Alert For High Water Levels

*A general 2.00″ to 4.00″ of rain has fallen along a line extending from Natural Tunnel State Park in Scott County to the City of Norton in Wise County and Council in southern Buchanan County, with 3.50″ to 4.00″ maximum totals in the High Knob Massif, as of early afternoon Sunday (May 12), along a Big Cherry Lake to Guest River Gorge corridor.

Roaring water and dangerously high levels are occurring on creeks draining the high terrain. Extreme caution is advised through the remainder of Sunday into early Monday. Strong rises are also occurring on the Clinch River, but it is expected to remain below flood stage.

The good news, following a weekend spent amid clouds above 3000 feet, is that the bulk of heavy rains have now passed. While another shower or local thunderstorm can not be ruled out, the focus now is on much drier air expected to overspread the mountains by Monday into Tuesday with seasonally cool conditions.

Pattern Changes Ahead

*Increasing showers and downpours in thunderstorms will begin to impact the mountain region in coming days, with the Friday-Sunday period of May 10-12 featuring an approaching frontal boundary that slows down across the Appalachians. Hit-miss activity Thursday will become more widespread in nature Friday afternoon into Saturday-Sunday as a upper wave interacts with the surface boundary.

A southwesterly upper air flow (above) ahead of a upper air trough will support occasional waves of showers & thunderstorms through this weekend. Air will turn cooler Saturday as the surface boundary temporarily passes south of the Cumberland Mountains and the low level flow turns northerly, with upslope flow and lowering clouds. A wave of low pressure will then enhance showers-thunderstorms on Mother’s Day (Sunday, May 12).

Heavy to locally excessive rainfall amounts will be possible through this weekend in advance of a much cooler, drier air mass currently expected to overspread the Appalachians by early next week. Those living along streams and in typically flood prone, poor drainage locations will need to monitor the possibility for rapid water level rises through this weekend.

Widespread 1.50″ to 3.50″ rainfall amounts from the Clinch River Valley of Scott County northward across the High Knob Massif into Dickenson County during May 2-5, combined with long-term antecedent wetness, sets the stage for potential high water concerns given additional heavy to locally excessive rainfall amounts upcoming through this weekend.

*Much cooler and drier air is currently expected to overspread the area during Monday into Tuesday of May 13-14, although cooler air will be noted Saturday on upsloping northerly air flow behind initial passage of a surface cold frontal boundary, which stalls, then lifts back northward across the region during Sunday.

A trough (above) in the upper air will replace upper air ridging aloft and be accompanied by much cooler, drier air (below) by May 13-14.

*The potential for air to become cold enough to support frost and near to below freezing temperatures, especially within typically colder mountain valleys away from major rivers and lakes, is being monitored for early next week.

This is not surprising, with minimum temperatures dropping into the 30s to low 40s within colder mountain valleys into morning hours of May 7 and into the 40s during May 8.

For more information reference: Spring 2019_High Knob Massif Area

Mountain Area Forecast ( May 9-11 )

Overnight Into Thursday Morning

Partly to mostly clear. Seasonally mild. Winds SE-S at 5-15 mph, with higher gusts, on mountain ridges and plateaus below 2700 feet. Winds S-SSW at 10-20 mph, with higher gusts, on mountain ridges above 2700 feet. Temperatures varying from low-middle 50s in cooler mountain valleys to 60s on exposed middle elevation ridges and plateaus.

Thursday Afternoon

Partly cloudy with a chance of hit-miss showers and thunderstorms. Winds S-SW at 5-15 mph with higher gusts on mountain ridges & plateaus. Temps varying from upper 60s to lower 70s at upper elevations to the upper 70s to lower 80s (locally warmer within downslope locations of northern Wise-Dickenson and Buchanan counties).

Thursday Night Into Friday Morning

Chance of local evening showers & thunderstorms, then mostly cloudy and mild. Winds S to SSW 5-10 mph, with higher gusts, along mountain ridges & plateaus below 2700 feet. Winds SSW to WSW at 10-25 mph, with higher gusts, mountain ridges above 2700 feet. Temperatures in the upper 50s to middle 60s. Local areas of fog (especially where rain fell).

Friday Afternoon

A chance of showers and thunderstorms. Local downpours. Any storm could be strong to locally severe. Winds SW 5-10 mph, higher gusts possible around thunderstorms. Temperatures varying from mid 60s to around 70 at upper elevations to the mid 70s to lower 80s (warmest lower elevations).

Friday Night Into Saturday Morning

Showers & thunderstorms becoming likely. Local downpours possible. Winds becoming northerly at generally less than 10 mph. Cloud bases dropping across upper elevations and into middle elevations between 2500-3000 feet in locations along and north of the High Knob Massif-Tennessee Valley Divide. Temperatures varying from low 50s to low 60s.

Saturday Morning Through The Afternoon

Showers and a chance for thunderstorms. Local downpours possible. Winds becoming light and variable in direction with elevation. Areas of fog, widespread at upper elevations. Temperatures in the 50s to mid-upper 60s (warmer south into the Great Valley and Tri-Cities).

Intervals of showers and downpours in thunderstorms are expected during the weekend. Locally heavy rainfall amounts will be possible, especially in advance of an upper air trough axis by late in the weekend.