textproduct: Louisville

KEY MESSAGES

* Strong to potentially severe thunderstorms will be possible overnight. Main threats are gusty winds and hail, mainly along and west of Interstate 65. Isolated flash flooding is also possible.

* Cooler and drier weather returns Sunday night through early next week.

* Another low pressure system will bring a chance for strong storms, heavy rainfall, and gusty non-thunderstorm winds Wednesday night into Thursday.

SHORT TERM /THROUGH SUNDAY/

Issued at 335 PM EDT Sat Jun 13 2026

The main focus for the short term is the potential for strong to potentially severe storms later this evening and into the overnight. These storms have the potential of producing strong gusty winds and very heavy rainfall with the potential of some hail. Storm Prediction Center continues to place generally the western half of the county warning area (CWA) in a Marginal Risk (Level 1/5) for severe weather for locations generally along and west of I-65.

While the threat is there, this remains a low confidence forecast as we continue to monitor a couple of convective complexes along the Mid Mississippi Valley. One of these convective complexes is working from so MO into far western KY and TN while the second one is starting to take shape over northeast MO into western IL. The first complex to the south looks like it should continue to go more east- southeast through the afternoon and evening. It may clip the far southwestern portion of our CWA but looking at the current meso analysis the better instability is more to the south and southeast of that system.

The second area in western IL is still unorganized and models have struggled all day trying to figure out to do with these features. If it can get better organized, the current instability gradient could bring this wave in later this evening right around or after 00z.

Some of the limiting factors for storm development and severe threat is the current convective debris clouds over IL, IN and parts of western and northern KY. If we get more clouds this would cool temperatures and also limit the amount. of available instability. As was also noted above, the CAMs have struggled all morning and early afternoon on the development of these features and how they interact with each other.

Forecast soundings continue to show 1500-2500 J/kg of SBCAPE from north to south around and a little after 00z. Shear looks to be lacking minimizing the tornado threat. That is why we continue to think the main threat from any potential strong to severe storms will be damaging wind gusts and hail.

The other note of concern is the increase of low-level moisture ahead of the cold front that is expected to arrive tomorrow morning. PWAT values climb to 1.8" to 2.0" ahead of the boundary later tonight and early morning. This will result in heavy rainfall. While storms are expected to move through fairly quickly, if we get any training of storms we could see some localized flash flooding concerns. Looking at the HREF Grand Ensemble, there are a few places mainly west of I-65 that has a 10-15% probability of exceeding 2 inches with these showers and storms. The best timing for showers and storms this evening continue to be between 00z and 04z (8pm to Midnight EDT). Then as was stated in the previous forecast, we could see a break in activity before the cold front arrives tomorrow between late morning and early afternoon.

A few clusters of showers and storms are possible as this boundary moves through but the risk of severe is much lower. Could see some lingering showers and isolated storms during the day tomorrow but we will see dewpoints fall and highs right around 80 degrees.

LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/

Issued at 335 PM EDT Sat Jun 13 2026

After the cold front pushes through the Ohio Valley, an upper level low will become stationary over Canada leading to broad troughing over the region. Surface high pressure will build behind the frontal boundary leading to northwesterly flow aloft. A drier and cooler air mass will move in and bring some slightly cooler temperatures for the start of the week. High temperatures for Monday will be in the low to mid 70s. On Tuesday, the surface high pressure will begin to shift to the east resulting in return flow by Tuesday night. Max temperature for Wednesday will be back into the low to mid 80s. Gusty winds can be expected for the mid part of the week as a pressure gradient forms across south central IN associated with a shortwave trough. Gusts Wednesday morning will start on the lighter side between 20-25 mph but increase through the day. Lingering rain showers will also be possible across the forecast area from this disturbance.

A low pressure centered over Michigan early Thursday will stretch a cold front through the region. A low level jet streak will build over the Ohio Valley, and with daytime mixing this will bring some higher wind gust possibly nearing 45 mph. As the cold front pushes through the area, showers and storms will be possible. By this time the return flow will have advected ample moisture into the area with PWAT values nearing 2". This will lead to some heavy downpours at time, and overall healthy rain showers. Timing currently is for the cold front to push through the CWA Thursday afternoon or evening, however there is still uncertainty as guidance is not in agreement. The timing will play a big factor in whether or not this system will have the potential for any severe threats. There is a signal for ample amount of instability (2000 J/kg) Thursday around 21z, while an axis of shear is along the IN/KY border. High pressure will begin to build behind the front bringing drier conditions for Friday with high temperatures in the mid 80s.

AVIATION /18Z TAFS THROUGH 00Z MONDAY/

Issued at 152 PM EDT Sat Jun 13 2026

VFR flight categories will remain for at least the next6 hours then the forecast becomes a little more complicated and tricky. Overall confidence is not high as a lot of the aviation impacts will be determined by what happens with a complex coming out of southern MO/northern AR. Models have struggled with how to handle this complex and potentially other complexes that may move into the area this evening and overnight. While we think showers and storms are possible overnight into tomorrow morning, timing is still in question and the overall impact. Cold front will come through tomorrow and we should have a period of MVFR CIG with slowly improving conditions.

LMK WATCHES/WARNINGS/ADVISORIES

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