textproduct: Louisville

KEY MESSAGES

* A few showers and isolated storms are possible this afternoon, especially east of I-65, with a very low likelihood in strong to severe storms occurring.

* Daily shower and storm chances for the middle part of the week before a weekend of mid 80s and clear skies.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 246 PM EDT Mon Aug 17 2026

A cold front is stretching from SE Indiana down through the MO Bootheel at this hour, and is poised to slide SE through the CWA through late afternoon and early evening. We have gotten moderately unstable (1500-2500 J/KG ML CAPE) along and ahead of this frontal boundary, however the overall deep layer shear is negligible, and not strong enough for any organized updrafts. In addition, mid level lapse rates are struggling around 5.5 C. The resulting shower activity triggering along the front is struggling, and expect this to continue through the evening. Can't rule out a few rumbles of thunder, but overall strong storms are not expected.

Temperatures and humidity will still stay pretty muggy ahead of the frontal passage, including temps still in the low 90s with mid 70s dew points. Some triple digit heat indices are still possible through afternoon and early evening down along the TN border.

Otherwise, drier air filters in tonight behind the front, and will allow for more comfortable low temperatures in the low and mid 60s. Some fog development may occur, however light surface winds promoting dry air advection and some variable upper cloudiness could be limiting factors to more widespread/dense fog concerns.

We'll see NW flow aloft void of any shortwave activity, and high pressure at the surface heading toward mid week. Tuesday will be dry in the post-frontal airmass with plenty of peaks of sunshine. Highs look to be in the low and mid 80s, which is a touch below normal for this time of year. Dry and seasonable low are then expected again Tuesday night.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 246 PM EDT Mon Aug 17 2026

*** Wednesday - Sunday ***

As the region continues in a zonal flow aloft, several shortwaves are expected to move into the Ohio Valley. This will bring rain chances back to the forecast for Wednesday and Thursday. A shortwave trough will begin to move in early Thursday morning, along with a frontal boundary pushing in from the north. A widespread area or line of rain and storms is forecasted to push through the area early Thursday morning. Marginal instability seems to be available overnight ahead of the storm system, with 30-40kts of bulk shear across western and central KY. Its still a little early to know for sure about a severe potential, however if the forcing from the shortwave and the frontal boundary are timed right severe weather would not be out of the question. By Thursday evening, an upper level trough will begin to dig into the Ohio Valley. Showers and storms will continue to linger with a decently unstable atmosphere and an axis of bulk shear (40-50kt) from a low level jet over the IN and KY border.

Once the trough completely builds in over the region, a drier period can be expected for Friday and the weekend. An area of surface high pressure and a drier airmass is expected to build over the area. Very pleasant weather is expected this weekend with maximum temperatures in the mid 80s, low 60 dew points, and clear skies.

AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 712 PM EDT Mon Aug 17 2026

Cold frontal boundary is pushing through the region this evening. It has already cleared HNB/SDF and will clear LEX in the next hour. A few showers will be possible at LEX/RGA this evening through about 18/0130Z or so. After that, look for a period of VFR conditions this evening and into the overnight period. Some patchy fog development will be possible at the terminals with the exception of SDF. The outlook for Tuesday calls for VFR conditions with light north-northwesterly winds.

LMK WATCHES/WARNINGS/ADVISORIES

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