textproduct: Louisville

KEY MESSAGES

* Dry and seasonable Labor Day expected with only a small chance of a shower or storm around the Lake Cumberland region by early evening.

* 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 west of I-65.

* A cold front arrives Thursday morning with 70-80% chance of showers and a few storms possible. Fairly widespread rainfall amounts between .25" and .5" are currently expected.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 241 AM EDT Mon Sep 7 2026

Things are quiet across the region at this hour with high pressure centered over the eastern Great Lakes, extending influence into our area. Light NE surface winds and a few upper clouds will continue this morning. This will allow for lows mostly in the low and mid 60s toward sunrise, although can't rule out a few upper 50s across our far NE. Light to steady NE/ENE winds continue today with plenty of sunshine to go along with a few mid and upper clouds at times. Temps should be a tick or two warmer than yesterday with max values mostly in the 85 to 90 degree range.

Almost all of the area stays dry today, although will have to continue mention of some isolated to widely scattered shower or storm chances down near the Lake Cumberland region this evening. Inverted surface trough looks to set up with dew points in the upper 60s to near 70 pooling in our far SE. This added low level moisture will aid the development of a modest instability axis on the order of 500-750 J/KG of ML CAPE, and could provide enough fuel for a few showers and storms assuming the weak surface convergence is enough of a trigger. Hi-res CAMs and other deterministic data suggests that at least a few showers or storms will develop by early evening. Overall, deep layer shear is weak so any storms would be pulse in nature.

Other than that, dry conditions continue through early week with upper ridging strengthening over the southern CONUS. This will allow temperatures to continue trending upward as we move through Tuesday. Another couple degree rise by then will allow for highs in the upper 80s to low 90s across the area.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 241 AM EDT Mon Sep 7 2026

Wednesday - Thursday Night...

The hottest day of the week looks to be Wednesday as upper ridging continues to dominate the southern half of the CONUS. Meanwhile, a steady SW surface flow will set up over our region between high pressure centered off the mid Atlantic coast, and a strong surface low over eastern Canada. In fact, the pressure gradient will be quite impressive for this time of year, and looks like we could see some 20-25 mph gusts from a very well mixed boundary layer. This looks like a pattern where temps could overachieve, so like where the NBM is toward the higher side of the guidance envelope, and similar to the 90th percentile ECM temp guidance. Peak heat indices could be a bit of a concern for Wednesday as they will likely reach into the low 100s for a time. Expect afternoon mixing may lower dew points enough through the afternoon to keep any Heat Advisory headlines from being needed, but it will be close. Overall, low to mid 90s expected for highs, with shower and storm chances holding off until later Wednesday night into Thursday.

A cold front trailing from the aforementioned strong eastern Canada surface low will approach for Thursday. Ahead of this feature, fairly widespread coverage of showers and storms is anticipated to drop into and through our region. Looks to be a fairly strong amount of deep layer shear across the northern half of our CWA where 35-45 knots may be realized. Across southern KY, values would be weaker and more in the 25-35 knot range. Weak to modest instability and particularly weak mid level lapse rates could be the limiting factor for whether any strong to severe storms will be possible, and timing of the frontal passage on Thursday will have a lot to do with that. Should fairly strong storms develop, then we may have to watch for a bit of training as the deep layer flow will be nearly parallel to the surface boundary. A few localized areas could see some higher rain totals in this setup, but overall the expected widespread rainfall between .25" and .5" for most will be welcome. Right now, LREF probabilities of 1" or more drop off to 10-15% or less.

Friday - Sunday...

Things are expected to be a bit cooler and overall drier by Friday as high pressure builds in behind the cold front. Perhaps a few showers linger across our southern CWA, but will only keep low chances in here. Temps settle back into the mid and upper 80s to end the week, at least briefly. The overall dry pattern should continue into the weekend although some weak troughing may allow for a few non-zero shower or storm chances. Better chances for the upper ridge to build back in by late weekend, and this will allow temps to rise back into the upper 80s and low 90s if it occurs. Only low to medium confidence in the weekend for now given some uncertainty in how the upper pattern will evolve by this time.

AVIATION /06Z TAFS THROUGH 12Z TUESDAY/

Issued at 127 AM EDT Mon Sep 7 2026

VFR will prevail through this forecast cycle with a light to steady NE surface wind thanks to high pressure centered over the eastern Great Lakes. A few mid to high clouds will be possible at times, but overall mostly clear/sunny skies expected.

LMK WATCHES/WARNINGS/ADVISORIES

KY...None. IN...None.