textproduct: Louisville

KEY MESSAGES

* Dry and hot/humid conditions are expected across the region today with highs in the lower 90s and heat indices in the mid-upper 90s.

* Northwest flow aloft pattern will set up across the region as we start the new work week. Clusters of showers and thunderstorms will likely move southeast across portions of the region during much of the week.

* Some of the storms during the week could be strong to severe with torrential rainfall, gusty winds, and frequent lightning. Excessive rainfall and flash flooding could across portions of east-central Kentucky over the coming week.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 310 AM EDT Sun Aug 9 2026

Currently, sat/obs show mostly clear skies over southern IN and western KY. Some mid-high level cloud cover was observed over central and eastern KY. Temperatures under the clear skies were in the upper 60s, but under the cloud cover, temps were in the low-mid 70s. For the remainder of the overnight period, not expecting any significant weather. Can't rule out some patchy fog down across southern KY where appreciable rain fell Saturday afternoon/evening. Expect temps to remain generally steady in the upper 60s to the lower 70s through sunrise.

For today, the upper level pattern will feature a mainly zonal flow across the Ohio Valley with a mid-level shortwave trough tracking from the northern Plains and into the Midwest and northern Ohio Valley. We're likely to see an MCS develop over the Midwest and then watch it track east-southeast into Indiana and Ohio this evening. Current guidance holds heights up a bit across our region today which will likely keep the MCS track to our north. Despite the ridge in place, we'll see instability develop during the afternoon with 1000-2000 J/kg of SBCAPE, though wind shear will be quite weak across the region. Overall guidance tonight is a bit drier, but can't rule out an isolated shower/storm across southern KY. Afternoon highs today will be in the upper 80s to the lower 90s. With dewpoints in the low-mid 70s, we'll see afternoon heat index readings rise into the mid-upper 90s.

For tonight, and MCS should be in progress across the eastern Midwest and upper Ohio Valley. Based on the flow pattern aloft, convective activity with the aforementioned shortwave trough axis should remain generally north of the region. Late tonight, this activity is forecast to push into eastern IN/western OH. There is a slight risk that some convective outflow could reach our northeast CWA and produce a small chance of a shower/storm. Current ensemble guidance keeps PoPs at less than 10%. Lows tonight will remain mild with readings in the lower 70s.

Moving into Monday, the flow aloft will remain mostly zonal with perhaps a slight northwest component as ridging builds over the western CONUS. The main belt of westerly flow will remain just to our north and much of the day will remain dry across the region. Partly to mostly sunny skies are expected with afternoon highs warming into the lower 90s. Dewpoints will be in the low-mid 70s and we'll see afternoon heat index values rise into the mid-upper 90s across the region. Some heat indices may approach 100 out toward the I-165 corridor. By late afternoon, we'll need to be on guard for some thunderstorm development as another perturbation will be approaching the region from the northwest. Some of the early CAM guidance suggests upstream MCS activity developing across IL/IN and this may drop southeast into portions of southern IN and into the northern Bluegrass. Current thinking is that much of this will remain along/north of the I-64 corridor. The overall guidance has trended a bit more south with this activity in the last few runs. So we've gone ahead and upped PoPs in this area for Monday afternoon/evening. Any convection Monday evening will likely diminish after sunset with lows remaining mild in the low-mid 70s.

LONG TERM /TUESDAY THROUGH SATURDAY/

Issued at 310 AM EDT Sun Aug 9 2026

Moving into the extended forecast period, the forecast thinking has not changed substantially in the last 24 hours. The flow regime over the CONUS will feature an amplifying ridge over the western US with downstream troughing across the eastern US. This will result in a northwest flow regime across the Ohio Valley. Numerous perturbations within the mean flow will drop southeast and into the base of the trough during the week. Each of these perturbations will likely generate clusters of showers and thunderstorms.

Initially, the storm track will be primarily north of the LMK CWA across IL/IN/OH. However, as the amplifying ridge grows out west, the flow pattern will tilt more to the north-northwest by mid-late week. While the initial clusters of showers and storms will start off passing north of the region, we expect the storm track to shift southward with time and episodic bouts of convection will affect portions of southern IN and central and eastern KY. Model soundings through the period continue show plentiful instability and a modest increase in the shear profile. So, strong to severe storms will be possible with torrential rainfall and damaging winds being the main threat. There will be the potential for excessive rainfall as some areas will see repeated storms. As of this writing, the best chances of excessive rainfall would likely be along and east of a line from Salem, IN southeast to Somerset, KY.

The highest chances of precipitation look to be in the Wednesday through Friday period. Forecast uncertainty increases by late week as the models diverge a bit on the placement of a frontal boundary which will likely be draped across the region. Depending on where the boundary resides will determine where higher precipitation chances will be needed. Overall, the pattern will be quite unsettled for the mid-late part of the week with near normal temperatures and above normal rainfall. Highs Tuesday and Wednesday will be in the upper 80s to the lower 90s. However, expect temps to cool off a bit with anticipated clouds/precipitation around in the Thursday-Saturday period with highs mainly in the 80s.

AVIATION /12Z TAFS THROUGH 18Z MONDAY/

Issued at 633 AM EDT Sun Aug 9 2026

VFR conditions are expected for the upcoming TAF period. Winds will start off light/variable this morning before winds pick up out of the southwest by mid-late morning. Expect a Cu field to develop during the day with bases around 5kft AGL. VFR conditions are expected tonight and into the day on Monday.

LMK WATCHES/WARNINGS/ADVISORIES

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