textproduct: Louisville

KEY MESSAGES

* Quiet weather is expected for today and tonight across the region.

* Shower and storm chances (50-80%) return by late Thursday, and linger through at least Saturday. Any training storms could result in localized flooding, especially Thursday night and Friday.

* Summerlike heat and humidity is forecast to return next work week. There is a 50-70% chance heat indices surpass 100 degrees by Tuesday.

SHORT TERM /THROUGH TONIGHT/

Issued at 304 AM EDT Tue Jun 23 2026

Surface cold front continues to move southeast of the region this morning. Back end of the low clouds has now cleared the Ohio River and will steadily work south and east through the remainder of the overnight hours. Temperatures in the clear skies have dropped off into the upper 50s and lower 60s, with mid 60s in locations still under the clouds. For the remainder of the overnight period, no significant weather is expected. Some patchy fog could develop in some of the low-lying areas that clear out later this morning. However, ongoing cloud cover is likely to limit fog production this morning. Winds this morning will remain out of the north.

For today, surface high pressure will continue to build into the region. Skies will start off sunny across southern IN and much of north-central and western KY. Low-level cloud cover will continue to move off to the southeast with most of the state going mostly sunny by the afternoon hours. Highs today will warm into the upper 70s in most areas. A few 80 degree readings will be seen down in the WABBLES/BG area over toward Lake Cumberland region.

For tonight, mostly clear skies are expected across the region with no significant weather. Look for lows in the mid-upper 50s, though some of our protected low-lying/sheltered areas could drop into the lower 50s.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 304 AM EDT Tue Jun 23 2026

With surface high pressure in place, light to calm winds Tuesday night will favor efficient radiational cooling for yet another unseasonably cool morning on Wednesday, especially if skies remain mostly clear as the High Resolution Ensemble Forecast (HREF) system suggests. Unsurprisingly, the National Blend of Models (NBM) suggests a 60-90% chance (highest east of I-65) for low temperatures under 60 degrees; as forecast dewpoints are in the mid 50s, this suggests some potential for patchy fog around sunrise. Otherwise, Wednesday should be yet another pleasant day with partly cloudy skies, a light southwesterly breeze, and highs in the low 80s.

The surface high will shift to the east Wednesday night, allowing low level flow from the southwest to return ahead of a mid level disturbance which is slated to enter the local area Thursday night. The increasing warmth (highs in the mid-upper 80s) and moisture (dewpoints in the upper 60s to low 70s) ahead of this feature will foster modest instability, with the Low Resolution Ensemble Forecast System (LREF) mean surface based convective available potential energy (SBCAPE) climbing to 1000-2000 J/kg by Thursday evening. Nonetheless, there's no clear sign of a forcing mechanism to initiate storms until the disturbance arrives around/after midnight. If we have storms during the afternoon/evening Thursday (20-40% chance), then they would pose a locally heavy rainfall risk given slow storm motion (driven by weak environmental shear) and a deep (>10 kft) warm cloud layer, as well as a low (but nonzero) wind risk from a wet microburst in collapsing storms. Chances increase for widespread storms Thursday night into Friday with the arrival of the aforementioned disturbance. While deep layer shear will increase (to 30-40 kt) with this feature, that shear will be oriented nearly parallel to the slow-moving cold front (forcing), suggesting potential for training storms, particularly on the nose of the low level jet (LLJ) where back-building would be most favored. Model differences surround the precise position, timing, and strength of that LLJ, lending low confidence in where the heaviest rainfall axis will occur and whether a severe weather risk will materialize. However, confidence is highest across areas north of a roughly Hardinsburg to Lexington line where NBM advertises 30-50% chances for more than 2 inches of rainfall by early Saturday morning.

Upper level ridging will develop across the nation's midsection over the weekend and expand eastward across the local area by early next week. With the approach of this ridge, northwest flow will keep a (30-60%) chance for storms in the forecast throughout the weekend across central KY/southern IN, while the risk decreases heading into next work week. Meanwhile, summerlike heat and humidity will return, with raw ensemble guidance from the Low Resolution Ensemble Forecast (LREF) giving a 50-70% (70-85%) chance for high temperatures of 90+ degF by Monday (Tuesday). After all of the recent rainfall, dewpoints should surge into the mid 70s, potentially resulting in triple digit heat indices. In addition, overnight lows in the mid to upper 70s are slated to push heat risk into the moderate to major categories, suggesting increased risk for heat illness, especially among vulnerable populations. Given this is still nearly a week away, the forecast is subject to change considerably, but warm-hot and humid weather looks like a distinct possibility next work week. Stay tuned.

AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 641 AM EDT Tue Jun 23 2026

High pressure will continue to build into the region today. Back edge of low clouds extends from KLEX southwest to KBWG. KHNB/KSDF are already in the clear and will remain that way for the remainder of the forecast period. Expect KLEX/KBWG to clear out between 23/12- 14Z and KRGA should clear out by 23/14-15Z. Winds will remain generally out of the north at 4-8kts and then become more northwest by mid-late afternoon. VFR conditions are expected for tonight and into Wednesday morning. There is a slight chance for some fog at KBWG Wed morning.

LMK WATCHES/WARNINGS/ADVISORIES

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