textproduct: Louisville

KEY MESSAGES

* The risk for heavy rainfall and flash flooding continues today across southern IN and central KY. Rainfall amounts of 1 to 3 inches are possible, with locally higher amounts due to training storms. Isolated significant flash flooding is possible.

* Summer heat and humidity build across the region next week, with triple digit heat indices likely (70-90% chance) west of I-65 on Monday and area-wide Tuesday through at least Friday. This will pose a risk for heat-related illness, especially among vulnerable populations.

SHORT TERM /THROUGH SUNDAY/

Issued at 413 AM EDT Sat Jun 27 2026

A significant rainfall and flash flooding event is in progress across southern Indiana, and the heavy rainfall threat is set to shift southward later today. Early this morning, scattered storms producing highly efficient rainfall are moving west to east across southern IN and north-central KY. A 25-30 kt WSW low-level jet continues to funnel moisture up the Lower OH River Valley. PW values approaching 2.2 inches and deep warm cloud depths are supporting more tropical rainfall processes. New Flash Flood Warnings are in effect for Dubois, Perry, Crawford, and Meade counties, and additional warnings are possible downstream (including in the Louisville Metro).

By 7-11 AM EDT this morning, convective clusters are forecast to have congealed more over central KY ahead of a convectively- generated wave/MCV. The 25 kt westerly LLJ weakens slightly and shifts ever so slightly south over central KY during the late morning and early afternoon hours. This trend continues, with the 25- 30 kt LLJ responding across south-central KY this evening in the left exit region of a 40 kt mid-level jet over TN. This should give southern IN a brief respite, with swaths of heavier rainfall shifting into central and southern KY from mid-morning into early afternoon.

Scattered showers and storms will remain possible in southern KY into the evening hours. However, the lull in the action along and north of I-64 will allow the northern areas to destabilize during peak heating. Scattered convective redevelopment appears likely across southern IN and northern KY by early to mid-afternoon. The still moist environment will still support locally heavy rainfall, so we have extended the Flood Watch for areas along and north of I- 64 through 8 PM EDT this evening. The Flood Watch for areas south of I-64 continues through 8 AM EDT Sunday.

Additional rainfall amounts of 1-3 inches appear possible early this morning through Sunday. Localized higher totals of 3-5 inches will be possible across south-central KY today into tonight. In addition to heavy rainfall today, some stronger storms will be capable of locally strong wind gusts. We do see a modest increase in low-level SRH this evening across southern KY, but overall the tornado threat is fairly low.

Overnight into early Sunday, shower and thunderstorm coverage should decrease over much of the area with the highest PoPs consolidating in a NW to SE oriented warm advection wing over western and south- central KY. Mid and upper level ridging amplifies over the MS Valley on Sunday, and increasing subsidence aloft will lessen precipitation chances and coverage. However, at least isolated showers and storms will remain possible into Sunday afternoon. Highs in the low 80s will be common today, with temperatures rising into the mid 80s to near 90 on Sunday.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/

Issued at 413 AM EDT Sat Jun 27 2026

A dramatic pattern change is still expected next week. Models suggest substantial amplification of an upper level ridge over the eastern CONUS. We expect to transition to a stretch of hot and oppressively humid conditions. For those currently experiencing flooding, it will be a notably drier stretch. Afternoon high temperatures are forecast to reach the low to mid 90s. With lingering humidity (sfc dewpoints in the mid 70s, heat indices of 100-110+ are likely each day.

Strong ridging aloft should keep us mostly dry through Thursday, though there is a 10% chance for isolated pulse convection by Thursday. There are signals the ridge may weaken somewhat heading into next weekend. Hot and humid conditions are likely to linger into the Fourth of July holiday, but we have a 30-40% chance for showers and storms on Friday and Saturday.

AVIATION /12Z TAFS THROUGH 18Z SUNDAY/

Issued at 709 AM EDT Sat Jun 27 2026

Multiple waves of showers and storms are moving west to east across Kentucky and southern Indiana Saturday morning. These will bring occasional visibility drops and perhaps (40-50% chance) lightning strikes to the airfields - both are included in PROB30 groups. The area should have a short lull in activity early this afternoon, though MVFR ceilings may linger. Another round of showers and thunderstorms is forecast to develop during the late afternoon and linger through the evening, possibly into the overnight period. Confidence is highest in this second wave at BWG where another PROB30 group was added, but there is a low (20-30%) chance at the other terminals as well. Winds will become predominantly southwesterly at 8-12kt by around 15z/11am EDT.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Flood Watch through this evening for KYZ030>043-049. Flood Watch through Sunday morning for KYZ023>029-045>048- 053>057-061>067-070>078-081-082. IN...Flood Watch through this evening for INZ076>079-083-084- 089>092.