Weather Headlines
ALERT For Accumulating Snow Sunday Night Into Monday With Hazardous Conditions Developing
This 4:00 PM update Sunday is to stress that increasing snow showers and squalls will be observed into Sunday Night-early Monday, with hazardous road conditions developing once again as instability increases.
Snow will accumulate from the floor of the Powell River in Lee County, upward into highest elevations. I do not yet understand why the NWS idea is that only elevations over 3500 feet will have significant accumulation?
With bitter air aloft moving over later tonight, this will be transported downward in convective snow showers and squalls to cool the boundary layer – especially within the zone where SW-WSW air flow trajectories must rise upon approaching the High Knob Massif.
The zone of heaviest snow observed so far (2.5″ to 6″) has been along and southwest of the High Knob Massif and Tennessee Valley Divide in far southwestern Virginia, because this has not been, and will not be, a NW Flow snowfall setting.
Previous Forecast (Still Valid)
ALERT For Periods Of Snow Friday Night Into Monday With Reduced Visibilities In Heavier Snow And Hazardous Road Conditions
This update at 3:40 pm on Friday is to cover the development of snow showers, with heavier squalls (already in my forecast) developing Friday night into Saturday with hazardous conditions. This follows a general 1″ to 2″ of snow Friday morning at elevations above 2000-2500 feet, with locally 3″ at the highest elevations in the High Knob Massif.
Snow showers and locally intense snow squalls will be likely from the predawn into the afternoon of Saturday (16 January 2021). An injection of Great Lake moisture will combine with bitter air aloft and steep lapse rates above the mountains to support snowfall with general 1″ to 4″ amounts expected.
Upon additional analysis, I am now adding the potential of Thundersnow to my forecast for Saturday and again for late Sunday into Monday.
For those who ask, I have NO, absolutely NO, explanation for why the MRX NWS Forecast Office has left Wise County out of the advisory, or why they leave northern Scott and northwest Lee, as well as Dickenson (RLX NWS FO) for this type of setting.
The error in leaving the documented snowiest terrain in Virginia (central-southern Wise) out of a setting like this is not explainable or based upon documented scientific data and certainly is in opposition to climate research (including not only mine but others).
I think forecasters are under-estimating the potential of this upcoming setting with a risk for whiteout type squalls that could, at least locally, contain lightning and thunder.
Locations that receive repetitive squalls could end up with higher snowfall totals than in my current forecast (which already are the highest being predicted).
Total Snowfall Forecast
(Friday AM through Monday AM)
2″ to 4″ below 2000 feet
(Less than 2″ in downslope sites)
4″ to 8″ above 2000 feet
(Locally higher amounts)
Snowfall will occur with separate waves,
the first during Friday morning, the second
late Friday night into Saturday and the third
wave later Sunday into early Monday.
Previous Forecast & Discussion
ALERT For Accumulating Snow Developing Between Sunrise And Mid-Morning Today (Friday Jan 15) Within Mid-Upper Elevations
Snow and mixed precipitation will develop Friday morning, with a general 1″ to 2″ expected at elevations above 2500 feet. Generally less than 1″ is expected at elevations below 1500 feet, except locally more along windward slopes north of the High Knob Massif.
An additional wave moving across the mountains will renew snow showers Sunday, with snow squalls again becoming possible beneath very cold air aloft by Sunday Night into Monday.
Additional 1″ to 3″ amounts will be possible with this wave from late Sunday into Monday.
Due to melting in between waves, especially at lower and middle elevations, total snowfall is expected to be greater than ground depths except at the highest elevations above 3300 feet.
Note that snow showers and flurries will be likely in between the main waves of more concentrated snow showers and squalls.
Extended Headline
Signals for a snowstorm are showing up in the extended range (20-30 January period); however, the placement, intensity, and timing remain uncertain and varied.
Stay tuned for updates.