textproduct: Morristown

KEY MESSAGES

Updated at 653 AM EDT Sat Sep 19 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 142 AM EDT Sat Sep 19 2026

Saturday and Sunday will feature decreasing heights aloft as the upper ridge, centered over the Arklatex region, begins to break down. That will place thee southern Appalachian region on the periphery of the retreating ridge, allowing for a mix of diurnally forced convection and thunderstorm complexes moving in from the northwest in this "Ring of Fire" type setup. Much of the CWA is in a Marginal risk area for a damaging wind threat tomorrow, while only in a general thunder area on SPC's Day 3 outlook. I wouldn't be surprised to see that expanded on Sunday. The thermodynamic setup for both Saturday and Sunday looks similar to today, that is to say DCAPE values in the 1,000 - 1,200 J/kg range, favorable lapse rates, and MLCAPE north of 1,500 J/kg. As such, it would not be hard to imagine a scenario where a handful of Sig Wx Advisories and a maybe a couple of severe thunderstorm warnings are issued.

Looking ahead to Monday and Tuesday, afternoon showers and storms remain in the forecast as the ridge continues to break down and an upper low, once over the Intermountain West, shifts east across the plains and into the Great Lakes region Sunday through Tuesday. Temperatures will remain well above normal through this time.

Tuesday night into Wednesday the upper low deepens over the Great Lakes region and leads to a pattern change characterized by much more notable troughing over the eastern CONUS as opposed to high pressure. In fact, we may have a legitimate cold front passage next Wednesday beneath the upper trough/low. In addition to increased chances for showers and storms this pattern will bring, 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 day where the official forecast is below 90 is next Wednesday. If they hold on to 90 through Tuesday, that would bring the streak up to 50 days.

AVIATION

(12Z TAFS) Issued at 653 AM EDT Sat Sep 19 2026

Areas of fog have developed across SW VA and NE TN early this morning. This has led to IFR to LIFR vsby and cigs at TRI. Conditions should improve quickly after sunrise with a return to VFR between 13-14Z. For TYS and CHA, VFR to start the period with only a few high clouds. I have included a PROB30 for -TSRA at both TYS and TRI this afternoon. Hi-res models show scattered thunderstorms developing in the early afternoon hours and dissipating by sunset. Confidence is not high enough to include CHA in the PROB30 so opted to keep it dry for now.

PRELIMINARY POINT TEMPS/POPS

Chattanooga Airport, TN 98 72 96 71 / 30 10 30 10 Knoxville McGhee Tyson Airport, TN 94 70 92 69 / 20 10 20 10 Oak Ridge, TN 93 69 92 68 / 30 10 30 10 Tri Cities Airport, TN 88 66 86 65 / 20 20 40 30

MRX WATCHES/WARNINGS/ADVISORIES

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