Autumn Color 2020_High Knob Massif Area

Autumn color has advanced significantly across the area since the beginning of this week, with conditions on 9 October featuring an array of nice colorations across many locations along and north of the High Knob Massif (Clintwood-Pound to Norton-Wise), with this weekend (10-11 October) through next weekend (17-18 October) expected to offer some of the best color above 3000 feet.

If color continues to advance rapidly below this elevation, a general peak will occur by 17-18 October in locations along and northwest-north-northeast of the High Knob Massif.

As autumn color begins peaking at upper elevations, remnant rains from Hurricane Delta will overspread the mountain region this weekend, with additional showers and thunderstorms into early next week.

Moderate to heavy rainfall, wind driven within upper elevations, will be detrimental to some leaves.

Time will tell what impact it has on the general peak, with brightening color on some trees as other trees experience leaf drop into next week. Trees with bright color currently, standing within exposed locations, will be at greatest risk of leaf fall.

Models are forecasting a general 1.00″ to 4.00″, with locally more in favored upslope locations and less in downslope locations on general SSE-SSW air flow trajectories across the southern Appalachians.

Heaviest rains are expected Sunday as the remnant core of Delta pushes across the region.

Colder Trend – Second Half of October

A colder trend in modeling is showing up during the second half of October, with high latitude blocking predicted to develop within positions that favor enhanced eastern USA upper air trough formation.

The 14th Annual High Knob Naturalist Rally will continue virtually through this week and next.

High Knob Hellbender 10K Race

Weather conditions for the 7th Annual Hellbender 10K will be nearly ideal this year, with light southwest winds and seasonally chilly conditions under partly to mostly sunny skies (featuring fair weather cumulus).

Frosty cold sunrise conditions in the Norton Valley will warm quickly through mid-morning. Air temperatures in the 40s (4° to 9° Celsius) can be expected along the course that follows a 10:00 AM start time Saturday.

Expect air to dry with increasing elevation. A drop in relative humidity values will occur above the valley floor, toward the summit level of the massif, through mid-morning into mid-day Saturday.

Mountain Valley Frost

Areas of frost were featured in colder valleys Friday morning, such as in the Norton Valley which had temps analogous to the summit level of the High Knob Massif (the main difference being low-mid 30s accompanied wind chills in the 20s at the summit).

NOTE: Significant differences are typical on these mornings between the Norton Valley and adjacent Wise Plateau, with colder temperatures and enhanced frost on the floor of the Norton Valley (including the Big Laurel to Esserville and Ramsey to Tacoma corridors), and low spots within the plateau, often contrasting with milder, frost-free conditions in exposed locations of the Wise Plateau and higher places within the City of Norton.

Forecasters should not confuse Norton with Lonesome Pine Airport in Wise (especially for those following obs), as they are within two distinctly different topographic settings with significant weather contrasts on nights featuring radiational cooling and cold air drainage.

The Norton Valley is influenced by cold air drainage from both the High Knob Massif and northeastern end of the Black Mountains versus the Wise Plateau which features only localized drainage into lower sections, especially those once known as The Big Glades.

Latent heat of condensation associated with fog formation will help to prevent or minimize any frost formation along major river valleys and near the larger, lower-elevation lakes.

River valley fog will continue to be a nocturnal feature, as typical at this time of year, to contrast with below freezing conditions developing overnight into Saturday morning within the colder, high elevation valleys from the High Knob Massif to Burkes Garden.

Cooler-Drier Than Normal Short-Term

Generally cooler and drier than average conditions will continue to dominate the short-term forecast period into next week, when a warming trend develops.

A drier pattern is very welcome in wake of wetness, with the past year featuring 100.29″ of total precipitation at Big Cherry Lake Dam in the High Knob Massif.

Big Cherry Dam Breaks 100.00″ During Past Year

Reference the above link for other totals observed during the water year from October 2019 to September 2020.