A 500 MB trough axis and an associated surface trough of low pressure produced diurnal convection that resulted in isolated flooding.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS MRX wrote it up.
A 500 MB trough axis and an associated surface trough of low pressure produced diurnal convection that resulted in isolated flooding.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Morristown, TN wrote its last area forecast discussion before the first event at Aug 6, 11:03 AM CST, 57 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Morristown TN 103 PM EDT Thu Aug 6 2020 .UPDATE... FOR 18Z AVIATION. && .DISCUSSION... Area radar and satellite imagery shows elevated convection across the plateau in response to a shortwave trough. Although the boundary layer may temporarily stabilize behind this convection, visible imagery is already showing an increase in the CU field across the plateau. RAP forecast soundings show an unstable airmass developing in response to increasing low level lapse rates as CAPE values rise into the 2000-3000j/kg range. Warming between 700-500mb will tend to cap and limited mid level lapse rates today which should keep much of the initial convection weak. However, similar to yesterday some of this convection will likely be able to breach the capping inversion. Any of these storms could become strong to severe with damaging winds the main threat. Heavy rainfall and localized flash flooding is also a concern this afternoon with PWs between 1.50-2.00 inches and increasing warm cloud depths. Only updates this morning was to align PoPs closer to radar trends and hi-res CAMs. Diegan && .AVIATION... 18Z TAF DISCUSSION. Afternoon showers and thunderstorms are currently developing and moving into the valley. These could impact CHA/TYS/TRI this afternoon with temporary reductions in CIGS and visb. Overall expecting VFR conditions to prevail this afternoon and most of the night. Do expect fog to develop again especially in areas that receive rainfall this afternoon. Guidance is hitting TYS and TRI with dense fog and this seems probable. Have persistent MVFR to IFR conditions tonight. Any fog will quickly scatter out by mid morning at all sites that do receive fog. VFR conditions expected toward the latter portions of the TAF period. Winds will remain light through the period. Diegan && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 69 91 69 95 70 / 50 10 0 10 10 Knoxville McGhee Tyson Airport, TN 67 88 67 91 67 / 30 10 0 10 10 Oak Ridge, TN 67 88 67 91 67 / 20 10 0 10 10 Tri Cities Airport, TN 64 85 63 88 63 / 70 40 0 10 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. &&
Hazardous Weather Outlook National Weather Service Morristown TN 330 AM EDT Thu Aug 6 2020 NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002- 005-006-008-070730- Cherokee-Clay-Scott-Campbell-Claiborne-Hancock-Hawkins-Sullivan- Johnson-Morgan-Anderson-Union-Grainger-Hamblen-Northwest Cocke- Cocke Smoky Mountains-Northwest Greene-Southeast Greene- Washington-Unicoi-Northwest Carter-Southeast Carter-Roane-Loudon- Knox-Jefferson-Northwest Blount-Blount Smoky Mountains- North Sevier-Sevier Smoky Mountains-Sequatchie-Bledsoe-Rhea-Meigs- McMinn-Northwest Monroe-Southeast Monroe-Marion-Hamilton-Bradley- West Polk-East Polk-Lee-Wise-Russell- 330 AM EDT Thu Aug 6 2020 /230 AM CDT Thu Aug 6 2020/ This Hazardous Weather Outlook is for portions of southwest North Carolina...east Tennessee and southwest Virginia. .DAY ONE...Today and Tonight Isolated to scattered thunderstorms will be possible this afternoon. A storm or two may become strong to possibly severe with damaging winds the main threat from any severe storm. .DAYS TWO THROUGH SEVEN...Friday through Wednesday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not needed at this time.
Special Weather Statement National Weather Service Morristown TN 124 PM EDT Thu Aug 6 2020 TNZ068-069-071-061815- Loudon TN-Knox TN-NW Blount TN- 124 PM EDT Thu Aug 6 2020 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN LOUDON... SOUTHWESTERN KNOX AND NORTHWESTERN BLOUNT COUNTIES UNTIL 215 PM EDT... At 124 PM EDT, Doppler radar was tracking a strong thunderstorm near Farragut, or near Lenoir City, moving east at 20 mph. Winds in excess of 40 mph will be possible with this storm. Locations impacted include... Knoxville, Maryville, Lenoir City, Alcoa, Farragut, Louisville, Rockford, Eagleton Village, Friendsville and Bearden. PRECAUTIONARY/PREPAREDNESS ACTIONS... This storm may intensify, so be certain to monitor local radio stations and available television stations for additional information and possible warnings from the National Weather Service. && LAT...LON 3572 8424 3586 8429 3601 8392 3576 8384 TIME...MOT...LOC 1724Z 248DEG 16KT 3580 8418 Diegan
Special Weather Statement
National Weather Service Morristown TN
1230 PM CDT Thu Aug 6 2020
TNZ081-082-061815-
Sequatchie TN-Bledsoe TN-
1230 PM CDT Thu Aug 6 2020
...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN SEQUATCHIE AND
SOUTHWESTERN BLEDSOE COUNTIES UNTIL 115 PM CDT...
At 1230 PM CDT, Doppler radar was tracking a strong thunderstorm near
Dunlap, moving east at 10 mph.
Winds in excess of 30 mph will be possible with this storm.
Locations impacted include...
Dunlap, Pikeville, Brayton, Palio, Cagle and Old Cumberland.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 3564 8521 3546 8513 3545 8515 3545 8517
3544 8518 3538 8543 3551 8548
TIME...MOT...LOC 1730Z 253DEG 11KT 3547 8538
DieganSpecial Weather Statement National Weather Service Morristown TN 133 PM EDT Thu Aug 6 2020 NCZ060-061-061815- Clay NC-Cherokee NC- 133 PM EDT Thu Aug 6 2020 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL CHEROKEE AND WESTERN CLAY COUNTIES UNTIL 215 PM EDT... At 133 PM EDT, Doppler radar was tracking a strong thunderstorm near Blairsville, moving northeast at 20 mph. Pea size hail and winds in excess of 40 mph will be possible with this storm. Locations impacted include... Murphy, Hayesville, Brasstown and Culberson. PRECAUTIONARY/PREPAREDNESS ACTIONS... This storm may intensify, so be certain to monitor local radio stations and available television stations for additional information and possible warnings from the National Weather Service. && LAT...LON 3499 8417 3520 8387 3499 8374 3498 8375 TIME...MOT...LOC 1733Z 246DEG 16KT 3496 8403 Diegan
Special Weather Statement National Weather Service Morristown TN 137 PM EDT Thu Aug 6 2020 VAZ001-002-005-061815- Scott VA-Wise VA-Lee VA- 137 PM EDT Thu Aug 6 2020 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN LEE...CENTRAL SCOTT AND SOUTHWESTERN WISE COUNTIES AND THE SOUTHWESTERN CITY OF NORTON UNTIL 215 PM EDT... At 137 PM EDT, Doppler radar was tracking a strong thunderstorm near Big Stone Gap, or 14 miles southwest of Norton, moving northeast at 20 mph. Winds in excess of 40 mph will be possible with this storm. Locations impacted include... Norton, Big Stone Gap, Appalachia, Duffield, Jasper, Fort Blackmore and Dryden. PRECAUTIONARY/PREPAREDNESS ACTIONS... This storm may intensify, so be certain to monitor local radio stations and available television stations for additional information and possible warnings from the National Weather Service. && LAT...LON 3668 8286 3681 8297 3698 8266 3676 8250 TIME...MOT...LOC 1737Z 242DEG 17KT 3678 8281 Diegan
The Northeast Alabama radar (KHTX), 113 km away, was scanning. The volume nearest the first event began at 18:18 UTC.
2 flash flood. Local standard time, as filed.
Water covering the road at the intersection of Summer City Road AND SR 30.
Creek shown out of its banks on social media, flooding yards and a few parked vehicles. A nearby fence was partially knocked down.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Tennessee in 2020Every state in 2020This day in weather historyWarnings in Tennessee, August 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 911244, 911246.