textproduct: Louisville

KEY MESSAGES

* A northwest flow pattern aloft will take residence across the region for much of the upcoming work week with clusters of showers and storms impacting portions of the central and eastern Ohio Valley. Across west-central Kentucky, dry and hot conditions are expected.

* Storms that develop will likely be strong/severe with torrential rainfall, intense lightning, and the potential for damaging winds. The highest risk of severe weather for today and Tuesday will be across southeastern Indiana and into portions of far northern Kentucky.

* Multiple clusters and/or wave of storms will likely train across portions of IN/OH and KY this week. This will lead to excessive rainfall and flash flooding. Locally, the highest risk for flooding would be across our northeastern portions of the forecast area (SE IN and the Bluegrass region).

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 322 AM EDT Mon Aug 10 2026

Early morning satellite imagery and surface observations show mostly clear skies across the region. Temperatures were mild with readings in the low-mid 70s. Area radars remain quiet with only just a few light shows moving southeast across southern Ohio. A sprinkle or light rain shower could affect the northeastern Bluegrass in the next hour. Otherwise, no significant weather is expected through sunrise with temperatures remaining in the lower 70s.

For today, we'll start off the period with mostly sunny skies and southwesterly flow. This will result in a continued moistening of the column throughout the day. Afternoon highs will warm into the upper 80s and lower 90s. With dewpoints in the 70s, we'll see afternoon heat indices push into the upper 90s with a few low 100's here and there. With the anticipated heating, we'll see instability develop later this afternoon, but shear across our region will remain rather weak, with the stronger flow remaining to our north and northeast. The upper flow across the region will become more northwesterly with time and a mid-level perturbation will push into the northern Ohio Valley from the west. This feature will likely kick off another cluster of strong to severe storms across portions of eastern IL this afternoon and this activity will slide east- southeast across IN and into portions of central/southern Ohio. Current thinking is that the I-70 corridor across IN/OH is where the bulk of the storms will be, but the overall track of the thunderstorm complex is still a bit uncertain. The best chances of storms today look to be across our southeastern IN counties and into the northern parts of the Bluegrass region. SPC has kept the slight risk north of the CWA, but a marginal risk does extend down to the I- 64 corridor. Overall, this seems well placed for now, given the expected convective evolution. Main storm hazards with this activity will be torrential rainfall, gusty/damaging winds, and intense lightning.

For tonight, the northwest flow regime will remain in place and additional clusters of showers and storms will likely move east- southeast along the instability gradient. We still think our SE IN and northern Bluegrass would be at most risk for storms in the current setup and we'll keep 30-40% PoP coverage going in those areas overnight. Lows tonight will be mild with readings in the low- mid 70s.

Moving into Tuesday, flow aloft will continue to be west- northwesterly from the Midwest down into the central Appalachians. A quasi-stationary boundary will be draped just north of the region from roughly northern IL into far northern KY (along the KY/OH border). The LMK CWA will remain on the southern side of this front with very warm temperatures and high moisture content. Afternoon highs on Tuesday will warm into the upper 80s and lower 90s with dewpoints in the low-mid 70s. This will produce another round of afternoon heat indices in the upper 90s to the lower 100s.

We expect plentiful instability to develop by mid-late afternoon with the highest instability (2000-3500 J/Kg MLCAPE) and shear (40- 45kts) along the aforementioned boundary from eastern IL through central IN and into central/southern OH. MLCAPE and shear values do decrease quite a bit the further south you go into Kentucky. Combination of disturbances aloft and convergence along the frontal boundary will lead to the development of convective clusters moving southeast along the boundary. The convective evolution remains a bit uncertain as there remains considerable uncertainty on where this boundary may be located and perhaps augmented by convective clusters earlier in the forecast period.

As of this writing, we feel the best chances of storms on Tuesday will be roughly east of a line from Jasper to Fort Knox down to around Somerset. Storms that do fire will be strong to severe with torrential rainfall, damaging winds, and intense lightning. The overall setup leads me to believe that a swath of damaging winds may accompany the Tuesday afternoon convection. At this time, the highest risk of that looks to be just north and northeast of the LMK forecast area.

Continued clusters of storms will likely linger into the evening hours Tuesday night before diminishing late. Lows will remain quite mild with readings only dropping into the lower 70s in the east, with mid 70s along and west of I-65.

In addition to the strong/severe storm risk, there will be an increasing risk of flash flooding across a portion of the LMK CWA. The highest risk of flooding will be in those areas where the quasi- stationary front resides. The highest flash flood risk at this time would be across portions of southeast IN, northern KY/southern Ohio and into the central Appalachians. Basin QPF amounts of a quarter to three quarters of an inch will be possible. However, much higher localized amounts of 3-4 inches will be possible in areas that see repeated rounds of storms.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 322 AM EDT Mon Aug 10 2026

Moving into the mid-late week period, the forecast reasoning has not changed significantly in the last 24-48 hours. An amplifying ridge is expected over the western CONUS with downstream troughing centered along the eastern US coast. Locally, a northwest flow regime will continue across the Ohio Valley. A stalled out frontal boundary will likely remain draped across or at least bisect the region during this time period. This boundary will likely stretch from central IL through central/southern IN and into eastern KY.

This boundary may slip a little more southward into KY on Wednesday and with a couple of perturbations moving through within the mean flow, more episodic bouts of thunderstorm activity are expected. In areas south of the quasi-stationary front, diurnal heating will lead to strong instability and with shear increasing across the region, strong to severe storms will be possible. The main hazards would be torrential rainfall, intense lightning, and the potential for damaging winds. Depending on where the front ends up, portions of western and possibly southern KY may remain dry and hot through the period. Daytime highs Wed/Thu will be in the upper 80s/lower 90s with overnight lows in the 70s.

Moving into the late week and weekend, we're starting to see a stronger signal/trend in the data with ridging building over eastern TX and into LA/MS/AL. If this scenario pans out, we'll see the stalled out frontal boundary across our region lift northward and push the storm track back to the north. This would also bring warmer temperatures back into the region. Current guidance shows highs in the upper 80s to around 90 for Fri-Sun across southern IN and the northern half of KY. Highs in the lower-mid 90s will be possible across western/southern KY, especially if they remain rain- free for much of this week.

AVIATION /06Z TAFS THROUGH 12Z TUESDAY/

Issued at 122 AM EDT Mon Aug 10 2026

For the remainder of the overnight period, VFR conditions are expected. A light south to southwest wind should keep the boundary layer mixed enough to prevent fog formation. Mainly dry conditions are expected for the daytime hours with gusty southwest winds. Sustained winds of 8-10kts and gusts to 20kts will be possible.

LMK WATCHES/WARNINGS/ADVISORIES

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