ALERT For Unseasonably Cold Temperatures And Wind Chills Into Saturday – Accumulating Snow Will Also Be Possible Tonight Into Saturday Morning ( Especially Within Middle-Upper Elevations )
A prolonged period of cold conditions is expected from tonight into this weekend. Scattered hit-miss rain & snow showers will be possible today, with the best chance for more widespread snow by tonight into Saturday morning. A general 1-3″ of snow is possible at upper elevations, above 3000 feet, with 1″ or less in middle elevations below 3000 feet ( little to no snow accumulation is expected at elevations below 1500-2000 feet ).
Overnight Into This Morning
Partly to mostly cloudy. Chance for rain or snow showers. Turning colder. W-NW winds 5-20 mph, with higher gusts. Temperatures dropping into the 30s, with 20s above 3200 feet in elevation. Wind chills in the 10s & 20s ( coldest at the highest elevations ).
This Afternoon
Partly cloudy with increasing clouds into late afternoon. Rain & snow showers developing. W-SW winds 5-20 mph, with higher gusts. Temperatures varying from the 30s in upper elevations to the 40s to middle 50s ( warmest in the downslope locations from Pound-Grundy ). Wind chills in the 20s & 30s at elevations above 2500 feet.
Tonight Into Saturday Morning
Rain & snow, changing to snow in most locations late. A period of moderate-heavy snow possible above 3000 feet. WNW-NW winds 10-25 mph, with higher gusts, along mid to upper elevation mountain ridges and plateaus. Temps dropping into mid-upper 10s at highest elevations to the mid-upper 20s to lower 30s ( warmest at low elevations ). Wind chills from 10s to around 20 degrees, except 0 to 10 degrees along high mountain crest lines.
Weather Discussion ( April 7-8 )
A chilly and windy Thursday graced the mountain landscape in wake of needed overnight rains.
Nora 4 SSE – NWS Site In Middle Elevations ( Elevation 2650 feet )
Superintendent Andrew Greear and veteran technician Joe Carter reported 0.40″ of rainfall at the City of Norton Water Plant up to 9:00 AM on Thursday.
Superintendent Gary Hampton reported 0.63″ of rainfall at both the Big Stone Gap Water Plant and Big Cherry Lake Dam into the morning hours of Thursday.
A total of 0.18″ fell in Clintwood up to 7:00 AM on Thursday, with 0.36″ reported by Wayne & Genevie Riner at Nora 4 SSE.
Gusty showers mixed with snow in middle elevations, as mostly all snow fell at highest elevations in the High Knob Massif, during late afternoon-early evening on Thursday.
A temperatures of 41 degrees was observed at the Norton Water Plant at 6:30 PM as the activity began to develop.
The activity late Thursday afternoon formed beneath cold air aloft with puffy to towering cumulus clouds observed over Norton-Wise and Pound-Clintwood.
Rue-anemone Against Mossy Blanket – April 2016
Focus now shifts to the next wave and cold front that will cause rain-snow showers to develop in earnest by late today into tonight. Depending upon how this activity sets up, via the best moisture stream, a period of moderate-heavy snow will become possible across upper elevations in portions of the Mountain Empire ( with several inches of sticking snow at highest elevations into Saturday morning ).
The high resolution NAM 4 KM Model has a bulls-eye centered over the eastern West Virginia highlands, with more than 6″ ( locally up to 10″+ ) above 3000 feet in elevation. As past climatology shows, and is well documented locally, the model tends to under-estimate snowfall in upper elevations of the High Knob Massif.
NAM 4 KM Model Total Snowfall Forecast
At this time, it appears that any snow accumulations below 3000 feet will be limited to 1″ or less, with little to no sticking snow at elevations below 1500-2000 feet.
The coldest air with this system will be felt Friday Night into Saturday and Saturday Night into Sunday Morning.
NAM 4 KM Model MIN Temperature Forecast Saturday Morning
MIN temperatures will drop into the 10s in upper elevations of the High Knob Massif, with 20s widespread across most of the middle to lower elevations within the mountains & northeastern sections of the Great Valley ( from the TRI area northeastwards ).
NAM 4 KM Model MIN Temperature Forecast Sunday Morning
A prolonged period of cold conditions is expected from Thursday night into this weekend. Rain and snow showers will be possible Thursday night into Friday, with the best chance for snow by late Friday into Saturday AM. The potential for several inches of snow will exist in upper elevations, especially above 3300 feet, with a general decrease in sticking as elevation decreases below 3000 to 3300 feet ( a little sticking will be possible to around 1500-2000 feet, on the upslope side of the mountains, by Saturday AM ).
Late Evening Into This Morning
Rain with a chance for thunder. Locally heavy rainfall. A break in rain by the predawn-sunrise period. Winds SSW-W at 10 to 25 mph, with higher gusts, decreasing some toward morning. Temperatures dropping into the 40s, with 30s at highest elevations. Wind chills in the 20s & 30s.
Mid-Morning Through This Afternoon
Showers redeveloping. SW-W winds 10-25 mph, with higher gusts, along middle-upper elevation mountain ridges & plateaus. Chilly. Temperatures varying from 30s at upper elevations to the 40s to lower 50s ( milder south toward the Tri-Cities ). Becoming partly cloudy by mid-late afternoon or early evening. Wind chill factors in the 30s and 40s ( coldest at highest elevations ).
Tonight Into Friday Morning
Partly to mostly cloudy. Chance for rain or snow showers. Turning colder. WNW winds 5-15 mph, with higher gusts. Temperatures dropping into the 30s, with 20s above 3200 feet in elevation. Wind chills in the 10s & 20s ( coldest at highest elevations ).
Weather Discussion ( April 6-7 )
Increasing clouds & gusty conditions Wednesday developed in wake of a frosty cold morning in mountain valleys. A 41 degree temperature spread was observed in Clintwood from 24 degrees in the morning to 65 degrees in the afternoon.
Nora 4 SSE – NWS Site In Middle Elevations ( Elevation 2650 feet )
A more “narrow” temperature spread was observed along exposed mountain ridges and plateaus, with readings varying from the 30s into the 50s ( only upper 40s to about 50 degrees at the summit level of the High Knob Massif ).
JKL Doppler At 11:51 PM – Thursday ( April 6, 2016 )
The focus tonight is on needed rain, with brief downpours in places, that is moving across the mountains ahead of the first of two cold fronts ( with initially dry air in place, some evaporation occurred to make totals at the ground less than estimated by Doppler radar up to midnight ).
Black Mountain MesoNET Up To 1:00 AM Thursday – April 7, 2016
It is a wind driven, cold rain along high mountain crest lines with recent gusts between 40-50 mph ( driving wind chills into 20s ).
USA Water Vapor Image At 12:15 AM Thursday – April 7, 2016
A trough visible in the upper air over the eastern USA will deepen during the next couple of days, with anomalously cold air for this time of year spilling south over the region.
European Model 850 MB TEMP Anomalies-Wind Vector Forecast – 8 AM Saturday
Cold air transport reaches its maximum Friday Night into Saturday, with a NW flow pattern that will also help carry enough moisture south from open Great Lake waters to support some spring snowfall.
NAM Model 500 MB Vorticity Forecast At 2:00 PM Friday – April 8, 2016
Diffluence ( upper air divergence ) ahead of an approaching vorticity maximum diving toward the base of the upper air trough will begin to generate lower elevation rain showers and upper elevation snow showers during Friday afternoon, with increasing snow showers into Friday Night when snow levels will begin dropping toward the middle elevations.
At the current time, best accumulations are expected above 3300 feet in elevation with decreased sticking as elevation decreases below this level. There will be a period of time ( generally from midnight-sunrise Saturday ) when snow levels could reach down into the 1500-2000 foot zone for locations along the upslope side of the Cumberland Mountains ( with respect to NW flow ). Snow amounts are expected to be limited for most places by duration of these best conditions for snowfall ( best sticking being on above ground objects, grass, leaves, and northern slopes outside of the highest elevations ). Please stay tuned for updates.
The coldest air is expected along mountains ridges into Saturday morning, with coldest air in mountain valleys likely into Sunday morning. Prolonged below freezing conditions are expected in all locations, with anomalously cold wind chills across higher terrain locations during Friday night into Saturday.
A Hard Freeze Will Occur Overnight Into This Morning In Mountain Valleys. Increasing Winds Along Upper Elevation Mountain Ridges Will Mix Downward Onto Middle Elevation Ridges-Plateaus Toward Morning With Little To No Frost Expected
A wintry cold period is expected from Thursday Night into this weekend, with potential for snow accumulation along the upslope side of the mountains with respect to NW-N air flow. Significant snow accumulations will be possible at the highest elevations.
Overnight Into This Morning
Unseasonably cold. A large vertical temperature spread developing between frosty valleys and milder but windy middle-upper elevation mountain ridges. ESE-SSE winds increasing into the overnight-morning to 5-15 mph, with higher gusts, on middle elevation ridges-plateaus below 2700 feet. Winds S-SW at 10-20 mph, with higher gusts, along upper elevation mountain ridges. Temperatures in the 30s, or rising into the 30s following any evening drops, along exposed middle-upper elevation mountain ridges and plateaus. Temps falling through the 20s within mountain valleys. Wind chills in the 20s on upper elevation ridges.
This Afternoon
Increasing clouds. Milder & windy. Chance of a shower by late. SSE-SSW winds 10-20 mph, with higher gusts, along middle elevation ridges-plateaus below 2700 feet. Winds SSW at 15-25 mph, with higher gusts, on mountain ridges above 2700 feet. Temperatures varying from 40s to around 50 degrees in upper elevations to the middle 50s to low-mid 60s ( 55-60 degrees in Norton-Wise ).
Tonight Into Thursday Morning
Rain with a chance for thunder. Locally heavy rainfall. Winds SSW-W at 10-25 mph, with higher gusts, decreasing some toward morning. Temperatures dropping into the 40s, with 30s at highest elevations into morning.
Weather Discussion ( April 5-6 )
A unseasonably cold air mass Tuesday featured morning MINS that varied from around 20 degrees at the summit level of the High Knob Massif to around 30 degrees amid valleys in lower elevations to the north ( a little milder conditions were reported south toward the Tri-Cities ).
Scenic & Patriotic Setting In Town Of Clintwood – Afternoon of April 5, 2016
A gorgeous afternoon featured beautifully blue, cloud-free skies with temperatures reaching low-mid 40s in Norton-Wise and the upper 40s in Clintwood.
Nora 4 SSE – NWS Site In Middle Elevations ( Elevation 2650 feet )
The setting tonight features temperatures falling through the 20s in colder mountain valleys ( 28 degrees at Clintwood 1 W as of Midnight ) as highest ridges become increasingly windy with near steady to rising temperatures.
An increasing vertical temperature spread between colder valleys and milder ridges will develop overnight into this morning. The off-setting factor along upper elevation ridges being an increase in wind chill factors ( making it feel like 20s or colder in gusts ).
Black Mountain MesoNET Up To 12:15 AM Wednesday – April 6, 2016
Temperatures will rise dramatically into today as southerly winds increase and mix downward across the entire area, with downslope locations in the Russell-Levisa Fork basins likely rising into the 60s ( marking 40+ degree temperature rises between this morning and this afternoon ).
Rain chances will increase dramatically by late today into tonight as the next weather system approaches. A chance for lightning-thunder and locally heavy rainfall will exist during the Wednesday Night-Thursday AM period.
NAM 12 KM Model Total Precipitation Forecast To 8 AM Saturday – April 9, 2016
Precipitation totals could top 1.00″, with the final period of this forecast cycle, from Thursday Night into Friday Night, featuring increasingly cold air and the chance for snow at higher elevations ( with snow levels dropping over time into middle elevations by late Friday Night into Saturday Morning ).
GFS Model Total Precipitation Forecast To 8 AM Saturday – April 9, 2016
ALERT For Widespread Freezing Conditions Overnight Into Tuesday Morning With Unseasonably Cold Wind Chills At Mid-Upper Elevations – Another Hard Freeze In Mountain Valleys Tuesday Night-Wednesday AM
*Low relative humidity this afternoon will increase the risk of fires ( although winds will be diminishing ). While it is against the law to burn outdoors until after 4 PM in the state of Virginia, it would be best NOT to burn anything until significant precipitation falls across the region.
A prolonged period of wintry cold, with an accumulating snow potential, is being monitored for late week into this weekend. Significant snow will be possible in upper elevations.
Overnight Into This Morning
Cloudy. Turning unseasonably cold. Chance for a few flurries ( mainly along the upslope side of the mountains ). N winds 5 to 15 mph, with higher gusts, below 2700 feet. Wind N at 10-20 mph, with higher gusts, along mountain ridges above 2700 feet. Temperatures dropping into mid-upper 10s at the highest elevations, with widespread 20s at middle-lower elevations along and north of the High Knob Massif-Tennessee Valley Divide ( milder in lower elevations to the south toward the Tri-Cities ). Winds chills dropping into the single digits and 10s, with sub-zero chill factors in gusts on highest ridges.
This Afternoon
Sunny. Deep blue skies & unseasonably cold. N-NE winds diminishing to 10 mph or less. Temperatures varying from the 30s in upper elevations to the 40s in low-mid elevations ( mid-upper 40s in Norton-Wise ) along & north of the High Knob Massif-Tennessee Valley Divide ( milder 50s south & southwest amid lower elevations of the Powell, Clinch, Holston river valleys toward the Tri-Cities ).
Tonight Into Wednesday Morning
Unseasonably cold. A large vertical temperature spread developing between frosty valleys and milder but windy middle-upper elevation mountain ridges. ESE-SSE winds increasing into the overnight-morning to 5-15 mph, with higher gusts, on middle elevation ridges-plateaus below 2700 feet. Winds S-SW at 10-20 mph, with higher gusts, along upper elevation mountain ridges. Temperatures in the 30s, or rising into the 30s following any evening drops, along exposed middle-upper elevation mountain ridges and plateaus. Temps falling through the 20s within mountain valleys. Wind chills in the 20s on upper elevation ridges.
Weather Discussion ( April 2-5 )
A very active, but continued drier than normal, weather pattern will be turning increasingly wintry heading into late week and the upcoming weekend.
Wind gusts during the early weekend reached 40-50+ mph with up to 17% of Wise County ( on the AEP Network ) out of electricity at one point due to damaging gusts. A continuation of a very windy pattern from March, but now with an increasingly cold turn.
Rough Generalization Of April 1987 Snowfall – Courtesy Of JKL NWSFO
The above graphic is a rough generalization of snow that fell during the great April 2-5 snowstorm in 1987. Snow depths reached 22″ to 24″ in Clintwood ( 33.8″ of total fall measured at Clintwood 1 W ), with 36″ in the City of Norton at the Norton Water Plant ( measured by Gary Hampton ).
A mean snow depth of 4 feet was reported by electrical engineer Carl Henderson, at the WSBN-TV PBS transmitter station atop the Eagle Knob of the High Knob Massif ( Blue Ridge Public Television ). Snow drifts of 5-10 feet occurred in exposed locations. Total snow fall was more than 3-4 feet in the Norton to High Knob Massif area since significant settlement and some sub-snow surface melting occurred during this prolonged upslope event.
Anyone remembering the 1987 snow event, or many other April falls of snow, will not doubt that snow can fall amid the mountains during this time of year.
With 28 years of records, in fact, the mean April snowfall atop the High Knob Massif has been around 7″ with only 4 out of 28 April’s not having measurable snow ( meaning it is more common to have than not to have snow accumulate during April atop the massif ).
European Ensembles MEAN 500 MB Height Anomalies Forecast – DAYS 3-7
The MEAN of the 51-Member European Ensembles are showing that the DAY 3-7 forecast period, from Thursday through this weekend, is looking particularly cold with true winter conditions developing beneath an anomalously deep eastern USA upper air trough ( late season winter cold ).
European Ensembles MEAN 850 MB TEMPS-Anomaly Forecast – DAYS 3-7
The MEAN 850 MB temperature during the DAY 3-7 period has the 0 degrees Celsius ( 32 F ) line south across the Great Smokies in the southern Appalachians, with around -2 C or upper 20s ( Fahrenheit ) air over the High Knob Massif area ( that is the MEAN for the DAY 3-7 period ). In other words, this is air that would be more typical of mean temperatures observed during the winter ( December-February ).
Higher sun angles at this time of year will tend to generate higher day-time temperatures, of course, with an air mass like this verses the low sun angle winter months; however, the fact remains that this will be MUCH below average for April and be cold enough to easily support snow at higher elevations.
GFS Model Total Snowfall Forecast Next 5 DAYS
It is too soon to yet determine actual snowfall totals, but the European Model has consistently been heavier across the southern Appalachians than the GFS Model ( above ).
Meanwhile, the focus is on unseasonably cold air and the need for you to protect any tender young plants that you may have already put out ( hopefully none to few ). Most native plants, such as our ephemeral wildflowers, will be able to with-stand the cold as MANY past events like the April 1987 period have been factored into their DNA.
Pennywort ( Obolaria virginica ) In The Cumberland Mountains
An unseasonably cold Tuesday ( today ) will naturally lead into another hard freeze in mountain valleys tonight, with temperatures falling through the 20s ( coldest valleys could dip into the 10s if mixing from increasing winds above does not disrupt nocturnal temperature inversion formation ).
Meanwhile, following any evening drop, temperatures will tend to rise into the overnight-morning of Wednesday as winds veer ESE-SW and increase in speed along middle to upper elevation mountain ridges ( enhancing a vertical temperature spread between valleys and ridges ).
Showers, with a chance for thunderstorms, develop late Wednesday into Thursday in advance of the big chill down that begins late Thursday into Friday AM.
NAM 12 KM Model Total Precipitation Forecast To 8 AM Friday ( April 8 )
Rainfall remains needed, following a much drier than normal pattern during the past 5 weeks. Surges of low dewpoint air, such as observed today ( Tuesday ), tend to enhance the danger of fires. So please do not burn.
ALERT For Widespread Freezing Conditions Developing Saturday Night Into Sunday AM With Unseasonably Cold Wind Chill Factors On Exposed Middle-Upper Elevation Mountain Ridges
*A Freeze Will Also Be Possible In Mountain Valleys That Have Calm Winds During Sunday Night-Monday AM As Strong SW Winds Develop Across Mid-Upper Elevation Ridges ( Caution Advised For Strong SW Winds At High Elevations, Mainly Above 3000 feet Into Monday AM ).
Overnight Into Saturday Morning
Mostly cloudy. A chance for sprinkles, with a period of light rain & showers to the southeast toward the TN-NC border. Turning colder. Winds W-WNW at 5-15 mph, with higher gusts, on middle-upper elevation mountain ridges-plateaus. Temps dropping into lower 30s at the High Knob Massif summit level by morning, with 40s at middle-lower elevations below 2700 feet.
Saturday Afternoon
Partly sunny. A period of mostly cloudy skies possible. Windy. Winds WSW-W at 10-25 mph, with higher gusts. Chilly with temperatures varying from upper 30s to low 40s at highest elevations in the High Knob Massif to the lower-middle 50s ( milder south toward the Tri-Cities and locally in downslope locations of the Russell-Levisa Fork basins ). Wind chills in the 20s to lower 30s along upper elevation mountain ridges.
*A period of enhanced winds along and behind a cold front will occur Saturday afternoon into Saturday evening. Gusts of 30-50 mph will be possible during this time. Caution Is Advised.
Saturday Night Into Sunday Morning
A period of clouds with a chance for a valley sprinkle or light rain shower and upper elevation flurry or light snow shower. Turning colder with skies becoming partly cloudy to mostly clear by morning. Winds becoming NW at 10-20 mph, with higher gusts. Temperatures dropping into the upper 10s to low 20s at highest elevations to the middle-upper 20s to around 30 degrees. Wind chills in the single digits & 10s along upper elevation mountain ridges. Wind chills in the upper 10s & 20s on middle elevation ridges.
Sunday Afternoon
Sunny & cold for the season. Winds becoming SW at 5-15 mph, with higher gusts. Temperatures varying from the upper 30s-lower 40s at upper elevations in the High Knob Massif to the upper 40s to middle 50s. Unseasonably cold wind chills in the 20s to lower 30s at highest elevations.
*Updated At 12:15 AM Monday
Sunday Night Into Monday Morning
Mostly clear. A large vertical temperature difference developing between mountain valleys with calm winds and middle-upper elevation mountain ridges with strong winds. SSW-WSW winds 15-25 mph, with higher gusts, developing into the overnight-morning on mid-upper elevation ridges, especially at elevations above 2500-2700 feet.
Temperatures varying from 20s to lower 30s in colder valleys to readings in the 40s, or rising into the 40s, along middle-upper elevation mountain ridges-plateaus.
The strongest SW winds are expected to be mainly above 2500 to 2700 feet overnight into Monday morning, with 30-40+ mph gusts being possible along mountain ridges. Wind speeds will increase with mixing at middle-lower elevations, below 2700 feet, into the day ahead of and along an approaching cold front.
Black Mountain MesoNET Up To 12:00 AM Monday – April 4, 2016
*Another widespread, hard freeze is expected into Tuesday Morning amid another period with very cold wind chills for this time of year ( especially at middle to upper elevations ).
A major, winter-like blast of cold air with a snowfall potential is looking likely by late this week into next weekend. Stay tuned for details.
Weather Discussion – Colder Pattern
Although most hate to hear it, a winter-like jet stream pattern is taking shape across North America with renewal of western USA ridging-eastern USA troughing in the upper air flow regime.
Beauty of Early Spring Phlox Following A Drier-Milder Than Average March
While up-down temperature variations will continue, it is clear that the pattern heading through next week and well into April is looking to be colder than average with even a few chances for snow in the mountains ( an anomalous for this time of year pattern that, as past climatology shows, may eventually generate some significant snowfall – at higher elevations, especially, of course ).
This was the pattern that I expected for March; however, that got side-tracked by a number of factors including development of an anomalous sub-tropical cut-off low and blocking Atlantic ridge as well as continued pulses of wave activity over the Arctic following an anomalously strong Sudden Stratospheric Warming event.
Flowering Quince ( Chaenomeles spp. ) With Pollen Formation
A record dry to one of the driest March’s ( depending upon the location ) on record got the pollen season off to an early start and has early spring flowering species running some 1-3 weeks ahead of schedule. Repeated bouts of significant cold upcoming will, no doubt, be detrimental to some of these early blooming species.
Rue-anemone ( Thalictrum thalictroides ) Is One Of The Hardy Wildflowers
Many native ephemeral wildflower species, like this lovely Rue-anemone above, will not be hurt and are use to cold as well as being covered up by spring falls of snow.
European Model 500 MB Height Anomaly Analysis – 8 AM Friday ( April 1 )
The pattern shown at the start of April, with ridging over both coasts of the USA ( above ) and cold air in the middle diving south and southeast ( below ) is forecast to become more intense with expansive troughing across the eastern USA during the next 10 days or more.
European Model 850 MB TEMP Anomaly Analysis – 8 AM Friday ( April 1 )
This is shown well by the 51-Member European Ensemble group where the MEAN 500 MB Height Anomalies become stronger and more intense from Days 1-5 into Days 6-10.
European Ensembles Forecast MEAN 500 MB Height Anomalies DAYS 1-5
This is very impressive, especially for a 51-Member MEAN, with troughing below making any winter period proud. At this time of year the cold air will be late season, modified, but still very significant ( especially with respect to early spring warmth observed by day during March ).
European Ensembles Forecast MEAN 500 MB Height Anomalies DAYS 6-10
A rough idea of how cold it will get, in the MEAN, is given by looking at the 51-Member Ensemble group’s 850 MB temps and their departures from normal ( in colors ).
European Ensembles MEAN 850 MB TEMP-Anomalies Forecast DAYS 1-5
During the next 10 days the 32 degree ( 0 degree Celsius ) line at 850 MB hovers over, or near, southwestern Virginia with mean temperature departures being 10 degrees ( F ) or more below average ( in the MEAN ).
European Ensembles MEAN 850 MB TEMP-Anomalies Forecast DAYS 6-10
In reality, some members of the 51-Ensemble group are much colder and some warmer than others, with the above being the MEAN of all averaged together during each 5-day period. Thus, one has to also figure that with intervals of warm air advection some of the cold spells will be well below the mean of departures shown.
The Bottom Line – An early start to spring in March is going to be stopped during the next 1-2 weeks as mean temperatures turn much below average.
While up-down temperature variations, both day-to-night and between days, are expected to continue the forecast pattern features colder than average temps and the potential for certain cold surges to be very significant ( with even some snow in the mountains ).
Stay tuned for updates as daily weather variations are worked out as time passes.
