textproduct: Morristown

KEY MESSAGES

Updated at 142 PM EDT Thu Aug 27 2026 - Scattered storms expected this afternoon and evening, with the possibility of a severe storm or two. Isolated to scattered storms expected on Friday too, with less coverage overall and little to no threat of severe storms.

- Most locations will be dry for the weekend with return of hot and humid conditions early next week.

DISCUSSION

Issued at 142 PM EDT Thu Aug 27 2026

Synoptic scale troughing from the Hudson Bay area southward through the eastern CONUS, along with upper ridging from the Four Corners region through the northern Rockies, will continue through Friday. A pattern change to a warmer and drier regime begins over the weekend, but before that happens we'll have some scattered storms to deal with this afternoon. More on that below. By Saturday morning the upper trough begins to pull away to the northeast and the western ridge starts its eastward trek towards the southern Appalachian region. The ridge should be centered over Tennessee by Monday afternoon, where it will remain through the end of the period, and lead to increasingly warm conditions across the NWS Morristown forecast area.

Going into a bit more detail, this afternoon we still have cyclonic flow aloft, with a shortwave slated to move through this afternoon and into the evening hours. This will push a weak front our direction, which, when coupled with slight height falls aloft and sufficient moisture and instability in place, should lead to the development of scattered thunderstorms later today. Expect initiation over the Appalachians and the higher terrain of the plateau areas, but convection will eventually spread into the valley as time progresses, especially later on as the front draws near and forces things eastward. The SPC Day 1 convective outlook has been adjusted today to expand the Marginal risk area southward to encompass much of our CWA. This seems reasonable to me. The normally bullish NAM (with regard to moisture and instability) is actually handling current surface conditions well I think, and it shows MLCAPE values ranging from near 2,000 J/kg in the south to around 3,000 J/kg in the central and northern valley late this afternoon and early evening, with over 7 C/km lapse rates aloft as well. DCAPE values are in the 1,000 - 1,200 J/kg range. In this environment, I wouldn't be surprised to see some strong to severe storms capable of some +60 mph winds develop. Coverage will be the limiting factor in our severe chances. No guidance source is overly enthusiastic with regards to storm coverage this afternoon, so the threat of severe storms should be isolated in nature. For Friday, expect less afternoon shower and thunderstorm coverage than today. Instability will also be less, so the threat of any strong to severe storms seem very low.

Looking ahead to next week, the upper ridge centered over Middle and East Tennessee will mean dry conditions and a notable warming trend. It doesn't appear that we will approach any record highs, but it will be warm, and heat index values could climb to around or even slightly over 100 degrees at times. For those who care about such things, August 24th was the day that average highs start their decline for the year, and October 9th is the last day where record highs in Knoxville reach the 90 degree mark. Don't lose hope, fall is on the way. I mean, for those who care about such things.

AVIATION

(00Z TAFS) Issued at 735 PM EDT Thu Aug 27 2026

Isolated SHRA/TSRA across the TN valley this evening. I removed the PROB30 in KCHA but left it for KTYS & KTRI given the towering CU present near those locations. Confidence is still low in any direct impacts to either of those terminals so I opted to keep PROB30 vs TEMPO group. Any additional development will be driven largely by outflow boundary interactions. Convection should taper off by 02z, with dry conditions overnight. Guidance continues to highlight FG development in the Valley tonight. At KTRI, I lowered VSBY from 5SM to 2SM given the increased confidence of fog formation. Winds go calm overnight and turn to the north around 5 to 7 knots Friday mid-morning. All sites return to VFR by mid- morning. Isolated showers Friday afternoon should remain east of the terminals, primarily along the mountains and terrain.

PRELIMINARY POINT TEMPS/POPS

Chattanooga Airport, TN 70 92 69 93 / 30 20 10 10 Knoxville McGhee Tyson Airport, TN 69 89 67 91 / 50 20 10 10 Oak Ridge, TN 68 88 67 90 / 40 30 10 0 Tri Cities Airport, TN 65 86 64 87 / 30 20 10 10

MRX WATCHES/WARNINGS/ADVISORIES

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