textproduct: Morristown

KEY MESSAGES

Updated at 749 PM EDT Fri Sep 18 2026

- Well above normal temperatures to persist through early next week. Heat Indices will remain in the upper 90s to lower 100s across the central east TN and southern TN valley through Monday.

- Temps cooling towards normal at the end of the forecast period, mid to late next week.

- Increasing rain chances this weekend into next week, similar to a typical summer pattern. Better chances for more widespread rain by Tue/Wed.

DISCUSSION

Issued at 238 PM EDT Fri Sep 18 2026

Isolated showers and storms are currently ongoing across the area and will persist until around 10 PM tonight. No severe weather is expected. Any areas that see a decent amount of rainfall today will likely see fog tonight.

Tomorrow, showers and storms are once again expected during the afternoon and evening hours, but coverage should be a little greater than today. This is due to the positioning of the high for tomorrow, which will be just west of our area. This puts us on the eastern periphery which means we will be in "Ring Of Fire" so to speak. Basically meaning, greater chances for showers and storms due to weak impulses moving through the northerly flow and into our area. We remain in a marginal risk for severe weather for tomorrow from SPC. The greatest threat will be damaging winds, possible straight line and/or downburst. The wind threat is due to good low-level lapse rates of around 7 to 8 deg C/km, DCAPE of around 1000 to 1200 J/kg, and drier air at surface which shows up in the soundings as an inverted V. Storms will likely begin to develop between 1 and 2 PM and dissipate by 10 PM. Again, a few strong to severe storms are possible.

For Sunday, almost the exact same setup as Saturday, though perhaps a little less coverage of showers and storms. SPC only has our area in the general thunder outlook but I wouldn't be surprised to see us upgraded to a marginal.

For Monday and Tuesday, showers and storms remain in the forecast as the ridge shifts further west and the flow becomes more zonal. A more zonal flow provides better chances for at least some isolated convection, less subsidence. Temps and heat indices remain elevated.

Tuesday night into Wednesday, an upper trough is set to swing through the area. In addition to increased chances for showers and storms, temperatures will begin cooling off behind on the backside of the trough. Drier and cooler conditions expected on Thursday and Friday. High temperatures will be in the 70s/80s as opposed to the 80s/90s. Overnight lows will be in the 50s/60s instead of the 60s/70s. So hold on for a few more days of heat, relief is on the way!

Lastly, until we see a relief in temps, Chattanooga will continue to build onto their record streak of 90 degrees or higher. They currently sit at 45 days, with several more days likely to add to the streak. The first official day where the forecast is below 90 is next Wednesday, which a high of 87.

AVIATION

(00Z TAFS) Issued at 749 PM EDT Fri Sep 18 2026

Convection should not impact any terminals the remainder of this evening before it dissipates. Fog could be an issue tonight, especially in the north. Given KTRI got some rain this afternoon, have gone with a TEMPO for lower VSBY and CIGS. Basically a persistence forecast. Another round of SHRA/TSRA is expected tomorrow. Given it's late it in the period, and uncertainties exist with respect to coverage, I didn't include this at any sites.

PRELIMINARY POINT TEMPS/POPS

Chattanooga Airport, TN 98 74 98 72 / 20 10 40 20 Knoxville McGhee Tyson Airport, TN 95 71 94 70 / 20 20 30 20 Oak Ridge, TN 95 70 93 70 / 40 20 30 10 Tri Cities Airport, TN 89 67 88 66 / 50 40 30 20

MRX WATCHES/WARNINGS/ADVISORIES

NC...NONE. TN...NONE. VA...NONE.