textproduct: Louisville

KEY MESSAGES

* Heat Advisory expanded to include all counties in forecast area. Daily highs in the 90s, with heat index values around or above 100F expected through Thursday, likely through Friday too.

* Major Heat Risk will continue to expand across the area. Practice heat safety by staying hydrated and limiting time outdoors.

* A weak cold front could bring scattered showers and storms to the area late Friday and Saturday.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 323 PM EDT Tue Sep 1 2026

Dense cu field has developed across the region today due to strong heating. Temps have reached the mid-90s, with heat indices in the upper 90s and lower 100s. Sfc high pressure will continue to dominate the forecast over the short term period, with dry weather expected for tonight. Considering the duration of hot temps and heat indices around 100F or above, the decision was made to expand the current Heat Advisory east.

For Wednesday, similar forecast is expected with sfc high pressure to the east, strong heating, and relatively muggy dewpoints. Temps peak tomorrow afternoon in the mid to upper 90s, with heat indices exceeding 100F. The HRRR suggests a few isolated showers developing tomorrow afternoon, but expect to stay dry as sfc high pressure keeps a strong influence. Even if something would develop, very weak wind profile will result in very weak shear.

Temperatures might even be a bit hotter on Thursday with highs solidly in the upper 90s. Major HeatRisk will continue to spread throughout the region. Given SDF has hit 97F today, we could end up seeing some temps hit 100F by Thursday.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 323 PM EDT Tue Sep 1 2026

===== Friday through the Weekend =====

The upper ridge will begin to build back to the west on Friday as upper troughing deepens over the northeast. This will result in a weak backdoor cold front to approach the region from the northeast sometime on Friday. We'll see an uptick in moisture advection on Friday, and perhaps some isolated to scattered showers and/or storms, especially for the Bluegrass region. We'll still be dealing with the heat then too, with forecast highs in the upper 90s, and sfc dewpoints creeping up into the mid-70s. Heat indices around above 100F are likely across the entire forecast area. The heat advisory will probably need to be extended into Friday too, but with a chance for PoPs, it makes the confidence a little lower.

Higher precip chances arrive on Saturday as that cold front sweeps into the forecast area. Thunderstorms will be possible Saturday afternoon and evening. Long range deterministic soundings show steep low level lapse rates and an uncapped profile, but weaker shear parameters could help keep storms unorganized. The wind profiles will be rather weak, with less than 20kts below 500 mb. We'll begin to see temps transition back to the 80s on Sunday, with split temps between the upper 80s in our east and lower 90s in our west.

AVIATION /00Z TAFS THROUGH 06Z THURSDAY/

Issued at 725 PM EDT Tue Sep 1 2026

VFR conditions and light winds are expected to continue overnight, with no fog expected Wednesday morning. For the day on Wednesday, the forecast is near persistence as high pressure over the southern Appalachians remains in control. As was the case this afternoon, a SCT cu field with bases around 5-7k ft should develop around 15-16Z. Additionally, winds should be generally less than 10kt during peak mixing, and may be quite variable between S/SW and W/NW due to weak forcing.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Heat Advisory until 8 PM EDT /7 PM CDT/ Thursday for KYZ023>043-045>049-053>057-061>067-070>078-081-082. IN...Heat Advisory until 8 PM EDT /7 PM CDT/ Thursday for INZ076>079-083-084-089>092.