ALERT For Snow & Hazardous Conditions Developing During The Predawn-Sunrise Period Of Tuesday (12 November)

A change from rain to heavy snow is expected during the predawn hours of Tuesday, with plunging air temperatures and a strong wind shift to NW-N upslope flow for locations along and north of the High Knob Massif and Tennessee Valley Divide. A transition to snow will occur across the mountain area, but heaviest snow amounts and worst conditions are anticipated in the above noted zone.

Widespread hazardous road conditions are expected to develop during the predawn to post-sunrise period of Tuesday. This will NOT be a slick spot type of scenario, but a setting that produces widespread snow covered roadways (especially secondary roads). Caution is advised.

A combination of low-level convergence and upper-level divergence into the right-rear quadrant of a strong 200-300 MB jetstreak will combine with orographic lift to generate heavy snowfall Tuesday morning. The potential exists for higher snowfall amounts than I am forecasting, with a notable model trend of increasing amounts.

While the greatest snow depths will tend to be on above ground objects, a rapid temperature drop and a long stretch of cold November nights will aid sticking of snowfall given rates of fall are expected to become intense as orographics and dynamics phase Tuesday morning.

Final Snowfall Forecast

A general 2″ to 4″ of snow are expected along and north of the High Knob Massif and Tennessee Valley Divide, with locally higher amounts possible above 3000-3500 feet in the High Knob Massif

*Target Snowfall: 3.0″ (+/-) 1.0″ Error Potential for Norton, Wise, Clintwood, and Nora 4 SSE, suggesting 2″ to 4″ snowfall potential during the period from 2:00 AM to 2:00 PM Tuesday (Locally higher amounts)

*The average of approximately 80 forecast models, when including all 72 members of the European and GFS ensembles, forecasts a mean of 3.2″ at the Wise gridpoint with a spread from 1.7″ to 5.5″ being given across all members.

Updated_11:00 PM Monday: A Winter Weather Advisory is now in effect for the Tri-Cities through Tuesday AM, which I think is an excellent decision by the MRX National Weather Service Forecast Office given expected snowfall rates, timing, and dropping temperatures.

ALERT For Bitterly Cold Air Temperatures And Wind Chill Tuesday With Record Cold Expected Wednesday AM (13 November)

Temperatures are expected to drop into the 0 to 10 (F) degree range into Wednesday morning, with potential for sub-zero minimums in colder mountain valleys if winds calm and skies can clear over snow cover.

Major Arctic Blast

A major blast of arctic air, which has now been long advertised by models, especially the European Group, will strike the Appalachians early next week with bitter air temperatures-wind chills and accumulating snow.

The current cold can be used as a guide, with temperatures early next week expected to be 10-15 degrees colder than today and tonight (November 8-9). Temperatures today (Nov 8) varied from mid-upper 10s to mid-upper 20s on High Knob, and from the low-mid 20s to low-mid 30s in Norton-Wise. Wind chills, however, will make conditions feel much colder next week.

The coldest 24-hour period, from 7 AM Tuesday to 7 AM Wednesday, of November 12-13, will feature the coldest air mass in the entire Northern Hemisphere, relative to climatological means, over the Appalachians from the Cumberland Mountains northeast to the Alleghanies.

Air temperatures are expected to drop to around 0 degrees at the summit level of the High Knob Massif, with readings plunging toward 10 degrees in Norton-Wise.

Snow cover could potentially make temps even colder, and this will need to be updated later. Irregardless of snowfall, wind chill values will be brutal for this time of year.

While there remains time for some adjustment in the magnitude of this cold blast, a strong arctic high and cross-polar flow will no doubt make it plenty bitter enough irregardless of exact values which are ultimately obtained.

Accumulating snow is expected to begin prior to sunrise Tuesday, November 12, with hazardous conditions likely to develop with falling temperatures and wet road surfaces.

Updated Late Week Potential

Majestic Rime Opens November 2019_High Knob Massif

A non-phasing scenario has been recently shown by forecast models of the European group, but a late week storm still looks to develop. At this time it appears to be just a little too far off toward the south and southeast to impact the Appalachians, but not the Atlantic Coast.

This, of course, remains outward into time so changes remain likely and potential for a storm impacting the Appalachians can not yet be written off as dead.

Stay tuned for later updates.