textproduct: Louisville

KEY MESSAGES

* Mostly dry and warmer today. A few light showers possible later this afternoon. Thunderstorms are not expected.

* The hottest day of the week will be Wednesday with highs in the low to mid 90s and peak heat indices in the low 100s along and west of I-65. A Heat Advisory has been issued for Wednesday afternoon.

* A cold front arrives Thursday morning with 80-90% chance of showers and a few storms possible. Fairly widespread rainfall between .5" - 1" is expected with locally higher amounts over 1.5" possible, especially along and north of I-64.

* This weekend is expected to remain active with multiple waves of showers and storms.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 255 PM EDT Tue Sep 8 2026

High pressure at the surface and strong ridging aloft has allowed for temperatures to warm today into the upper 80s and low 90s. Southwesterly flow has increased dew points into the upper 60s and low 70s. Heat indices are in the upper 90s this afternoon. A broken cumulus deck has developed and isolated, brief light showers will continue through the afternoon. Showers will remain brief and are not expected to intensify given the strong subsidence over the region. This evening, low clouds will dissipate and southerly flow will remain light. This will prevent efficient radiational cooling tonight and temperatures will bottom out in the upper 60s over the far east, valley areas and low-mid 70s elsewhere.

On Wednesday, the surface high pressure will push eastward and a strong low pressure will begin to push into Great Lakes. This will allow the pressure gradient over the Ohio Valley to tighten. Breezy southwesterly winds sustained around 15mph and gusting up to 25- 30mph are expected through the afternoon. Given this impressive pattern, temperatures tend to overachieve. Expecting to see highs in the low-mid 90s. Dew points are expected to increase over the region, which will place peak heat indices in the 95-105F range. A bust potential for northern areas will be the potential for increased cloud coverage and late afternoon showers and storms. A Heat Advisory has been issued for Wednesday from Noon ET to 8PM ET.

Later in the afternoon and into the evening hours, a pre-frontal trough is expected to push south into southern Indiana. Showers and storms will be widespread along this trough. Instability will grow in the afternoon and deep-layer shear of 25-30kts will support a few storms. PWATs are expected to be 2.0-2.2 inches, which is at the max of climatology for this time of year. Therefore, the main threat will be water-loaded downbursts leading to gusty to damaging winds and very heavy rainfall. Instability will wane quickly into the evening hours. Though, the cold front and troughing will approach, which will increase lift and shear. Additionally, a LLJ will set up over the Ohio River and flow will run parallel to the front. As the front stalls, this will likely create training showers and storms through night and into the morning on Thursday. Given the dry antecedent conditions, we can take quite a bit of water, though some flooding may be possible. The threat for damaging winds will remain over southern Indiana and the threat for flooding will extent south to the Bluegrass Parkway. HREF LPMMs show a few swaths of 3 inches of rainfall possible. Though the average rainfall will be around 0.5- 1 inches.

LONG TERM /THURSDAY THROUGH MONDAY/

Issued at 255 PM EDT Tue Sep 8 2026

On Thursday, the front will practically stall over the region and continued convergence along the front will keep widespread showers and storms over the region. Later Thursday and into Friday, an upper trough moves across the Ohio Valley and gives the surface front some southward momentum. At this time, showers and storms will cease over the northern half of the region and remain over the southern half through Friday.

Beyond Friday, the front will remain in the region and the upper pattern will remain active with multiple shortwaves moving over the region. Periods of showers and storms are expected through the weekend and into early next week. Ridging looks to build in from the south early next week, which will lead to warmer than normal temperatures.

AVIATION /18Z TAFS THROUGH 00Z THURSDAY/

Issued at 128 PM EDT Tue Sep 8 2026

VFR conditions are expected through this TAF forecast. A BKN 3500- 5000ft cumulus deck has developed across the region. Very light isolated showers will be possible through the afternoon. This evening, winds will relax and remain out of the south. On Wednesday, winds will quickly pick up out of the southwest around 9-13kts and gust up to 25kts in the afternoon. Wednesday evening, a cold front will approach from the north and bring a line of showers and storms with it, though this is beyond the current TAF forecast period.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Heat Advisory from noon EDT /11 AM CDT/ to 8 PM EDT /7 PM CDT/ Wednesday for KYZ023>032-061-062-070>072. IN...Heat Advisory from noon EDT /11 AM CDT/ to 8 PM EDT /7 PM CDT/ Wednesday for INZ076>079-083-084-089>092.