The Storm Prediction Center Has Issued A Slight Risk For Severe Thunderstorm Development Wednesday Afternoon-Evening Into The Overnight ( With An Enhanced-Moderate Risk Toward The Southwest )
Storm Prediction Center Risk Regions ( Updated 2:05 AM on April 5, 2017 )Storm Prediction Center Summary Discussion
Stay tuned to NOAA Weather Radio and your favorite media sources for Watches and Warnings that may be needed later Wednesday into Wednesday night.
The Potential For Accumulating Snowfall Is Also Being Monitored For Thursday Into Friday ( Significant Snow Amounts Will Be Possible, Especially At The Middle To Upper Elevations Above 2500 to 3000 Feet ).
Overnight Into Tuesday Morning
Showers likely. A chance of thunder. SSW to WSW winds increasing to 10-20 mph, with higher gusts ( especially on middle to upper elevation mountain ridges. Temperatures widespread in the upper 40s to mid-upper 50s. Dense fog on high mountain ridges ( widespread in High Knob Massif ).
Tuesday Afternoon
Partly to mostly sunny. Warm. SW-W winds 5-15 mph, with higher gusts. Temperatures varying from lower-middle 60s in upper elevations to the lower-middle 70s.
Tuesday Night Into Wednesday Morning
Partly to mostly clear. Light winds. Large vertical temp spread between colder valleys and milder ridges. Temps varying from 30s to lower 40s in colder valleys to the lower-middle 50s along exposed ridges.
Wednesday Afternoon
Partly sunny ( high clouds ). Warm & windy. A chance of hit-miss afternoon showers & thunderstorms ( any storms could become strong to severe ). SSE to S winds 10-20 mph, with higher gusts. Temperatures varying from 50s at highest elevations to the upper 60s to middle 70s.
Wednesday Evening Into Thursday Morning
Showers & thunderstorms. Some storms could be strong to severe. Downpours likely. Widespread dense fog ( capping orographic clouds ) at upper elevations in High Knob Massif. Winds shifting SW & increasing to 10-20 mph, with higher gusts. Turning colder by morning. Evening temperatures widespread in the 50s, then dropping into the 40s and 30s by morning ( coldest at upper elevations ).
Rain showers will change to snow showers at highest elevations in the High Knob Massif during Thursday morning, with snow levels dropping during the day into middle and perhaps lower elevations ( by late ) along the upslope side of the mountains. Accumulations during the day are currently expected to be mainly at the highest elevations, with sticking snow levels then dropping rapidly through middle elevations by mid-late PM into early evening.
Thursday Afternoon
Windy & turning cold. Rain showers changing to snow showers. Sticking snow levels dropping toward 2000 to 2500 feet by late. SW winds shifting WNW at 15-25 mph, with higher gusts. Temperatures falling into the 30s at lower-middle elevations, into the 20s at upper elevations, within locations along and north to northwest of the High Knob Massif-Tennessee Valley Divide ( milder to the south ). Wind chills dropping into the 10s and 20s.
Widespread snow, heavy at times, is expected along the upslope side of the mountains ( WNW-NW of the Cumberland-Allegheny Front ) Thursday evening into Friday morning. Significant snow amounts will be possible, especially at mid-upper elevations above 2000-3000+ feet.
Thursday Night Into Friday Morning
Snow & snow showers. Snow heavy at times. Windy. Cold. Winds WNW-NW at 15-25 mph, with higher gusts. Temps varying from upper 20s to lower 30s to the upper 10s to lower 20s at highest elevations ( milder lee of mountains into the Great Valley ). Wind chill factors varying from 10s to lower 20s to the single digits and 10s ( except near to below zero in stronger gusts at highest elevations in the High Knob Massif and other major mountain ranges ).
Cold night-time temperatures will continue through this upcoming weekend, especially in mountain valleys.
Weather Discussion ( Blast Of Winter )
A clash of spring and winter is the main focus for coming days, with strong-severe thunderstorms ( and a possible outbreak of severe storms ) giving way to upslope snow.
Although spring activity has been increasing in the natural world, the Ole Man Of Winter has different ideas amid this 30th Year Anniversary Week of the great April 2-5, 1987 snowstorm that buried the mountain landscape.
Yellow Tulips ( Tulipa spp. ) of John & Mae Mullins Gardens – April 2, 2017
The April 2-5, 1987 snowstorm produced snow depths of 20″ to 26″ in Clintwood ( total fall was 33.8″ ). Gary Hampton reported 3 feet of snow depth at the City of Norton Water Plant, at the base of the High Knob Massif, with electrical engineer Carl Henderson, of Blue Ridge Public Television, reporting 2-6 feet ( 4 feet average ) depths on Eagle Knob of the High Knob Massif.
Honey Bee ( Apis spp. ) Working A Pussy Willow ( Salix discolor ) – April 2, 2017
Although snowfall amounts are not expected to be anything like April 1987, it is certainly possible that 6″ to 12″ of snow could fall in upper elevations of the High Knob Massif. It remains too early to forecast exact amounts, but the signal and pattern is very strong and has been consistent among ensembles and operational runs of medium range models for a strong orographic upslope event ( where snowfall is enhanced along the windward side of the mountain chain via forced convergence and upward rise of air on WNW-NW flow streaming from a Great Lake’s moisture source ).
As is almost always the case at this time of year, this will be an elevation biased event ( greatest snowfall amounts will be at the highest elevations ) with decreasing sticking & snow amounts as elevation decreases. In addition, at all elevations, more snow will tend to fall than is ever able to remain on the ground at any given time during the event.
Due to strong inverse orographics ( i.e., negative forcing ) lee of the major mountain barriers, snowfall and amounts are expected to be very limited downstream of the High Knob Massif-Tennessee Valley Divide and Blue Ridge.
As already noted above, please stay tuned for updates and possible changes in this scenario.
Storm Prediction Center Risk Regions ( Updated 2:05 AM on April 5, 2017 )
Meanwhile, the front end of this next storm system will again bring showers and thunderstorms with an enhanced to moderate risk from southern Kentucky through southern Tennessee. A slight risk is now outlooked across much of the Mountain Empire. Note that this could change again depending upon how activity develops Wednesday.
Stay tuned to NOAA Weather Radio and your favorite media sources for Watches and Warnings that may be needed later Wednesday into Wednesday night.
High Knob Massif Webcam – University Of Virginia’s College At Wise
Nice orographic clouds during Monday afternoon ( March 3 ), with capping pilatus ( above ) and multiple wave clouds ( below ) on SW air flow trajectories streaming into & across the High Knob Massif.
High Knob Massif Webcam – University Of Virginia’s College At Wise
