1000 Joules Per Kilogram
Saturday, September 5, 2026 · 12:17 AM
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Major to extreme heat risk continues through this weekend with heat index values of one hundred five to one hundred ten degrees. A Heat Advisory remains in effect. Isolated to scattered thunderstorms expected Saturday afternoon with a low risk for severe weather due to strong to damaging winds. Heat risk lessens early next week, but temperatures remain above-normal through the forecast period. Weak disturbance rolling from the north Saturday afternoon pushing on through High pressure shifting out to the west Middle Tennessee burning under mid-nineties heat Boundary layer drying out down low Inverted-V on the sounding chart The fuel is waiting for the sky to break Waiting for the spark in the heat of the day Weak wind shear won't organize the storm But the downdraft energy is off the scale The cold front forcing on the eastern half Is gonna send the air crashing down like a nail! Dry air underneath the cloud base high Triple digits cooking up the afternoon sky When the column drops it's gonna smash the land Over one thousand joules per kilogram! Marginal risk across the eastern zones Proximity to forcing gives a better shot Pop-up cells with a heavy core Damaging gusts hitting ninety-five degrees Daytime heating vanishes at sunset hour Activity diminishes and leaves us dry A quiet night before the front clears out Leaving us baking in the sun again Dry air underneath the cloud base high Triple digits cooking up the afternoon sky When the column drops it's gonna smash the land Over one thousand joules per kilogram! One thousand joules! Falling from the sky! Loss of daytime heating! Drier air on Sunday! One thousand joules per kilogram!
The forecast discussion
KEY MESSAGES
Updated at 1217 AM CDT Sat Sep 5 2026
- Major to extreme heat risk continues through this weekend with heat index values of 105 to 110 degrees.
A Heat Advisory remains in effect.
- Isolated to scattered thunderstorms expected Saturday afternoon with a low risk for severe weather due to strong to damaging winds.
- Heat risk lessens early next week, but temperatures remain above-normal through the forecast period.
SHORT TERM
(Tonight through Sunday Night) Issued at 1032 PM CDT Fri Sep 4 2026
Today's activity has diminished, and a quiet but warm night is ahead.
The area will still be under the influence of strong high pressure although it will be shifting towards the west this weekend.
Still, hot temperatures with highs well into the 90s will continue Saturday.
Temperatures dip a couple more degrees on Sunday with the high over the Plains, but will still be in the mid-90s for southwest Middle TN with triple digit heat indices.
These temperatures are still well above normal for September, and with several days of these temperatures, heat risk will still be major across western Middle TN. As such, have extended the Heat Advisory for this area into Sunday.
As far as rain goes, as the high shifts west, this will open the door for a weak disturbance and cold front to move through the area Saturday, allowing for isolated to scattered thunderstorms to develop during the afternoon and evening.
Wind shear will be weak with this system which lessens the threat for any organized severe weather risk.
But forecast soundings look like inverted-Vs with plenty of DCAPE of 1000+ J/kg.
This will support a strong to damaging wind threat.
A marginal risk is still in place for Saturday across the eastern half of the area where forcing is a bit better in proximity to the front.
But any thunderstorm Saturday will be capable of producing gusty winds.
Activity should diminish quickly after sunset with the loss of daytime heating.
Drier air filters in for Sunday.
LONG TERM
(Monday through next Saturday) Issued at 1032 PM CDT Fri Sep 4 2026
On Monday, Middle TN is between the high still to the west and troughing to the east.
This allows for a low chance of diurnally- driven storms, primarily across the Plateau.
But by Tuesday, the high works its way back over the southeastern US which keeps temperatures in the 90s through the end of next week.
These temperatures don't look like they'll be as hot as this current heat wave with heat index values staying below that 105 degree heat advisory criteria.
But these above normal readings for September will still be uncomfortable.
With the high overhead, it does bring dry conditions for at least Tuesday & Wednesday.
We'll have to look ahead to next Thursday for the possibility of a pattern shift and the return of some low rain chances.