Area Forecast Discussion

KEY MESSAGES

Updated at 228 PM EDT Sun May 17 2026

- Isolated storms are possible this evening, especially in southern areas. Strong winds and hail up to 1 inch in diameter are possible, but coverage is expected to be limited.

- Widespread rain chances return Wednesday through next week.

- High temperatures will rise well into the 80s to around 90 degrees for many today through Tuesday, followed by moderation of temperatures.

DISCUSSION

Issued at 228 PM EDT Sun May 17 2026

Currently this afternoon, broad ridging is in place across the eastern U.S. ahead of deepening troughing over the Rockies. The Bermuda High continues to strengthen in the Atlantic, leading to increased southerly flow and temperatures rising near the 90-degree mark. With moisture advection compared to yesterday, there is a low- end chance for diurnal convection, especially in the south. While there's virtually 0 shear, mid-level lapse rates are at or above 7 C/km with MLCAPE rising above 1,000 J/kg. The main question is about initiation, which could end up being very minimal per some of the CAMs. Any storms would pose a marginal wind and hail threat in this environment. On Monday, troughing to the northwest will lift as it ejects into the northern Great Plains with a developing surface low tracking towards the Great Lakes. Locally, 500mb heights will surpass 5,880m, which is at or above normals for July. Similarly hot temperatures can be expected with slightly less moisture leading to even lower chances for diurnal storms.

By Tuesday, the cold front associated with the Great Lakes low will begin to advance towards the Ohio River Valley with the pattern locally remaining similarly hot and dry. By Wednesday, however, the front will move through the Ohio River Valley with better moisture advection out ahead. This will lead to a widespread increase in chances for showers and storms. Thursday and Friday, the front will move towards the region before getting pulled back northward into the weekend. This will keep rain chances elevated for the rest of the period. At this time, there is still no strong indication of an environment supportive of organized or severe storms, which is also shown in the CIPS analogs. Isolated stronger storms will be possible as in most summer convection days. Overall coverage is uncertain this far out, but hopefully many places see rainfall as Knoxville and Chattanooga continue to be at the lowest year-to-date rainfall since 2007.

AVIATION

(18Z TAFS) Issued at 121 PM EDT Sun May 17 2026

Isolated storms are possible by early evening, mainly around CHA and TYS. A TEMPO was included at CHA due to better chances with VCTS at TYS. It is very possible that storms stay away from both sites. Otherwise, southwesterly winds will gradually diminish through the evening with cloud cover generally around 5,000 to 10,000 feet.

PRELIMINARY POINT TEMPS/POPS

MRX WATCHES / WARNINGS / ADVISORIES

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