textproduct: Louisville

KEY MESSAGES

* Another round of showers and storms is currently ongoing with an MCV moving through the region, departing by late Monday morning. Any storms that develop will have the capability of producing damaging winds and brief heavy rainfall.

* A few showers and isolated storms are possible Monday afternoon, especially east of I-75, with a very low likelihood in strong to severe storms occurring.

* A reprieve from the hot and humid weather, as well as showers and storms, comes Monday evening once the cold front departs to the south. Showers and storms arrive again for the mid and late week time frame, however temperatures should be slightly below normal for this time of year.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 338 AM EDT Mon Aug 17 2026

A cluster of showers and thunderstorms currently over southern Illinois and southwest Indiana is tracking eastward towards our CWA. This cluster will move over southern Indiana and north central Kentucky through the remainder of the overnight, exiting off to the east by the mid-mornign hours. Per the latest SPC mesoanalysis, while the cluster is in an area of 30-40 kt 0-6 km bulk shear thanks to a modest low-level jet, the system will move away from the highest area of elevated instability (~1500 J/kg MUCAPE) over the coming hours, allowing it to weaken some as it moves over the area. A low-level inversion over the region will also limit the potential some for storms to become strong to severe, though gusty winds, frequent lightning, and localized heavy rainfall will still be a concern until the showers and storms considerably dissipate.

As this system moves through, a weak frontal boundary will slowly push southeastward across the region, bringing with it a much-needed reprieve from the heat and humidity experienced over the past several days. There will be chances for showers and isolated thunderstorms during the afternoon hours, with the concern for any strong to severe storms being very low. For areas along and south of the front (south central Kentucky) increased instability (HREF mean CAPE > 2000 J/kg) will result in 40-60% chances of showers and isolated storms. For places behind the front, chances for precipitation will be much lower (15-30%). For afternoon temperatures, highs for places north of the front will be in the mid to upper 80s, with areas south of the front in the upper 80s/low 90s.

For Monday night, the cold front will finally depart off to our southeast, with surface high pressure building in behind. In addition to the temperature and humidity relief, this will also provide a brief break from showers and storms over the region. Overnight temperatures Monday and Tuesday night will be very comfortable, with mid to upper 60s lows Tuesday morning and low to mid 60s lows Wednesday morning forecast. For Tuesday afternoon, expect temperatures in the low to mid 80s along and north of the Parkways and in the upper 80s for areas south. Broad zonal flow aloft will also prevail over the region starting early Tuesday and continuing through the end of the short term forecast period.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 338 PM EDT Mon Aug 17 2026

While zonal flow will aloft will continue on Wednesday, a broader pattern shift will begin to take place across most of the CONUS. The upper ridge out west will amplify through the early portions of the weekend as the upper trough over the eastern portions of the country begins to dig southward. The initial digging of this trough will come late Wednesday into Thursday as an embedded shortwave and surface cold front moves towards the Ohio Valley. Conditions over southern Indiana and central Kentucky will be dry for the daytime hours, with highs in the mid to upper 80s forecast north of the Parkways, and places getting into the low 90s south. Chances for showers and storms will increase Wednesday night, with widespread 45-65% POPs forecast. There is still uncertainty in the guidance as to whether these storms will line up with the best instability and wind shear, so intensity of these storms is still uncertain.

The broad shortwave will slowly move through the region, finally departing to the east by Friday. As a result, chances for showers and storms (30-50%) will linger from late Wednesday night into early Friday. Available moisture will slowly decrease as the previously- mentioned frontal boundary pushes southward, exiting out of the area by Thursday night. LREF PW of ~1.8" across the area late Wednesday will decrease to less than 1.4" by Friday morning, which should help limit the extent of persistent heavy rainfall. With the multiple rounds of showers and storms, as well as the passing cold front, afternoon temperatures will remain in the 80s Thursday and Friday, with morning lows in the upper 60s Thursday and low to mid 60s Friday.

The axis of the upper trough and an additional shortwave will move over the region by the latter half of the weekend, though deterministic and ensemble guidance shows varying outputs on the timing and progression of these features. Lower end chances for showers and storms will accompany these features, but once the axis and shortwave moves through, calmer conditions are likely to follow. Afternoon highs will be in the 80s, with morning lows in the 60s Saturday and SUnday.

AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 139 PM EDT Mon Aug 17 2026

A cold front is sliding southward through the area this afternoon and early evening, and winds will shift from a steady WNW to NW to NNW component as this occurs. A isolated to widely scattered showers and a few storms are expected this afternoon and early evening along this passing frontal boundary, mainly at SDF/LEX/RGA. Hinted at this with Prob30 coverage in the TAFs. Winds should be light out of the north or calm overnight with mostly clear skies. Some fog may develop in the MVFR range at all sites except SDF. Look for dry and VFR tomorrow, however a few-sct lower level clouds may be around in the morning until better mixing gets going.

LMK WATCHES/WARNINGS/ADVISORIES

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