textproduct: Louisville

KEY MESSAGES

* This afternoon and evening, widely scattered thunderstorms will bring heavy downpours, lightning, and gusty winds.

* Late tonight into early Sunday morning, a line of showers and thunderstorms will push into southern IN and northern KY while weakening. Isolated strong to severe wind gusts are possible, but confidence in damaging 60+ mph winds is low.

* Forecast confidence is increasing in strong to severe thunderstorms Tuesday afternoon and evening. The main severe weather hazard is damaging winds.

* Warm and humid conditions linger through Tuesday, with highs mostly in the upper 80s and lower 90s. Cooler than average temperatures move in from Wednesday through the weekend in the low to mid 80s.

SHORT TERM /THROUGH SUNDAY/

Issued at 335 PM EDT Sat Jul 18 2026

A fairly robust upper level trough is pivoting southeast over Ontario and Quebec this afternoon, and a 1000 mb sfc low is analyzed over far southwestern Quebec. A hot and humid airmass is in place across southern IN and central KY ahead of a cold front, which is draped SW through portions of the Great Lakes and Midwest. While we currently lack any notable low-level forcing, a weak, remnant mid- level wave has contributed to deeper moisture and greater convective coverage across the eastern half of KY this afternoon. Isolated to widely scattered showers and storms are expected to continue into the evening hours, and briefly stronger storms may produce brief heavy rainfall, lightning, and localized strong wind gusts of 40-50+ mph. Outside of the spotty convection, temperatures are in the upper 80s to lower 90s and heat index values are in the mid 90s to low 100s.

Tonight, scattered pulse convection will gradually wane in coverage and attention will turn to the southward-moving cold front to our north. A west-to-east oriented band of showers and storms is forecast to move SSE into our southern IN and northern KY counties between 11 PM - 3 AM EDT. Moderate instability (1000-1500 J/kg MLCAPE) will likely still be present, though we will see increasing SBCIN with the development of a shallow inversion. The wind profile will be unidirectional from the NW with only up to 15-20 kts of shear. The line appears likely to become outflow-dominant and weaken fairly quickly through the early morning hours. We do not expect the line to push through all of central KY before diminishing. The only convective hazards will be locally gusty winds and lightning, and the confidence in damaging 60+ mph winds is low.

Temperatures will drop into the lower 70s for lows Sunday morning. Most areas should start off Sunday dry despite the weak cool front pushing through central KY. A few isolated showers will be possible over central KY Sunday morning. Scattered showers and storms will increase in coverage Sunday afternoon across south-central KY. The southern half of the forecast area (south of the front) should destabilize fairly quickly. The highest rain chances (40-70%) will be south of a line from Hardinsburg to Berea. Drier air advecting in from the north behind the front will keep the northern areas dry on Sunday. Forecast highs on Sunday are in the 85-90 degree range. Heat indices should briefly top out near 100 across south-central KY in the afternoon (outside of convection.

LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/

Issued at 335 PM EDT Sat Jul 18 2026

===== Monday - Saturday =====

Diurnally-driven, scattered convection will remain possible on Monday, especially across south-central KY. The sfc boundary hangs up over that area before drifting north as a warm front. Shear remains very weak, so only PM pulse convection is expected with no organized severe threat. Afternoon temperatures will rise into the upper 80s to near 90.

Forecast confidence continues to increase in a more potent severe storm risk Tuesday afternoon into Tuesday night. Multiple mid-level shortwave disturbances should phase in a digging upper level trough over eastern Canada and the Great Lakes. This deeper wave will spread 40-50 kt mid-level NW winds as far south as the Ohio Valley, providing enhanced forcing and sufficient deep shear for organized convection. A QLCS appears possible ahead of a seasonally strong cold front, which could bring swaths of strong to severe wind gusts to the area Tue afternoon into Tue night.

For the rest of the week, Tuesday's cold front will clear the CWA sometime early Wednesday, knocking highs down into the low to mid 80s and dry skies. Thursday through Saturday are trending cooler than average as the overall synoptic pattern supports upper level troughing in the eastern CONUS and ridging in the intermountain west. Highs generally will remain in the low to mid 80s.

AVIATION /18Z TAFS THROUGH 00Z MONDAY/

Issued at 149 PM EDT Sat Jul 18 2026

Scattered shra/tsra will continue this afternoon and evening, with pulse convection decreasing in coverage after sunset. However, a broken line of shra/tsra will push south into southern IN and northern KY after 04Z Sunday. Brief TSRA impacts will be possible at HNB, SDF, and LEX. This line will weaken and gradually diminish early Sunday morning as it pushes further south into central KY.

Brief IFR conditions will be possible in any storms. Outside of storms, low-end MVFR ceilings appear possible early Sunday morning at LEX/RGA - mainly between 09-16Z Sunday. Prevailing WSW winds near 10+ kts through sunset, with winds weakening this evening. Light winds will veer from the north on Sunday in the wake of a cool front.

LMK WATCHES/WARNINGS/ADVISORIES

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