textproduct: Louisville

KEY MESSAGES

* Unsettled weather pattern to continue for the next 24 hours. Additional rounds of showers and storms with intense rainfall are expected this afternoon through Wednesday morning. Basin average rainfall of 1-3 inches with localized amounts of 4-7+ inches will be possible in heavier swaths.

* Despite morning showers Wednesday morning, if sufficient clearing occurs, hot and humid conditions are expected on Wednesday and again Thursday. Peak afternoon heat indices of 90-100 degrees are possible.

* 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.

UPDATE

Issued at 959 PM EDT Tue Jun 9 2026

Linear MCS is taking shape over central IN which will be the main focus for the overnight into the early mornings. SPC updated the day 1 outlook and scaled back the Slight (Level 2/5) to a Marginal (Level 1/5). This includes a large portion of our southern IN counties with it north of the Ohio River. While we can't completely rule out the severe threat the main concern remains flash flooding. PWAT values are around 2 inches and these storms across Indiana have had a history of 2-3 inches per hour rain rate and a few 3.5 inches to almost 4 inches. Timing and placement of the heaviest and steadiest of convection remains the main challenge. The HRRR has been handling things fairly well but as of the 18z to even the 00z the main convection has started to show the main line of activity going from Scott and Jefferson counties in Indiana to Oldham, Franklin to Woodford/Fayette and points to the southeast. This doesn't mean we can't see a shift back to the west but it seems the trend is further to the east than what was though earlier this afternoon. Updated PoPs in the grid to reflect current precipitation and to lower PoP further to the southwest where I think locations south of I-64 and west of I-65 could be mainly dry.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 308 PM EDT Tue Jun 9 2026

Earlier convective cluster continues to move off to the southeast into southeastern KY this afternoon. In the wake of convection, we're seeing skies clear out a bit across western and west-central KY where temperatures have warmed into the lower 80s. Where rain has been ongoing, temperatures remained in the low-mid 70s. This has produced not only a temperature gradient, but a developing instability gradient has also been generated. Mesoanalysis shows developing instability within the warm sector with MLCAPE values approaching 2500 J/kg. Vertical wind shear remains poor based on mesoanalysis and point based soundings. Scattered convection has regenerated between Paducah and Bowling Green and is not all that organized. Given the environment, wet downbursts will be the primary convective hazard along with heavy rainfall. This area also resides in an east-west PWAT axis with values around 2.1-2.2 inches, which is above the climatological daily max locally.

There are a few boundaries out there across the region. However, am not overly confident on the amount of low-level vorticity that may be in place. It is possible that some of this scattered convection could ingest this low-level vorticity into the vertical and result in a low-end tornado risk. However, this is conditional based on how the convective evolution develops over the next several hours. If a more organized convective cluster can get established, then the severe risk would also increase.

In the short term, now through this evening, the best chances of convection look to be within the warm sector which currently resides south of a line from Hartford, KY (Ohio County) to Liberty, KY (Casey County). Storms in this area will have some forward propagation to keep residence time short at any one location. However, given the depth of the moisture, intense rainfall, gusty winds, and lightning would be the primary convective threats. Some localized flooding is possible, though this area of southern KY dodged the earlier rainfall this morning and has slightly higher FFG values. Nonetheless, isolated/scattered hydro issues could occur where storms train over the same areas.

Moving into tonight, we may see a brief period of drier conditions for time this evening as the southern KY convection moves off to the southeast. However, there is a concerning signal in the CAMs of another MCS developing out ahead of an approaching vort max coming out of Missouri. There remains considerable spread among the various CAMs with the potential track of this MCS. Some are favoring the western part of our CWA, while others are favoring the Bluegrass region. 09/12Z HREF generally splits the difference and has an axis of higher precipitation across the central portions of the forecast area. The general consensus of the guidance suggests that convection will likely develop to our northwest late this evening and then dive southeast through the CWA late in the overnight period. While the front end of the MCS will probably race east-southeast, many of the CAMs show the classic backbuilding of the MCS to the northwest on the heels of the nocturnal low-level jet axis that will likely be present across the western portions of the forecast area. Thus, we could end up with a similar scenario as we've seen this morning. Based on the spread in the guidance and widespread rainfall this morning, we have gone ahead and expanded the Flood Watch to cover the whole forecast area and also expanded it in time until noon EDT Wednesday.

In terms of additional rainfall amounts, another basin average of 1 to 3 inches is expected through Wednesday morning. However, 09/12Z HREF PMM suggest localized swaths of 4-7+ inch amounts could across portions of southern Indiana and into central KY. This is on top of the basin wide 1-4 inches that we've seen already today. FFG guidance will be a lot less tonight, so amounts of 1-2 inches could easily lead to hydrologic issues in substantially wet areas.

Moving into Wednesday morning, we're expecting convection to be in progress across the area. However, much of the guidance shoves this activity to our southeast by late morning with drier conditions in the afternoon hours. Overall confidence in how much we'll clear tomorrow leads to some below average confidence on how much we'll warm up. If sufficient clearing occurs, we could see temperatures top out in the upper 80s to the lower 90s. With dewpoints remaining in the 70s, this would produce heat indices in the mid-upper 90s with some locations out across the I-165 corridor and west approaching 100. On the other hand, if widespread convection lingers and we have trouble clearing out, temperatures and afternoon heat indices would end up being lower. Drier conditions are expected for Wednesday night with lows only dropping into the lower 70s.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 308 PM EDT Tue Jun 9 2026

Thursday - Monday ...

As low level ridging and surface high pressure gets pushed off to the SE, a weak shortwave disturbance brings lingering rain shower Thursday morning. Showers are expected to be light and brief. Otherwise, partly clear skies and high temperatures will warm into the upper 80s and low 90s on Thursday. A strengthening low pressure system in Canada will move in a trough over the Ohio Valley. This will lead to a tightening pressure gradient across southern IN and along the Ohio River. Along with daytime mixing, wind gusts are expected Thursday afternoon and evening between 20-30 MPH. A trailing cold front will then push through during the day Friday bringing a line of rain and a few storms. SPC has has issued a 15- 29% probability for severe weather in the Bluegrass area. The surface based instability is averaging around 1500 J/kg for the afternoon, however wind shear values are lacking as the axis is displaced to the NW.

Behind the cold front, a drier air mass will move into the area along with an area of surface high pressure for Saturday. High temperatures are expected to be slightly cooler in the mid 80s for the weekend. Saturday evening into Sunday another mid-level shortwave will move east and bring lingering rain showers. Monday morning/ afternoon a surface low pressure will eject out of the southern plains into the Great Lakes region. An associated cold front will push through the region Monday evening into Tuesday. As this system moves NE, southerly flow will advect ample moisture into the Ohio Valley increasing PWATS to 1.5" - 2". A low level jet streak on the downstream side of the trough will be centered over region bringing higher wind gusts around 30-35 MPH. There could be a severe threat potential will this system as the environmental shear values will be 40-45 kts, and marginal storm relative helicity. However, the available instability for convection will depend on the timing of the cold front.

AVIATION /00Z TAFS THROUGH 06Z THURSDAY/

Issued at 803 PM EDT Tue Jun 9 2026

The main impact in the TAFs through the overnight will be the potential development of a complex of showers and thunderstorms across central IN later this evening. Once this complex forms it is expected to drop south towards the Ohio River and into north central KY. The main challenge is there has been a shift in placement of the main convection shifting it more east of I-65 from SDF to LEX to RGA. Also, the other challenge and there is low confidence on duration of showers and storms too. All of this will depend on where the convective line develops and then how it works southward. Do anticipate a period of at least MVFR flight categories where we get some of these showers and storms from SDF to LEX to RGA before becoming VFR later tomorrow afternoon. Winds generally remain out of the south to SSE through the forecast period.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Flood Watch through Wednesday morning for KYZ023>043-045>049- 053>057-061>067-070>078-081-082. IN...Flood Watch through Wednesday morning for INZ076>079-083-084- 089>092.