A humid air mass containing outflow boundaries from previous convection triggered isolated diurnal downpours.
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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 humid air mass containing outflow boundaries from previous convection triggered isolated diurnal downpours.
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 17, 2:29 PM EST, 2 hours 16 minutes earlier.
Area Forecast Discussion National Weather Service Morristown TN 329 PM EDT Fri Aug 17 2018 .SHORT TERM...(Tonight and Saturday)... Upper trough over the Great Lakes and Ohio Valley will lift northeast with a positive tilted trough/shear axis remaining across the Ohio and Tennessee Valleys through Saturday. Associated frontal boundary will remain north of the area with the only low-level forcing mechanism being the terrain features. Southwestery flow will continue to pull abundant moisture into the region with PWs of 1.7-2.0 inches. MLCAPEs of 1500-2000 J/Kg today and Saturday afternoon, so plenty of instability to produce scattered storms. Again, best coverage over the elevated terrain. Main concern will be isolated damaging winds (trees down) and torrential rains with localized flash flooding possible. Plenty of low-level moisture, recent rains at spots, and some breaks in the cloud cover will allow for patchy fog development late tonight/early Saturday morning. .LONG TERM...(Saturday night through Thursday)... Long term forecast still looks to be unsettled with a continual chance for showers and thunderstorms. Upper trough over the area and weak front moving through this weekend keeps area wet Saturday night and the front may move just to the south early Sunday. This should allow some drying before front moves back north as a warm front later Sunday into Monday. Localized flooding possible into the evening Saturday with high precipitable water values. Next trough to move into the region Monday with increasing southwest flow and another stronger cold front to approach Tuesday. Heavy rainfall may be another problem Tuesday into Wednesday with the next front and some strong storms ahead of the front. Behind the mid week front later Wednesday decreasing rain chances as drier and cooler air mass settles over the region. Have left slight chance pops near the mountains. Temperatures near to slightly below normal during the day and above normal at night through Wednesday. Thursday and Friday mornings will be significantly cooler with clearing skies...in the lower to mid 60s with mid to upper 50s mountains and valleys in the northeast. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 72 83 71 86 / 70 70 50 50 Knoxville McGhee Tyson Airport, TN 70 83 70 85 / 60 70 70 50 Oak Ridge, TN 71 82 71 85 / 70 70 60 50 Tri Cities Airport, TN 68 82 67 83 / 60 70 70 50 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. &&
Hazardous Weather Outlook National Weather Service Morristown TN 314 PM EDT Fri Aug 17 2018 NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002- 005-006-008-181915- 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-NW 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-Russell-Washington- 314 PM EDT Fri Aug 17 2018 /214 PM CDT Fri Aug 17 2018/ This Hazardous Weather Outlook is for portions of Southwest North Carolina...East Tennessee and Southwest Virginia. .DAY ONE...This Afternoon and Tonight Scattered showers and thunderstorms are expected this afternoon and tonight as an upper disturbance moves in from the west. Some of these stronger thunderstorms could become severe with the primary threats being damaging winds and frequent cloud to ground lightning. In addition, ample moisture will support periods of heavy rainfall. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Scattered showers and thunderstorms are expected once again both Saturday and Sunday, especially during the afternoon and evening. Some of these stronger thunderstorms could become severe with the primary threats being damaging winds and frequent cloud to ground lightning. In addition, ample moisture will support periods of heavy rainfall. Another system will move across the region Monday and Tuesday producing another round of potential strong to severe thunderstorms. Once again, the primary threats being damaging winds, frequent cloud to ground lightning and torrential rains. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The Northeast Alabama radar (KHTX), 140 km away, was scanning. The volume nearest the first event began at 21:44 UTC.
2 flash flood. Local standard time, as filed.
Minor flooding resulted in at least three road closures.
Several roads closed for flooding.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Tennessee in 2018Every state in 2018This day in weather historyWarnings in Tennessee, August 2018
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: 782849, 782846.