Monthly Archives: December 2017

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.