ALERT For Freezing Fog-Rain At High Elevations Saturday Evening Prior To A Change Over Into Snow During The Overnight Into Sunday Morning
Air temperatures reached 32 degrees at the summit level of the High Knob Massif prior to sunset Saturday. Caution Is Advised for those traveling State Route 619, Routes 238, 237, and other high country roads, at elevations above 3500 feet, through Saturday evening due to dense fog and sub-freezing temperatures.
ALERT For Snow Accumulations of 1-3″ Above 3000 Feet Elevation, With Locally Higher Amounts, Into Sunday-Sunday Night ( With Riming ). Snow Depths Of 1″ or Less Are Expected At Elevations Below 3000 Feet. Unseasonably Cold Conditions, With Temps Remaining Below Freezing Through Sunday At The Upper Elevations Will Combine With Gusty NW-N Winds To Generate Low Wind Chill Values.
Rain will change to snow overnight into Sunday morning as a low pressure system develops east of the mountains to increase NW-N upslope flow into the windward side of the Cumberland-Allegheny and Blue Ridge ranges. Greatest snow accumulations will occur in upper elevations, above 3000 to 3500 feet, with lesser amounts in middle elevations between 2000-3000 feet ( especially along the Cumberland-Allegheny mountain ranges where sticking snow levels will be the lowest ). While the woods, grass, and above ground objects will tend to accumulate the most snow, some roadways at high elevations will also become snow covered.
Saturday Night Into Sunday Morning
Cold & blustery with rain showers changing to snow showers and flurries ( evening freezing rain & fog at the highest elevations ). NW-NNW winds 5-15 mph, with higher gusts, along middle to upper elevation mountain ridges and plateaus. Temperatures dropping into the low 20s to lower 30s ( coldest at highest elevations ). Milder south into river valleys of the Clinch, Powell, Holston ( Great Valley ) . Wind chills in the 10s & 20s, except dropping to around 10 degrees or lower on peaks above 3600 feet. Rime formation in the upper elevations above 3300 feet.
Sunday Morning Through The Afternoon
Gusty & unseasonably cold. Snow showers & flurries, especially along the upslope side of the mountains. NW-N winds at 10-20 mph, with higher gusts, on middle to upper elevation mountain ridges-plateaus. Temperatures varying from the 20s in upper elevations to the mid-upper 30s. Low cloud bases with riming at high elevations. Winds chills in the 10s and 20s to lower 30s, except single digits in gusts on high peaks above 3600 feet.
Sunday Night Into Monday Morning
Mostly cloudy with a chance of snow showers & flurries. WNW to NW winds 5-15 mph, with higher gusts. Temps widespread in the 20s, except 10s possible on highest crest lines of the High Knob Massif ( and in colder high valleys if any predawn-sunrise clearing occurs ). Wind chill factors in the 10s & 20s along mountain ridges, except locally lower on highest peaks.
Monday Afternoon
Mostly sunny. Gusty. SSW-SW winds 10-20 mph, with higher gusts ( especially along mountain ridges-plateaus ). Temperatures warming into the lower 40s to lower 50s. Winds chills in 20s and 30s ( coldest highest elevations ).
Weather Discussion ( Wintry Blast )
Sunday Afternoon Update
A wintry day has featured widespread sticking snow at elevations above 2000 to 2500 feet across Wise-Dickenson counties into northern Scott County, with some fairly large snow flakes falling in the more vigorous showers.
Snow Falling At The University Of Virginia’s College At Wise
My friend Wayne Riner submits a great shot showing snow on the pumpkin, at a fitting time of the year too!
Snow On The Pumpkin – Long Ridge of Sandy Ridge – Elevation 2650 Feet
A combination of snow-sleet has been falling in Clintwood with only brief sticking at 1560 feet elevation. The sticking snow has been mainly above 2000 feet.
Eagle Knob of High Knob Massif At 4:09 PM on October 29, 2017
The greatest snowfall amounts reported so far have been around 2″ at upper elevations in the high country.
Snow has even covered the road and graveled areas up on Eagle Knob, where the air temperature has been hovering around 25 degrees all day at top of the high country. The best sticking, as figured, being in woods and over grass.
Expect some more sticking at mid-upper elevations through Sunday evening, with the possibility that the lower limit of sticking ( at least on above ground objects ) may slip just under 2000 feet across the upslope zone before moisture wanes in the low-level flow overnight into Monday AM.
Previous Discussion
The beauty of a mid-autumn sunset was forgotten into Saturday as conditions turned simply NASTY within the mountains, with low cloud bases, rain, and falling temps.
Beautiful Sunset In Flag Rock Recreation Area – October 27, 2017
Air temperatures reached 0 degrees Celsius ( 32 F ) at the summit level of the High Knob Massif prior to sunset Saturday, as rain and dense fog engulfed the high country. Cooling on upsloping NW-N winds taking air temps down quicker than aloft, where readings remained above freezing. Rainfall totals topped 1.50″ along the high country into Saturday evening.
European Model 500 MB Analysis At 8:00 AM Saturday – October 27, 2017
A deep air upper trough ( above ) digging southward into the eastern USA is trying to capture newly named Tropical Storm Philippe, and IF the timing had been only a little bit different a much bigger impact could result; however, such a setting as Superstorm Sandy is rare.
As it is, low pressure will develop east of the Appalachians and help pull cold air aloft over the mountains as a strong low-level NW-N upslope flow develops into Sunday.
European Model 850 MB Analysis At 8:00 AM Saturday – October 28, 2017
While cold air flooded into the mountains Saturday PM into Saturday Night, generating simply NASTY conditions as was expected, forecast models show that temps aloft do not cool enough to support snow until overnight into the morning hours of Sunday along the Cumberland-Allegheny fronts.
NAM 3 KM Model Forecast Snowfall Pattern
Forecast models struggle with amounts and almost always under-estimate snowfall within the High Knob Massif at the expense of very often over-estimating amounts modeled to fit the Eastern Continental Divide, as climatology-research well documents. The general pattern of NW-N upslope flow is correct; however, with leeward depletion.
Snowfall totals of more than 6″ will likely occur on some peaks, being most widespread and heaviest along the backbone of the Allegheny Front in central-northern West Virginia. Early in the snow season highest snow amounts are typically biased toward highest elevations and favored upslope zones to an even greater extent than they are during the winter months. Except for rare events, like Superstorm Sandy, early season snows during October are typically upper elevation favored ( average snowfall during October being just over 2″ at top of the High Knob high country ).
In this case, unseasonable cold will be the major factor for all locations ( from top to bottom ) through Sunday.
European Model 51-Member Ensemble Mean 850 MB Temp Anomalies: Days 6-10
While cold air really grips much of Canada, the ensemble mean is showing a big warming trend with periods of wet conditions developing across the central-eastern USA during the first week of November.
