textproduct: Louisville

KEY MESSAGES

* Strong to severe storms will be possible late this afternoon and tonight. Damaging winds and isolated tornadoes would be the main threats with this activity. The highest risk of severe weather is generally along and north of the WK/BG Parkways.

* Heavy rainfall from thunderstorms may pose a flood risk for much of southern Indiana. A Flood Watch has been posted for this afternoon through Monday morning.

* A somewhat unsettled pattern is expected through early week with temperatures slightly below normal and off and on shower and storm chances possible, especially across southern KY.

SHORT TERM /THROUGH TONIGHT/

Issued at 329 AM EDT Sun Jun 21 2026

Early this morning, a weak frontal boundary was noted from Dubois county Indiana over toward the Lexington Metro area. Skies along the boundary were generally partly cloudy with a few weak returns showing up. Across southern KY, skies were mostly clear. For the remainder of the night, this weak boundary is forecast to drift northward and a few light showers will be possible across southern IN and over into the northern Bluegrass region. Temperatures will remain in the low-mid 60s. A few of our valley areas could drop into the upper 50s.

After sunrise, we'll see winds across the area shift to the southeast during the morning hours but become southwest during the afternoon. We'll see a gradual increase in the pressure gradient which will lead to winds becoming a little more gusty during the afternoon hours. Mostly sunny skies will be seen across the region this morning and into the afternoon hours. Convective cloud debris from convection to our west will stream eastward and some areas could go partly cloudy this afternoon. Afternoon highs will warm into the 82-87 degree range across southern Indiana and the northern half of Kentucky. Across southern Kentucky, highs of 84-89 are expected. A few scattered thunderstorms can't be ruled out across the area this afternoon. However, model soundings do show a warm layer up around 700 mb which may provide enough capping to keep convection from developing. The highest chances of any storms would really be across our far northwest CWA in the mid-late afternoon hours.

For tonight, we'll be watching the remnant MCV pushing through eastern KS early this morning as rolls through MO this afternoon and eventually into IL/IN late this afternoon and evening. Associated with the MCV will be an area of surface low pressure that will move eastward across MO/IL/IN and into OH. Current model solutions continue to show spread with the strength of this low and it's impacts on the low-level shear profile. The convective evolution for tonight also remains quite uncertain with several scenarios that could play out.

The multi-model consensus continues to suggest that a cluster of storms associated with the aforementioned MCV will move across IL this afternoon and into SW/Central IN this evening. Model soundings here would support a mix of mulit-cellular and supercellular convection with a damaging wind/tornado threat. Overall highest tornado threat locally would be across our southern IN counties. Despite good low-level wind profiles on the soundings, LCL's are forecast to remain high and the overall instability profile remains rather marginal. This cluster of storms would eventually move east into southeast IN/northern KY and southern OH later this evening.

In the wake of that MCV, the main uncertainty of the convective evolution remains in what happens along the trailing frontal boundary. Some of the CAMs develop a healthy line of convection across southern IN and drive it east-southeast across the LMK CWA with a convective wind threat. However, there are several CAM solutions that suggest more robust convective development may occur over southern MO and then move into southwest/western KY late tonight and then into northwest TN, which could leave a relative gap in coverage...or at least a relative min in coverage over portions of central KY. Looking at the 21/00Z HREF guidance, we can see that the best instability remains out across southwest IN/far western KY this evening (generally west of the I-165 corridor), but then significantly drops off after sunset with the loss of heating. The HREF solutions really do not have much instability late this evening and into the overnight into areas east of I-65. Thus, any linear convection pushing through the region will likely weaken with time and eastern extent.

SPC has opted to keep the slight risk of severe across our region relatively unchanged from the previous day two outlook. This is a reasonable approach at this time given the uncertainty with the convective evolution. Some adjustments to the outlook will probably occur later today as the convective evolution begins to reveal itself.

In terms of QPF/Hydro issues, integrated vapor transport will be quite high across the region this afternoon as moisture pools ahead of the approaching frontal boundary. The highest QPF looks to occur from southern IL into southern IN with 00Z HREF PMM guidance showing the potential for localized 3-4 inch swaths occurring with the MCV pushing through. Given the recent rains over the last couple of weeks and the potential for training of storms across this region, have collaborated with surrounding offices to hoist a flood watch for our southern IN counties with this forecast package. As the convective evolution become more clear, additional expansions to this watch may be required for portions of northern KY (mainly along/north of the Parkways) where soils remain saturated from the last couple of weeks worth of heavy rainfall.

LONG TERM /MONDAY THROUGH SATURDAY/

Issued at 329 AM EDT Sun Jun 21 2026

Lingering rain showers will continue to move SE with the cold front during the day on Monday, and clear out by Monday night. High pressure will build in behind the cold front with northwesterly flow aloft. Tuesday is expected to be dry and the flow aloft will bring in drier air. Maximum temperatures to start the week will be slightly cooler in the low 80s with dewpoints in the upper 50s and low 60s.

A mid level shortwave will develop over Missouri and Arkansas on Wednesday, and will move east over the Ohio Valley Wednesday night. This will bring rain showers Wednesday night into Thursday across the forecast area. Additionally, a surface low pressure develops in the Great Lakes region Wednesday night into Thursday with a cold front stretching through the central CONUS. The cold front will push through the Ohio Valley on Thursday leading to additional rain showers. QPF amounts remain low for Wednesday and Thursday with amounts under 0.25", and only 5-15% probability of 0.5" across the forecast area. Maximum temperatures for the middle half of the week will warm into the mid 80s.

Another shortwave disturbance will move in from the Plains on Friday and will lead to a broader troughing area over the region. Rain chances will return once again across the area Friday afternoon and evening. Friday evening a LLJ will also move in bringing wind gusts ranging near 30mph. Rain showers are likely to linger through the day on Saturday, and hopefully clear for a dry Sunday. Rainfall amounts are slightly higher for Friday into Saturday with a 40-50% chance of receiving greater that 0.5". Maximum temperatures to end the week and into the weekend will hold in the mid to upper 80s.

AVIATION /18Z TAFS THROUGH 00Z TUESDAY/

Issued at 202 PM EDT Sun Jun 21 2026

We begin the period under VFR conditions, but to the west over Illinois a line of thunderstorms is advancing this way. This line is expected to begin moving across southern Indiana between 22 and 00z before continuing southeast towards all the TAF sites. Ahead of the line it's possible isolated to scattered showers and/or thunderstorms could develop, but ceilings are expected to remain well in VFR ranges. The main line could remain strong enough to drop visibilities for short periods of time. Behind the line, and after 6z, ceilings are expected to begin dropping from the west into MVFR and IFR conditions near HNB before the lowering continue eastward towards the other TAF sites.

LMK WATCHES/WARNINGS/ADVISORIES

KY...None. IN...Flood Watch through Monday morning for INZ076>079-083-084- 089>092.