Showers & Possible Thunderstorms Will Increase Into Early Hours Of Friday. Much Colder Air, With Falling Temperatures Are Expected Friday Into Saturday AM.
*The first snowflakes of the season could fall at highest elevations by Friday Night into Saturday Morning ( with light riming on peaks in freezing fog by Saturday AM ).
Below freezing temperatures are expected at highest elevations by Saturday morning, with a heavy frost-freeze developing in many mountain valleys by Sunday morning ( below freezing temps ).
Middle elevation mountain ridges and exposed portions of plateaus will have limited frost with mixing and generally above freezing temperatures. Locally dense fog will be possible along major lakes and rivers-wetlands.
Overnight Into Wednesday Morning
Partly cloudy. Breezy-gusty along ridges. Local areas of valley fog. Winds SSW-SW 5-15 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet. SW to WSW winds 10-20 mph, with higher gusts, on mountain ridges above 2700 feet. Temperatures varying from 40s to lower 50s in cooler mountain valleys to upper 50s to lower 60s along exposed ridges-plateaus.
Wednesday Afternoon
Partly cloudy. Unseasonably warm. Winds SSW-SW 5-10 mph, with some higher gusts. Temperatures varying from upper 60s to lower 70s in upper elevations to the upper 70s to lower 80s ( warmer south into the Great Valley ).
Wednesday Night Into Thursday Morning
Partly to mostly clear. Winds SSE-SSW 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges. Temps varying from 40s to lower 50s in cooler mountain valleys to the lower-middle 60s ( warmest along exposed ridges and plateaus ).
Thursday Afternoon
Partly-mostly cloudy. Unseasonably warm. Chance of a shower. Winds SW 5 to 10 mph with some higher gusts. Temps varying from mid-upper 60s in the upper elevations to mid 70s to around 80 degrees ( warmer south into river valleys of the Clinch & Holston ).
Thursday Night Into Friday Morning
Showers & thunderstorms becoming likely. Locally heavy rain. Gusty SW winds shifting to NW by morning at 10-20 mph, with higher gusts. Temperatures dropping into the mid 40s to middle 50s by morning ( coldest in the upper elevations ). Wind chills dropping into 30s & 40s on mid-upper elevation mountain ridges by morning.
Mid-Morning Friday Through The Afternoon
Nasty & colder. Showers & drizzle. Low clouds with dense fog across the upper elevations. NW winds 10-25 mph, with higher gusts. Temperatures falling into the mid-upper 30s at upper elevations and into the 40s to around 50 degrees at lower-middle elevations ( along and north-northwest of the High Knob Massif-Tennessee Valley Divide / milder lee of mountains ). Wind chills dropping into the 20s to lower 30s at highest elevations, with middle 30s to lower 40s below 3000 feet in elevation.
Friday Night Into Saturday Morning
Gusty & cold. Showers & drizzle at lower-middle elevations, with a mix or snow showers at highest elevations. Dense fog above 2700-3000 ft. NW winds 10-20 mph, with higher gusts. Temperatures varying from around 30 degrees at the summit level of the High Knob Massif to middle 30s to lower 40s. Wind chills varying from 10s to lower 20s across upper elevation mountain ridges to the upper 20s & 30s at lower-middle elevations ( below 3000 feet ).
*Skies Friday Night may develop breaks lee of the mountains into the Great Valley, with gusty conditions, and little to no precip on downsloping NW winds.
Weather Discussion ( Strong Front )
A large vertical temperature spread is being observed between exposed ridges-plateaus and colder valleys in early hours of the overnight on this Thursday.
As I expected, a strong inversion has formed with deep, sheltered valleys in low-mid 50s at Midnight versus readings still in mid 60s to around 70 degrees along exposed mid-upper elevation ridges.
Tulip-poplar Leaf ( Liriodendron tulipifera ) – October 19, 2016
This update mainly addresses the push of cold air expected to hit Friday into this weekend, with little to no changes in my previous forecast through Thursday.
Storm Prediction Center Updated Risk Regions
Strong height falls continue to suggest that a nice band of showers and thunderstorms will form along-ahead of the cold front later Thursday into early hours of Friday.
NOTE this will tend to bring down many leaves into Friday, so be cautious of slick places on roadways that may be leaf covered.
NAM 4 KM Model Total Precipitation Forecast
High-resolution short-range models continue to be in good agreement with the European Group in forecasting showers and downpours, with embedded thunderstorms, to arrive by late Thursday into early hours of Friday.
NAM 4 KM Model Surface TEMP Forecast – 8 AM Friday on October 21, 2016
A sharp temperature drop follows with reading sliding into the 40s in Norton-Wise during the day Friday, with 30s at highest elevations atop the High Knob Massif. Gusty NW winds will make it feel even colder. A WINTER COAT will feel good Friday, especially by later in the day.
NAM 4 KM Model Surface TEMP Forecast – 2 PM Friday on October 21, 2016
While the first snowflakes continue to look likely in places along the high Appalachians, the big story for most will be this nasty temperature plunge Friday into Saturday that will make conditions ( in wake of unseasonable warmth ) feel like a summer jump into winter. Get ready!
Previous Discussion
The sun is about to set upon this stretch of unseasonably warm October conditions.
Approaching Sunset Along Northwest Flank of High Knob Massif – October 16
A strong autumn cold front will be the main weather maker by late Thursday into Friday, with showers & thunderstorms expected along-ahead of the boundary.
Storm Prediction Center Outlook – Thursday Into Friday Morning ( Oct 20-21 )
A blast of chill will follow the frontal passage to make the day-light hours of Friday raw & NASTY with cold conditions ( especially in upslope locales along and north to northwest of the High Knob Massif & Tennessee Valley Divide ).
The forecast map by later Friday looks like one straight out of the winter season, as low pressure intensifies over the NE USA. This will increase the pressure gradient along the Appalachians with a notable NW flow from the Great Lakes and cold air transport!
NAM 12 KM Model 10 Meter Winds & Surface Pattern – 8 PM Friday ( Oct 21 )
Temperatures will be dropping into the 40s in Norton-Wise during Friday afternoon, with 30s at highest elevations in the High Knob Massif. Chill factors on gusty NW winds will make conditions feel even colder. Get prepared now!
NAM 4 KM Model Rainfall Forecast To 8:00 AM Friday – October 21, 2016
Rainfall totals are likely to be heaviest along and west of the Appalachians into early Friday, with more showers and drizzle likely into Friday afternoon & night ( even the first flakes of snow could fall at highest elevations Friday night into early Saturday before conditions begin to improve ).
Mostly cloudy. Low cloud bases across high terrain with dense fog. Light & variable winds. Temperatures varying from the 40s to lower 50s.
Friday Afternoon
Partly-mostly cloudy. Small chance of showers-sprinkles. Light SSE-SSW winds. Temperatures varying from upper 50s to lower 60s in upper elevations to the upper 60s to lower 70s.
Friday Night Into Saturday Morning
Mostly cloudy. Small chance of a shower-sprinkle. Winds SSE-SW at 5-10 mph, with higher gusts, along mid-upper elevation mountain ridges-plateaus. Temperatures from the 40s in coolest valleys to the lower-middle 50s.
Saturday Afternoon
Becoming partly cloudy. Light SSE-S winds, except 5-10 mph with some higher gusts at highest elevations. Temps varying from low-mid 60s in upper elevations to the lower to middle 70s.
Saturday Night Into Sunday Morning
Partly-mostly clear. Areas of valley fog. Winds S to SW at 5-15 mph, with higher gusts, along middle-upper elevation mountain ridges. Temperatures varying from 40s in cooler mountain valleys to the lower-middle 50s.
Sunday Afternoon
Partly cloudy. Light SSW-SW winds generally less than 10 mph. Mild. Temperatures varying from 60s in the upper elevations to the lower-middle 70s.
Weather Discussion ( Mild Pattern )
Some spectacular autumn color has developed in mid-upper elevations of the High Knob Massif, with this weekend thru next week currently expected to offer some of the best color as the peak approaches.
A major reason color is so dependably spectacular in the massif year after year is due to a combination of factors. Endemic, rich northern hardwoods within a mixed-mesophytic forest growing atop both calcareous and clastic stratas amid the wettest area in Virginia ( on average over the long-term ) are driving forces that are superimposed upon a sprawling mass of elevated terrain full of high basins ( wetland valleys, lakes, coves ) & complex terrain.
Autumn Color In Upper Elevations of High Knob Massif – October 12, 2016
Although behind schedule, in general, a significant advance in color changes have been observed during the past week amid seasonally cool conditions and abundant sunshine.
Autumn Color In High Valleys of Big Cherry Basin – October 12, 2016
The MEAN temperature observed during October 1-12 within high valleys of Big Cherry Lake basin was 52.1 degrees ( the average of sensor locations ), varying from the lower 60s by day to lower 40s at night ( 30s being observed during October 9-12 ).
October 1-12 Conditions Observed In The Tri-Cities
It is easier to understand the observed differences in color changes when one compares this to the Tri-Cities, amid the Great Valley, where the October 1-12 mean was 61.7 degrees or approximately 10 degrees warmer than local high basins.
The coldest October on record in the Tri-Cities had a MEAN temp of 50.1 degrees in 1988 ( the average is 56.3 degrees ). So conditions recorded in high valleys of Big Cherry Lake during October 1-12 this year would be considered MUCH below average for the TRI.
Autumn In Crest Zone of High Knob Massif – October 12, 2016
Although decreases in sunlight along with cooler conditions trigger autumn colorations, it is important to note that its not only the colder nights but also the much cooler days.
Black Mountain MesoNET for October 1-12, 2016
The highest temperature observed during the October 1-12 period at the MesoNET site atop Black Mountain ( 4031 feet ) has been 69 degrees, the same as recorded in high valleys of Big Cherry Lake basin ( one sensor location there reaching just 68 degrees ).
High valleys, which are plentiful in the High Knob Massif, tend to have lower MEAN temperatures than might be expected due not only to much colder nights ( than are observed along high ridges when radiation rules over advection ) but also to these cooler daytime temps.
So the best, brightest and most advanced color typically begins developing first along the high basins where cold air drainage occurs at night and days are relatively cool due to elevation in combination with exposure. In most autumns color begins to develop in mid-September, with significant colorations often observed by late September-early October.
Autumn 2016, by contrast, did not see significant color changes begin until early-mid October ( 1-2 weeks later than typical ).
European 51-Member Ensemble MEAN 500 MB Height Anomaly – 8 AM Oct 20
Looking ahead, a mostly dry and mild pattern rules into next week when there is increasing evidence that a large storm system ( of some form ) will develop across the eastern USA.
The MEAN of the 51-Member European Ensembles have in recent days been showing a potential phasing event between a tropical cyclone and a mid-latitude upper air trough which would lead to an orographic forcing episode along the Appalachians.
European 51-Member Ensemble MEAN 500 MB Height Anomaly – 8 AM Oct 21
Needlessly to say, IF that occurred it would be a major precipitation maker for the Mountain Empire. However, it remains too far out in time to know exactly what will occur.
The latest 00z run of the operational European Model coming out as I write now continues to also show such an event. Every run that continues to replicate this will increase the odds of a major event that could again be a headline making storm system. It should be stressed again, of course, that its too early to be sure.
Due to changes at high latitudes, with building heights near Greenland and in the Gulf of Alaska next week, it does appear likely that much cooler ( colder ) air will arrive in 7-10 days. Certainly that increases the odds that there could indeed be cyclogenesis…BUT will that occur in such a position as to give much needed rainfall to those places that need it along the mountains while sparing flood ravaged locations to the east?
Mostly clear to partly cloudy ( high clouds ). Chilly. Frost in colder mountain valleys. Winds ESE to S at 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges. Temps varying from 30 to 35 degrees in colder valleys to the middle-upper 40s ( exposed ridges ). Fog along main streams, lakes & wetlands.
Tuesday Afternoon
Partly to mostly sunny. Light S to SW winds. Temperatures varying from the upper 50s to lower 60s in upper elevations to the upper 60s to lower 70s ( warmer in the Great Valley ).
Tuesday Night Into Wednesday Morning
Mostly clear. Chilly. Light SSE-SW winds along mid-upper elevation mountain ridges. Temperatures varying from 30 to 35 degrees in colder mountain valleys to mid-upper 40s. Frost in colder mountain valleys, with fog along main streams, lakes & wetlands.
Wednesday Afternoon
Mostly sunny. Pleasant. Light SSE-SSW winds. Temps varying from lower-mid 60s in upper elevations to the lower-middle 70s ( warmer south into the Great Valley ).
Wednesday Night Into Thursday Morning
Partly-mostly clear ( high clouds ). Winds becoming SSW-WSW at 5 to 15 mph, with higher gusts, along mid-upper elevation mountain ridges. Temperatures varying from the 30s in colder mountain valleys to the upper 40s to low 50s.
Weather Discussion ( Nice Pattern )
Cold to chilly nights and pleasant days will continue to be featured this week as a nice autumn pattern controls the mountain region.
European Model 850 MB Temp & Surface Analysis at 8 AM Monday – October 10
Patchy to widespread frost formed in mountain valleys into morning hours of Monday as low temperatures fell into the 30 to 35 degree range in typically colder mountain valleys from Wise and Dickenson counties to Tazewell County.
This pattern will be repeated into Tuesday-Wednesday mornings, with fog also forming along main streams, lakes & wetlands. By contrast, thermal belt sites will sit high and dry with nocturnal temperatures which are milder and no chance for frost and fog.
NAM 12 KM Model Total Precipitation Forecast – Next 84 Hours
The pattern remains mostly dry through the work week, with some increased chances for showers by this weekend into next week as a mild ( for October ) pattern rules.
Rain showers & rain developing. Winds shifting NE-N and increasing to 10-20 mph, with higher gusts, on mid-upper elevation mountain ridges and plateaus by morning. Cloud bases dropping with dense fog formation on higher ridges. Temps dropping into the 50s to around 60 degrees by morning ( 40s wind chills at highest elevations ).
Saturday Morning-Afternoon
A chance of rain showers-drizzle. Windy & chilly. Low cloud bases with dense fog above 2500-3000 feet along and north of the High Knob Massif & Tennessee Valley Divide. Becoming partly cloudy late. Winds N to NE at 10-20 mph, with higher gusts. Temps steady or falling into 50s lower-middle elevations and dropping to the 40s-low 50s in upper elevations. Wind chills in upper 30s to lower 40s at highest elevations. Milder conditions lee of the High Knob Massif into river valleys of the Clinch, Powell & Holston drainages.
Saturday Night Into Sunday Morning
Becoming clear. Chilly. Windy across mid-upper elevation mountain ridges. Winds N-NE 5-15 mph, with higher gusts, along middle elevation ridges-plateaus below 2700 feet. N-NE winds 10-20 mph, with higher gusts, on upper elevation mountain ridges. Temperatures dropping into the 30s to lower 40s ( frost and/or fog could occur in any valleys that might be able to decouple, with light-calm winds ). Wind chills in 30s and 40s along ridges-plateaus, except locally into the 20s to lower 30s during gusts on high peaks.
Sunday Afternoon
Sunny. Seasonably cool. N winds 5-15 mph, with higher gusts. Temperatures varying from mid-upper 40s in the upper elevations to the mid 50s to around 60 degrees ( wind chills continuing to be a factor at highest elevations ).
Sunday Night Into Monday Morning
Clear. Frost possible in colder valleys. Winds NNW-NNE at 5 to 15 mph, with some higher gusts, along the mid to upper elevation mountain ridges. Temperatures varying from the upper 20s to lower 30s in colder valleys to the upper 30s to lower 40s ( fog possible along main streams-lakes ).
*Multiple nights with the potential of frost formation in mountain valleys is being watched for into the new work week.
Weather Discussion ( Big Changes )
Saturday Night Update
My update Saturday Night is to decrease sustained wind speeds a little into Sunday AM, following a very windy Saturday afternoon in mid-upper elevations.
Orographic forcing aided rainfall amounts as the pressure gradient increased Saturday across the High Knob Massif area, with 1.00″ to 1.50″ rain amounts being common.
This included the water plant at Appalachia Lake where Mark Quillin reported 1.38″ of rainfall. This was in contrast to only 0.31″ of rain measured in Clintwood and just 0.25″ measured lee of the mountains in the Tri-Cities.
High Knob Massif MesoNET
An average MIN of 42.1 degrees was observed in the wetland valley during the past 10 days ( i.e., September 28-October 7 period ).
Most of the massif area was engulfed in clouds, with high valleys holding steady near 60 degrees until early Saturday afternoon when a temperature drop started ( temps were several degrees cooler atop adjacent ridges all day ).
By late Saturday afternoon wind chills were notable along the high ridges, as my Field Studies In Microclimatology Class can testify too ( despite layered clothing it felt cold as strong winds swirled fog & occasional rain showers across the high country ).
Many leaves came down, and partially covered roads in the massif, as color is really increasing from Wise on upward in elevation. Hopefully, below the highest ridges, this leaf fall will not be detrimental to the upcoming peak.
Previous Discussion
ALERT For Dense Fog Developing Into Saturday Morning At Middle-Upper Elevations Along And North Of The High Knob Massif & Tennessee Valley Divide
High Knob Massif Webcam – University Of Virginia’s College At Wise
Orographic pilatus clouds capping the High Knob Massif late Friday was a signal of big weather changes into this weekend, as the pressure gradient around Matthew cranks up orographics behind a passing cold front pushing across the Appalachians. This means a CHILLY weekend ahead!
NAM 4 KM Model 10 M Wind & Streamline Forecast at 6 AM Saturday
As Hurricane Matthew crawls along the South Carolina coast an increasing northerly flow will develop across the Appalachians, increasing upslope into the High Knob Massif and Tennessee Valley Divide during the predawn-morning hours of Saturday. This will cause a drop in cloud bases, with dense fog formation engulfing higher terrain locales above the 2500-3000 foot level ( e.g., amid, or just above, the Town of Wise & Sandy Ridge on upward in elevation ).
NAM 4 KM Model 10 M Wind & Streamline Forecast at 2 PM Saturday
Drier air will eventually get pulled into the circulation, but low clouds ( and dense fog at higher elevations ) could last for much of the day Saturday before dissipating ( with a rise in cloud bases likely before a complete clearing by Saturday Night into Sunday morning when some valleys could then develop fog as others develop frost IF vertical mixing can locally relax enough to allow a run at dewpoints, which remains to be seen as Matthew churns ).
Most all of this weekend will be dominated by gusty winds across higher elevations, especially mountain ridges, where frost will not be able to form but true wind chills will be felt for the first time ( for a prolonged period ) this autumn.
As the pressure gradient begins to relax, Sunday Night into Monday AM will offer a much better chance for formation of frost in colder mountain valleys. Stay tuned.
*An ALERT For Dense Fog Formation May Be Needed For Middle-Upper Elevations Along & North Of The High Knob Massif-Tennessee Valley Divide Friday Night Into Saturday
*One or more nights with potential of frost formation is being watched for mid-upper elevation mountain valleys next week.
Overnight Into Thursday Morning
Mostly clear. Chilly. Areas of valley fog. SSE winds 5 to 10 mph, with some higher gusts, along middle-upper elevation mountain ridges. Temperatures varying from upper 30s to lower 40s in colder mountain valleys to upper 40s-low 50s.
Thursday Afternoon
Mostly sunny. Pleasant. Winds E-SE at 5-10 mph. Temperatures varying from low-mid 60s in upper elevations to the lower-middle 70s.
Thursday Night Into Friday Morning
Becoming partly-mostly cloudy. Winds ESE-SE at 5-20 mph, with higher gusts, on middle to upper elevation mountain ridges. Temperatures varying from the mid-upper 40s to the upper 50s ( warmest on exposed mid elevation ridges ).
Friday Afternoon
Mostly cloudy. ESE-ENE winds mostly less than 10 mph. Small chance of a shower or sprinkle. Temps varying from upper 50s to lower 60s in upper elevations to the upper 60s to lower 70s ( warmer in the Great Valley all these days ).
Friday Night Into Saturday Morning
Rain showers & rain developing. Winds shifting NE-N and increasing to 10-20 mph, with higher gusts, on mid-upper elevation mountain ridges-plateaus. Cloud bases dropping with dense fog on higher ridges ( possibly down to the level of Wise ). Temps dropping into the 50s to around 60 degrees by morning ( 40s wind chills at highest elevations ).
Saturday Morning-Afternoon
A chance of rain showers-drizzle. Windy & chilly. Low cloud bases with dense fog above 2500-3000 feet along and north of the High Knob Massif & Tennessee Valley Divide. Becoming partly cloudy late. Winds N to NE at 15-25 mph, with higher gusts. Temps steady or falling in the 50s lower-middle elevations and dropping to the 40s-low 50s in upper elevations. Wind chills in upper 30s to lower 40s at highest elevations. Milder conditions lee of the High Knob Massif into river valleys of the Clinch, Powell & Holston drainages.
Weather Discussion ( Chilly Weekend )
Thursday Evening Update
As CAT 4 Matthew gets closer to the Florida coast I have updated to define conditions here through Saturday PM.
Infrared Image At 8:15 PM Thursday – October 6, 2016
Some significant rain will rotate west-northwest into the Appalachians Friday Night-Saturday, with a sharp cut-off likely near or just southwest of the High Knob Massif and Tennessee Valley Divide. The heaviest rains are expected generally along and east-southeast of the Blue Ridge, with at least the chance for some heavier amounts in favored orographic locations with increasing upslope along the western side of the mountain chain.
NAM 12 KM Model Total Rainfall Forecast – 2:00 PM Thursday Model Run
The timing between arrival of a cold front, from the west, and moisture wrapping around the broad circulation of Matthew will help to dictate where the heavier downpours develop.
NAM 12 KM Model Total Rainfall Forecast – 8:00 PM Thursday Model Run
The NAM Model group is wanting to develop rain along the Appalachians as moisture interacts with a cold front from the west, with a sharp cut-off producing little to no rainfall in foothills of Kentucky westward of the mountains. This will bear watching given the increasing upslope along the western side of the mountain chain from enhanced flow around Matthew ( i.e., an increasing pressure gradient ).
NAM 4 KM Model Total Rainfall Forecast – 2:00 PM Thursday Model RunNAM 4 KM Model Total Rainfall Forecast – 8:00 PM Thursday Model Run
Regardless of local rain amounts, cloud bases will be dropping on increasingly gusty NE-N winds into Saturday with upsloping and chilly conditions expected ( especially for locations along and NE-NW of the High Knob Massif and Tennessee Valley Divide ). Skies will become partly cloudy, then clear, as drier air invades later Saturday into Sunday ( with windy conditions continuing ).
The Bottom Line…A very chilly weekend is ahead for the mountains with the first true wind chill factors of the autumn season expected across higher elevations as a cold frontal passage combines with an increasing pressure gradient around Matthew. Rain & low clouds ( dense fog at higher elevations ) into Saturday giving way to clearing, gusty conditions later Saturday or Saturday Night-Sunday before conditions calm.
Previous Discussion
Temperatures are chilly in mountain valleys tonight, with 40s to lower 50s at Midnight Thursday, as sinking air north of Hurricane Matthew is drying the vertical column.
NAM 12 KM Forecast Sounding Above Wise At 2:00 AM Thursday – October 6
The effect being further enhanced with SE-SSE downsloping along the western side of the Appalachians at low-levels.
Water Vapor Image At 12:15 AM Thursday – October 6, 2016
Hurricane Matthew is looking better organized on IR imagery in recent hours, after passing Cuba & Haiti, and continues wobbling toward the northwest ( the wobble due to fluxes in convection ).
IR Image of Hurricane Matthew at 12:30 AM Thursday – October 6, 2016
The current National Hurricane Center track forecast is closely following the 51-member European Ensemble MEAN.
National Hurricane Center 11 PM Advisory – October 5, 2016
Meanwhile, back here in the Appalachians the current indirect influences from Matthew will become a little more notable into Friday Night-Saturday as the pressure gradient increases. Windy conditions and dropping cloud bases will develop along the mountains on upsloping northerly flow to generate chilly temperatures and some showers-drizzle ( the greatest coverage of showers-rain is expected along and well east of the Blue Ridge ).
Saturday could be a very chilly day along and north-northwest of the High Knob Massif and Tennessee Valley Divide, with temps in the 50s dropping into the 40s at upper elevations ( temps falling into the 50s at lower-middle elevations ). Windy conditions will make it feel colder, especially along mountain ridges-plateaus. Stay tuned for updates.
Partly to mostly clear. Areas of dense fog. Light N to NE winds mostly less than 10 mph on mid-upper elevation mountain ridges. Temperatures varying from the low-mid 40s in upper elevation valleys to the low 50s.
Monday Afternoon
Partly cloudy. Light NE-ENE winds. Temperatures varying from upper 50s to lower 60s in upper elevations to the low to mid 70s.
Monday Night Into Tuesday Morning
Partly-mostly cloudy. Areas of dense valley fog. Winds becoming ESE-SSE at 5-15 mph, with higher gusts, along middle-upper elevation mountain ridges. Temperatures varying from the 40s in cooler mountain valleys to mid-upper 50s.
Tuesday Afternoon
Partly-mostly cloudy. Small chance of a rain shower. Winds SE to SSE at 5-10 mph, with higher gusts. Temps varying from low-mid 60s in upper elevations to the mid 70s ( warmer, every day, as usual into the Great Valley ).
Tuesday Night Into Wednesday Morning
Partly-mostly clear. Areas of valley fog. Winds SE-SSE 5-15 mph, with higher gusts, on mid-upper elevation mountain ridges. Temperatures varying from 40-45 degrees in colder mountain valleys to the low-middle 50s.
Wednesday Afternoon
Mostly sunny. Winds E to NE at 5-10 mph. Temperatures varying from low-mid 60s in upper elevations to the mid-upper 70s.
Chilly temperatures are expected into Thursday AM with low dewpoint air developing beneath subsidence and drying north of Hurricane Matthew. MINS are forecast to vary from the 30s to lower 40s in colder mountain valleys to the mid-upper 40s.
Weather Discussion ( Mostly Dry )
Some light showers and sprinkles fell upon the high country of the High Knob Massif during Sunday PM, of October 2, as MAX temperatures climbed to around 60 degrees ( from AM MINS in the mid 40s ).
Changing Autumn Colors at Big Cherry Lake – October 2, 2016
Sections of upper slopes are developing significant color changes while lower slopes, below 2700-3000 feet, remain mostly green.
Color Changes In Big Cherry Lake Basin – October 2, 2016
October 2016 opened foggy and chilly in high valleys, with low temperatures dipping to around 40 degrees in the basin of Big Cherry Lake ( the lowest temps reported in Virginia ).
High Valley of Big Cherry Basin – Opening To October 2016
Following mid 50s to lower 60s during the afternoon of October 1, in wake of the High Knob Hellbender 10K Race, skies became mostly cloudy into Sunday and eventually produced ( as noted above ) some sprinkles-light showers.
NAM 12 KM Model Total Precipitation Forecast To 8 AM Thursday – October 6
While a few rain showers can not be ruled out, especially into Tuesday ( October 4 ), most of the week will again be devoid of any significant rainfall. In fact, the most recent run of the European Model says most of the next 10 days will remain generally dry ( save for a few showers ).
I measured a total of 0.68″ at Big Cherry Dam for the past week, which brought the September 2016 total to 3.40″ ( well below the average ) and the yearly tally to 51.48″ ( with missing moisture in evaporation between hand-measurements not being included ).
Model Composite Track Forecast For Hurricane Matthew
The main weather focus in the eastern USA this week will be on powerful Hurricane Matthew. While the mean of all tracks remain off the Atlantic Coast, the exact track is far from set and all interests along the coast will have to keep watching this cyclone very closely.
While no direct impacts are expected locally, indirect effects will, as I so often teach, be observed in the form of sinking air that acts to rebuild and reinforce the upper ridging over the region to allow days to warm as the storm approaches ( this could allow nights to trend cooler in mountain valleys if drying around and below 850 MB occurs due to the general subsidence regime – especially along the western Appalachians ).
Model Composite Track Forecast For Hurricane Matthew
A distinct and important westward trend in the composite of model forecast tracks for Hurricane Matthew has been observed during the past 18-hours ( compared the above graphic to the one issued at 2:00 AM or 06z on October 3 ).
Low clouds. Dense fog widespread at upper elevations into the overnight hours, then lifting bases possible by morning. Locally dense fog at middle to lower elevations. Scattered showers with local thunder & small hail possible ( drier to the west & southwest of Pennington Gap ). Light & variable winds. Temperatures dropping into the 40s to lower 50s.
Friday Afternoon
Cloud bases lifting. Becoming mostly to partly cloudy. Seasonally cool. W-SW winds 5-10 mph, with higher gusts, especially on mid-upper elevation ridges-plateaus. Temps varying from the mid-upper 50s in the upper elevations to the mid-upper 60s.
Friday Night Into Saturday Morning
Partly-mostly clear. Chilly. SSW-SW winds 5-10 mph, with higher gusts, along mid-upper elevation mountain ridges. Temperatures varying from the upper 30s to lower 40s in colder valleys of the upper elevations to the mid 40s to around 50 degrees ( milder ridges ). Areas of valley fog.
High Knob Hellbender 10K Race Forecast
A seasonally cool but dry race is forecast this year, with some low clouds and fog possible in a layer that could stream along the base-lower portions of the massif from Powell Valley during the morning, on light SW flow, prior to dissipating into partly cloudy skies as temps warm.
Some variations in temperature along the race course this year will include a start in the 50s ( following early AM lows in the 40s ) within downtown Norton, a rise to around 60 degrees above Legion Park and below the Flag Rock Recreation Area junction with State Route 619, then a fall back into the 50s with increasing elevation above Flag Rock ( these temps for the 10:00 AM to Noon period ).
Please note that breezy SSW-SW winds at upper elevations will make conditions feel more like the upper 40s to lower 50s.
10:00 AM Start In Downtown Norton
55 degrees – A Layer of fog and clouds will be possible just above downtown, along lower slopes of the massif, otherwise partly cloudy conditions are expected.
12:00 Noon At Summit of High Knob
54 degrees ( a crisp feels-like temperature of 48-52 degrees ) beneath partly cloudy skies. SSW to SW winds of 5-10 mph, with some higher gusts.
*This forecast is a go. Good Luck to all runners & walkers!
Saturday Afternoon
Partly-mostly sunny. Winds S-SW 5-10 mph, with some higher gusts ( especially on mid-upper elevation ridges ). Temperatures varying from upper 50s to lower 60s in the upper elevations to the upper 60s to lower 70s ( warmer southward into the Great Valley ).
Saturday Night Into Sunday Morning
Partly to mostly clear. Winds SSW-WSW winds 5-15 mph, with higher gusts, on middle to upper elevation mountain ridges. Temperatures varying from 40-45 degrees in cooler mountain valleys to the lower-middle 50s.
Weather Discussion ( Autumn Changes )
A significant weather change in conditions was observed during the Tuesday PM to Thursday PM period, as noted by these dramatically contrasting views from the High Knob Massif Webcam at UVA-Wise.
High Knob Massif Webcam – University Of Virginia’s College At Wise
From pristine autumn skies to a complete obscuring of upper elevations within low clouds and dense fog ( below ).
High Knob Massif Webcam – University Of Virginia’s College At Wise
Conditions in upper elevations of the High Knob Massif were chilly prior to this radical conditions change on September 29, as noted by these readings recorded on the High Knob Massif MesoNET.
High Knob Massif MesoNET – September 27, 2016
Although green still dominates the forest, and autumn color is running well behind its typical schedule in upper elevations of the High Knob Massif, some changes are occurring and many trees are now on the brink of changing-brightening with colorations.
Early Color Changes – Northern Slopes of High Knob Massif – September 28
Note along the crest of this high ridge that some trees are flagged, a rather atypical observation for deciduous northern hardwoods versus spruce-fir crestlines ( where coniferous growth is more conducive to flagging of limbs at high elevations ).
High Knob Massif MesoNET – September 28, 2016
AM MINS dipped into the upper 30s to lower 40s within colder mountain valleys during September 28 ( 42 degrees in Clintwood ). Coldest conditions occurring in places not impacted by dense fog. Wetland valleys upstream of Big Cherry Lake having dense fog on every night so far during September in places near Beaver dams.
Black Mountain MesoNET – September 29, 2016
Note wind chills into the lower 40s have been recorded at 4031 feet elevation by the Black Mountain MesoNET, with likely somewhat lower chills at places like High Knob Meadow ( Lookout ).
Conditions in upper elevations during September 29 were simply nasty, with dense fog all day across the High Knob Massif where numerous showers ( some with thunder-hail ) held temperatures in the 40s to lower 50s during the PM.
European Model 500 MB Analysis At 8 AM Thursday – September 29, 2016
A upper-level low has cut itself off from the main jet stream flow across North America. It will be key to conditions that are observed on Saturday for the High Knob Hellbender.
NAM 12 KM Model 925 MB RH Forecast At 10 AM Saturday
Looking ahead, my forecast for this year’s grueling climb from downtown Norton to the summit level of High Knob, the infamous High Knob Hellbender 10K Race, is dependent upon the current upper-level low moving enough to allow for drier air to stream into the area.
NAM 12 KM Model Forecast Sounding At 10 AM Saturday
Should this low be slower to move than models currently indicate, which is always possible with upper-lows, then a more cloudy race could result.
Partly to mostly clear. Areas of river valley and lake fog. Light winds becoming SW at 10-20 mph, with higher gusts, by morning on middle to upper elevation mountain ridges. Temperatures varying from 50s in cooler mountain valleys to the mid-upper 60s.
Monday Afternoon
Partly-mostly cloudy. A chance of showers-thunderstorms, then showers and thunderstorms becoming likely by late in the afternoon-early evening. More humid. Winds SW-WSW 10-20 mph, with higher gusts ( especially along mid-upper elevation mountain ridges ). Temperatures varying from upper 60s-lower 70s in upper elevations to the upper 70s to lower 80s ( warmer south into the Great Valley ).
Monday Night Into Tuesday Morning
Any evening showers ending. Turning chilly. Low clouds and dense fog at higher elevations above 2500-3000 feet. Winds becoming NNW-N at 5-10 mph, with higher gusts, on mid-upper elevation mountain ridges. Temps dropping into the 40s to lower-middle 50s ( warmer in lower elevation valleys of the Clinch, Powell, Holston river basins ).
Tuesday Afternoon
Becoming mostly sunny. Cool. Light WNW-NW winds. Temps varying from the 50s to lower 60s in upper elevations to the upper 60s to lower 70s.
Tuesday Night Into Wednesday Morning
Partly-mostly clear. Chilly. Winds WSW-WNW at mostly less than 10 mph on mid-upper elevation mountain ridges. Temperatures varying from mid-upper 30s in colder valleys to the mid-upper 40s. Areas of valley fog, especially along major rivers-lakes. Patchy frost possible in coldest valleys.
Numerous showers & thundershowers, some with possible hail due to cold air aloft, are being monitored for mid-late week amid chilly air associated with a slow moving upper-level low pressure.
Weather Discussion ( Autumn Arrives )
The big weather news this week will be the arrival of true autumn air, with chilly conditions expected to be felt across the mountains ( some will say cold given Summer 2016 ).
European 51-Member Ensemble MEAN 500 MB Height Anomalies
While low dewpoint air will pour into the mountains Tuesday, and linger into early Wednesday, it appears that a slow moving upper level low pressure will develop to dominate mid-late week.
European 51-Member Ensemble MEAN 850 MB Temps & Anomalies
This type of pattern would generate very chilly conditions, especially in upper elevations, with exact positioning and movement of the upper low helping to ultimately dictate day to day weather during September 28-October 1.
Partly-mostly clear. Areas of valley fog. E-SSE winds generally less than 10 mph along mid-upper elevation mountain ridges. Temps varying from 50-55 degrees within cooler mountain valleys to the low-mid 60s.
Friday Afternoon
Partly cloudy. Winds becoming N to NE at mostly less than 10 mph. Temperatures varying from 70-75 degrees in upper elevations to the upper 70s to lower 80s ( warmer south into the Great Valley ).
Friday Night Into Saturday Morning
Mostly clear. Winds N-NE at mostly less than 10 mph along mid-upper elevation mountain ridges. Temps varying from low-mid 50s in cooler mountain valleys to low-mid 60s. Areas of valley fog ( especially along main rivers-lakes ).
Saturday Afternoon
Partly cloudy. Winds NNW-NNE at mostly less than 10 mph. Temps varying from low-mid 70s in upper elevations to the low-mid 80s ( warmer south into the Great Valley ).
Saturday Night Into Sunday Morning
Partly-mostly clear. Areas of valley fog. Winds light & variable. Temperatures varying from 50s in cooler mountain valleys to the low-middle 60s.
Sunday Afternoon
Partly-mostly cloudy. Chance of a hit-miss shower or thunderstorm. Light winds. Temperatures varying from 70-75 degrees in the upper elevations to the lower-middle 80s ( warmer south into the Great Valley ).
The potential for the first mountain valley frost of the season, especially in mid-upper elevation valleys, is being monitored for the middle of next week ( fog will be likely in river valleys ). If a cut-off upper low develops over the region this will limit frost potential, so stay tuned for later updates.
Weather Discussion ( Nice Saturday )
A great weather day graced the 10th Annual High Knob Naturalist Rally during Saturday, with a large turn out enjoying the many activities offered.
Majestic Late PM Light In High Valley of High Knob Massif – September 24, 2016
As expected, the afternoon MAX reached the low-middle 70s following morning MINS in the low-mid 50s.
High Knob Massif High Valley MesoNET – 11:00 AM to 4:50 PM
The Saturday PM MAX reached 74 degrees at one high valley location, with another sensor located in the upper valley recording a MAX of only 72 degrees. Humidity levels and temps were higher than typical for this time of year, of course, but conditions did feel nice ( even cool through the morning ) in the shade during the PM.
Previous Discussion
A pleasant week of weather conditions in the mountains will continue into Saturday, with nearly ideal temperatures expected for the 10th Annual High Knob Naturalist Rally.
*As always this is sponsored by The Clinch Coalition and their supporters and is an awesome event for all ages. And it’s free, within the Clinch Ranger’s District’s Jefferson National Forest.
Fern Glade In Upper Valley of Big Cherry Basin – September 20, 2016
Max temperatures in the upper valley of Big Cherry Lake basin reached 74 degrees during September 11-20, with a mean daily high of around 71 degrees ( 3200 ft elevation ).
Conditions on Saturday ( September 24 ) should be similar amid the High Knob Lake Recreation Area, at an average elevation of 3500-3600 feet above mean sea level. Warm for this time of year, but pleasant versus lower elevations within the Clinch, Powell, and Holston drainage basins.
NAM 12 KM Model Total Rainfall Next 84-Hours
The NAM 12 KM Model, as well as the GFS and now European, are forecasting a chance for showers & thunderstorms to be on the increase during Sunday into Monday ahead of a cold front that should usher in the coolest air mass of the early autumn season by Tuesday-Wednesday ( September 27-28 ).
Operational European Model 850 MB Temp Anomalies – DAYS 5-9
The most recent European Ensemble MEAN has trended closer to the operational run of the model, increasing the odds that cooling will be significant during Sept 27-29.
European 51-Member MEAN 850 MB Temp Anomalies
Although the upper air trough next week will be progressive and lift back out, with upper ridge formation occurring once again, lingering lower dewpoint air in wake of the upper trough will allow nights ( especially in valleys ) to continue running on the cool side through the final days of September 2016.
Mostly clear. Areas of dense valley fog. Winds N-NE at 5-10 mph along mid-upper elevation mountain ridges ( mainly at or above 2700 feet elevation ). Temperatures varying from the low-mid 50s to around 60 degrees.
Tuesday Afternoon
Partly to mostly sunny. NE winds 5 to 15 mph, with some higher gusts along mountain ridges. Temperatures varying from upper 60s to low 70s in upper elevations to the upper 70s to lower 80s ( hotter south into the Great Valley ).
Tuesday Night Into Wednesday Morning
Mostly clear. Areas of valley fog. Winds NNE-ENE 5-10 mph with higher gusts on mid-upper elevation mountain ridges. Temperatures varying from 50-55 degrees in cooler valleys to lower-middle 60s.
Wednesday Afternoon
Partly-mostly sunny. NE-ENE winds 5-10 mph, with higher gusts. Temperatures varying from low-mid 70s in the upper elevations to lower-middle 80s ( hotter south into the Great Valley of eastern Tennessee ).
Wednesday Night Into Thursday Morning
Mostly clear. Areas of valley fog. Winds ENE-ESE 5-15 mph, with higher gusts, along middle-upper elevation mountain ridges. Temperatures varying from 50-55 degrees in cooler mountain valleys to lower-middle 60s ( exposed ridges ).
Thursday Afternoon
Partly-mostly sunny. ENE-ESE winds 5-10 mph. Temps varying from low-mid 70s in upper elevations to the low-middle 80s ( hotter south into the Great Valley ).
Weather Discussion ( Soaking Rain )
A real soaker of a rain fell across the mountain area during Sunday into the wee hours of Monday ( September 18-19 ).
National Weather Service Observations
Rain developed early and the PM MAX only reached 68 degrees in Clintwood during Sunday, amid a good amount of fog. The upper elevations in the High Knob Massif were obscured in dense fog, or orographic clouds, well into Monday morning.
Specific rainfall totals reached 1.87″ in the City of Norton, making 2.43″ in September and 43.38″ in 2016, with 2.08″ observed in Clintwood ( 2.18″ Sept / 32.69″ in 2016 ). More than 2.00″ of rain also fell across much of the High Knob Massif where 2016 totals are now 50.00-55.00″+ .
NAM 12 KM Model Total Rainfall Forecast Next 84-Hours
The mountain region is back into another dry stretch, being caught between heavy rainfall producing systems well to the northwest and east. Yes, again a subsidence regime will rule.
While a shower working in from the east or northeast can not be completely ruled out, most of the region along and west of the Cumberland Mountain range looks to remain dry.
GFS Model Total Rainfall Forecast To 8 AM Sunday – September 25, 2016
If conditions remain dry through Saturday that would be great news for the 10th Annual High Knob Naturalist Rally to be held in the majestic High Knob Lake Recreation Area.
*As always this is sponsored by The Clinch Coalition and their supporters and is an awesome event for all ages. And it’s free.
The first real cool shot of Autumn 2016 is still being tracked to arrive by the middle of next week. Initial indications are that the coolest air will move across the Great Lakes into the northeastern USA, but some impact is expected across the southern Appalachians ( stay tuned for details ).
