textproduct: Louisville

KEY MESSAGES

* Hot and humid conditions continue over the next several days. Afternoon temperatures in the low-to-mid 90s and heat indices between 100-115 combined with limited nighttime cooling will lead to adverse heat-related impacts if precautions are not taken.

* Hot and humid for the Fourth of July holiday weekend, with isolated to scattered storms possible in the afternoon and evening Thursday into early next week. Localized flash flooding and/or localized gusty winds will be possible each afternoon and evening with showers and storms.

SHORT TERM /THROUGH TONIGHT/

Issued at 402 AM EDT Wed Jul 1 2026

Early this morning, temperatures are generally in the 70s across central KY and southern IN, with urban locations generally closer to 80 while rural locations are closer to 70. Mostly clear skies on nighttime microphysics satellite imagery reveals areas of valley fog which are most notable across east KY, but can also be seen in the river valleys of central KY and southern IN. Have added patchy fog mention through sunrise this morning mainly for river valleys, although a broader area of patchy fog mention was also included across areas which received the heaviest rainfall this past weekend.

Once the sun comes up and mixes out the patchy fog, heat and humidity should again be the main impact across the area with temperatures warming quickly through the 80s later this morning. A scattered cu field may help to provide some shade by mid-to-late morning; however, these clouds should gradually mix out later in the day. Modest increases in 1000-850 mb thicknesses compared to Tuesday should support highs a few degrees above persistence this afternoon. With that being said, have nudged temperatures down a few degrees below NBM guidance given recent high biases; this still results in forecast highs between 91-96 across the area this afternoon. With dewpoints remaining in the 70s, heat indices should again climb into the 100s across the area this afternoon, with isolated instances of 110+ heat indices possible, especially west of I-65. Make sure to take any necessary heat-related precautions today and over the next several days, including limiting time outdoors during peak heating hours, wearing light-colored clothing, and remaining well hydrated.

The forecast remains dry this afternoon and evening, and while there may be scattered showers and storms that form across the TN valley, warm temperatures in the 850-700 mb layer beneath the center of the upper-level ridge should help to suppress convective potential through this evening.

Tonight, muggy conditions are again expected with patchy fog again possible in sheltered locations and near bodies of water. Temperatures are only expected to fall into the 70s Thursday morning, with urban centers likely remaining at or above 80 degrees for much of the evening and early overnight period.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 402 AM EDT Wed Jul 1 2026

Synopsis...

As we approach Independence Day weekend, upper-level ridging which has been in control over the region so far this week is expected to shift slightly to the east toward the Mid-Atlantic and Carolinas. While this shift in the synoptic pattern will be subtle, it should be sufficient to allow for a plume of rich moisture with 1.7-1.9" PWAT values to move into the TN and lower Ohio Valleys Thursday into Friday. While larger scale forcing will be ill-defined, smaller- scale/more subtle disturbances are expected to track within the easterly flow on the southern/SW side of the upper ridge, providing some forcing for afternoon/evening showers and storms.

As we head through the weekend and into early next week, the synoptic pattern across the lower 48 should become more zonal, with ridging over the eastern US and troughing over the western US gradually transitioning to a broad, flat ridge across much of the CONUS. While there is not much in the way of a signal for a well- defined front or other forcing mechanism, the residual hot and humid air mass should support continuing afternoon and evening storm chances as we head into early next week.

Heat and Humidity...

Continued hot and humid conditions are expected through at least early next week, though ensemble guidance does show a gradual stepping down of temperatures beginning later this weekend as values approach climatological norms. While this slight cooling trend is partially due to decreasing strength of the upper ridge, greater expected coverage of clouds and precipitation is likely also contributing to the downward trend in temperatures. If expected coverage of afternoon/evening showers and storms decreases (increases) from current progs, this would likely lead to an increase (decrease) in expected high temperatures, especially over the weekend.

At this time, Thursday and Friday are expected to feature the greatest heat impacts, with high temperatures in the low-to-mid 90s and lows only falling into the 70s. The lack of cooling at night will become increasingly impactful, especially in urban areas. As a result of the continued combination of heat and humidity leading to afternoon heat indices between 100-115 and limited cooling overnight over the next several days, the duration-based Extreme Heat Warning highlights the threat well, even if many locations do not hit criteria each afternoon.

Shower and Storm Chances Gradually Return...

The increasing moisture and subtle forcing mentioned above should support daily afternoon and evening shower and storm chances beginning on Thursday and gradually increasing in coverage through the weekend and into early next week. This is also due in part thanks to a gradually weakening capping inversion between 850-700 mb leading to less CIN as we get later into the forecast period. With relatively weak flow throughout the column, effective bulk shear should generally be 15 kt or less, leading to more of a pulse convection environment with fairly slow/erratic storm motions. The main threats from storms aside from lightning would be heavy rainfall leading to isolated flash flooding as well as strong gusty winds from collapsing taller storm cores.

AVIATION /12Z TAFS THROUGH 18Z THURSDAY/

Issued at 657 AM EDT Wed Jul 1 2026

Any lingering patchy fog is expected to dissipate by 13Z, with VFR conditions likely through most of the current forecast period. While there is an outside chance of brief MVFR cu later this morning, the probability of this looks to be low. Light SW winds are expected through the day today, with speeds generally below 8 kt. Light and variable winds are expected after sunset tonight, with another low confidence potential for MVFR/IFR fog after 06Z Thursday, mainly for RGA/BWG/HNB.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Extreme Heat Warning until 9 PM EDT /8 PM CDT/ Friday for KYZ023>043-045>049-053>057-061>067-070>078-081-082. IN...Extreme Heat Warning until 9 PM EDT /8 PM CDT/ Friday for INZ076>079-083-084-089>092.