Plentiful Instability
Sunday, September 6, 2026 · 6:33 PM
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Slight relief from the heat arrives tomorrow but temperatures will remain above normal through the period. Low rain chances for areas east of Interstate sixty-five Monday afternoon. The Heat Advisory remains in effect until eight P.M. tonight. Triple digit heat indices expected across southwest Middle Tennessee. A surface low sits just to our north. A boundary draped along the border. The twelve zulu sounding recorded over one thousand Joules per kilogram of downdraft convective available potential energy. Shear is meager. Shear is meager. But the instability is waiting. Drifting south into the evening heat Isolated pulse on the radar screen Downburst potential east of the highway Holding breath while the column collapses The soundings hold the collapse Draped along the state line Shear is meager tonight Plentiful instability! Plentiful instability! Plentiful instability! Plentiful instability! Plentiful instability! PLENTIFUL INSTABILITY!
The forecast discussion
KEY MESSAGES
Updated at 628 PM CDT Sun Sep 6 2026
- Slight relief from the heat arrives tomorrow but temperatures will remain above-normal through the period.
- Low rain chances for areas east of I-65 Monday afternoon.
SHORT TERM
(Rest of today through Monday) Issued at 1130 AM CDT Sun Sep 6 2026
The Heat Advisory remains in effect until 8 PM tonight with triple digit heat indices expected across southwest Middle TN. A surface low is located just to our north with a stalled boundary draped roughly along the TN/KY border.
As this boundary drifts south later today, a few isolated showers and storms may be possible east of I-65. While shear is meager, instability will be plentiful and the KOHX 12z sounding recorded over 1,000 J/kg of DCAPE.
Therefore, although the chance for storms is low, there's potential for any storm to produce strong wind gusts.
A more pleasant temperature forecast is on tap for Labor Day with highs a few degrees cooler in the mid-80s to low-90s.
There's a low to medium chance (30-40%) of isolated to widely scattered showers and storms east of I-65 tomorrow afternoon.
LONG TERM
(Monday Night through next Sunday) Issued at 1130 AM CDT Sun Sep 6 2026
High temperatures will gradually build back to the upper-80s to mid- 90s by Wednesday but PoPs will remain very low (< 10%) as an upper- ridge builds over the southern CONUS.
An upper low will move across Ontario and Quebec later this week and cause a surface front to traverse Middle TN on Thursday.
This will introduce our highest PoPs of the week (45-60%) and bring a slight reduction in temperatures on Friday (mid-80s to low-90s).
Daily low to medium chances (20-50%) for showers and storms will linger through next weekend.