textproduct: Louisville

KEY MESSAGES

* Heat Advisory continues for counties west of Scott County, IN and Clinton County, KY. * Scattered storms with a low-end gusty wind threat ends this evening, especially across the western CWA.

* Cooler and much drier air moves in Sunday-Monday with another quick heatwave moving in Tuesday-Wednesday.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 337 PM EDT Sat Sep 5 2026

===== This Evening - Sunday Night =====

Anticipating additional scattered convection this afternoon and evening. Already seeing scattered cumulus forming along the stalled out boundary over our west/southwestern counties towards Bowling Green. These areas will likely see the first of any storms. As the evening progresses, these storms will grow in coverage, more so across the west. There is decent instability with mixed layer CAPE upwards of 2,500 to 3,000 J/kg according to the latest mesoanalysis. Downdraft cape is near or just above 1,000 J/kg as well, meaning any storm that develops carries mainly a risk of strong winds from downburst and possibly small hail considering the amount of instability. Considering how dry the CWA has been, we're not necessarily concerned with flooding with these storms, however should one or two train over the same areas, low-end flash flooding is a possibility. Latest HREF LPMM data suggests isolated areas 2- 3". However, the whole area has a ~90% of remaining under 0.5" this afternoon according to the latest HREF guidance as well.

That being said, this afternoon has been hot with heat indices reaching the mid 100s in the central and western CWA. A heat advisory continues until 8 PM EDT for this excessive heat. Good news is that after any storms this evening, a backdoor cold front will sweep through thanks to a trough over the eastern seaboard. This will help drop dew points and temperatures overnight and into tomorrow. Lows tonight will be in the upper 60s and low 70s, with the coolest areas in the NE closest to the approaching front.

By Sunday morning, there will be a notable difference in how muggy the air will feel. With a continued NE flow, dew points will continue to drop throughout the day, making highs in the low to mid and isolated upper 80s that much more comfortable. Skies will be mostly clear and PWATs will decrease to the climatological 20th percentile or lower. Meaning this will be a very dry air mass moving in Sunday afternoon and evening. Lows Sunday are cooler in the low to mid 60s.

LONG TERM /MONDAY THROUGH SATURDAY/

Issued at 337 PM EDT Sat Sep 5 2026

===== Monday - Saturday =====

Beginning Monday morning, we remain on the cool side of a surface high with a continued NE flow keeping highs in the mid to upper 80s. As dry as the air mass will be, PoPs will remain near zero for the whole CWA with near normal highs. Overall synoptic pattern changes slightly as an Omega pattern begins to break down some. The ridge in place over the plains will begin to move south with more of a zonal flow setting up over our area through the week.

At the surface, high pressure at the surface will shift east, and a southeasterly to eventually southwesterly flow will return. Highs will be boosted as a result into the 90s once again by Tuesday- Wednesday. With the weakened ridge over the plains, a trough will move through our area by later Wednesday and Thursday morning. A boundary will set up somewhere over the Ohio Valley acting as an axis for moisture to travel on. Rain chances mixed with storms returns by then with slightly cooler highs in the mid to upper 80s. Depending on how far south the boundary pushes later in the week will determine if highs remain in the 80s by Friday and Saturday or not. For now, expect drier conditions to return by next weekend.

AVIATION /18Z TAFS THROUGH 00Z MONDAY/

Issued at 241 PM EDT Sat Sep 5 2026

Variable light winds and mostly clear skies will transition to a predominant NW wind and scattered storms later this afternoon and evening. Moving in from the north, any storms that develop will have the potential to bring temporary MVFR-IFR ceilings and visibilities with wind gusts up to 35 kts. Those that dodge storms will remain VFR with a predominant light NW flow. Once storms fade, light to calm winds with SCT-BKN cloud cover will move in overnight. High-end MVFR to low end VFR ceilings move in later in the morning with VFR conditions returning Sunday afternoon.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for KYZ023>031-038-045-046-053-054-061>065-070>078-081-082. IN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for INZ076>078-083-084-089>092.