Hit-Miss Tropical Downpours & Thunderstorms Will Continue This Week With A Threat For Localized Water Problems In A Steamy, Jungle-like Air Mass
A jungle-like high water content air mass will continue to grip the mountain region through coming days. Heavy to locally excessive rainfall will be possible in places amid a hit or miss pattern.
Remain alert if heavy rain develops over or upstream of your location. Stay tuned to NOAA Weather Radio and your favorite media sources for possible warnings or advisories.
Overnight Into Mid-Morning Tuesday
A chance of showers & thunderstorms, especially toward morning. Areas of dense fog. Light winds, except SW-W at 5-10 mph along upper elevation mountain ridges. Humid with temperatures in the 60s.
Tuesday Mid-Morning Through The Afternoon
Showers & downpours in thunderstorms becoming likely. Locally heavy rainfall. Winds becoming northerly at less than 10 mph ( outside storms ). Temperatures varying from upper 60s to lower 70s at highest elevations to the mid 70s to around 80 degrees ( hotter south into the Great Valley ).
*This period will bear watching for prolonged dense fog formation across higher elevations amid the moisture laden atmosphere.
Tuesday Night Into Wednesday Morning
A chance of showers & thunderstorms. Areas of dense fog. Winds N-NE at 5-10 mph, with higher gusts, along middle to upper elevation mountain ridges. Humid. Temps in the 60s.
Partly cloudy. Chance of showers and thunderstorms. Winds E-NE at 5-10 mph, with higher gusts ( especially on higher mountain ridges ). Temperatures varying from the upper 60s to lower 70s at highest elevations to the upper 70s to middle 80s ( hotter south into the Great Valley ).
Wednesday Night Into Thursday Morning
Partly cloudy. A chance of showers & thunderstorms, especially during the evening. Areas of dense valley fog. Winds SSE-SSW at 5-10 mph on mid-upper elevation mountain ridges. Temps in the 60s.
Weather Discussion ( July 31-Aug 4 )
A tropical, jungle atmosphere has a firm grip upon the Cumberland Mountains where hefty July and summer rainfall totals have been observed.
Although July 2016 was generally 2 to 4 degrees Fahrenheit warmer than average across the region, differences in the actual observed conditions were simply amazing.
MEAN July temperatures of 73.6 degrees in Wise ( above ) and 73.2 degrees in Clintwood ( below ) featured one day during the month at or above 90 degrees amid above average rainfall.
The MEAN July temperature in the Tri-Cities was 78.6 degrees, making it the second hottest on record amid dryness with only 2.89″ of total rainfall.
To put the above into better perspective, had the Tri-Cities experienced the same temperatures as Wise and Clintwood the month would have been cooler than average by 1.0 to 1.4 degrees Fahrenheit.
Heading up into the high Cumberlands the MEAN July temp at the 4031 foot level on Black Mountain was 69.4 degrees, which would have ranked as the COLDEST on record in the Tri-Cities ( even though it was significantly warmer than average for July at this high elevation ). Rather amazing when you consider it by the actual numbers observed!
Dr. Phil Shelton, professor emeritus extraordinaire at the University Of Virginia’s College At Wise, recently found the Hermit Thrush ( Catharus guttatus ) for the 4th consecutive year atop the High Knob Massif.
This means that this northern bird species is nesting atop the high country in the massif along with many other birds, such as the Veery Thrush ( Catharus fuscescens ), possessing northern affinities.
Temperatures on northern slopes in the massif are coolest, and tend to be cooler than exposed summits and open expanses around larger lakes.
Although the lake level at Big Cherry is around 3117.0 feet above sea level, down about 3 vertical feet, it is not due to dryness and drought but rather to a large amount of water that has been released from the Dam during the past 4-6 weeks to help augment flow on the Powell River as it enters much drier terrain toward the Virginia-Tennessee stateline.
A key factor in relatively cooler summer conditions in upper elevations of the Cumberlands being abundant clouds and wetness, with the MEAN July rainfall recorded during the past 8-years being 7.03″ at Big Cherry Lake Dam prior to July 2016 which has been significantly wetter.
A total of 8.98″ of July rainfall was measured on the north base of the High Knob Massif at the City of Norton Water Plant ( 14.04″ since the beginning of Meteorological Summer on June 1 ).
Only 2.89″ of July rainfall ( 5.02″ since June 1 ) was measured officially in the Tri-Cities, Tn., aiding the large number of 90+ degree days observed due to dry ground and limited moisture for evaporation and evapotranspiration processes which help cool the air and support more cloud formations and showers-thunderstorms ( also cooling air ).
The sun does not heat air directly. Instead the sun heats surfaces of the earth which then heat the overlying air. If the ground is dry, with limited moisture for evaporation ( which uses up some of the insolation ), then a positive feedback for heating ( and often dryness ) develops during the summer season to help promote higher temperatures.
Looking ahead there is little change in the forecast setting this week, with short-range models continuing to look like they have a bad case of the measles as guesses are made about where more tropical downpours may fall ( a brief break in the action may occur during mid-week if the NE wind flow can advect in more stable air…stay tuned ).
A gully washing downpour struck UVA-Wise Monday afternoon, August 1, with torrential rain like might be seen in the Amazon, spiced with lightning-thunder, before it quickly abated. This caused ponding of water along numerous roadways in Wise.
The Bottom Line…A jungle-like environment will continue to support hit-miss tropical downpours above the wet terrain, with more organized action possible at times…especially later in the week and weekend as another front stalls across the region.