textproduct: Louisville

KEY MESSAGES

* Isolated to scattered slow moving showers and storms (20-40% coverage) are possible east of I-65 for the remainder of the afternoon, and across most of the area Thursday. Most locations will remain dry.

* Better shower and storm chances, along with summer warmth and humidity, will return later this week, peaking at 45-65% Friday into Saturday.

* Lower chances for showers and storms Sunday (10-20%)-Monday (20- 40%), with increasing chances Tuesday night through Wednesday (40- 60%).

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 333 PM EDT Wed Aug 5 2026

This Afternoon through Tonight...

On the east side of a subtle pseudo-stationary boundary from Lake Cumberland through the Bluegrass, isolated-to-scattered showers and a few storms have begun to develop. The boundary placement is a result of an upper-level trough encroaching from the northwest and a departing closed low off to our southeast. From the most recent SPC mesoanalysis, PWs over 1.5" will allow for heavier downpours to occur, posing a very localized threat for flash flooding. MLCAPE values > 1000 J/kg occupy this environment, but very weak wind shear will result in garden variety storms with very slow storm motion for the rest of the afternoon/early evening. To the north and west of the boundary, conditions will remain warm and dry, with slightly more manageable dew points in the mid-to-upper 60s.

For tonight, as the upper trough moves towards the Ohio Valley, the closed low will dissipate off to our east as ridging builds in thanks in part due to the western Atlantic high. Conditions will be dry and mild ahead of the trough that also has a mid-level shortwave expected to move through the area on Thursday. Expect overnight lows in the upper 60s/low 70s, with mid-to-upper level clouds building from west to east as the night progresses. A few areas of patchy fog may develop tonight, mainly east of I-65, though increasing cloud cover should limit this considerably.

Thursday and Thursday Night...

The mid-level shortwave and upper-level trough will graze the northern portions of the CWA on Thursday, mainly over north central Kentucky and southern Indiana. With winds shifting from the north to the south with the building ridge off to the east, increased moisture transport will allow PWs to climb during the day (most recent HREF outputting 1.6-1.8" PW). While HREF SBCAPE values around 1000-1500 J/kg are likely tomorrow afternoon, wind shear will still be weak, so while the area for possible showers and thunderstorms will expand some, we still only expect a slight chance (20-40%) for garden variety showers and storms. The main concerns would be heavier downpours, gusty winds, and frequent lightning. For near- stationary storms, the high PW values would again pose a very localized flooding issue. For many places, conditions will be dry tomorrow, and with increased southerly flow, temperatures will rise into the upper 80s, with dew points getting into the low-to-mid 70s. On Thursday night, the southern periphery of the upper trough will continue to linger over the northern portion of the CWA. As the shortwave on Thursday departs to the north and east, another subtle wave will enter into southern Indiana by late Thursday night. With ample moisture still in place, there is a slight chance (20-40%) for showers and an isolated thunderstorm in north central Kentucky and southern Indiana. With cloud cover in place, overnight temperatures will not drop much, with lows in the low 70s expected.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 333 PM EDT Wed Aug 5 2026

Friday and Saturday...

Broad upper-level troughing over the Midwest and Great Lakes will settle in by the end of the week and continue into the weekend, while ridging over the western Atlantic and southeast CONUS will settle in. A surface boundary will linger off to our north over northern Indiana, Illinois, and Ohio, keeping our region in an area of higher moisture (LREF PW > 1.7") and in the path of multiple shortwaves moving through. Some of the higher chances for showers and isolated-to-scattered thunderstorms will take place late Friday through midday Saturday (45-65%), with the main concerns again being heavier downpours, frequent lightning, and gusty winds. Deep layer shear will still be relatively weak (< 20 kt), so any concerns for strong to severe storms is still very minimal. Southerly flow will also make conditions hot and muggy, with highs in the upper 80s/low 90s and heat indices in the mid-to-upper 90s.

Sunday through Middle Next Week...

The upper trough over the Midwest/Great Lakes becomes less amplified as ridging from the Atlantic/SE CONUS high tries to build westward. The mid/upper-level flow over our region becomes more zonal in nature, with PWs also decreasing some (most recent LREF outputs 1.4- 1.6" PW). The jet stream will be further north, keeping more of the traversing shortwaves off to the north and reducing our chances for precipitation into the early parts of next week. Southerly surface flow will keep temperatures in the upper 80s/low 90s Sunday through Tuesday before the frontal boundary begins to move southward. The shifting of the front will be in part due to the amplification of the western CONUS ridge, as well as a deepening of an upper level trough over the Hudson Bay. LREF cluster guidance does show variability in the timing and progression of these features, with the mean output bringing the front through Tuesday night into Wednesday. Regardless of timing, this will bring back higher chances for showers and storms (40-60% chance) ahead of the front as it moves through the region.

AVIATION /00Z TAFS THROUGH 06Z FRIDAY/

Issued at 735 PM EDT Wed Aug 5 2026

Showers and storms have dissipated over the region this evening. As the sun sets, winds will relax to calm or light and mostly out of the south. Given light winds and recent precip, fog may develop in the early morning. Fog has been included at BWG/RGA/LEX. Fog will burn off within a few hours of sunrise. By late morning, winds will veer to the west and remain light around 5-8kts through the afternoon.

LMK WATCHES/WARNINGS/ADVISORIES

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