ALERT For Torrential Downpours In Thunderstorms Along With Dangerous Lightning And The Possibility Of Local Wind Damage & Hail
A ring of fire convective pattern is expected to dominate mountain area weather conditions during the coming week with periodic disturbances enhancing potential for clusters of thunderstorms. Daytime heating and instability will also trigger localized storms.
Remain tuned to NOAA Weather Radio and your favorite media sources for possible watches and warnings which may be needed during coming days.
Overnight Into Monday Morning
Partly to mostly cloudy. Areas of valley fog. Chance of a shower or thunderstorm. SW winds 5-15 mph, with higher gusts, along mid-upper elevation mountain ridges. Temps in the middle 50s to the middle 60s.
Monday Morning Through The Afternoon
Periods of showers & thunderstorms. Some storms could be strong to locally severe. Downpours likely. Winds SSW to WSW at 5-15 mph with higher gusts in some storms. Temps varing from the 60s in upper elevations to the 70s to around 80 degrees middle-lower elevations ( especially northwest to north of the High Knob Massif-TN Valley Divide ).
Monday Night Into Tuesday Morning
A chance of showers & thunderstorms. Downpours possible. Winds SE-SW at 5-10 mph with higher gusts. Areas of fog. Warm and humid with temperatures in the upper 50s to middle-upper 60s.
Tuesday Morning Through The Afternoon
Chance of showers & thunderstorms. Some storms could be strong to locally severe. Downpours likely. Winds S-SW at 5-15 mph with higher gusts. Temps varing from upper 60s in upper elevations to the 70s to lower 80s. Warmer south into the Great Valley.
Tuesday Night Into Wednesday Morning
Chance of showers & thunderstorms. Downpours possible. Winds S to SW at 5-10 mph, with higher gusts, on ridges at elevations below 2700 feet. Winds SSW to WSW 10-20 mph with higher gusts above 2700 feet. Areas of fog. Warm and humid with temps in the upper 50s to middle-upper 60s.
Weather Discussion ( Stormy Pattern )
A stormy weather pattern is the main focus of this forecast period as intervals of showers and downpours in booming thunderstorms roam the mountain landscape.
Pickem-Stone Mountain of High Knob Massif – Afternoon of June 9, 2018
A thunderstorm rapidly developed over the High Knob Massif during the mid-late afternoon of June 9, with 0.60″ to 2.00″ of rainfall estimated by Doppler radar centered over the basin heads of Big Cherry Lake, High Knob Lake, and the Norton Reservoirs.
*The temperature on Eagle Knob dropped from an afternoon MAX of 71.1 degrees at 5:40 PM to 59.5 degrees at 6:20 PM. Significant run-off at an elevation above 4100 feet occurred amid the heavy rainfall.
While local, hit-miss gully washing thunderstorms are expected amid unstable air the real driver of the upcoming pattern will be disturbances moving across the mountains in a general WNW upper air flow, north of steamy, heat anchored over the southern Plains & southwestern USA.
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 1-5
A possible change during the 6-10 day forecast period by next weekend and the following week is being watched that could enhance the inflow of moisture from the deep tropics.
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 6-10
The Bottom Line…A temperate rain forest environment is expected to rule mountain area weather through coming days. Remain alert to changing conditions.
Hit-miss showers and downpours in thunderstorms will remain possible through Sunday before a refreshing air mass change arrives to kick off the first full week of June.
Summer 2018 Arrives Early At Upper Norton Reservoir
This will also mark the beginning of a new pattern that may continue well into the summer season.
European Model 500 MB Height Anomalies Forecast For June 2-6, 2018
A heat dome will remain anchored over the western USA, with a surface center developing near the Red River Valley along the Texas-Oklahoma border.
European Model 850 MB Temperature Forecast For June 2-6, 2018
The Mountain Empire will initially cool down into next week as much drier, low dewpoint air surges into the area around the eastern periphery of the blazing heat.
European Model 500 MB Height Anomalies Forecast For June 7-11, 2018
This sets up a nice stretch of weather, with chilly nights in mountain valleys, until later in the 6-10 day forecast period when the heat dome begins to expand. Due to wet ground and it’s position a ring of fire convective pattern may arise.
European Model 850 MB Temperature Forecast For June 7-11, 2018
While the core of the heat will remain locked in place well to the west, enough heat and instability will surge eastward to support clusters of showers and thunderstorms.
A pattern like this can become locked into place for an extended period of time, with periodic expansions of the heat dome triggering clusters of thunderstorms which hold true heat at bay and occasionally allow drier, less humid air to return during a heat dome contraction phase prior to the next expansion.
The above being the idealized scenario based upon current soil moisture variations across the nation, plus past climatology of similar settings.
A MCS ( Mesoscale Convective System ) – thunderstorm cluster will be pushing into the mountain area by mid to late afternoon ( 4:00 to 6:00 PM ) with a threat of damaging winds, lightning, and torrential rainfall.
*Several thunderstorm clusters will be moving east toward the Appalachians through this afternoon-evening. Models currently predict the second and third clusters to become most severe ( the final cluster possibly impacting a region west of the mountains…but remain alert throughout the remainder of this afternoon-evening ).
Storm Prediction Center – Damaging Wind Risk Forecast
The greatest threats remain west of the mountains according to the Storm Prediction Center, but local risks should be respected and have the potential to become greater than currently indicated with partial clearing in advance of the developing thunderstorm clusters adding to instability in high dewpoint air.
These storms will be capable of generating torrential rainfall, such that strong water level rises will also be at least a local threat ( ultimately, perhaps, becoming the greatest threat given such a wet May 2018…any activity that trains or moves repeatedly across the same corridor will therefore be especially prone to trigger flash flooding ).
GOES-16 Visible Image
Stay Tuned to NOAA Weather Radio and your favorite media sources for possible watches and warnings that may be needed.
ALERT Continues For Torrential Downpours In Hit-Miss Showers & Thunderstorms Through Tuesday
A local flash flood risk will continue to impact the mountain area through Tuesday amid muggy air.
A weak boundary passing across the mountains will decrease the threat of downpours from north to south during Wednesday, with much more pleasant air now expected during Thursday into Friday.
This will be a relatively short-lived break with a return of deep, tropical moisture expected to renew the threat of torrential rain producing showers and thunderstorms during the Memorial Day Holiday period.
Overnight Into Tuesday Morning
Partly to mostly cloudy with areas of dense fog. Chance of a local shower. Winds S to SW at 5-15 mph, with higher gusts above 2700 feet. Humid. Temperature varying from the upper 50s to low-mid 60s.
Tuesday Morning Through The Afternoon
Partly to mostly cloudy, warm and humid with hit-miss showers & thunderstorms. SSW-WSW winds 5-15 mph, with higher gusts. Temperatures varying from the lower 70s at upper elevations to the upper 70s to lower 80s.
Tuesday Evening Into Wednesday Morning
Partly to mostly cloudy with a chance of hit-miss showers and downpours in thunderstorms. SW winds 5-15 mph, with higher gusts, on mid-upper elevation mountain ridges & exposed plateaus. Winds shifting WNW-NW during the morning. Areas of dense fog in valleys. Temps varying from the 50s to low-mid 60s.
Wednesday Afternoon
Chance of a shower or thunderstorm, especially to the south. Becoming less humid and more refreshing from north to south, with deepening blue skies aloft. Winds NW-N at 5-10 mph with higher gusts.
Wednesday Night Into Thursday Morning
Clear & cooler. Areas of dense river valley and lower elevation fog. Light valley winds. Variable winds at generally less than 10 mph on mid-upper elevation mountain ridges. Temperatures varying from the lower-middle 40s in colder valleys to the lower to middle 50s ( coldest in upper elevations ).
*A returning tropical air mass will renew the threat of downpours during the Memorial Day Holiday Period into next week.
Weather Discussion ( Flash Flooding )
A pattern featuring torrential, hit or miss, downpours which started last week continues until a weak boundary gives the mountain area a short-lived break from late Wednesday into Friday.
Black Mountain Mesonet Data For The 1-Hour Period Ending At 5:25 PM
A 3.59″ deluge was captured by the mesonet site on Black Mountain, with 0.43″ accumulating in 5 minutes ( 5.16″ per hour rainfall rate ) during the height of the thunderstorm, late Monday afternoon ( pushing the May rainfall total to over 9.00″ ). By contrast, as has been the nature of this pattern, little rain fell only a short distance away in the City of Norton.
While the pattern since last week has possessed an easterly air flow component on numerous days, favoring the eastern side of the Blue Ridge where up to 10.00″+ of rain has locally fallen in May, it has also been characterized by a moisture feedback to further enhance the hit-miss nature of convective activity.
A convective feedback develops when heavy rainfall initially saturates a area to enhance evaporation-evapotranspiration into the overlying atmosphere over the local area. This then acts to aid new rainfall development via the local presence of extra latent heat release from moisture input into the overlying atmosphere.
At the same time, locations missed by heavy rainfall have much less moisture injection into the overlying atmosphere above them and a enhanced tendency toward having lighter rain amounts and missing torrential downpours.
These feedbacks can last for days to weeks in a persistent pattern, or change in their placement with a pattern break and shift back into a tropical-type of regime ( such as appears to be upcoming as the final days of May slip into early June ).
Black Mountain Mesonet Data For The 1-Hour Period Ending At 4:25 PM
Clintwood has been under a wet feedback in recent days with 1.60″+ of rain causing flash flooding in and around town during Monday afternoon ( pushing the May rainfall tally to over 6.00″ ).
Month To Date Rainfall Totals To 8 AM May 21, 2018
This recent pattern has generated a large difference between places like Mount LeConte ( at the summit of the Great Smokies on the western side of the mountain range with 2.24″ reported during May 1-20 ) and Mount Mitchell ( on the eastern side of the chain with 8.92″ reported during May 1-20 ). Totals, as noted previously, have also varied greatly over more localized distances. Reported 1981-2010 precipitation totals are nearly the same for both peaks, to illustrate the anomalous nature of this short-term pattern ( * ).
*Mount LeConte typically reports much more than Grandfather Mountain, but during this pattern it has received around a FOOT less rainfall to again illustrate the anomaly associated with recent easterly flow of tropical air into the eastern flank of the Blue Ridge ( long-term MEAN annual flow has a westerly component to favor Mount LeConte for the most precipitation ).
While the regional trend of heaviest rains along and east of the Appalachians has been captured by NWS stations and a composite of Doppler Radar rain estimates, the local scale hit-miss nature must be looked at using individual Doppler radar estimation graphics ( like the MRX example below ).
MRX Doppler Rainfall Estimate For Monday ( May 21, 2018 )
Rain amounts during Monday afternoon varied by 2.00″ or more in Dickenson County over just a few air miles. Ditto for numerous other locations across the region.
ALERT For Torrential Rain In Hit-Miss Showers And Downpours In Thunderstorms During May 15-18
Increasing moisture from the Gulf of Mexico and Caribbean will combine with disturbances in the westerlies to trigger showers and downpours in thunderstorms beginning on Tuesday afternoon and continuing through the work week.
Overnight Into Tuesday Morning
High clouds & mild. Light valley winds. Winds S-SW at less than 10 mph on mountain ridges-plateaus below 2700 feet. SSW to SW winds 5-15 mph, with higher gusts, on mountain ridges above 2700 feet. Temperatures varying from 50s in cooler mountain valleys to the mid-upper 60s.
Tuesday Afternoon
Mostly cloudy with a chance of hit-miss showers and thunderstorms. Heavy rainfall possible, especially by late afternoon. Light & variable winds, except gusty in heavier storms. Temperatures varying from upper 60s to lower 70s at highest elevations to the lower 80s ( warmer south into the Great Valley ).
Tuesday Night Into Wednesday Morning
Mostly cloudy with a chance of showers & thunderstorms, especially during the evening. Areas of fog, dense in places receiving heavy rain. Light winds, except S-SW at 5-15 mph with higher gusts on mid-upper elevation mountain ridges. Temperatures in the 50s to lower-mid 60s.
Wednesday Afternoon Through Friday Afternoon
Partly-mostly cloudy with intervals of hit-miss showers and downpours in thunderstorms. Locally heavy rain amounts. Temperatures in 60s & 70s during the day and 50s to lower 60s at night ( generally coolest at upper elevations ).
Weather Discussion ( Summer Pattern )
A jump straight from spring into a summer-like pattern during the past week will kick into high gear during coming days as tropical moisture increases both horizontally and vertically through the atmosphere.
Wild Stonecrop ( Sedum ternatum )
Although the forest canopy has now closed at the lower elevations in the foothills of eastern Kentucky, and within the Tennessee Valley, it remains partially to fully open in higher elevations of the mountains.
NAM 12 KM Model Total Rainfall Forecast Through 8 AM Thursday – May 17
Humidification and relative mildness will enhance the progression of spring upward through higher elevations during the next week to 10 days, with a threat for tropical downpours to signal that this transition into summer is for real with staying power through the next couple of weeks.
European Model Ensemble Mean 500 MB Height Anomalies: Days 6-10
Bermuda High pressure off the east Coast and a general southwesterly flow aloft will continue the warm, humid pattern with intervals of showers & thunderstorms during the next week to 10 days ( while it will not rain, of course, all the time, a wetter and more humid pattern is coming to signal an early arrival of summer in the Mountain Empire ).
True summer will arrive as the forest canopy matures across all elevations and evapotranspiration increases to feed low-level moisture back into the overlying atmosphere ( * ).
*This process starts in lowlands, below 2000 feet, and progresses upward through higher terrain locations as spring progresses. It annually begins during the explosive April 15-May 15 period, at elevations below 3000 to 3500 feet, and advances to the highest summits through late May into early June.
ALERT For Strong SE-SSE Winds Monday Into Tuesday Morning – Especially At Upper Elevations And Within Mountain Wave Zones Lee Of The High Knob Massif, Pine Mountain & Clinch Mountain
Strong SE-SSE winds are expected to continue and increase in strength through the remainder of the overnight into the daylight hours of Monday. Strongest winds are expected at upper elevations and within mountain wave zones such as the Clinch River Valley of Tazewell-Russell counties, Powell Valley in Wise County, and locations along & just lee of the Pine Mountain ridge near the Virginia-Kentucky stateline.
A wet pattern features the heaviest rain amounts along the eastern slopes of the Blue Ridge, and locally within upslope locations of the High Knob Massif-Cumberland Mountains.
Although Monday will feature a chance of thunderstorms, the better chance arises on Tuesday with locally heavy rain amounts expected.
Storm Prediction Center Thunderstorm Outlook – 8 AM Tuesday to 8 AM Wednesday
A cooler than average temperature pattern will continue this week, but signs for a shift to above average temps is now increasing as the month of May arrives.
Maples Budding In High Knob Lake Basin on April 21, 2018
Early spring conditions in the high country remain on display in wake of a cold April 1-21 period.
Observed April Temperatures In High Country of High Knob Massif
Numerous days with temperatures dropping into the 10s to lower 20s have been recorded, including up to 9.0 inches of snowfall at the highest elevations during the month.
Mostly clear ( high clouds ) and cold. Large vertical temperature difference between colder mountain valleys & exposed middle-upper elevation mountain ridges-plateaus. Variable winds generally less than 10 mph on ridges. Calm valley winds. Temperatures varying from low-mid 20s in the colder valleys to the mid-upper 30s to near 40 degrees on exposed mountain ridges.
Saturday Afternoon
Partly-mostly sunny with high clouds. Light winds. Temps varying from the upper 50s to low 60s at upper elevations to the upper 60s to lower 70s.
Saturday Night Into Sunday Morning
High clouds. Large vertical temperature spread developing between sheltered valleys and exposed mountain ridges and plateaus. Winds SSE-SSW at 5-10 mph, with higher gusts, on exposed mid-upper elevation mountain ridges-plateaus. Temperatures varying from upper 20s to mid 30s in valleys to the mid-upper 40s on exposed mountain ridges.
Sunday Afternoon
Becoming mostly cloudy. Small chance of a rain shower. Seasonally cool. SE-S winds 5-15 mph with some higher gusts on mountain ridges. Temperatures varying from the lower 50s to the lower-mid 60s ( coolest highest elevations.
Sunday Night Into Monday Morning
Cloudy & windy. Chance of rain showers by morning. SE-SSE winds 10-25 mph, with higher gusts. Temperatures mainly in the 40s to around 50 degrees ( falling to near 40 degrees at highest elevations ).
Weather Discussion ( Chilly Pattern )
Frosty cold conditions were developing in mountain valleys late Friday night into the early hours of Saturday as a chilly pattern continues for this time of year.
Mid-Spring Snow In High Knob Massif – April 16, 2018
Although large temperature swings have occurred during the past week, the general pattern continues to be cooler than average for mid-spring.
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 1-5
Upcoming days will continue to feature near to below average conditions through the end of April, with a trend on the European Ensembles toward cooler conditions in the final days of this month ( it would not be impossible that more April snowflakes fly, at least at high elevations ).
European 51-Member Ensemble Mean 500 MB Height Anomalies: Days 6-10
Coolest conditions in the next few days will occur along the eastern slopes of the Appalachian chain, on SE flow, before a shift back to the western side of the Appalachians occurs with a return of westerly to northwesterly flow. This period will also feature periods of rain and showers.
GFS Ensemble Mean Total Precipitation Forecast – Next 10 Days
ALERT For Strong To Roaring SW Winds Overnight Through Friday PM In The Cumberland Mountains
A strong pressure gradient in advance of the next storm system developing over the central United States will generated strong ( roaring ) SW winds through April 13.
Lonesome Pine Airport In Wise
Winds will be especially strong at mid-upper elevations and within mountain wave breaking locations along and north to northeast of the High Knob Massif and Black Mountain in northern portions of Wise-Dickenson counties ( in surges ).
ALERT For Accumulating Snow Mainly At Mid-Upper Elevations Through Early Monday Morning – Locally At Elevations As Low As 1500 Feet Along & North Of The High Knob Massif
Heavy Snow On Eagle Knob of High Knob Massif
Update At 5:30 AM Monday – Snow is falling heavy enough to begin sticking with temps above freezing in Clintwood, with roadways now covered at upper elevations within the High Knob Massif where temperatures are in the 20s.
Some slick travel will be possible on higher elevation roads, especially those that cross through terrain above 3000 feet, but due to the snowfall rates some brief slushy travel will also be likely at elevations below 3000 feet.
University Of Virginia’s College At Wise – Accumulating Snow
A upper air disturbance will be crossing the mountains into Monday with another round of snow. Most significant amounts are expected at elevations above 3000 feet, with lesser totals in middle elevations between 2000-3000 feet. Limited sticking is expected below 2000 feet. Due to the timing of heaviest snow, snowfall rates could be highest around-before AM commutes.
Snowfall Forecast – Monday AM ( April 9 )
1″ or less at elevations below 3000 feet
1″ to 2″ at elevations above 3000-3500 feet
Locally higher amounts are possible at highest elevations where air temperatures have been coldest ( generally near or below freezing during the weekend ).
Sunday Night Into Monday Morning
Lowering and thickening clouds with a rain-snow mix and snow developing during the predawn-morning. A period of moderate to heavy snow will be possible, especially at mid to upper elevations. Light NE surface winds to breezy SW winds highest elevations. Temps varying from the 20s to low-mid 30s.
Monday Morning Through The Afternoon
Morning snow giving way to a chance of light rain showers. SW winds shifting NW by late at generally 10 mph or less. Temps varying from 30s in upper elevations to the mid-upper 40s ( milder to the south into the Great Valley ). Orographic clouds ( dense fog ) at highest elevations.
Monday Night Through Tuesday Morning
Mostly cloudy. Chance of flurries, especially at upper elevations in the High Knob Massif, then becoming partly cloudy into morning. NW-N winds 5-10 mph with some higher gusts. Temperatures in the 20s to low-mid 30s, coldest at upper elevations. Wind chills in the 20s to low 30s, except 10s at highest elevations.
Tuesday Afternoon
Partly cloudy. Seasonably chilly. NW winds 5-10 mph. Temperatures varying from upper 30s to low 40s in upper elevations to the upper 40s to low-mid 50s ( milder south into the Great Valley ).
Tuesday Night Into Wednesday Morning
Mostly cloudy, then becoming partly to mostly clear by morning. Light WNW-NW winds. Temperatures varying from low-mid 20s in mountain valleys to the low-mid 30s, locally colder within high valleys of the High Knob Massif.
A warmer and more active spring rain-thunderstorm pattern is being monitored for late this coming week into RACE Weekend at Bristol. Stay tuned for later updates.
Weather Discussion ( Winter Lingers )
Monday Evening Update
A wintry morning in April greeted your Monday as snow fell briskly from the predawn through the post-sunrise period.
Eagle Knob of High Knob Massif at 7:09 AM – April 9, 2018 ( Moderate-Heavy Snow )
The greatest snow amounts occurred in upper elevations of the high country, with up to 0.28″ of water equivalent reported at both Big Cherry Lake Dam and on Eagle Knob ( 2-3″ of snow ).
To the east, Joe Fields measured 1″ of snow on the ground in the High Chaparral community at 8:30 AM. Amounts were generally less than 1″ at elevations below 3000 feet ( 0.5″ depth Clintwood ) with 0.6″ ( 0.06″ water equivalent ) reported by Wayne & Genevie Riner on Long Ridge of Sandy Ridge up to observation time.
Long Ridge In Dickenson County At 8:52 AM – April 9, 2018
I think humans and ALL Creatures Great & Small will certainly welcome true Spring when it finally arrives to stay this year, as the Ole Man Of Winter is beginning to ”wear out his welcome.”
University Of Virginia’s College At Wise
Snow melted away relatively fast in Wise but lingered throughout the day, beneath some nice mountain waves, along northern slopes at upper elevations.
*This latest event brings the days with 1″ or more of snow depth to 11 weeks for the 2017-18 winter season on northern slopes at the upper elevations in the High Knob Massif ( High Knob Lake Basin ).
While a few snow flurries are falling on High Knob tonight, the main focus through Wednesday will just be cold temps with mountain valleys experiencing another hard freeze during Tuesday Night into Wednesday AM.
Previous Discussion
Winter conditions will linger for a few more days before a major pattern change introduces a warmer spring-storm regime by late in the upcoming week-next weekend.
High Knob Massif Webcam – University Of Virginia’s College At Wise
An unseasonably cold Sunday morning for April greeted the mountain landscape with temperatures varying from 10s at upper elevations to the 20s ( 22 degrees in Clintwood ).
High Knob Massif Webcam – University Of Virginia’s College At Wise
Sunday remained so cold that extensive rime covering the high country of the High Knob Massif was actually able to linger throughout the daylight hours at highest elevations ( with snow on northern slopes ).
Quite a feat, indeed, for early April given that the Noon Solar Angle over the High Knob peak is now 61.1 degrees.
A solar angle of 61.1 degrees above the horizon at noon means that insolation ( incoming solar radiation ) is being spread across 1.14 units of surface area to generate a solar intensity of 87.5 percent of what it would be if the sun were directly overhead ( * ).
*The sun is NEVER directly overhead outside the tropics ( 23.5 degrees N to 23.5 degrees S ) and reaches a maximum over the High Knob peak during the Summer Solstice when the noon solar angle is 77.0 degrees ( June 21 ).
At that time insolation is spread across 1.026 units of surface area to generate a solar intensity of 97.4% of what if would be if the sun were directly overhead. Although MAX solar intensity occurs in June, due to seasonal lag-time forced by the slower accumulation of heat by surfaces the MAX in mean annual temperature typically does not occur until July. Interestingly, in the High Knob Massif, highest annual temps sometimes occur during Spring, prior to full leaf maturation, as clouds become so abundant during Summer that insolation is increasingly blocked.
European Model 850 MB Temp Analysis At 8 AM Sunday – April 8, 2018
The Sunday morning 850 MB temperature analysis from the European Model certainly showed this unseasonable April cold, and the anomalies ( below ) associated with it.
European Model 850 MB Temp Anomalies At 8 AM Sunday – April 8, 2018
Looking ahead this eastern USA trough will be replaced, at least for a short time, by ridging forming in advance of an upper wave that is looking increasingly potent on forecast charts by late this coming week into the weekend.
European Model 51-Member Ensemble Mean 500 MB Anomalies: Days 4-8
The focus in coming days will be on this wave and whether or not it does intensify to develop a negative tilt or if the wave maintains a positive tilt ( the former = a much more potent system ). Significant rain and thunderstorms could result amid an increasingly large temperature gradient if the wave undergoes significant amplification ( since cold air will remain abundant to the north across Canada ).
More cold air, and perhaps even more snow, will be possible if this upcoming wave amplifies significantly by around the April 15-16 period ( way out in time and merely speculation at this point, so check back for updates ).
Unseasonably Cold Conditions Will Continue Through Sunday In Wake Of A Wintry Saturday
Eagle Knob of High Knob Massif – Early Evening of April 7, 2018
Although a little snow stuck to roads at highest elevations, and the graveled lots, most of the 1″ to 2″ of accumulation was in the woods, on grass and above ground objects ( with rime formation on trees ).
A snowfall total of 1.2″ was officially measured in Clintwood during this late season event ( 1″ being the maximum depth ).
Former Alert
ALERT For Significant Snowfall Developing During The Predawn-Morning Hours Of Saturday ( April 7 )
A wave of low pressure following what is a climatologically favored track for significant snowfall will be developing by late Friday into Saturday, with rain changing to heavy, wet snow. While the most significant accumulations are likely at mid-upper elevations, the combination of recent cold and fast falling snow is expected to present a hazard across the area, especially in locations beneath upslope flow on NW-N air flow trajectories along & north of the High Knob Massif and Tennessee Valley Divide.
Snowfall Forecast – Saturday Into Saturday Evening
General 1″ to 3″ at elevations below 3000 feet in locations along and north of the High Knob Massif-TN Valley Divide
Target Snowfall of 2″ ( +/- ) 1″ for Norton-Wise. This implies the potential for 1-3″ of snowfall within the 2000-3000 foot zone.
Locally higher amounts possible above 3000 feet.
There is currently a low-moderate chance that snowfall could be heavy enough to cause power outages, so please check back for a update as the storm track and intensity becomes more certain.
Overnight Into Friday Morning
Partly cloudy ( high clouds ). Windy across ridges. SW winds 5-15 mph, with higher gusts, along mountain ridges and plateaus below 2700 feet. SW winds 10-20 mph, with higher gusts, on mountain ridges above 2700 feet. Temps varying from 20s to low 30s in sheltered valleys to the low-mid 40s on exposed middle elevation ridges-plateaus.
Friday Afternoon
Becoming cloudy with a chance of rain showers by late. SW winds 10-20 mph with higher gusts. Temperatures varying from low-mid 40s in upper elevations to the mid-upper 50s to around 60 degrees ( downslope locations ).
Friday Night Into Saturday Morning
Rain, heavy at times. Turning colder. Rain changing to a mix or snow into the predawn-morning. SW winds shifting NNW-NNE at 10-20 mph with higher gusts. Temperatures dropping into the 20s to lower 30s, especially in locations along and north of the High Knob Massif-Tennessee Valley Divide. Wind chills dropping into the 10s and 20s, except colder at highest elevations.
Saturday Morning Through The Afternoon
Cold & gusty with snow showers and snow, especially in the mid-late afternoon. Winds N-NNE at 5-15 mph with higher gusts. Temps varying from the lower 20s to the lower 30s in locations along & north of the High Knob Massif-Tennessee Valley Divide. Milder to the south into the Great Valley. Low clouds with riming at the highest elevations.
Saturday Night Into Sunday Morning
Evening snow showers & flurries giving way to clearing skies and diminishing valley winds. Unseasonably cold. Winds NW-N at 5 to 10 mph, with higher gusts, along the middle-upper elevation mountain ridges. Temps dropping into the low 10s to low-mid 20s ( coldest upper elevations ). Wind chills in the single digits and 10s, except colder in gusts at highest elevations.
Sunday Afternoon
Increasing mid-high altitude clouds. Light NW-NE winds. Temperatures varying from 30s at upper elevations to the 40s at lower-middle elevations ( especially along-north of the High Knob Massif-Tennessee Valley Divide ).
A major pattern change into Spring is being tracked for next week, with an increasing threat for strong-severe thunderstorms by late next week-weekend ( possible squall line ahead of a negatively tilted upper-air trough ). Stay tuned for later updates.
Weather Discussion ( Heavy Snow? )
Early Overnight ( Saturday ) Update
Forecast models continue to struggle with this system, with the European Model group solution being followed since it has been most consistent during the past couple days.
If the European Model solution holds, a low pressure will track south of the area and be over South Carolina by 8:00 PM Saturday, placing the Cumberland Mountains in northerly upslope flow and generating the best conditions for snowfall during the mid-late afternoon into the evening prior to clearing skies into Sunday.
Previous Discussion
Although forecast models have struggled to pinpoint this system, a clear southward trend has occurred during the past 24-36 hours with a mean track that now is fitting past climatology of heavy snow producing systems within the High Knob Massif area. Will this trend hold? Check back for an update into Friday night.
*Winter Storm Watches to the north may need to be moved south, as the heaviest snowfall is looking more likely across the higher terrain of the southern-central Appalachians.
Bloodroot ( Sanguinaria canadensis ) – April 5, 2018
Bloodroot, with a distinctive leaf ready to curl around it’s lovely bloom, has been covered many times in spring by snowfall in the mountains ( it is now blooming at low-middle elevations along & north of the High Knob Massif, and has been blooming, or even past bloom, in milder locations toward the southwest & south ).
European Model 850 MB Analysis At 8:00 AM Thursday – April 5, 2018
Ideal cooling conditions beneath High pressure allowed temperatures to drop into the 10s amid high valleys and along highest mountain ridges in the High Knob Massif during morning hours of April 5. An official minimum of 24.6 degrees was recorded in Clintwood ( the air temp had dropped back to a frosty 30 degrees at 3:50 AM Friday ).
GFS Model Total Snowfall Forecast Through Saturday
Models clearly have some work to do yet before they come into agreement, with the European Model and the mean of its cluster currently being closer to the GFS Model than to the NAM Model ( the 00z April 6 run ).
NAM 12 KM Model Total Snowfall Forecast Through Saturday
So the BEST option at this present time is to look at the storm track versus past climatology and to use that as a strong bias, the result suggesting that the NAM will be increasing its output of snow in coming runs to fit what similar tracks in the past have generated ( thus, potential exists that total snowfall may be heavier than currently suggested and this will need to be updated late today into tonight ).
