Mountain Area Forecast ( Dec 18-20 )

Dense Freezing Fog Will Now Be The Main Factor Into Monday For Locations At Middle To Upper Elevations Along & North Of The High Knob Massif & Tennessee Valley Divide ( Above 2000-2500 Feet In Elevation )

*Visibility near zero at times, within this orographically generated upslope cloud deck of freezing fog, is expected.  Caution Is Advised.

An ALERT Continues For Strong Winds At Middle To Upper Elevations Into Sunday.  Wind Gusts Of 30-50+ MPH Will Continue Into The Predawn-Sunrise Period.

ALERT For Icing From Mid-Morning To Afternoon Hours On Sunday With Freezing Rain And Sleet In Addition To A Flash Freeze Up In Counties Along Either Side Of The Virginia-Kentucky Border.

**Vertical temperature profiles and wind fields indicate that a change to freezing rain then to sleet will be more likely than snow given that SW-WSW flow continues aloft in the 825-725 MB layer.  

This keeps an above freezing layer aloft which will change snow falling aloft into rain that will initially freeze, before changing into sleet as the cold air deepens in the vertical above the surface.  In addition, any wetness lingering from heavy morning rain will tend to freeze on porches, decks, and other surfaces amid a rapid temperature drop between mid-morning and early afternoon.

 With LUCK the bulk of precipitation will push east before temps drop below freezing; however, freezing fog, drizzle and a general freeze up remain likely.  Therefore I feel that an ALERT is the right call for everyone to become aware of these threats ( as it takes only a bit of icing to cause problems ).

Overnight Into Sunday Morning

Showers with a chance for thunderstorms.  Locally heavy rainfall.  ROARING Winds.  SSW-SW winds 15-25 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet.  Winds SSW-SW 20-35 mph with higher gusts along upper elevation mountain ridges.  Mild with temperatures steady or rising into the 50s to near 60 degrees.

Sunday Mid-Morning Into Sunday Afternoon

Rain mixing with and changing to freezing rain & sleet.  A period of snow possible.  Windy.  Turning sharply colder.  Low cloud bases-freezing fog at upper elevations dropping into mid elevations late.  SW winds shifting NW to N at 5-15 mph, with higher gusts.  Temps falling into the 30s and 20s, except into the upper 10s at highest elevations by late.  Wind chills dropping into 10s & 20s, except single digits at highest elevations by late.

Sunday Night Into Monday Mid-Morning

Low clouds with dense freezing fog across middle to upper elevations.  Chance for light snow, sleet or freezing drizzle.  Winds N-NE at 5-15 mph, with higher gusts.  Temperatures dropping into the mid 10s to mid 20s ( coldest at highest elevations ).  Winds chills in the single digits & 10s, except around or below 0 degrees in gusts on highest peaks.

Monday Mid-Morning Through Monday Afternoon

Cloudy to mostly cloudy below 3600 feet.  Partly to mostly sunny above 3600 feet.  Cold.  Winds N-NE at mostly less than 10 mph.  Temperatures varying from mid 20s to low 30s ( upper 20s to around 30 degrees Norton-Wise ).

Monday Night Into Tuesday Morning

Low clouds below 3600 feet in the evening, then low clouds mainly below 3000 feet by morning.  Partly cloudy above.  Cold.  Winds Light & variable with vertical elevation.  The temperatures varying in the 20s beneath clouds.  Temps rising to around or above freezing along upper elevation mountain ridges above 3300-3500 feet.

Weather Discussion ( Nasty Mess )

Monday Morning Update

I have updated my forecast for today to account for epic conditions in the vertical due to a strong inversion that I have highlighted now for a couple days.

Elevations below 3600 feet this morning are beneath a layer of clouds which marks the inversion, while conditions are mostly sunny ( with some high clouds ) above that level.

If vertical mixing increases enough it could mix out the low clouds into middle elevations ( with sunshine ) later today; however, it is likely that lower elevations will remain under the cloud deck.  Middle elevations also have a good chance of staying under the deck.  If so, then it will be a raw, cold day for those places within middle-lower elevations.

Right now, conditions are simply epic with at least a portion of the heavily rimed crest zone of the High Knob Massif like an island above a sea of clouds ( Black Mountain’s summit and the twin Beartown’s are also above the deck ).

Sunday Afternoon Update

The main focus now will be on freezing fog and a continued drop in temperatures tonight into Monday morning.  Light frozen forms of precipitation may continue to fall at times, with a warm layer aloft generating a strong inversion that will trap clouds well into Monday.

This is an orographically forced or generated fog so visibility will at times be near zero.  Extreme Caution is advised given that it is also a freezing fog with riming.

While Winter Wonderland Conditions will be developing into Monday, it will take a while before all the terrain will again become visible given this cloud trapping inversion aloft ( the same warm layer which kept snow flakes at a minimum, with freezing rain and sleet being the primary forms reported Sunday ).

Meanwhile, SLOW DOWN and Be Safe…Checking For Ice On Porches, Decks, Walks, Roads And Anything  You Need To Be Walking-Traveling On Outside.

Mid-Day Sunday Update

I have updated my forecast to allow for some snow mixing in or a period of light snow.  Temperatures have dropped into the upper 20s on High Knob as of 11:30 AM with some flakes of snow mixing with freezing rain-sleet.

Prior to freeze up the event total precipitation reached 1.84″ on Eagle Knob of the High Knob Massif.  That means more than 2.00″ given tremendous overnight winds = a lowered rain gauge catch.  

Peak wind gusts around 50 MPH were recorded in Wise, where sustained speeds as high as 35 MPH occurred.  Peak wind gusts of 50-70+ MPH were common at higher elevations.

Sleet is now the main precipitation type in Clintwood, so all forms of frozen will be possible into this afternoon.

While the bulk of precipitation will be moving east of the area, the main concern continues to be icing from temps dropping below freezing into this afternoon along with lowering clouds bases and formation of freezing fog at middle-upper elevations along and north to northwest of the High Knob Massif and Tennessee Valley Divide.  Light frozen forms of precipitation will continue to be possible.

Previous Discussion

Reference My 121716 Forecast Discussion For More Details.

For those who love snow I have bad news, especially if model forecast soundings in the vertical are on target.

Winter Wonderland Conditions are; however, likely to develop with freezing rain, sleet, freezing fog and, just perhaps, freezing drizzle all occurring.  This will be the most pronounced for those living in middle to upper elevations ( above 2000-2500 feet ), but all of this area should remain alert to these threats.

Models tend to handle temperatures aloft better than within the more complex realm of the planetary boundary layer; thus, more confidence can generally be put into forecast temperatures above the DIRECT frictional influence of terrain features.  They can still be in error, of course, if anything can lift the air enough to erase the warm layer ( in this case ).  A SW-WSW flow aloft is however a notorious set up for frozen forms at the surface other than snow.

The problem is the 825 to 725 mb layer, seen on these soundings by the RED TEMPERATURE LINE that crosses to the right ( above 32 F ) side of the dashed blue line which rises on an angle upward from the 0 ( 0 degree Celsius or 32 Fahrenheit point ) at the bottom.

Observe that occurs above the PBL ( boundary layer ) where low-level winds shift SW-WSW, as indicated by the wind barbs along the right side ( right of the RED-GREEN lines ).  So the model says that warmer air will continue to be transported aloft over cold air transport ( advection ) in low-levels.  That = A MESS.  The only good news being that heaviest precipitation should be east of the area by the time elevations below 3000 feet drop below freezing.

Arctic air will simply surge into the western slopes of the mountains Sunday but a lingering warm layer aloft, above the mountains, will cause snow falling aloft to melt into rain that first freezes below on surfaces near the ground before changing into sleet ( sleet will develop at low-mid elevations, especially, as cold air deepens vertically ).

It appears that the greatest potential for freezing rain and sleet of significance will be from the elevation of Wise upward; however, as many may understand from experience it takes only a little ice to cause problems.  So even if the bulk of precipitation is to the east there remains an icing threat from multiple factors.

Locations along and north to northwest of the High Knob Massif-Tennessee Valley Divide will also be at highest risk given that the terrain will tend to block and slow the incoming arctic air ( delaying it enough to help reduce the risk for locations lee of the front range into river valleys of the Clinch & Holston ).

*If the Virginia side of the border gets lucky ( the KY side being unlucky ) then maybe Black & Pine mountains might be able to slow down the cold air transport enough to allow most of the precipitation to push east.  Locations around and above 3000 feet; however, remain likely in this case to  have temperatures go below freezing before rain ends.  An abundance of lingering low-level moisture will support the formation of freezing fog at elevations above 2000-2500 ft, and freezing drizzle-sleet for all elevations, along & north to northwest of the High Knob Massif-TN Valley Divide from late Sunday into Monday ( so icy conditions to some extent look to be upcoming for most places in this area ).

Meanwhile, ROARING winds continue to be the story at mid to upper elevations along the Cumberland Mountains ahead of an approaching squall line and band of rain west of the Appalachians in Kentucky & Tennessee.

Many gusts over 50 mph ( to around 60 mph ) have been recorded at 2774 feet on Pine Mountain.  No forecasters should doubt that the high country above 3000 to over 4200 feet is not being blasted by this powerful SW flow which climatologically is the most windy and the most common trajectory in the Cumberland Mountains.

Winds are BLASTING the summit of the High Knob Massif with everything rockin’ tonight.  That was, of course, in my forecast and is no wonder given the potent SW wind field over top of the region ( below ).  It should not ever be forgot that hundreds of people live above 3000 feet in the massif, so it is not just trees and the mountain being blasted!

A total of 0.25″ to 0.50″+ ( 0.44″ highest rain gauge report but with significant undercatch in high winds ) has fallen so far across the High Knob Massif, with heavy rains and embedded thunderstorms likely by the predawn of Sunday.

Additional heavy precipitation amounts are likely into Sunday, especially as the strong SW winds help enhance amounts into lifting zones of the High Knob Massif and Black-Pine mountains.

The Storm Prediction Center maintains a marginal risk for severe thunderstorms up to the Virginia-Kentucky border, with the primary risk being wind damage.

Stay tuned to NOAA Weather Radio and your favorite media sources for possible watches-warnings and any other advisories that might be needed.

Temperatures across Kentucky at 3:25 AM Sunday:

Mountain Area Forecast ( Dec 16-18 )

Reference My Forecast For Today For The New Update

ALERT For A Major Storm System Impacting The Mountain Region Friday Night Into Sunday

Multiple Threats:

*Bitter COLD Air Will Continue To Be Felt Into Friday Morning With Single Digits & 10s

Bitter cold will continue to dominate the mountain area into Friday with single digits and 10s.  The coldest temps will occur in upper elevation mountain valleys and on ridges with 5 above to -5 below zero readings.

*HIGH Winds With ROARING S-SW Speeds Developing Friday Night Into Saturday

**Hurricane Force wind gusts ( 75 mph or higher ) will be possible at the High Knob Lookout on Saturday, especially during the pre-dawn to mid-morning period.  Any visitors should avoid going inside of the Lookout Tower where air funneling could blow someone over the walls ( it offers no protection ).

Gusty winds will begin developing across middle-upper elevations Friday and become STRONG Friday Night Into Saturday.  Gusts of 40-60+ mph will be possible by the predawn to mid-morning period of Saturday, especially within higher elevations.  Strong & gusty winds will continue into Saturday Night & Sunday.

*Mix-Frozen Possible At Onset Of Precipitation Into Saturday Morning – Especially In Colder Valleys And On Northern Slopes & North Slope Roadways Where Frozen Surfaces Will Take Longer To Thaw

Although strong winds and enhanced mixing will help air temperatures to rise above freezing across the area, some surfaces will remain frozen and/or partially frozen due to current bitter cold air and a limited above freezing time period at or above freezing prior to onset of precipitation.

*Heavy Rainfall & Embedded thunderstorms Will Be Possible In Advance Of Sunday Cold Air With Strong Rises Possible On Streams

 Strong SSW-SW upslope flow will again cause enhanced rainfall amounts along and southwest of the High Knob Massif and Tennessee Valley Divide.  Given precipitation totals of 7.00″ to 10.00″+ since November 28, and at least partially frozen ground, strong rises on streams will be likely in locations having heavy rainfall ( as will ponding within low-lying, poor drainage locations ).

*A Change To Frozen Precipitation & Snow Will Be Possible Sunday, With Potential For An Ice Up On Walkways, Porches-Decks, and Roads

Strong cold air transport back into the mountains behind a potent cold front Sunday will change rain into frozen forms that will transition into snow.  Accumulating snow will be possible, especially along and west-northwest of the High Knob Massif and Tennessee Valley Divide in counties along either side of the Virginia-Kentucky stateline.

Stay tuned to NOAA Weather Radio and your favorite media sources for updates on significant and rapidly changing weather conditions into this weekend.

Overnight Into Friday Morning

Mostly cloudy ( high clouds and a “ring around the moon” ).  Bitterly cold.  Light winds, except N-NW shifting S at 5-15 mph with a few higher gusts on upper elevation mountain ridges.  Temperatures in the single digits to lower 10s, except locally as cold as 5 above to -5 degrees below zero within valleys and on ridges at upper elevations ( before rising overnight into morning on the highest ridges ).

Friday Afternoon

Cloudy ( mid-high altitude clouds ).  Cold.  SSE-S winds increasing to 5-15 mph, with higher gusts, on mountain ridges & plateaus below 2700 feet.  S-SW winds increasing to 10-20 mph, with higher gusts, on mountain ridges above 2700 feet.  Temperatures varying from mid-upper 20s to low-mid 30s ( coldest in upper elevations ).  Wind chills in the 10s & 20s ( coldest in upper elevations ).

Friday Night Into Saturday Morning

Cloudy.  Showers developing.  Thunder possible.  Caution for frozen surfaces at onset of precipitation.  Windy.  SSE-SSW winds 15-25 mph with higher gusts along mountain ridges-plateaus below 2700 feet.  Winds SSW to SW 20-35 mph, with higher gusts, on mountain ridges above 2700 ft.  Temps rising into the 30s & 40s ( wind chills in 20s & 30s ).

*Due to strong upslope flow the potential for low clouds and dense fog will need to be watched Saturday ( in addition to the showers ) from the High Knob Massif and Tennessee Valley Divide ( Norton-Wise area ) southwest, to contrast with higher cloud bases and/or periods of sunshine in downslope locations to the northeast where temps could be much milder in places like Pound & Clintwood.

Saturday Afternoon

Low clouds and fog from the High Knob Massif & Tennessee Valley Divide southwest.  Partly sunny to the northeast into northern Wise, Dickenson-Buchanan counties.  Chance of showers & drizzle in the upslope zone with chilly conditions.  Windy.  SSW-SW winds 10-20 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet.  Winds SSW-SW 20-35 mph with higher gusts along upper elevation ridges.  Temperatures varying from 40s to around 50 degrees in the upslope zone to the 50s to lower 60s in downslope locations.

*The highest temperatures may actually occur Saturday Night into the predawn of Sunday, especially if low clouds-fog develop on the strong upslope flow for the daylight hours of Saturday from Wise and Norton southwest.  Extremes in the area could vary from the upper 40s to around 50 degrees in upslope areas of the High Knob Landform to 60s in Pound, Clintwood, Haysi, and Grundy.

Saturday Night Into Predawn Of Sunday

Showers with a chance for thunderstorms.  Locally heavy rainfall.  Windy.  SSW-SW winds 15-25 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet.  Winds SSW-SW 20-35 mph with higher gusts along upper elevation mountain ridges.  Mild with temperatures rising into the 50s to near 60 degrees ( locally above 60 degrees in downslope locales of northern Wise, Dickenson-Buchanan counties around Pound, Clintwood, Haysi and Grundy ).

Sunday Morning Into Sunday Afternoon

Rain mixing with and changing to sleet & snow.  A chance for freezing rain.  Windy.  Turning much colder.  SW winds shifting NW to N at 10-20 mph, with higher gusts.  Temps falling into the 20s and 30s, except into the 10s at highest elevations by late.  Wind chills dropping into 10s & 20s, except single digits at highest elevations by late.

*A light to potentially moderate accumulation of snowfall will be possible during Sunday, especially along and west to northwest of the High Knob Massif and Tennessee Valley Divide.  Icing will also be possible, with amounts of ice versus snow dictating how much snow depth develops.  Stay tuned for later updates.

Weather Discussion ( Major Changes )

Saturday Afternoon Update

Roaring winds and strong SW upslope flow through the area I define as the High Knob Landform is doing its thing today, with low clouds, fog, light showers-drizzle and chilly temps versus locations adjacent to it with breaks in the overcast and temperatures of 55 to 60 degrees ( downsloping zone ).

I came to define the High Knob Landform ( geologic Powell Valley Anticline of the Cumberland Overthrust Block ) decades ago now partly due to this feature which I found to be an aspect of its long-term climatology.  An aspect of local weather that is predictable  as well, in advance.  During many winter seasons, of course, it can generate what has been termed as “freak” falls of snow; however, they are not freak at all and are part of this same pattern being experienced today ( just with colder air ).

Here it is more than just an inversion as is being experienced today upon the Tennessee Valley floor, within portions of the Tri-Cities.  

Here it is part of true orographic forcing that features deep, low-level cooling as air is lifted 3,000 vertical feet between northern Tennessee and the High Knob Massif.  It works to enhance mean annual precipitation amounts and is one factor critical to making the High Knob Massif area the wettest terrain in Virginia.

Rainfall totals today have topped 0.25″ in the High Knob Massif versus only a few hundreds in the downslope zone.

Differences from southwest to northeast along air flow illustrates the change in conditions from the zone where air is rising toward the High Knob Massif-Tennessee Valley Divide ( above ) to where air sinks downstream of the high terrain ( below ).  Similar milder conditions have been experienced today in Pound and Clintwood, as was forecast, amid the downsloping zone ( 57.3 degrees being the max reached so far in Clintwood ).

All temperatures will continue to warm through the atmosphere in advance of a strong cold front that will arrive by Sunday morning.  Winds will also continue to ROAR as they are doing outside my home right now!

*I do not understand why wind advisories were dropped, or never issued to begin with in some cases, amid the middle of such a very strong wind event.

Meanwhile, a Tornado Watch is now in effect across much of middle Kentucky and Tennessee and are next to Winter Weather Advisories ( something rarely seen ).

The most complicated part of this system is to come, as convection continues to develop ahead of a sharp temp plunge that will change heavy rain to frozen forms on Sunday.  The vertical temp profile is going to become absolutely critical to how much frozen precipitation actually falls and in what proportions.

Check back late tonight as I make updates to the forecast based upon the evolution of convection and new forecast model data.

Friday Evening Update

Winds are now ROARING across mountain ridges above 2700 feet in elevation, with sustained speeds around 30 mph and gusts of 40-50+ mph.

Sheltered valleys remain at or a little below freezing, with most other locations now easing above 32 degrees.

Light showers forming in the lift of the High Knob Massif have wet the ground and camera on Eagle Knob, as the lower atmosphere is beginning to moisten up.

Friday Afternoon Update

I have updated for a complete overcast with thickening of mid-high clouds across the region.  I have lowered my MAX temperatures, which already were the coldest forecast, by a little due to this with low-mid 30s at low-mid elevations.  Some places may not reach this until the end of this day.

SSW winds are increasing at high elevations, with much stronger speeds coming into Friday Night.  Waves are already forming in the turbulence aloft.

Note that it is the long wave lines, which go across this view from right to left, that are the orographic waves.  Other waves that are smaller looking have formed due to wind shear aloft with WNW flow streaming across developing S-SW low-level flow.

A strong temperature inversion will be developing into Saturday and may keep strong winds above many valleys until later mixing can break up the inversion.  That already has been factored into my forecast, as you note I talk about “mountain ridges-plateaus” when referring to winds.

The inversion formation shows up very well on this NAM 12 KM Model forecast sounding above Norton-Wise at 7 AM Saturday, with much milder temperatures at High Knob Massif summit levels versus low elevations.  Also note that wind speeds reach maximum intensity near the inversion top ( where red-green temperature-dewpoint lines bulge back toward the right ).

With little sun to heat up surfaces today, only what has been able to penetrate through clouds, this raises concern for frozen surface development overnight into Saturday Morning when everyone will need to take extra caution as precipitation develops – with valleys having a higher potential than high ridges.

Due to strong upslope flow and this inversion formation there will be a high potential for low clouds, damp and chilly conditions during most of Saturday in the upslope zone from the Tennessee Valley Divide ( e.g., Wise ) and High Knob Massif southwest toward Big Stone Gap into the Powell River basin of Lee County versus locations toward the northeast where low-level sinking ( inverse forcing ) will help warm up communities around Pound, Clintwood, Haysi and Grundy ( to note a few ), especially if strong mountain waves aid breakup of the inversion.

I have rearranged my Saturday forecast to account for this, breaking out Saturday Afternoon by itself to allow for temp warming in the SW upslope flow zone into Saturday Night and the predawn hours of Sunday.

Initial Discussion

Arctic and sub-tropical air masses will clash, literally right over top of the Mountain Empire, to generate WILD & LARGE changes in weather conditions through this weekend.

Turbulence ahead of an advancing arctic cold front interacted with the mountain terrain to generate a simply spectacular sunset above UVA-Wise on Thursday ( note the stacked lenticular clouds, at bottom of view, along edge of this wave filled cloud mass ).

An array of mostly high altitude clouds, with some mid-level clouds, will be the only thing to hold back temp drops overnight into Friday morning given an extremely dry air mass of true arctic origin ( and the fact that despite this time of year, and local climatology, there is no snow covering the ground to aid temperature drops ).

Such powerful winds, both near the surface and aloft, developing with this system are in direct response to huge temp changes, or gradients, forming between arctic and sub-tropical air masses.

Always a clear signal for a storm system of vigor, and one to be closely watched, is a 150-200+ MPH jet streak with a quad supporting upward vertical motion ( such as the Right Rear quadrant shown above ) moving over the mountains.  This will supply part of the dynamics aloft that will have to be closely followed to see how well they couple with low-level forcing generated by a strong push on the mountain terrain by a jet of powerful low-level winds.

*The most potent outcomes arise when upper-level dynamics and orographics couple together.  These settings can also be ones in which models struggle most to resolve mesoscale conditions.

The storm event is just coming into range of short-range, higher resolution models, so it is likely that some changes will occur in their output during the next 24-hours.

Given forecast wind speeds, by the European Model group, and now the short-range models, orographic forcing will become a bigger factor in the forecast than they are currently showing; although, you can see ( above ) how the NAM 4 KM tries to show major terrain features it has trouble resolving local topography.

Although thunderstorms are not expected to be a huge factor locally, the air will become unstable aloft initially and then vertically through the column from the surface to support embedded lightning & thunder.  A case where the currently cold atmosphere can be deceptive.  At the least, convective precipitation will be likely and this will be a factor in precipitation amounts to some extent.

The Drought Monitor does not always reflect local conditions in orographic areas, like the High Knob Massif, where with exception of Autumn 2016 the year has been seasonably wet.

While I understand farmers in the region have been hurt by a lack of summer-autumn rains, especially toward the VA-TN border, there is no longer a drought of any significance in the High Knob Massif area where the level of Big Cherry Lake has risen 9.8 vertical FEET this month to fill this major water supply up to its spillway.  Run-off along South Fork  of the Powell will be more significant for this event since the Dam will now not be holding back as much water.

It will be important to check back for updates and to keep alert for these rapid weather changes through this weekend.  While I tried to cover most of the bases, some forecast model twists & turns will undoubtedly arise as this major weather system develops.

Mountain Area Forecast ( Dec 13-15 )

ALERT FOR BITTER COLD CONDITIONS DEVELOPING WEDNESDAY NIGHT INTO THURSDAY WITH SINGLE DIGIT AND SUB-ZERO WIND CHILLS

Low Cloud Bases And Dense Fog Will Increase Across Mid To Upper Elevations Overnight Into Wednesday Morning, With Freezing Levels Dropping Into The Norton-Wise Area By Morning.  Caution Is Advised.

Overnight Into Mid-Morning Tuesday

Partly-mostly cloudy ( mainly high clouds following break up of low clouds-dense evening fog across high mtn ridges ).  Areas of fog possible in some lower elevation locations.  W-NW winds 5 to 15 mph shifting to SSE-SSW into morning.  Temperatures varying from 20s in colder valleys at upper elevations to the low-mid 30s, except rising temperatures overnight into morning along high mountain ridges.

Mid-Morning Through Tuesday Afternoon

Cloudy with light rain and showers developing.  Light SSE-SSW winds shifting SW by late.  Chilly with temperatures mostly in the 30s to low-mid 40s ( steady or falling into the 30s in upper elevations above 3000 feet ).

Tuesday Night Into Wednesday Morning

Cloudy with a chance for drizzle or high elevation light snow.  Cloud bases lowering with dense fog formation from around the elevation of Wise upward toward midnight into the morning.  Freezing fog developing by morning at locales above 2500 to 3000 feet.  NNW-NNE winds 5-10 mph, with higher gusts, along mid-upper elevation ridges-plateaus.  Temperatures varying from low-mid 20s to low-mid 30s, coldest in upper elevations.  Wind chills in the 10s and 20s.

Wednesday Afternoon

Mostly cloudy.  Low clouds possibly lingering across high elevation crestlines ( or lifting briefly ).  Seasonably cold.  N-NW winds mostly less than 10 mph.  Temps varying from upper 20s to lower 30s in upper elevations to the mid 30s to around 40 degrees.

Wednesday Night Into Thursday Morning

Partly to mostly cloudy.  Becoming windy and bitterly cold.  Chance of flurries and snow showers.  Light accumulations of very dry, fluffy snow possible along upslope side of the mountains.  WNW-NW winds 10-20 mph, with higher gusts.  Temperatures varying from to 0 to 5 degrees at highest elevations to the lower-middle 10s ( a little “milder” lee of the mountains into valleys of the Clinch, Powell, Holston ).  Wind chill factors in the single digits above and below zero, except -10 to -20 degrees below zero along upper elevation mountain ridges ( especially in the many gusts expected ).

Weather Discussion ( More Bitter Air )

Tuesday Night Update

I have updated the forecast to include more clouds through Wednesday into Wednesday night.  At the present time low cloud bases are engulfing locales above 3000 feet elevation, with very dense fog that is freezing at highest elevations.

As colder air arrives overnight, on northerly upslope flow, the threat for dense fog engulfing Wise and adjacent locales will increase with bases being in or just above the town.

Interesting clouds were observed above the High Knob Massif and Norton-Wise area during Tuesday ( above ) amid chilly showers.

As bitter air arrives Wednesday Night into Thursday there could be some snow showers; however, with no connection to Great Lake moisture sources any accumulations will be light ( as has been the recent trend ).

*Frozen precipitation types ( mainly sleet and/or freezing rain ) are being monitored at the onset of another storm system set to impact the region by late Friday Night-early Saturday before a change to all rain.  A change back to frozen types and/or snow will then be possible as cold air tries to catch deep moisture Sunday.  Significant rain will be possible in the middle.  Stay tuned for updates on this messy looking storm system. 

Previous Discussion

While more bitter air is on the way, the first topic is about another soaking rainfall with heavy 1.00″ to 2.00″ amounts in upslope locales of the High Knob Massif-Black Mountain corridor during Monday.

Whitewater creeks are again gushing with Big Stony Creek near the red alert level at 4 vertical feet of water depth.  A automated rain gauge at top of its 42 square mile watershed reported 1.40″ of rainfall; however, with 20-30 mph sustained winds and gusts of 40 to 50+ mph, there was at least a 20-30% undercatch on the gauge located at 4196 feet above sea level.

Caleb Ramsey measured 1.10″ of rainfall at the City of Norton Water Plant up to 9:00 AM Monday, with more rainfall after this time ( 3.76″ December / 52.33″ 2016 ).

The latest rainfall came between a couple of gorgeous sunsets, with mountain waves being illumnated late Sunday ( above ) as winds ROARED across the High Knob Massif in advance of the rains.  More waves were seen lingering after the rain event late Monday ( below ).

A much weaker system will develop more cold rain showers across the area Tuesday, with a wind shift to northerly into Tuesday Night-Wednesday Morning likely to lower cloud bases on upslope to engulf Wise and adjacent communities in dense fog ( by the Midnight-Sunrise period ).  Situations like this typically generate very dense fog that can be dangerous to those not expecting the low visibilities.

*If happening in the Tri-Cities this would generate a Dense Fog Advisory, but here it is nearly always overlooked and has simply become neglected despite covering hundreds of square miles in  the upslope advection zone ( orographically generated clouds ).

The main short-term feature will be another bitter hit of arctic cold air, with the MEAN of the 51-Member European Ensemble group forecasting temperature anomalies on the order of 20-30+ degrees Fahrenheit below average by early Thursday.  This will mean air temperatures near 0 degrees at the top of the high country, with 10s in “milder” locales at lower-middle elevations in the mountains.

Wind chill factors of 0 to -20 below zero are expected across upper elevations, especially amid the many gusts that will occur, with single digits to around 10 degrees at lower & middle elevations in the Cumberland Mountains.  CAUTION IS CERTAINLY ADVISED.

A dramatic temperature increase is expected as the next significant rain maker develops by this weekend, with a strong 850 MB low-level jet stream developing once again  to crank up orographics for yet more heavy rainfall.

Forecast vector wind flow is nearly ideal versus climatology for another heavy rainfall event within the High Knob Massif – Black Mountain corridor, with potential for more rain than just received.  This will need to be closely followed as it could push creeks hard enough to cause water problems.

While there could be some frozen on the edges, I can not stress enough yet again that the pattern is simply not what one would want for significant snowfall in the southern Appalachians.  In fact, it may be warming in the MEAN during the week before Christmas to continue what is currently the only drought going…a Snow Drought.

*Things can, of course, change quickly and this does not mean there will not be a White Christmas this year.  It also does not mean that there will not be significant snowfall this winter.  During the October-December 2015 period only a trace to 0.5″ accumulated in the mountain area.  Some 78″ followed during January-February atop the High Knob Massif, with 40-50″ in the Norton-Wise area.  So do not give up yet snow lovers!

Mountain Area Forecast ( Dec 10-12 )

Alert For Strong Winds Developing Mid-Late Sunday Afternoon Into Monday Morning With ROARING SSW- SW Speeds ( Widespread Gusts of 30-50+ mph )

Heavy Rainfall Will Also Develop Along The High Knob Landform And Upslope Locations Of The High Knob Massif And Tennessee Valley Divide Into Monday.  Rainfall Totals  Of 1.00″ to 2.00″ Are Likely, With Locally Higher Amounts.  Lesser 0.50″ to 1.00″ Totals Are Expected In Downslope Sites Across Northern Wise, Dickenson & Buchanan Counties ( e.g., Pound, Clintwood, Haysi, Grundy ).

Overnight Into Saturday Morning

Partly cloudy.  A few flurries in upslope locations of the High Knob Massif.  Bitter.  Winds SW-W at 5-10 mph, with some higher gusts, along mid-upper elevation mountain ridges.  Temperatures in the single digits to lower 10s.  Wind chills in the single digits along mountain ridges.

Saturday Afternoon

Partly to mostly sunny.  Cold.  Light and variable winds.  Temperatures varying from mid 20s to mid 30s ( coldest in upper elevations ).

Saturday Night Into Sunday Morning

Partly to mostly clear.  SSW-SW winds increasing to 5-15 mph, with higher gusts, on mid-upper elevation mountain ridges.  Temperatures varying from 10s in mountain valleys to the 20s, except temperatures rising slowly overnight into morning along mid-upper elevation slopes-ridges to around freezing.  Wind chills in the 10s and 20s, except single digits in gusts at highest elevations.

Sunday Afternoon

Partly sunny ( high clouds ).  Increasing clouds late.  Becoming windy.  S-SSW winds 5-15 mph, with higher gusts, below 2700 feet.  SSW-SW winds 15-25 mph, with higher gusts, on mountain ridges above 2700 feet.  Temps varying from mid-upper 30s to the mid 40s.  Wind chills in the 10s and 20s along upper elevation mountain ridges.

Sunday Night Into Mid-Morning Monday

Increasing clouds.  Rain developing into the predawn and morning.  Downpours likely in upslope locations, with wind driven rain.  Winds SSW-SW 15-25 mph, with higher gusts, on mountain ridges-plateaus below 2700 feet.  Winds SW 25-35 mph, with gusts over 50 mph in upper elevations.  Temperatures in the mid 30s to mid 40s, with strong late evening-overnight temp rises possible in downslope sites north-northeast of the High Knob Massif-Tennessee Valley Divide ( rising into mid-upper 40s to around 50 degrees ).

Mid-Morning Monday Into Monday Afternoon

Rain.  Heavy at times in the morning giving way to light rain and showers before diminishing to drizzle into the afternoon.  Low clouds with dense fog on highest ridges.  SW winds shifting W and decreasing.  Temperatures near steady or slowly falling in the 40s below 3000 feet.  Temps dropping into and/or through the 30s above 3000 feet.

*Strong rises on creeks draining the High Knob Massif and Black Mountain area ( along the VA-KY border ) will be possible Monday if heavy rainfall is realized, with efficient run-off on partially frozen ground in wake of prolonged arctic cold.

Weather Discussion ( Wet Pattern )

Some flakes of snow continue to fly along upslope sides of the High Knob Massif into this overnight, but only flurries.

A dusting up to around 0.5″-1″ accumulated into Friday morning, covering roads ( and riming trees at highest elevations ) for the first time this cold season.  Air temperatures Friday morning varied from bitter single digits at highest elevations ( with sub-zero wind chills ) to the lower 20s in more sheltered valleys of the lower terrain ( below 2000 feet ).

While the short-term drought, dryness, is now essentially history across the High Knob Massif with respect to total precipitation, a snow drought lingers.  Season to date snowfall totals are getting MUCH behind average.

Hundreds of Millions of Gallons of water have been gained by the Big Cherry Lake since November 30 via a total water level rise of 7.5 vertical feet ( with a slow rise currently continuing ).  The lake is now within a couple feet or so of being full, and I expect this next rainfall event to finish the job and likely generate overflow of the Dam’s spillway by the middle of next week.

Focus now shifts to the next weather system which develops a ROARING 60 knot 850 MB low-level jet up along the west side of the Appalachians by Sunday Night into Monday AM.

This forecast is supported by the European Model group which has 40 knot winds along the Virginia-Kentucky border by 7 PM Sunday, increasing into the night-Monday morning to around 60 knots.

These strong winds work to also crank up the orographics with moderate-heavy rainfall becoming likely along and southwest of the Tennessee Valley Divide and High Knob Massif into Monday.  Model rainfall predictions will be too low in this zone; although, rain gauges at higher elevations will struggle to catch this wind driven fall of rain.

Strong winds will cause significant rain gauge undercatches, especially in higher elevations, where rain will fall horizontally during a substantial portion of this upcoming event.

A stormy pattern continues through the extended, with a bounty of arctic air toward the north dropping into the USA; however, blocking from Greenland toward Alaska is not in the best position for significant snowfall over the southern Appalachians.  It could get close, and only a small change on any given event could be enough to allow the first significant snowfall to occur.  Local odds would be greatly increased if snow can get laid down to our north across the Ohio Valley ( which then would help nudge the baroclinic zone southward…and the mean storm track ).

Although the European shows a couple more shots of arctic air in the next 10 days, the ensemble MEAN illustrates that the southern Appalachians remain along the edge of the cold air ( in the mean ).

When an area is on the edge it is precarious, such that each event will have to be closely followed through the next 10 days to see if any tracks further south and/or amplifies enough to mix cold air with moisture over this region.

As snow cover increases to the north it will increase odds of getting a significant snowstorm developing south in time.  Until that happens; however, a snow drought is now the main precipitation anomaly in the massif area.

Some signs for a significant ( major ) storm are showing up out in the 7-10 day period, but heavy rain versus snow remains an open potential with rain currently being most favored.  Stay tuned for updates, as a major rainfall coming after December 12-13 and more cold air to freeze the ground would not be a good thing.

Mountain Area Forecast ( Dec 6-9 )

A Blast Of Bitter Cold Air & Wind Chills Will Strike The Mountains With Falling Temperatures Thursday Into Friday Morning.  Some Flurries And Snow Showers Will Be Possible But Any Accumulations Look Light.

Overnight Into Mid-Morning Tuesday

Cloudy.  Low cloud bases & dense fog at highest elevations.  Rain developing.  Downpours possible by the predawn and early morning.  Areas of fog becoming more widespread.  SE-S winds 5-10 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet.  Winds SSE-SSW 10-20 mph, with higher gusts, on mountain ridges above 2700 feet.  Temperatures widespread in the 40s.  Wind chill factors in the 30s to around 40 degrees.

Mid-Morning Into Tuesday Afternoon

 Rain, with local downpours, giving way to showers during the mid-late afternoon.  Areas of fog.  Winds shifting SW to WNW at 5 to 15 mph, with higher gusts, at elevations below 2700 feet.  Winds SW-WNW 10-20 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures varying from upper 30s to upper 40s.  Wind chill factors in the 30s ( locally below freezing on highest peaks in gusts ).

Tuesday Night Into Wednesday Morning

Cloudy and colder.  Cloud bases dropping to obscure mid-upper elevations along & north of the High Knob Massif and Tennessee Valley Divide.  Fog becoming freezing fog with riming in upper elevations ( above 3300 feet ).  NW-N winds 5-10 mph, with some higher gusts.  Temperatures dropping into the mid 20s to mid 30s ( coldest highest elevations ).

Wednesday Afternoon

Skies becoming partly to mostly sunny ( high clouds possible by mid-late afternoon ).  Light & variable winds.  Temps varying from low-mid 30s in upper elevations to the low-mid 40s ( warmer south into the Great Valley ).

Wednesday Night Into Mid-Morning Thursday

  High clouds early giving way to lowering clouds with a chance of valley rain showers-mix and mountain snow showers by morning.  Winds WNW-NNW 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges.  Mountain valleys dropping into 20s before rising overnight toward morning with increasing clouds.  Mountain ridges falling to around freezing in mid-elevations and into the middle 20s in upper elevations.  Wind chills in 10s & 20s.

Thursday Afternoon

Becoming partly to mostly sunny.  Steady to slowly falling temperatures.  Winds WNW-NW at 10-20 mph, with higher gusts.  Temperatures dropping into the middle-upper 20s to lower-middle 30s by late afternoon, except into upper 10s to lower 20s atop highest peaks by late.  Wind chills in the 10s and 20s, except single digits on upper elevation mountain ridges ( milder leeward of mountains into the Great Valley ).

Thursday Night Into Friday Morning

Becoming mostly cloudy.  Turning bitter cold.  Chance of flurries and snow showers.  Winds WNW-NW 5-15 mph, with higher gusts.  Temperatures varying from single digits to lower 10s at highest elevations to the 10s to lower 20s.  Wind chills in the single digits & 10s, except locally below zero in gusts on highest mountain ridges.  Riming on upper elevation mountain ridges ( mainly above 3300 feet ).

 A dusting up to 1″ of snow will be possible, with some slick patches.  As of 5:30 AM Friday the air temperature was 9 degrees on Eagle Knob of the High Knob Massif ( wind chills of -5 to -10 degrees below zero are being reported in gusts above 4000 feet ).

Clouds, flurries and snow showers will remain likely into mid-morning before beginning to dissipate.

Weather Discussion ( Arctic Blast )

Tuesday Night Update

While my forecast was very good through Tuesday, I’ve had to do some major surgery on the next few days as models struggle with this first major arctic blast.  Small changes could result in some accumulating snow, but right now the consensus is for little to no accumulation as arctic air hits.

Meanwhile, another heavy rainfall event of up to 2.67″ atop Eagle Knob of the High Knob Massif since Sunday AM has whitewater rolling out of the massif, with the stream gauge on Big Stony Creek peaking at just 13″ below the flood stage.  This all has fallen following a literal flat-line ( below ) through Autumn 2016, with little variations on steep creeks.

A general 7.00″ to 8.00″ of total rainfall since November 26 in the massif has generated around 6 vertical feet of water level rise on Big Cherry Lake, and it is still rising.

Most of 2016 had abundant precipitation, with many surges in whitewater to ROARING levels during the January 1 to September 1 period ( below ) prior to the flat-lining.

The biggest water flows coming with rain + melt down of winter snowpacks early in the year ( during Winter 2015-16 ).

Precipitation for 2016 has now reached into the 60.00″ to 65.00″+ range in upper elevations of the High Knob Massif, from Big Cherry Lake basin into High Knob Lake basin.

Previous Discussion

Another soaking rain Tuesday will give way to a brief shift into upsloping NW-N winds Tuesday Night into Wednesday Morning that will lower clouds bases once again along the windward slopes of the High Knob Massif-Tennessee Valley Divide, with another round of light riming possible at high elevations above 3300 feet.

Meanwhile, the HRRR Model seems to be doing best at picking up the orographic enhancement along windward slopes of the Cumberland Mountains ( High Knob Landform and the Tennessee Valley Divide ), Cumberland Plateau and Blue Ridge overnight into Tuesday.  Rainfall amounts in the favored upslope locations should range in the 1.00″ to 1.50″ category for this event ( potentially heavier, at least locally, pending the influence of upper dynamics ).

The main focus during this forecast period is on a blast of arctic air pouring south from northwestern Canada into the USA, with arrival time here set for Thursday into Friday.

This has now been well advertised for some time, especially by the European Ensembles, with a sprawling 1050 MB High Pressure across northwestern Canada.  Although relatively short-lived, this will be real deal arctic cold and will mean business for the time in which it grips the Appalachians.

While cold is certain, the amount of snowfall remains in question with the best current thinking being for upper elevations to have the best opportunity for 1″ or more of accumulation.  Little to no accumulations are currently expected across lower elevations ( especially below elevations of 1500-2000 feet ).

Stay tuned as this potential will be updated.

Mountain Area Forecast ( Dec 2-4 )

Overnight Into Friday Morning

Partly to mostly clear.  Cold.  Winds W-NW 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges.  Temperatures varying from 10s to low 20s in colder valleys to the upper 20s to lower 30s.  Wind chills in the 10s & 20s along higher ridges.

Friday Afternoon

Mostly sunny.  Seasonally cold.  W-NW winds 5-15 mph with some higher gusts ( especially along ridges ).  Temperatures varying from upper 20s to lower 30s in upper elevations to the upper 30s to lower-middle 40s.  Wind chills in the 20s and 30s, with 10s in stronger gusts on the highest peaks.

Friday Night Into Saturday Morning

Becoming cloudy.  Chance of a few flurries.  Low clouds possible into morning with dense fog & riming at highest elevations along-north of the High Knob Massif-Tennessee Valley Divide ( mainly above 3000 feet ).  Winds NW-N 5-15 mph along mid-upper elevation mountain ridges.  Temps varying from around 20 degrees on highest peaks to the middle 20s to lower 30s.  Wind chills in single digits & 10s across upper elevations to the 20s.

Saturday Mid-Morning Into The Afternoon

Morning low clouds giving way to sunshine and high clouds.  Light NNW-NNE winds.  Temperatures varying from upper 20s to lower 30s in upper elevations to the upper 30s to low 40s ( milder in valleys of the Clinch, Powell, and Holston ).

Saturday Night Into Sunday Morning

 Increasing clouds.  Mixed precipitation or snow becoming possible into morning.  Light winds, except becoming SSE-SW at 5-10 mph on mid-upper elevation ridges.  Temps in the 20s to mid 30s ( steady or slowly rising along upper elevation mountain ridges before precipitation onset ).

Sunday Afternoon

Any high elevation snow or mixed precipitation changing to rain.  Otherwise, raw and rainy with nasty conditions.  Increasing SE-S winds at 5-15 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet.  Winds SSE-SSW 10-20 mph, with higher gusts, along upper elevation mountain ridges.  Temperatures in the 30s to low-mid 40s.  Wind chills in the 20s and 30s along higher ridges.

A chance for development of mixed precipitation, or snow at upper elevations, will be possible Sunday before a change to rain at all elevations by later Sunday into Monday.  Some light accumulations, up to 1″ or locally more on the highest peaks, will be possible before a change to rain.

Weather Discussion ( Active Pattern )

Late Saturday Night Update

A nice riming event into Saturday morning capped the high country with super-cooled water deposited upon vegetation and trees, producing growth into the wind.

Rime formation started during evening hours of December 2 and continued into the afternoon of December 3 at highest elevations.

The day ( Saturday ) was cold as even valleys in the high country struggled to break freezing, with 34 degrees being reached in the Big Cherry Lake basin by late afternoon.

Initially dry air is causing evaporation as a large shield of precipitation begins moving into the region.  Evaporative cooling is expected to cause a period of snow and/or mixed precipitation into Sunday AM before a change to all rain.  Lower-middle elevations are likely to have little to no accumulation, with locations above 3000 to 3500 feet having the best opportunity for some sticking.

This continues the active pattern and marks the start of another period with significant precipitation.  A major blast of cold air follows by late week as the polar jet stream slips farther and farther south over time, following the baroclinic zone that is developing southward ( a natural, predictable tendency driven through increasing snow cover to the north as I taught my class weeks ago in our Field Studies course at UVA-Wise ).

Previous Discussion

An active weather pattern continues in wake of a heavy rainfall event.  A few preliminary totals included:

Clintwood 1 W: 2.87″
Nora 4 SSE: 2.96″
Coeburn ( In Town ): 3.61″
UVA-Wise NWS: 3.62″
Appalachia ( In Town ): 3.97″
City of Norton WP: 3.98″
Black Mountain Mesonet: 5.00″

Widespread 4.00″ to 5.00″ rain amounts were common from the High Knob Massif to Black Mountain and northern parts of Lee County.  A general 3 to 4 vertical feet of rise occurred on steep creeks ( like Big Stony ) draining the high country surrounding High Knob, with similar rises observed so far on water supply lakes in the City of Norton & Big Stone Gap.

Some minor systems will impact the mountain area this weekend with a chance for lowering cloud bases into early Saturday that could generate a flake and/or some riming in upper elevations before giving way to high altitude clouds ahead of the next system.

Another healthy precipitation event is on tap for Monday into Tuesday ( December 5-6 ), with the latest run of the 51-Member European Ensemble group forecasting a MEAN basin average total of 1.00″ to 2.00″ ( again implying, as observed during the last event, some heavier totals ).

With chilly, drier low-level air in place initially by later Saturday into early Sunday the leading edge of developing precipitation could begin as some mixture or snow early on Sunday before changing into all rain at all elevations.  At least, that is the current thinking.  Stay tuned for updates.

In the extended, building Arctic High Pressure over northwestern Canada will become a major player in weather conditions across the USA by middle to latter portions of this first full week of December ( above ).

The coldest air will ooze its way down the eastern side of the Rockies before spreading eastward, with modification over mostly snow-free ground.  This will turn temperatures well below average by later next week, with the magnitude of the cold yet to be determined ( as is any snowfall ).

Mountain Area Forecast ( Nov 29-Dec 1 )

***A NO BURN BAN REMAINS IN EFFECT

ALERT For Strong Wind Gusts & Heavy Rainfall Developing Into The Overnight-Wednesday AM

Strong rises along creeks & streams will be possible along the Cumberland Mountains & Cumberland Plateaus into Wednesday with developing showers & embedded thunderstorms.  Locally strong to severe wind gusts, with downward transfer of high momentum air aloft, will also be possible.

Remain alert for ponding of water along roadways and in low-lying, poor drainage areas.  Some drains could be stopped up by leaves, with no major rains observed since mid-September.

Tune Into NOAA Weather Radio And Your Favorite Media Sources For National Weather Service Watches, Warnings & Advisories.

Tuesday Evening Into Wednesday Morning

Increasing clouds with showers and thunderstorms developing into the overnight-morning.  Locally heavy rainfall.  SSE-SSW winds increasing to 10-20 mph, with higher gusts, below 2700 feet.  SSW-SW winds 20-30 mph, with higher gusts, along mountain ridges above 2700 feet.  Evening temperature dropping into the upper 30s to low 40s in sheltered valleys, then rising in the overnight into the 50s.  Otherwise, temps in the upper 40s to middle 50s.

Wednesday Afternoon

Rain & showers diminishing during mid-late afternoon.  Windy.  SW winds 15-25 mph, with higher gusts.  Temps in the 50s to lower 60s, dropping during late afternoon into the 40s to lower 50s.

Wednesday Night Into Thursday Morning

Cloudy and  chilly.  Gusty.  A chance of drizzle or high elevation sleet pellets and flurries.  WSW winds 10-20 mph, with higher gusts.  Temperatures varying from upper 20s to the mid-upper 30s.  Wind chills in the 10s and 20s ( coldest at the highest elevations ).

Thursday Afternoon

Partly cloudy.  Seasonally cold.  Winds WSW-WNW at 5-15 mph, with higher gusts.  Temperatures varying from low-mid 30s in upper elevations to the low-middle 40s.  Wind chills in the 20s and 30s ( coldest at highest elevations ).

Weather Discussion ( Heavy Rainfall )

An outbreak of strong-severe thunderstorms over the Dixie States will spread heavy rain northeast to the Appalachians overnight into Wednesday morning.  Although storms will tend to weaken, locally strong-severe wind gusts could remain possible in stronger activity.

The Storm Prediction Center maintains a Marginal Risk for severe thunderstorms ( main threat being wind damage ).

Otherwise, an increasing pressure gradient will strengthen winds into the overnight-Wednesday and help orographic forcing for rainfall.

Winds will continue to be gusty into Wednesday Night and Thursday Morning as the mild air gives way to much colder air to the west behind this wave of rain and storms.

A couple more storm systems are on tap by this weekend and/or next week, with significant precipitation.  Ensembles currently being split on timing of the next system by this weekend.  Arctic air will also begin to make a move south into the USA next week.  Stay tuned for updates as details become more clear.

Mountain Area Forecast ( Nov 27-29 )

***A NO BURN BAN REMAINS IN EFFECT

ALERT For High ( ROARING ) SSE-SSW Winds Monday Into Monday Night.  Wind Gusts Of 40-60+ MPH Will Become Likely By Late Monday.  Caution Is Advised.

Tune Into NOAA Weather Radio And Your Favorite Media Sources For National Weather Service Watches, Warnings & Advisories.

Another period of STRONG winds will become likely Tuesday Night Into Wednesday.  Check back for updates.

Rainfall amounts by late Wednesday Into Thursday ( November 30 to December 1 ) could be enough to cause strong rises along creeks and streams, with enhancement expected to be greatest in favored orographic forcing zones along the Cumberland Mountains and the adjoining Cumberland Plateau into Tennessee ( esp. Wednesday ).

Overnight Into Sunday Morning

Mostly clear.  Cold.  Winds becoming light & variable, except along upper elevation mountain ridges where WSW-WNW winds of 5-10 mph will occur.  Temperatures varying from the 10s to mid 20s ( 10-15 in colder valleys versus steady or slowing rising temperatures along highest ridges into the 30s overnight into morning ).

Sunday Afternoon

Partly-mostly sunny ( high clouds ).  Milder.  Light SSW-SW winds increasing to 5-15 mph by sunset.  Temps from the mid-upper 40s to the mid-upper 50s ( coolest at highest elevations ).

Sunday Night Into Monday Morning

Increasing mid-high altitude clouds.  S winds 5-15 mph, with higher gusts, along mountain ridges below 2700 feet.  Winds SSW-SW 10-20 mph, with higher gusts, along upper elevation mountain ridges.  Temperatures varying from the upper 20s to lower 30s in colder valleys to the mid-upper 40s along exposed mountain ridges ( wind chills in the 20s and 30s on ridges ).

Monday Afternoon

Mostly cloudy.  Becoming windy.  SSE winds 15-25 mph, with higher gusts, below 2700 feet.  Winds SSE to S 25-35 mph, with higher gusts, on mountain ridges above 2700 feet.  Winds could gust over 50 mph at high elevations and with any mountain waves that develop.  Temperatures varying from 40s in the upper elevations to the 50s at lower-middle elevations.

Monday Night Into Tuesday Morning

 Cloud bases lowering-thickening with rain developing.  Periods of locally heavy rain possible.  Windy.  Winds SSE-S at 20-40 mph, with higher gusts, shifting SW by morning.  Temperatures steady or slowing rising in the 50s.  Winds could gust over 50 mph at high elevations and with any mountain waves that may develop ( esp. Monday Night ).

A second wave of heavier rainfall is currently expected to impact the mountain area on Wednesday.  Rainfall amounts may need to be closely followed, with strong rises possible along streams.  Stay tuned for later updates on this heavy rainfall potential.

Weather Discussion ( Significant Rain )

Sunday Evening Update

While there remains some run-to-run differences on rainfall amounts, models have settled on a significant rainfall event during the Tuesday-Wednesday period.

Orographic forcing will enhance amounts in favored places, such as the High Knob Massif where forecast trajectories are close to the long-term MEAN climatological air flow within the 925-850 MB zone ( esp. into Wednesday ).

*Although some models are splitting rainfall nearly evenly between the two waves, the second wave is likely to be most productive given that the atmosphere will ( by then ) be wet, saturated in nature and more unstable than initially.

Previous Discussion

Although Saturday temperatures struggled to break the freezing point at high elevations in the High Knob Massif, following morning riming on high peaks, the air mass will be changing in coming days as temperatures-dewpoints rise in advance of a couple waves of significant rainfall.

Air rises and the cloud thickens amid the ridge of each wave, while the cloud thins as air sinks into the trough of each wave ( think of oceans waves, except these are flowing through the fluid atmosphere ).

NW Flow mountain waves were prolific on Saturday, before moisture decreased by later in the day, with a couple dozen or more being counted on NASA visible imagery across the main generation zone from the VA-KY border to the TN-NC border.

Meanwhile, with clear skies and decoupled winds many mountain valleys will drop into the 10s by Sunday morning, with coldest valleys already in the 10s as of Midnight.  This is in contrast to temperatures which are rising into the 30s along higher mountain ridges ( from evening 20s ).

The main story this week will be the shift into a wet pattern that brings a couple waves of significant rainfall.  Heaviest rains are expected on Wednesday, just beyond the time of the above graphic.  It will be important to tune back in as this event comes into range of short-range models.

The European Model and its Ensemble MEAN has been very consistent in showing the heaviest wave of rain developing Wednesday into early Thursday, boosting totals.  Although precipitation spreads are large, varying from just under 1.00″ upward to 6.00″ on the 51-Members at the Wise ( KLNP ) gridpoint, the MEAN is around 2.00″ to imply that local amounts will be greater ( as also is well supported by local climatology ).

The development of ROARING SSE-SSW winds later Monday into early Tuesday will signal the upcoming rain event.

Mountain Area Forecast ( Nov 25-27 )

***A NO BURN BAN REMAINS IN EFFECT

ALERT For Dense Fog & Freezing Fog Across Upper Elevations Above 3000 Feet Into Saturday Morning.  Locally Lower Bases In Places Along & N to NW From The High Knob Massif and Tennessee Valley Divide.

As of 10:00 PM Friday air temperatures had dropped to freezing ( 32 F ) on the highest peaks, with low cloud bases producing dense fog at elevations above 3000 feet.  The freezing fog level will drop toward 3000 feet overnight, with very low visibilities at times.  Some freezing drizzle and/or drizzle will be possible into Saturday morning.

A Drop In Cloud Bases Is Being Monitored For Later Friday Into Saturday Morning On Upsloping NNW-NW Winds, with Freezing Fog Possible At Higher Elevations Above 3000-3300 Feet Along & North Of The High Knob Massif-Tennessee Valley Divide.

Overnight Into Black Friday Morning

Partly to mostly cloudy.  Areas of fog.  S-SW winds 5-15 mph with higher gusts ( especially along upper elevation ridges ).  Temperatures varying from 30s in mountain valleys to the 40s across exposed mid-upper elevation ridges.  Wind chills in the 30s along high ridges.

Friday Afternoon

Mostly cloudy.  Turning cooler.  Chance of sprinkles or light rain showers & drizzle.  N-NW winds 5-15 mph, with higher gusts on ridges.  Temperatures varying from the mid 40s to the mid 50s ( coolest at high elevations ).  Wind chills in the 30s and 40s ( coldest at highest elevations ).

Friday Night Into Saturday Morning

Cloudy.  Turning colder.  Low clouds with dense fog across higher ridges becoming freezing fog.  Winds NNW to NW at 5-15 mph.  Temperatures varying from low 20s to lower 30s  ( around 20 on highest peaks ).  Wind chills in the 10s & 20s.

Saturday Afternoon

Low clouds giving way to partly-mostly cloudy skies.  Winds NW-N at 5-10 mph.  Temperatures varying from 30s to low 40s ( around 30 degrees at highest elevations ).  Winds chills in the 20s & 30s ( around 20 degrees on highest peaks ).

Saturday Night Into Sunday Morning

Mostly clear.  Cold.  Winds becoming light & variable, except along upper elevation mountain ridges where NW winds of 5-10 mph will occur.  Temperatures varying from the 10s to mid 20s ( 10-15 in colder valleys versus steady or slowing rising temperatures along highest ridges into the 30s overnight into morning ).

Weather Discussion ( Wet Pattern )

Friday Night Update

A developing inversion below 850 MB is combining with cold air advection on upsloping NNW-NW winds to develop dense fog at high elevations along the Cumberlands.

Friday evening visibility has been very low on Eagle Knob of the High Knob Massif, with cloud bases having dropped downward to around 3100 feet in elevation as of 9:45 PM.

Freezing fog developing at highest elevations will drop into the overnight toward 3000 feet and could locally get a little lower along & north to northwest of the High Knob Massif.  Some freezing drizzle ( or just drizzle at lower elevations ) will also be possible into Saturday morning.

Cloud bases will lift into Saturday afternoon, but much of the day could remain cloudy along the upslope side of the mountains ( keeping conditions raw and cold ).

Previous Discussion

Smoky conditions again became a significant issue across the region on Wednesday, with lingering Thanksgiving day smoke beneath partly-mostly cloudy skies.

Wayne Riner Photograph Thoughts:
Wildfires filled the morning sky with smoke, turning the sun red and blurry.

Thanksgiving day MAXS reached around 50 degrees at highest elevations ( versus 60-65 at lower elevations ) with dense fog and low cloud bases obscuring high crest lines during much of the day.  Rainfall only totaled around 0.05″ at Big Cherry Lake Dam.

A wind shift Friday, with development of N-NW flow, will again push away the smoke and turn air chilly in the Cumberland Mountains.

Clouds and the potential for some freezing fog at high elevations is being watched for late Friday into Saturday morning and will be dependent upon the transport of low-level moisture into the area.  A low-level inversion could alter this, so stay tuned for updates.

There appears to be more uncertainty in the short-term, with fine details, than in the big picture of the longer term which looks to turn wet across the Mountain Empire.

Reference My 112316 Forecast Discussion For Previous Details.

There have been no changes in my previous thinking, with model ensemble groups actually becoming stronger and in better agreement with a flow pattern conducive to a shift into wetness across the Mountain Empire next week.

The European Ensemble MEAN basin average rainfall is around 1.50″ during the next 7 days, with 2.50″ to 3.00″+ during the next 14 days ( which means the potential for locally heavier amounts ).

A deepening southwesterly flow, with a tap into Gulf of Mexico moisture ( a lacking ingredient in recent months ), will be a key factor in this shift to wetness.

Rainfall can not be truly counted, of course, until it becomes measured in the rain gauge…but certainly the upcoming pattern offers much hope and represents a radical shift from Autumn 2016.

Mountain Area Forecast ( Nov 21-23 )

***A NO BURN BAN REMAINS IN EFFECT

Overnight Into Monday Morning

Clear & cold.  WNW-NW winds 5-15 mph, with higher gusts, along middle elevation ridges and plateaus below 2700 feet.  Winds NW at 10 to 20 mph, with higher gusts, on mountain ridges above 3000 feet.  Temperatures in the 10s to mid 20s, coldest in sheltered valleys and along highest ridges.  Wind chills 0 to 10 degrees on exposed ridges in upper elevations to the 10s and lower 20s.

Monday Afternoon

Mostly sunny.  Continued chilly.  NW winds 5-15 mph, with higher gusts.  Temperatures varying from upper 20s to low 30s in upper elevations to the upper 30s to lower 40s.

Monday Night Into Tuesday Morning

Becoming partly cloudy ( high clouds ).  Winds NW-N 5-10 mph, with higher gusts, on mid-upper elevation mountain ridges.  Temperatures varying from 10 to 15 degrees in the colder valleys ( locally even colder ) to middle 20s to lower 30s ( warmest on exposed ridges where temps will be near steady or slowly rising ).

Tuesday Afternoon

Partly-mostly sunny ( high clouds ).  Light & variable winds.  Near inversional conditions developing with temperatures varying in the upper 30s to upper 40s ( some valleys being nearly as cool or cooler than adjacent ridges ).  Milder in some spots, especially into the Great Valley.

Tuesday Night Into Wednesday Morning

Increasing clouds into the overnight-morning.  Winds S-SW at 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges.  Temperatures varying from 20s in colder valleys to the mid 30s to low-mid 40s on exposed ridges.

Weather Discussion ( Chilly )

Monday PM Update

My afternoon update is to zero in better on MIN temps tonight with 10 to 15 degrees expected in colder valleys to contrast with milder readings on exposed ridges ( no place; however, will feel mild ).  Local MINS may actually dip just below 10 degrees in coldest upper elevation valley spots if high altitude clouds do not thicken into the overnight.

*The coldest MIN temperature recorded in high valleys so far this autumn has been 8 degrees on the morning of November 13.

I took a NASA visible image today to illustrate how close sticking snow came to the NW upslope flow corridor of the Mountain Empire, highlighting the sprawling High Knob Massif and Mount Rogers for reference points.  Smoke plumes from the larger fires remain visible as well.

Previous Discussion

Following the first widespread snowflakes, sleet pellets, and a bit of riming at highest elevations, the air mass is seasonally chilly.  Although winds remain gusty on high ridges, deep valleys have decoupled ( winds calmed ) to allow sheltered valleys & hollows to join high ridges as coldest places into Monday morning ( locations between these extremes, in thermal belts, being “milder” ).

*The above being especially true for the Russell Fork & Levisa Fork basins, and locally in the Upper Tennessee Basin, where terrain is highly dissected.  Cross-barrier speed up flow will prevent this for mostly all locations along the eastern slopes ( Blue Ridge ) where turbulent mixing will be enhanced into Monday morning.

Wind chills Sunday evening have occasionally dipped to between 0 and 5 degrees along highest ridges with air temperatures around 20 degrees.  This is part of a sub-freezing period that will last into Tuesday in some places amid upper elevations of the High Knob Massif ( the longest sub-freezing period since last winter ).

With low sun angles it is getting that time of year in the mountains where temperature inversions by day, not just during night, become possible at times.  Tuesday will offer conditions at least favoring near inversional temps with some hollows-valleys being nearly as cool, or locally cooler, than adjacent ridges ( temperatures typically decrease with increasing elevation during day-time hours, with opposite or inversional conditions often being common at night ).

Finally I can say that I really like the look of the extended period upcoming during the next 1 to 2+ weeks, with rising pressures across the Arctic Basin and decreasing heights and pressures over Middle Latitudes that will be working together with a southward developing baroclinic ( temp ) zone to push the MEAN jet stream and storm track south.

While a mid-November change in the pattern has occurred, as I had been expecting for some time, everyone knows that what we are really seeking is precipitation to ease forest fire conditions and help depleted mountain lake water supplies.  This pattern is going to now make that possible as it continues to evolve during the remainder of November into early December.  Finally!

The above forecast chart at DAY 10 is certain to change, but the synoptic-scale trend is very clear with a much better setting for precipitation events ( both in the frequency of their occurrences and in amounts ) as November wanes and December arrives.  This shows up well, with highest confidence, on MEAN ensemble charts such as that of the 51-Member European group.

This means increased chances for needed precipitation with a strong signal for another major storm system showing up by the end of November.  The difference this time, with a southward suppressed jet stream, being the chance to tap Gulf of Mexico moisture for enhanced precipitation totals.

Although this most recent event was by no means a drought buster or even a good dent maker, the general 0.30″ of precipitation that was received in the High Knob Massif area was more than models forecast.  I expect this trend to continue as more and more events develop winds that push against the mountain terrain, cranking up the orographic forcing which helps make the massif area the wettest in Virginia over the long-term.

The 21-Member GFS ( USA ) Model ensemble group shows the basic agreement in increasing precipitation amounts across the eastern USA during the next couple of weeks.  Most importantly, the much more stable and reliable 51-Member European group supports this trend.  In addition, the Canadian Ensembles as well as the Japanese ( JMA ) Model are also on board.  Details of specific events, of course, to be worked out as time passes.

I do not go by any single model, but instead like to use ensembles and their MEANS ( especially the European ), with currently very good agreement among global model ensemble groups about this increasing precipitation trend.

*I am not legally allowed to show ( display ) the European Model or its Ensembles precipitation graphics, only the most basic charts from it.