textproduct: Morristown

KEY MESSAGES

Updated at 103 PM EDT Sat Sep 5 2026 - Very hot conditions will continue again today 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.

- Heat Advisory is in effect through 8 PM EDT this evening for most of East Tennessee.

- Today, storms will be more isolated in the southern Valley and more scattered from around Knoxville northward. Some storms may become strong to severe, with damaging wind gusts the primary threat.

UPDATE

Issued at 1057 AM EDT Sat Sep 5 2026

A MCV moving across the central Appalachians and a outflow boundary moving southeast across southwest VA, northeast TN, and northern Plateau will produce scattered to widespread thunderstorms over this area for the next couple of hours. Have increased PoPs over this region. Airmass is quickly destabilizing with MLCAPES approaching 2500 with DCAPES of 900-1200. Localized damaging winds, frequent lightning, and possibly small hail will be the main concern. SPC mentioned a possible watch.

DISCUSSION

Issued at 147 AM EDT Sat Sep 5 2026

In the upper levels, the trough dips into the Ohio Valley as the ridge narrows to the west centered over the Great Plains. At the surface, a weak cold front will move through the region this evening, bringing a better chance for showers and storms especially from Knoxville northward. With better synoptic lift in place today, there is a higher chance for strong to severe storms especially in northeast Tennessee and southwest Virginia (SPC Slight risk), closer to the trough. The rest of the region is under a marginal risk for severe. Storm activity will likely be more isolated from around Knoxville southward. Guidance is starting to hint at a minor short wave or two moving through the pattern from Kentucky into East Tennessee. HRRR is picking up on an organized cluster moving down from Kentucky possibly in the early afternoon hours. With good instability (about 2500 J/kg) but weak deep layer shear and high freezing levels, the primary threat will be damaging straight-line winds. Hail less than one inch will be possible in the strongest storms. It is hard to nail down the frontal timing since the front is weak but I am thinking it will be more in the evening or overnight for actual frontal passage. An organized cluster of storms or MCS moving down from Kentucky will be possible this afternoon through late evening. The CAMs have a couple of waves of storms coming down from Kentucky one in the early afternoon and one in the evening, generally weakening as they move south.

Slightly cooler temps expected by Sunday after frontal passage. Although, not so much near Chattanooga despite what appears to be a clean frontal passage. There will still be some showers and storms mainly in the easternmost counties Sunday as the region stays sandwiched between a ridge to the west and a trough to the east. Monday will have cooler temps (although still very warm) with highs in the Tennessee Valley mainly in the upper 80s.

By Monday and especially Tuesday the ridge will drift back into the Southeast, bringing hot, dry conditions through at least midweek. It doesn't look quite as hot as this week was, highs will likely be in the lower 90s for the Central and Southern Tennessee Valley opposed to the upper 90s from this past week.

Daily Record High Maximum Temperatures

Date Chattanooga Knoxville Tri-Cities Oak Ridge 09-05 104(1925) 103(1954) 99(1954) 102(1954)

AVIATION

(18Z TAFS) Issued at 103 PM EDT Sat Sep 5 2026

An outflow boundary is moving across the central valley. Scattered storms expected near TYS for the next several hours. Depending on how far south this boundary moves will decide on ending chances of convection. Airmass stablizes behind this boundary and will remove chances of convection at TRI. For CHA, depending how far south this boundary moves, scattered storms are possible there as well late this afternoon.

Besides the storms, development of fog and low clouds are expected at TRI and possibly TYS early Sunday morning.

PRELIMINARY POINT TEMPS/POPS

Chattanooga Airport, TN 74 97 73 91 / 20 20 10 30 Knoxville McGhee Tyson Airport, TN 72 92 69 90 / 30 20 0 50 Oak Ridge, TN 71 91 68 90 / 30 20 0 40 Tri Cities Airport, TN 67 86 66 85 / 40 40 10 0

MRX WATCHES/WARNINGS/ADVISORIES

NC...NONE. TN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening 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.