textproduct: Morristown

KEY MESSAGES

Updated at 123 PM EDT Thu Sep 3 2026 - Very hot conditions are expected through the rest of the week with highs reaching well into the 90s and heat index values approaching or exceeding 100 for most places outside the higher elevations. Take frequent breaks and drink plenty of water when outdoors this week!

- Temperatures will gradually moderate some through the weekend with a return of isolated to scattered showers and storms.

- A few storms Friday afternoon/evening mainly north and then including the remainder of the area Saturday may become strong to severe, with damaging wind gusts the primary threat.

DISCUSSION

Issued at 123 PM EDT Thu Sep 3 2026

There are two main talking points for the forecast period. The first is the continued heat across the region, driven by a strong upper ridge located overhead. And the second is the chances for severe storms on Saturday as the ridge shifts westward...briefly.

First of all, the upper ridge responsible for our heatwave this week will remain situated over the southern Appalachian region today and Friday. Deterministic guidance shows highs in the 95-100 degree range throughout the valley this afternoon and again on Friday. Dewpoints will remain in the upper 60s to low 70s both days, resulting in afternoon heat index values in the 100-105 degree range. Model guidance shows the ridge being almost perfectly centered over the MRX forecast area during the day tomorrow, with an expansion in warmer H85 temps noted. I could see us eking out another degree or two above what the NBM guidance is showing, which is also supported by some guidance sources including the ECMWF. If that happens, advisory criteria would definitely be reached further north. Since we're going to be close to advisory criteria today in areas outside the Heat Advisory that was issued yesterday, and there's a decent shot we'd need it tomorrow, I went ahead and expanded it effective this afternoon. The ridge shifts west on Saturday, allowing a "cold" front to move through, and remains centered over the Great Plains through Tuesday before shifting back east again. In other words, the heat returns next week it seems. Lastly, I've included a Climate section below to highlight some potential records that are in jeopardy in the coming days.

With regards to severe chances on Saturday, a deep trough digs over the west coast Friday into Saturday, allowing the ridge to shift west to the plains and a trough to strengthen along the eastern seaboard. This will send at least one impulse through the Ohio valley, southern Appalachians, and into the Carolinas on Saturday and push a cold front through the region. Forecast soundings show some rather extreme instability values over the forecast area on Saturday afternoon, characterized by mixed layer CAPE values of 2,500 to 4,000 J/kg, coincident with mid level lapse rates of over 6.5 C/km in some cases. Any storm that can get a sustained updraft going in that environment will have little to no issues become strong to severe. Downbursts and even large hail would be on the table, despite freezing levels above 13,000 ft. Thankfully, shear is on the low-end of the spectrum in terms of supporting organized convection, so coverage is expected to be somewhat sparse.

The "cold" front knocks highs down into the 80s to 90s for Sunday through Tuesday, but as I mentioned above the ridge shifts back east by mid-week next week so I suspect we'll see a return of quite warm temperatures.

---- Climate section ----

I wanted to highlight the Chattanooga area in the climate section. Currently they're sitting at 30 straight days (valid 9/2/2026) of highs at/above 90 degrees, which is tied for 4th place. High temperatures are forecast to remain at/above 90 degrees through the forecast period. Unless something goes off the rails and a thunderstorm impacts their max temps one day, there's a very good chance they break the all time record of consecutive days at/above 90 next week. Contrast this with Tri-Cities and Knoxville, which don't have active streaks that even rank in the top 50.

Below are some tables that highlight daily record highs for all 4 climate sites through next week, as well as some information on the 90 degree day streak for Chattanooga specifically.

Chattanooga 90 Degree Day Streak

Rank Days Ending Date 1 38 08-02-1993 2 32 08-29-2007 3 31 07-21-1954 4 30 09-02-2026 5 29 08-16-2010

Daily Record High Maximum Temperatures

Date Chattanooga Knoxville Tri-Cities Oak Ridge 09-03 100(1954) 98(2011) 96(2011) 99(2011) 09-04 102(1954) 101(1954) 99(1954) 100(1954) 09-05 104(1925) 103(1954) 99(1954) 102(1954) 09-06 103(1925) 101(1954) 100(1954) 102(1954) 09-07 104(1925) 102(1925) 100(1954) 99(1954) 09-08 100(1925) 96(1941) 92(2002) 95(1999) 09-09 102(1925) 100(1925) 95(1954) 97(1954)

AVIATION

(18Z TAFS) Issued at 123 PM EDT Thu Sep 3 2026

Will go with a persistence forecast at KTRI and include at least a hedge towards fog development by putting in some 3SM VSBY early tomorrow morning. Otherwise VFR conditions are expected to prevail at all sites. ISOLD SHRA/TSRA could develop this afternoon and again tomorrow but they're not expected to impact any terminals.

PRELIMINARY POINT TEMPS/POPS

Chattanooga Airport, TN 75 99 76 98 / 0 10 0 30 Knoxville McGhee Tyson Airport, TN 74 97 75 96 / 0 10 0 20 Oak Ridge, TN 74 98 74 96 / 0 10 10 30 Tri Cities Airport, TN 70 95 70 91 / 0 10 10 50

MRX WATCHES/WARNINGS/ADVISORIES

NC...NONE. TN...Heat Advisory until 8 PM EDT /7 PM CDT/ Friday for Anderson- Bledsoe-Bradley-Campbell-Claiborne-Grainger-Hamblen- Hamilton-Hancock-Hawkins-Jefferson-Knox-Loudon-Marion- McMinn-Meigs-Morgan-North Sevier-Northwest Blount-Northwest Cocke-Northwest Greene-Northwest Monroe-Rhea-Roane-Scott TN- Sequatchie-Union-West Polk.

VA...NONE.