Scattered thunderstorms formed in the unstable air in the vicinity of a surface low pressure area riding along a weak frontal boundary. Some of the storms were slow moving and generated some minor nuisance flooding.
Every event with a place to put it. Tap one for its entry below.
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.
Scattered thunderstorms formed in the unstable air in the vicinity of a surface low pressure area riding along a weak frontal boundary. Some of the storms were slow moving and generated some minor nuisance flooding. There was even a weak tornado that developed over the extreme northeast corner of Tennessee.
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 May 12, 12:05 PM EST, 1 hour earlier.
Area Forecast Discussion National Weather Service Morristown TN 105 PM EDT Fri May 12 2017 .AVIATION... A moisture-rich environment and a low pressure system tracking across the area will result in periods of showers and thunderstorms at all TAF sites through the evening. The most likely timing for storms at all sites is between 20Z and 00Z. IFR vis with heavy rain will be possible, although brief, with mainly MVFR vis/cigs expected. Most rain should exit around midnight, but as cooler air builds in behind a cold front, low cigs are expected through the night and tomorrow morning. MVFR cigs are the most likely scenario, although IFR at times cannot be ruled out. && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && DGS
Hazardous Weather Outlook National Weather Service Morristown TN 309 AM EDT Fri May 12 2017 NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002- 005-006-008-130715- 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- 309 AM EDT Fri May 12 2017 /209 AM CDT Fri May 12 2017/ This Hazardous Weather Outlook is for portions of Southwest North Carolina...East Tennessee and Southwest Virginia. .DAY ONE...Today and Tonight Widespread showers and thunderstorms can be expected today into tonight. Heavy rainfall with the possibility of localized flooding will be the biggest threat, but a few strong to marginally severe storms will be possible especially across southeast Tennessee and extreme southwest North Carolina. Damaging winds and small hail with be possible with the strongest activity. .DAYS TWO THROUGH SEVEN...Saturday through Thursday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated at this time.
The Knoxville radar (KMRX), 119 km away, was scanning. The volume nearest the first event began at 18:06 UTC.
4 heavy rain, 3 thunderstorm wind, 1 hail, 1 tornado. Local standard time, as filed.
A large tree was uprooted along Bristol Caverns Highway.
Quarter size hail was reported.
In this area, trees were reported down, a storage shed was blown from its foundation, and a metal roof was peeled off of a double wide structure.
A tree was reported down along County Road 460.
Minor street flooding along Clearwater Road.
This was a very small and brief tornado that remained on the ground for less than 8 minutes and 250 yards while causing widespread roof damage to two homes, as well as completely destroying two sheds and a carport structure. Everyone interviewed stated that the system was rain shielded, thereby not allowing any witnesses to the event. The storm moved almost due east dropping out of the Holston Mountains and into the valley floor below where the brief EF-0 spun up before weakening into a straight line wind event with estimated winds of 50-70 mph for another one quarter mile. The straight line winds also caused some minor roof damage as well as completely destroying a dilapidated barn.
Minor flooding of Upper Middle Creek Road and near Catons Chapel Elementary School.
Minor street flooding around Johnson City.
Minor flooding on Piney Flats Road.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Tennessee in 2017Every state in 2017This day in weather historyThe tornado archive for Tennessee, 2017Warnings in Tennessee, May 2017
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: 687916, 687914, 687918, 687920, 695160, 687939, 695166, 695164, 695165.