textproduct: Louisville

KEY MESSAGES

* Unsettled weather with localized area of heavy rainfall and flash flooding are possible across KY and southern IN tonight through Tuesday night. While basin average rainfall of 1-2.5 inches are expected, localized amounts of 3-6 inches will be possible in heavier swaths.

* Despite some morning showers and weak storms on Wednesday, hot temperatures and mugginess are expected Wednesday and Thursday, with peak afternoon heat index values between 90-100.

* An approaching cold front later in the week provide more opportunity for rain and some storms Thursday evening through Friday, though timing is still uncertain.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 321 PM EDT Mon Jun 8 2026

Upper level ridge axis was located just east of the Ohio Valley stretching from the Gulf coast northward into the eastern Great Lakes region. The first in a series of shortwave troughs is lifting through the region this afternoon. This feature brought a swath of heavy rainfall earlier to portions of Logan and Warren counties where 1.5-3 inches of rain fell. Across the rest of the region, rainfall has generally be lighter with quarter to a half inch being reported.

While this first batch of rain continues off to the northeast this afternoon, we'll see a brief break in the rain across the central and western areas over the next few hours. Afternoon visible satellite imagery shows a well defined MCV southwest of St. Louis. To the east/southeast of this feature, scattered convection has redeveloped with some afternoon heating. Model soundings here show weak low-mid level lapse rates, but a strongly moist airmass with PWATs up over 2 inches. Shear profiles are also pretty weak, so any strong storm that develops would most likely produce wet downburst. Additionally, while PWATs are above the daily climo max, soundings also show high freezing levels with warm cloud depths that will result in efficient precipitation production with any storms resulting in a localized flood threat.

For tonight, it appears that we'll see some additional convective development out ahead of the aforementioned MCV near St. Louis. Convective models differ, but the overall model consensus suggests that a band of convection with very heavy rainfall will develop across portions of southern IL and then move east-southeast into southwest IN and NW KY during the overnight hours. The recent HRRR runs support this scenario, though the 08/12Z NAM take much of this precipitation through western KY into northwest TN. Much of the Bluegrass region may end up seeing little precipitation during the overnight hours.

For Tuesday, convection is likely to be in progress across the region at the start of the period. Expect convection to roll eastward into the Bluegrass region during the morning hours with additional redevelopment and/or backbuilding to occur during the afternoon/evening hours. The western part of the forecast area may get a break Tuesday morning and into the afternoon. However, latest MPAS runs suggest convection backbuilding across the area with a train of convection slowly moving across much of central/eastern KY as we move into Tuesday night. 08/12Z HREF PMM probs show a rainfall maximum across our west-central forecast area (mainly across Grayson and southern Hardin/northern Hart counties).

Overall, the forecast messaging on the hydro side has not changed significantly since this morning. Through Tuesday night, basin average rainfall of 1-2.5 inches continues to look reasonable. However, more localized amounts of 3-6 inches are possible given the environment and our particular setup here. Current Flood Watch looks well placed for tonight and into Tuesday morning. However, an eastward expansion may be required in subsequent forecasts as the convective models gain a foothold on the evolution of the environment.

Oppressive humidity will be seen across the area on Tuesday as high temperatures will likely climb into the low-mid 80s in the east and back toward the I-65 corridor. Some upper 80s will be possible out back toward the I-165 area. With dewpoints well into the mid 70s, heat indices may get into the lower 90s across our far western areas that see any significant sun.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 321 PM EDT Mon Jun 8 2026

Wednesday - Sunday ...

As the mid-level shortwave moves east, lingering rain showers will continue to move SE out of the region Wednesday morning. Once the rain clears the clouds will start to clear as well. Maximum temperatures for Wednesday and Thursday will warm into upper 80s and low 90s. With SW flow remaining dominant in the Ohio Valley, warm and moist air will keep dewpoints in the mid to upper 70s. In addition, the apparent temperatures will likely hit the upper 90s and low 100s for both days. Caution will need to be taken as this heat wave affects the Ohio Valley. A low level jet will move across southern IN Thursday morning bringing 20-25 MPH winds gusts along the Ohio River. Ample moisture and daytime heating will keep lingering rain showers for Thursday afternoon and evening.

As a low pressure system builds over Canada, a cold front will stretch SSW through the Great Lakes region into the central Plains. Friday morning this cold front will begin to push through the area bringing a line of rain showers ahead of it. At this time, no severe threats are expected as the passage of the front will occur overnight limiting the available instability. A tightening pressure gradient will also build over the region leading to gusty winds Friday morning nearing 30 MPH. Any rain that passes through on Friday will have the best chance for daily QPF of at least 0.5". PWATS will continue to be above 1" ahead of the boundary, however will drop off post passage. A drier airmass will move in behind the boundary with a more northwesterly flow. Maximum temperatures will still warm into the upper 80s on Friday with dewpoints in the mid 70s (prior to the front).

Weak surface high pressure will build in for Saturday leaving us mostly dry through the day, however increasing rain chances will move back in by Sunday. Another trailing cold front from a low pressure in Canada that will stretch NW of KY will bring lingering rain showers Sunday evening ahead of the boundary. High temperatures for the weekend will stay consistent in the mid to upper 80s, with dewpoints back down in the low to mid 60s.

AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 108 PM EDT Mon Jun 8 2026

Mix of MVFR/IFR conditions are expected through the afternoon hours as an area of rich moisture will surge into the region from the south. A band of showers with embedded storms will move northward through southern IN and north-central/east-central KY this afternoon. Behind this wave, we'll just see isolated-scattered convection in the late afternoon. Cigs could improve once this first wave of convection pulls through. Secondary surge of showers/storms expected to come in later this evening and into the overnight.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Flood Watch through Tuesday evening for KYZ023>031-034-038-045- 046-053-054-061>065-070>078-081-082. IN...Flood Watch through Tuesday evening for INZ076>078-083-084- 089>092.