Highly anomalous low level jet associated with a strong upper level shortwave brought an early morning thunderstorm complex through Tennessee, with flash flooding around Knoxville and damaging straight line winds in the southernmost counties.
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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.
Highly anomalous low level jet associated with a strong upper level shortwave brought an early morning thunderstorm complex through Tennessee, with flash flooding around Knoxville and damaging straight line winds in the southernmost counties.
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 10, 1:22 AM CST, 1 hour 18 minutes earlier.
Area Forecast Discussion National Weather Service Morristown TN 322 AM EDT Thu Aug 10 2023 ...New SHORT TERM, LONG TERM... .SHORT TERM... (Today and tonight) Issued at 315 AM EDT Thu Aug 10 2023 Key Messages: 1. Showers and thunderstorms moving through during early morning hours this morning. Some of these storms may be strong to severe and localized flooding is possible as well. 2. Behind the MCS, Some isolated to scattered weaker convection possible during the day across the area, and mainly south tonight. Discussion: An MCS to our west is beginning to move into our western counties and will quickly move across our area over the next few hours. Anomalously strong shear for this time of year is in place. However, the convective energy is mostly elevated, and SBCAPE is very limited. There continues to be a threat of damaging wind gusts especially with any bowing structures early this morning. Current indications are that the warm front will stay to our south, but if it manages to nudge close enough to our southern border there will be a threat of an isolated tornado across our southern counties given the impressive low level shear and low LCL heights. The convection will be moving quickly in this strong flow which will help to lower the flooding threat, but the ground is moist and very heavy rain rates may lead to localized flooding especially in any areas that see training. Once the MCS moves through, we will see deep layer drying from west to east. Models suggest some scattered to isolated weaker convection will be around especially north today as some short wave energy moves by, and perhaps across the south tonight as another weak impulse is forecast to brush our southern counties. Patchy fog is expected tonight as well. High temperatures today will be below normal, then lows tonight will be near seasonal normals. && .LONG TERM... (Friday through Wednesday) Issued at 315 AM EDT Thu Aug 10 2023 Key Messages: 1. Active weather continues Friday through the weekend with daily chances of showers and storms. Warmer temperatures over the weekend with heat index values possibly near heat advisory criteria in the southern valley. 2. Stronger storm system arrives Monday and Monday night bringing another chance of showers and storms. 3. Cooler and mostly dry Tuesday and Wednesday. Discussion: Friday weak surface high pressure develops across the northern part of the forecast area. However another weak upper level wave will move through the westerly flow. The front moving through today will still be close enough Friday to enhance showers and thunderstorms over southern areas. The precipitation will progress from west to east with highest chances in the south. NAM model is most aggressive with significant complex crossing southern areas during the morning and early afternoon. GFS and ECMWF not as strong with convection and have less coverage. Will have scattered showers and storms in the forecast with highest rain chances south. Friday night expect convection to dissipate rapidly and skies clearing with some patchy fog. Saturday upper level ridging builds northward and weak surface high builds across the eastern Tennessee Valley and southern Appalchians. Flow is still from the northwest and GFS and ECMWF models drop a system from the Ohio Valley into Tennessee but weakens it as it crosses the state. For this convection higher rain chances will be in the north and lower chances south. Sunday and Sunday night more disturbances either develop or move over the region. This keeps rain chances higher during the day and evening. With the northwest flow and model differences the timing of the disturbances is still uncertain. Another significant upper trough will dive south into the Tennessee Valley Monday. Both ECMWF and GFS show a very developed system moving across the Great lakes and Ohio Valley. This system will give us the best chance of precipitation in the extended forecast with showers and storms likely northern sections Monday afternoon and evening. GFS is faster and ECMWF a little slower and has more of the precipitation farther north until Monday night. Behind this system the airmass dries out with only slight chances of rain lingering Tuesday and Wednesday mostly dry. Temperatures Friday will be near average but then slightly above average Saturday and Sunday, cooling slightly Monday. Tuesday and Wednesday temperatures below average during the day. Lows will be warm Friday through Tuesday but much cooler behind the front Wednesday morning. && .AVIATION... (06Z TAFS) Issued at 114 AM EDT Thu Aug 10 2023 Showers and thunderstorms will move through early in the period. There also may be a few showers or thunderstorms around at CHA later in the period as well, but probability is much lower. Gusty winds and IFR vsby with heavy rain are likely with the convection early. May see some MVFR cigs linger especially at TRI for a few hours after the storms, but trend will be to VFR all sites behind the convection. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 85 72 88 72 / 70 40 50 10 Knoxville McGhee Tyson Airport, TN 82 70 85 70 / 70 20 40 10 Oak Ridge, TN 82 69 85 70 / 70 10 40 10 Tri Cities Airport, TN 78 65 82 66 / 80 10 30 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && SHORT TERM... LONG TERM....TD AVIATION...
Hazardous Weather Outlook National Weather Service Morristown TN 321 AM EDT Thu Aug 10 2023 NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002- 005-006-008-110730- Cherokee-Clay-Scott TN-Campbell-Claiborne-Hancock-Hawkins- Sullivan-Johnson-Morgan-Anderson-Union-Grainger-Hamblen- Northwest Cocke-Cocke Smoky Mountains-Northwest Greene- Southeast Greene-Washington TN-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-Scott VA-Russell-Washington VA- 321 AM EDT Thu Aug 10 2023 /221 AM CDT Thu Aug 10 2023/ This Hazardous Weather Outlook is for portions of southwest North Carolina...east Tennessee and southwest Virginia. .DAY ONE...Today and Tonight Showers and thunderstorms are moving across the area early this morning, and some of these storms may be strong to severe with damaging winds the primary threat. There is also a low threat of an isolated tornado mainly south. In addition, heavy rainfall may lead to localized flooding. .DAYS TWO THROUGH SEVEN...Friday through Wednesday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter reports may be needed early this morning.
Special Weather Statement
National Weather Service Morristown TN
401 AM EDT Thu Aug 10 2023
TNZ081>084-098-099-100845-
Sequatchie TN-Rhea TN-Bledsoe TN-Marion TN-Hamilton TN-Meigs TN-
401 AM EDT Thu Aug 10 2023
...STRONG THUNDERSTORMS WILL IMPACT SOUTHWESTERN RHEA...SEQUATCHIE...
WEST CENTRAL MEIGS...SOUTHWESTERN BLEDSOE...MARION AND HAMILTON
COUNTIES THROUGH 445 AM EDT/345 AM CDT/...
At 400 AM EDT/300 AM CDT/, Doppler radar was tracking strong
thunderstorms along a line extending from 13 miles north of
Gruetli-Laager to near New Market. Movement was east at 60 mph.
HAZARD...Wind gusts up to 50 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Chattanooga, Dayton, Dunlap, Jasper, Pikeville, Soddy-Daisy, Signal
Mountain, South Pittsburg, Walden, and Lakesite.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
&&
LAT...LON 3524 8582 3522 8574 3524 8569 3529 8571
3532 8557 3538 8549 3541 8549 3541 8551
3542 8551 3543 8554 3549 8554 3553 8560
3554 8556 3555 8546 3563 8535 3561 8481
3498 8529 3499 8586 3521 8586 3522 8587
TIME...MOT...LOC 0800Z 256DEG 75KT 3556 8558 3495 8636
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH
DHThe Northeast Alabama radar (KHTX), 49 km away, was scanning. The volume nearest the first event began at 08:40 UTC.
3 flash flood, 2 thunderstorm wind. Local standard time, as filed.
Several trees were blown down by severe thunderstorm wind gusts.
Several trees across the county were blown down by powerful thunderstorm winds.
Flooding of roads reported from West Knoxville to Dutch Valley Drive in northeast Knoxville.
Flooding near the intersection of Middlebrook Pike and Sutherland Avenue, while nearby a car stalled in high water near Middlebrook Pike and Webster Avenue.
Pistol Creek was nearing its banks, and numerous roads were flooding.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Tennessee in 2023Every state in 2023This day in weather historyWarnings in Tennessee, August 2023
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: 1120675, 1120676, 1133797, 1133799, 1133800.