textproduct: Louisville

KEY MESSAGES

* Hot and humid conditions this weekend with highs in the low/mid 90s and heat indices up to 109 degrees both days. Heat Advisory is in effect this weekend for a large portion of southern IN, central and southern KY.

* Scattered showers and isolated storms are possible (20-30% chance) across areas mainly east of a Salem, Indiana to Richmond, Kentucky line this afternoon and evening. Any storms that form could produce strong to damaging winds.

* Another round of showers and storms are possible late Sunday ahead of a cold front moving through the region. Any storms that become severe would be capable of producing damaging winds.

* A reprieve from the hot and humid weather, as well as showers and storms, comes Monday evening once the cold front departs to the south. Showers and storms arrive again for the late week time frame, however temperatures should be slightly below normal for this time of year.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 233 PM EDT Sat Aug 15 2026

Currently, isolated showers and storms are developing to the east of the forecast area. A few have developed over the Blue Grass region, but have not been severe. Storm development has the ability to continue through this evening as the environment is plenty unstable with the diurnal heating. The combination of weak mid level lapse rates and weak to marginal deep layer shear should limit overall storm intensity.

An upper level ridge continues to hold over the region, bringing mostly clear skies and warm temperatures. A Heat Advisory remains in effect through Sunday evening for areas west of the Bluegrass. Heat indices are expected to reach triple digits again Sunday with a 80- 90% chance of greater than 100F west of I-65. As the ridge begins to decay due to a trough building in the west, the Ohio Valley will transition to a nearly zonal upper level flow.

A frontal boundary is expected to start pushing through the area Sunday evening with a weak surface low. This has the potential to bring in a broken line from the NW Sunday evening into the night hours. The main hazard for these storms would be strong to damaging winds, with PWAT values 2"+ throughout the whole area and 1000-1500 J/kg of DCAPE Sunday evening. Additionally, an MCV is forecasted to develop over Nebraska and Kansas and track over south central Indiana. Guidance is bringing another round of storms through Sunday night into the early morning of Monday. The environment remains marginal with 15-20kts of low level shear and roughly 1500J/kg of SBCAPE. Overall confidence in these two systems are low as it will depend of the MCV development and where is tracks.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 233 PM EDT Sat Aug 15 2026

Monday - Monday Night...

We'll keep shallow amplitude NW flow aloft in place on the NE periphery of the upper ridge through much of the upcoming work week. Expect isolated to scattered shower and storm chances in the forecast for Monday as a surface cold front trailing from a weak New England surface low slides south across our CWA. There may be just enough overlap between modest deep layer flow yielding 25-30 knots of 0-6 km shear, and moderate instability characterized by 1500-2500 J/KG of ML CAPE. However, the best shear will be farther north, and with the front sliding SE through the day, it appears any window for that overlap would be pretty short. Just a general t-storm risk on the current Day 3 Outlook, and that seems reasonable for now. Any better overlap timing between the two may end up yielding a Marginal Risk so will keep an eye on that trend.

The frontal boundary sinking south will start to provide some relief from the heat and humidity across our northern CWA through the day. It will still be hot and humid across southern KY on Monday ahead of the front, and will be looking for low 90s for highs along with max heat indices approaching 100F. Monday night should trend dry with the loss of heating, with lows settling into a more comfortable 65 to 70 degree range.

Tuesday - Wednesday Afternoon...

The upper ridge will retrograde to the SW CONUS through mid week, allowing slight more established NW flow over our area. Doesn't look to be a lot of notable shortwave activity embedded in the flow through mid week, and this combined with surface high pressure building in behind the passing cool front we should see mostly dry conditions through Wednesday. Highs should mostly range between 85 to 90 each day, although southern KY could reach the low 90s again by Wednesday. Makes sense being closer to the upper ridge.

Wednesday Evening - Saturday...

Shower and storm activity looks to pick up again as early as Wednesday evening, and through much of the late week, as a cool front trailing from an anomalously strong eastern Canada system drops south into our area. In addition, models generally agree in increased shortwave activity embedded with in the NW flow aloft still in place over our area. With multiple triggers in place, we'll carry shower and storm chances through late week into the weekend. The shortwaves should help to continually reinforce slightly cooler air across the region, and temps will run below normal for this time of year in the low and mid 80s for much of this time. It is possible that troughing gets established well enough by Saturday that more of the convective activity is off to our south and east and we stay drier, however confidence is low given model variability for now.

AVIATION /18Z TAFS THROUGH 00Z MONDAY/

Issued at 115 PM EDT Sat Aug 15 2026

VFR conditions will continue throughout the forecast period. Mostly clear skies with FEW to SCT at 250 will continue through the day and tonight. Winds will continue out of the SW today and tomorrow, but some sites may see a more SSW wind overnight. Rain chances remain low (20-30%) for a few isolated showers and storms this afternoon and evening. TAF were kept dry due to low confidence in any development and specific locations.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Heat Advisory until 9 PM EDT /8 PM CDT/ Sunday for KYZ023>031- 034-038-039-045-046-053-054-061>065-070>078-081-082. IN...Heat Advisory until 9 PM EDT /8 PM CDT/ Sunday for INZ076>078- 083-084-089>092.