textproduct: Morristown

KEY MESSAGES

Updated at 238 PM EDT Mon Aug 17 2026

- Showers and storms will move through the area today into this evening, and some will likely be strong to severe with damaging winds the primary threat. Localized flash flooding is also possible especially north.

- Drier and not quite as hot mid week, then chances for showers and storms increase again Thursday into the weekend.

DISCUSSION

Issued at 238 PM EDT Mon Aug 17 2026

The heat advisory will be allowed to continue this afternoon. The showers and storms will bring an abrupt end to the worst of today's heat as they move through any given location.

The weak cold front to our west and northwest will move in this evening and will be near our eastern border by early Tuesday. The atmosphere ahead of the front features MLCAPE values generally in the 1500-2500 J/kg range with steep low level lapse rates and effective bulk shear around 20 to 35 kt (higher values are across the north). Significant DCAPE and high PWAT values are also in place. CAMS generally show the convection organizing into a line or line segments, and damaging straight line winds are the primary threat. A very low, but non-zero threat of a brief tornado spin up exists as well mainly across northern areas. Very heavy rainfall rates can be expected given PWAT values climbing to around 2 inches, and localized flash flooding will be possible in areas that see prolonged or repeated rounds of heavy rainfall especially across the northern half of the area where the ground is still wet from the recent rains.

Surface high pressure will build in behind the front Tuesday and will provide drier and slightly less hot conditions for Tuesday into Wednesday. While it will still be on the hot side with high temperatures generally above seasonal normals (especially Wednesday), lower humidity will keep heat index values lower than recent days.

By Thursday and Friday models show another shortwave or multiple short waves moving in with the upper trough over the eastern CONUS deepening, and another weak cold front is likely to push through our area sometime in that time frame as well. However, the models are still struggling with the details for the later periods. The ensemble approach of the NBM has chances for showers and storms increasing again for Thursday and Friday and continuing into Saturday. Sunday and Monday currently look drier as the trough axis shifts to our east and surface high pressure builds in, although confidence is not high that far out. Temperatures for the weekend currently look to be not far either side of normal for this time of year.

AVIATION

(18Z TAFS) Issued at 1239 PM EDT Mon Aug 17 2026

Showers and thunderstorms will move through this afternoon/early evening. Will see VFR conditions for the first part of the period, other than with any thunderstorms or heavier showers when conditions may dip to MVFR or lower. Brief strong gusty winds will also be also possible with storms with the most likely direction from the west or northwest. Late tonight into early Tuesday MVFR or lower conditions are likely at TRI in low clouds and/or fog, with conditions likely to dip at least briefly to MVFR at TYS. Both locations will return to VFR late in the period.

PRELIMINARY POINT TEMPS/POPS

Chattanooga Airport, TN 74 93 69 95 / 30 0 0 0 Knoxville McGhee Tyson Airport, TN 73 89 68 92 / 60 10 0 0 Oak Ridge, TN 71 89 66 91 / 40 0 0 0 Tri Cities Airport, TN 69 85 64 88 / 60 10 0 0

MRX WATCHES/WARNINGS/ADVISORIES

NC...NONE. TN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for Anderson-Bledsoe-Bradley-Hamilton-Knox-Loudon-Marion-McMinn- Meigs-Morgan-North Sevier-Northwest Blount-Northwest Monroe- Rhea-Roane-Sequatchie-West Polk.

VA...NONE.