the most recent clipper within upper elevations of the High Knob Massif to Burkes Garden area, with Joe & Darlene Fields measuring 2″ of ground depth ( 1.8″ ) Wednesday in the High Chaparral community ( with 3″ or locally more at highest elevations ).

A morning snow depth of 3″ was also reported in Burkes Garden.  These totals were ironically more than counties within the Winter Weather Advisory ( officially posted by the NWS ); although, Wise County and adjacent high elevation areas were not included!
Eagle Knob of High Knob Massif At 9:58 AM on December 13, 2017

Roads were slick and snow covered in the high country, with the road on Eagle Knob ( above ) being solidly covered despite much blowing ( horizontal ) snow that generated large depth variations along the high ridges.

121117 Forecast

Mountain Area Forecast ( Dec 11-13 )

ALERT For Strong SW Winds Into The Overnight In Advance Of Much Colder Air & Snow Squalls

Strong SW winds will continue to ROAR along the Cumberland Mountains into the overnight in advance of a strong cold front.  Caution is advised.

ALERT For Accumulating Snow Tuesday With A Sharp Temperature Plunge Through The Afternoon Into The Evening – Low Wind Chills And Hazardous Conditions Are Expected – Especially Along & North to Northwest Of The High Knob Massif and Tennessee Valley Divide

An Arctic Cold Front will push across the mountains Tuesday and will be accompanied by snow showers, flurries, snow squalls and sharply dropping temperatures and wind chill factors.  Moderate to strong orographic forcing and increasing instability aloft will create whiteout conditions at times.  Widespread snow is expected along and north to northwest of the High Knob Massif-Tennessee Valley Divide, with more scattered activity in downslope locations to the southwest and southeast.

Monday Night Into Tuesday Morning

Partly to mostly clear through the evening, then increasing overnight clouds with a chance of flurries & snow showers developing around sunrise.  Windy.  Winds SW-W at 15-25 mph, with higher gusts, along mountain ridges & exposed plateaus below 2700 feet.  Winds SW to WNW at 20-30 mph, with higher gusts, along mountain ridges above 2700 feet.  Rapid evening temperature drop in sheltered valleys, then temps rising overnight with mixing.  Turning colder at mid to upper elevations by sunrise.  Temperatures dropping into the lower 20s to lower 30s.  Wind chills falling into the 10s and 20s, except single digits toward morning on highest mountain ridges.

Tuesday Morning Through The Afternoon

Snow showers, flurries, and snow squalls.  A whiteout snow burst possible along the Arctic Front, then hit-miss bursts of heavy snow possible through the afternoon.  Windy and turning bitterly cold.  WNW-NW winds 10-25 mph, with higher gusts.  Temperatures falling through the 20s at middle-lower elevations, and through the 10s at upper elevations above 3000 feet.  Wind chills dropping into single digits and 10s in middle-lower elevations and to below zero across upper elevations ( as low as -10 degrees below zero possible on highest peaks by late ).

Tuesday Night Into Wednesday Morning

A chance of snow showers, flurries, and localized squalls through the evening, then partial clearing possible by the predawn to sunrise period.  Windy & bitter cold.  WNW-NW winds 10-20 mph, with higher gusts.  Temperatures in the 10s, with single digits at upper elevations.  Wind chills in the 0 to 10 above range at middle elevations and in the 0 to -10 degree below zero range at upper elevations ( except locally -10 to -20 below on highest peaks in gusts ).

Widespread snow accumulations of 1-2″ are expected along and to north-northwest of the High Knob Massif-Tennessee Valley Divide, with locally higher amounts of up to 3″+ in locales experiencing numerous squalls or snowstreaks.

More scattered snow amounts are expected in downslope locations from Big Stone Gap through central-western Lee County, southward into the Great Valley of northeastern Tennessee and southwestern Virginia.

 

Weather Discussion ( Arctic Front )

A simply gorgeous sunset was observed Sunday following a round of mostly light snow that dropped a dusting to 1″ on the mountain area into early Sunday.

High Knob Massif Webcam – University Of Virginia’s College At Wise

Strong winds and low wind chills over the high country on Sunday were generating an array of nice orographic wave clouds.  A few being observed from UVA-Wise near sunset.

High Knob Massif Webcam – University Of Virginia’s College At Wise  

High resolution visible imagery Monday revealed lingering snow from the southern snowstorm that dropped rare and impressive amounts of snow far to the south.

Lingering Snow From Southern Storm – December 11, 2017

I have just updated my forecast for an ALERT to cover the Strong SW winds which are roaring across the mountains.

Black Mountain Mesonet For The 1-Hour Period Ending At 8:55 PM ( December 11 )

While strong winds were already in my forecast for tonight, wind speeds at mid-upper elevations have increased above what were predicted earlier, with 40-50+ mph gusts, so an ALERT is needed for locations where many people live.

As often occurs, with mountain wave formation, strong gusts are penetrating down to valley floors in the Pound-Clintwood corridor ( this is not recognized beyond myself so it must not really occur ). 
Black Mountain Mesonet For The 1-Hour Period Ending At 7:55 PM ( December 11 )

The main focus beyond these roaring winds tonight will be bitterly cold air pouring into the mountains Tuesday, along with moderate-strong orographic forcing and increasing vertical instability as very cold air aloft steepens the lapse rates through Tuesday afternoon.

NAM 12 KM Model 850 MB Forecast At 10:00 AM Tuesday – December 12, 2017

A WINDEX event is developing into Tuesday and conditions along and west-northwest of the lifting zones of the High Knob Massif and Tennessee Valley Divide, which includes most all of Wise-Dickenson counties, are going to get bad with whiteout conditions at times in addition to plunging temperatures and wind chill factors ( this despite the lack of recognition officially ).

Due to very cold air aloft, some intense squalls may also spill over into the Great Valley.

*Tuesday will be nothing like the Saturday Night into early Sunday period and any forecaster who thinks it will needs to return to school for more training!

120917 Forecast

Mountain Area Forecast ( Dec 9-11 )

The Coldest Air Of This Early Winter Season Will Arrive Tuesday Into Wednesday Morning.  An Alert For Bitterly Cold Air And Accumulating Snow Will Likely Be Needed.  Snow Squalls With Whiteout Conditions Will Be Likely Tuesday – A New Forecast Will Be Issued Monday PM ( Stay Tuned For Updates ).

Previous Alert

Accumulating Snow From A Clipper System Will Be Likely Saturday Night Into Sunday Morning In Upslope Locations On W-NW Air Flow

A clipper system will cause snow showers and flurries to develop by Saturday evening, with a burst or two of snow possible.  Windy and bitter conditions will accompany a drop in temperatures.
Snowfall accumulations from 0.5″ up to 1-2″ are expected, with greatest amounts in upslope locations with respect to W-NW air flow.  Little to no snow accumulation is expected in downslope locations.  While locally higher amounts could occur in the High Knob high country, the moisture tap from the Great Lakes will be limited, the system fast moving, and the time for accumulations of relatively short duration to help limit amounts.  This will be a dry ( low density ) fluff in contrast to the wet snow that fell over the Tennessee Valley and Blue Ridge during December 8-9 AM.

Saturday Afternoon

Partly to mostly sunny then becoming cloudy with a chance of snow showers or flurries by late. Cold.  SSW-WSW winds 5-15 mph, with higher gusts.  Temperatures varying from the mid-upper 20s in upper elevations to mid-upper 30s.  Wind chills in the 10s & 20s ( coldest highest elevations ).

Saturday Night Into Sunday Morning

Windy & colder with snow showers & flurries.  Winds W-WNW at 10-20 mph, with higher gusts ( especially along mountain ridges ).  Temperatures dropping into the low-mid 10s to lower 20s ( coldest highest elevations ).  Wind chills in the single digits and 10s, except below zero in gusts along high mountain ridges.  Rime formation highest peaks.

Sunday Afternoon

Partly cloudy.  Gusty & cold.  SSW-WSW winds 10-20 mph, with higher gusts.  Temperatures varying from the mid-upper 20s in upper elevations to the mid-upper 30s.  Wind chills in the 10s and 20s, especially along mountain ridges and exposed plateaus.

Sunday Night Into Monday Morning

Partly cloudy to clear.  Windy.  SW winds 5-15 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet.  WSW-WNW winds 15-25 mph, with higher gusts, on mountain ridges above 2700 feet.  Temperatures mainly in the 20s to lower 30s.  Wind chills in 10s to low 20s, except single digits  in gusts along high mountain ridges.

 

Weather Discussion ( Rare Event )

Bare ground from the High Knob Massif to Snowshoe and Canaan Mountain early Saturday marked a rare event for these 100″+ a year snowfall summits, as snow covered the landscape only miles to the east and southeast.

The summit of the High Knob Massif had rime but only a trace of snowfall during Friday into Saturday Morning ( December 8-9 ).
High Knob Massif Webcam – University Of Virginia’s College At Wise

The first official 1″ of snow was recorded in the Tri-Cities, with more in places like Johnson City, versus a barren land within the Norton-Wise and High Knob Massif area.

Cumberland Square Park In Bristol
State of Franklin In Johnson City

Although this gradient ( difference ) in snowfall was expected, it is still rare for the High Knob Massif and Snowshoe-Canaan to be shut-out during such a system.

December 9_24-Hour Report – Charleston, Wv., NWS Forecast Office

Some of the greatest reports in GIS Format

Snowfall Report ( Snow Total In Left-Hand Column In Inches ) – December 9, 2017

As much as 15-18″ of snow was reported in southwestern portions of North Carolina, with locally 10-12″ in parts of Georgia and Alabama.  Snow even fell on Pensacola in the Florida panhandle, as well as in Brownsville, Texas.

Snowfall Report ( Snow Total In Left-Hand Column In Inches ) – December 9, 2017

Although less snow fell in Grayson Highlands State Park than in locations farther southwest along the Blue Ridge, the scene is still plenty wintry at the 4,000 foot level.

View From Grayson Highlands State Park at 12:09 PM on December 9, 2017

120817 Forecast

Mountain Area Forecast ( Dec 8-10 )

ALERT For Accumulating Snow Friday Into Friday Night – Especially Along & South of the High Knob Massif and Tennessee Valley Divide

An increasing gradient of snowfall is likely from northwest to southeast across the area, with limited snow along and north to northwest of a Pennington Gap to Clintwood line where little snow is expected to accumulate through Friday Night ( less than 1″ ).
A zone along the Tennessee Valley Divide, including Norton-Wise, Banner Mountain, Sandy Ridge, and adjacent communities could see 1″ or more of snow, with heavier snow more likely from the High Knob Massif south & southeast across the Tennessee Valley toward the Blue Ridge ( general 1″ to 4″ ).  A rare setting where more snow may fall in the Tri-Cities than in Norton-Wise. 
The heaviest snow, with 4-8″+, will be likely along and east of the Blue Ridge and Tennessee-North Carolina border.

Only a slight shift in the track of this system could change the placement of these amounts, but the general increase in snowfall from northwest to southeast will hold.

Friday Morning Through This Afternoon

Cloudy with morning flurries giving way to developing snow, especially along and south of the High Knob Massif and Tennessee Valley Divide.  Light winds.  Temperatures varying from upper 10s to lower 20s highest elevations to the upper 20s to lower 30s.

Friday Night Into Saturday Morning

Cold with periods of snow, especially along and southeast to east of the Virginia-Kentucky stateline into the overnight before tapering to flurries.  Light winds becoming W-NW.  Temperatures varying from low-mid 10s to low-mid 20s, coldest at highest elevations.  Wind chills in single digits within highest elevations.

My Mesoscale Discussion

Moisture From A Southern System And Front Over The Southeastern USA Will Transport Moisture Into Cold Air In Place Over The Southern Appalachians During Friday Into Early Saturday AM With Widespread Snow Accumulations.  A Sharp Cut-off Will Be Likely Along The Western & Northwestern Side Of This System.

This is an evolving situation with only a small shift in the track of the main moisture band having large implications on the snowfall potential across the Mountain Empire.  As of late Thursday Night a small but notable westward shift was occurring in models, and I expect this could continue due to the formation of the Right Rear Quadrant Entrance Region Of A 250-300 MB Jet Streak.  Upper air divergence beneath this region could allow snowfall to build west to the High Knob Massif & Tennessee Valley Divide and will need to be closely monitored during the next 12-24 hours.

GFS Model 300 MB Forecast At 7:00 PM Friday – December 8, 2017

The GFS Model is farther west than the 00z European with the core of this developing Jet Streak, and the NAM 12 KM Model is also a little farther west than the European despite having a moisture field farther east.  Thus, given this is a developing Jet Streak, there is significant potential for a continued westward shift in accumulating snowfall across the Tennessee Valley toward the Virginia-Kentucky stateline during Friday into Friday Night.

**Cross-isobaric ageostrophic circulation developing within the right-rear entrance region of the jet streak will be the synoptic mechanism capable of forcing a westward shift; albeit small, in the snowband extent.  This often has some natural interaction with the three-dimensional terrain.  Past climatology of similar systems dictates that locations along and southeast of the VA-KY border are typically at highest risk for expansion beyond what most models tend to indicate.
In this case, only time will tell exactly where the western edge of 1-3″+ of sticking snow sets up Friday into Friday Night.  New runs of models overnight into Friday will be important to monitor.
NAM 12 KM Model 300 MB Forecast At 2:00 AM Saturday – December 9, 2017

The coldest air is along the west side of the Appalachians such that any moisture reaching this area will have a lower snow density ( higher snow to water ratio ) than locations farther east and southeast.  Drier air is also over this area, thus the battle will be on between lift and drier air.  If the synoptic-scale lift becomes strong enough it will allow the snowband to build west more than models currently show, while if the synoptic-scale lift is weaker then the snowband will remain farther east.

Odds for 3-6″ of snow are high for locations along and east of the Tennessee-North Carolina border, with 1-3″ toward the west.  At this time the westward extent remains in play and could cover the Tri-Cities, and could reach as far west-northwest as the Virginia-Kentucky line.

NAM 12 KM Model 500 MB Vorticity Forecast At 7:00 AM Saturday

A second system will drop into the developing upper air trough and phase with southern energy to form a large storm for the East Coast.  Note how close it is to phasing over the southern Appalachians.

NAM 12 KM Model 500 MB Vorticity Forecast At 7:00 PM Saturday

A tap of some Great Lake moisture will combine with this to generate snow showers, flurries, and possibly a burst or two of snow Saturday Night into Sunday AM, with best accumulations expected along the front range of the Cumberland-Allegheny mountains.

A general 1″ to 2″ of dry snow will be possible along and north to northwest of the High Knob Massif & Tennessee Valley Divide during Saturday Night into Sunday AM.  The main unknown, will this be on top of any prior snow from the southern system?

120517 Forecast

Mountain Area Forecast ( Dec 5-8 )

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 ).

Black Mountain Mesonet Up To Midnight
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 ).

Reference Early Winter 2017 In The High Knob Massif Area as I recap November 2017 statistics ( adding more as I get time ).
High Knob Massif Webcam – University Of Virginia’s College At Wise

A majestic sunset graced December 4, with strong S-SW winds at mid-upper elevations being the only negative factor to signal changes upcoming.

Black Mountain Mesonet

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.

Flatwoods Mountain Mesosnet

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.

NAM 12 KM Model Total Precipitation Forecast Next 48-Hours

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 ).

Super Moon – December 3, 2017

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.

European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 1-5

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.

European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 6-10

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.

500 MB Height Anomaly Pattern – December 9-29 In 1989

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.

European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 1-5

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.

European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 6-10

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.

112717 Forecast

Mountain Area Forecast ( Nov 27-29 )

Overnight Into Monday Morning

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!

Lonesome Pine Airport In Wise

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 ).

NAM 12 KM Model Total Rainfall Next 84-Hours

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.

European Model 500 MB Height Anomalies Analysis at 7 AM November 28, 2017

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.

Reference My 110417 Forecast Discussion for more details.
European Model 30 MB Forecast At 7 AM December 8, 2017

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

High Knob Massif Webcam – University Of Virginia’s College At Wise

This view illustrates the pattern currently embracing the mountain landscape, dry and mostly clear with cold nights and seasonally cool days.

Arctic Oscillation Index

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.

500 MB Height Anomalies During November 10-24, 2017

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.

PRISM Model Analysis of November 1-25 Temps – Courtesy of WxBell Analytics

Instead, the month of November has trended to near or below average in temps from this region northward.

Pacific North American Oscillation

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.

GFS Model Ensembles AO Forecast

If these teleconnection forecasts hold

GFS Model Ensembles NAO Forecast

through coming days this week, the BIG NEWS

GFS Model Ensembles PNA Forecast

will be the shift into WINTER across the eastern USA

GFS Model Ensembles EPO Forecast

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.

+PNA Courtesy of North Carolina State University Climate Office

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.

112017 Forecast

Mountain Area Forecast ( Nov 20-23 )

Overnight Into Monday Morning

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.

Black Mountain Mesonet

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 ).

NAM Model Forecast Sounding Above Wise at 7 AM Thanksgiving

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

High Knob Massif Webcam – University Of Virginia’s College At Wise

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.

Black Mountain Mesonet – Ending At 10:40 AM Tuesday

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.

Black Mountain Mesonet – Ending At 1:40 PM Tuesday

Temperatures reached mid-upper 50s in the Wise area, but again never felt that warm due to these gusty SW winds.

Lonesome Pine Airport In Wise

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.

High Knob Massif Webcam – University Of Virginia’s College At Wise
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.

Peak Gusts Courtesy Of Jackson, KY NWS Forecast Office

Clintwood 1 W NWS was out of electricity for 16 hours, with some locations out longer in Dickenson and Wise counties.

Sunday Morning ( Nov 19 ) Snow In High Chaparral of High Knob Massif

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.

European Model 850 MB Analysis At 7 AM Sunday – November 19, 2017

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.

European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 1-5

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.

European 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 6-10

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.

Happy Thanksgiving To Everyone!

111417 Forecast

Mountain Area Forecast ( Nov 14 )

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.

110917 Forecast

Mountain Area Forecast ( Nov 9-12 )

Thursday Night Into Friday Morning

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.

High Knob Massif Webcam – University Of Virginia’s College At Wise

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.

High Knob Massif Webcam – University Of Virginia’s College At Wise

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.
European 51-Member Ensemble MEAN 500 MB Height Anomalies: Days 1-5

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.

European 51-Member Ensemble MEAN 850 MB Temp Anomalies: Days 1-5

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.

European 51-Member Ensemble MEAN 500 MB Height Anomalies: Days 6-10

If this trend is real, it will become more evident in forecasts at 6-10 day time frames as we progress through next week.

European 51-Member Ensemble MEAN 850 MB Temp Anomalies: Days 6-10

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.