textproduct: Louisville

KEY MESSAGES

* Hot and humid conditions continue through the end of the week and into the Independence Day holiday. Afternoon temperatures warming 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.

* Increasing afternoon and evening shower and storm chances are expected this weekend into early next week. A few strong storms with gusty winds and heavy rainfall will be possible.

* Unsettled, muggy weather continues through early-to-mid next week with modest relief from hot temperatures likely.

SHORT TERM /THROUGH TONIGHT/

Issued at 326 AM EDT Thu Jul 2 2026

Early this morning, temperatures have dropped into the 70s across most of central KY and southern IN, with a few locations in the urban centers still near 80 degrees as of 06Z. The ample quantity of near-sfc moisture with sfc dewpoints in the mid 70s will limit any further cooling, with temperatures only dropping a few more degrees between now and sunrise. The near-sfc moisture has also allowed for patchy fog to develop, especially in river valleys, so we'll continue mention of this in the forecast through around 8 AM.

Not much change is expected in the overall pattern today as ridging aloft and high pressure near the sfc remains fairly stationary over Appalachia. As has been the case the past few days, low-level moisture should mix up into a scattered cu field during the late morning hours, though temperatures should still quickly warm through the 80s and approach 90 degrees by midday. By the afternoon hours, temperatures in the low-to-mid 90s with dewpoints in the mid-to- upper 70s should again lead to heat index values ranging from 100- 115 across the area. Be sure to take necessary heat precautions this afternoon and evening, including limiting time outdoors, remaining hydrated, and wearing light-colored clothing.

In addition to heat and humidity continuing, we will introduce a low (10-25%) chance for thunderstorms this afternoon and evening, mainly across south central KY. With the center of the upper ridge shifting slightly eastward later today, there is expected to be modest cooling around 700 mb, weakening the strength of the cap that has been in place so far this week. 00Z hi-res guidance suite has several solutions which have convection initiating over middle TN this afternoon, with showers and storms approaching our southern KY counties by early evening. If convection can fire, it will have ample instability to work with, as HREF median SBCAPE progs show around 4000 J/kg, with high-end progs showing 5000+ J/kg. Stronger, taller storms will carry a damaging wind threat, as DCAPE and microburst composite parameter values are elevated thanks to steep low-level lapse rates and some mid-level dry air. The storm potential should decrease quickly after sunset as the PBL stabilizes and storm fuel dwindles.

Tonight, another muggy night is expected across the area with temperatures slowly dropping through the 80s and into the mid-to- upper 70s by Friday morning. Patchy fog development will again be possible Friday morning, especially if any areas do see heavy rain this afternoon/evening.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 326 AM EDT Thu Jul 2 2026

Hot and humid conditions are expected to continue on Friday with upper-level ridging remaining the dominant feature over the southeast US. Confidence in the temperature forecast will begin to decrease as the coverage and potential for showers and storms increases; however, 1000-850 mb thicknesses suggest the potential that Friday could be the warmest day of the week, so no changes are planned for the Extreme Heat Warning duration at this time.

The potential for showers and storms Friday and Saturday continues to carry quite a bit of uncertainty. While very high amounts of instability (4000+ J/kg SBCAPE) will remain, forcing mechanisms are not well-defined, with mesoscale factors such as differential heating and the locations of residual outflow boundaries likely playing an important role in convective initiation. As a result, we'll continue to advertise a low-end chance (20-30%) for storms during the afternoon and evening barring any model convergence on a more likely solution, and a washout for the 4th looks unlikely at this time. Continued weak flow aloft will limit deep-layer shear, with pulse convection and wet microbursts continuing to pose an isolated damaging wind threat Friday into Saturday.

By the second half of the upcoming weekend, ridging over the southeast US will begin to weaken as a weak shortwave brings a front toward the region Sunday into Monday. This front should provide a more well-defined forcing mechanism for showers and storms, and coverage of showers and storms should be greater for the second half of the weekend into early next week. Accordingly, the forecast features higher (30-40%) PoPs Sunday into Monday. The increased coverage of clouds, showers, and storms should cause high temperatures to trend downward over the weekend, though upper 80s and low 90s are still expected during this period. Nighttime lows are expected to remain mild, only dropping into the 70s.

Early-to-mid next week, upper ridging is expected to build over the northern Plains as shortwave troughing slides across the northeast US. The sfc front associated with that shortwave is currently expected to stall close to the Ohio Valley sometime early next week. Along and south of this front, ensemble mean PW values will continue to be anomalously high, with 1.5-1.75" PW continuing through the first half of next week. Continued unsettled weather is likely with the front in the vicinity, with scattered afternoon and evening showers and storms likely through the extended forecast period. This expectation of unsettled weather is reflected in the CPC 6-10 and 8- 14 day precipitation outlook, which shows higher probabilities for above normal precipitation across the region. Temperatures should remain near or slightly above climo, with exact values varying based on coverage of clouds and precipitation.

AVIATION /12Z TAFS THROUGH 18Z FRIDAY/

Issued at 656 AM EDT Thu Jul 2 2026

Patchy fog and mist should scatter out over the next few hours, with moisture mixing up into another scattered cu field later this morning. Aside from brief dips in VIS over the next 1-2 hours, VFR conditions are expected through the current forecast period, along with light and variable winds. Isolated TSRA remains possible at BWG between 21-01Z, but the probability remains low enough to refrain from PROB30 mention at this time. Tonight, patchy fog will again be possible at most forecast sites after 06Z, but confidence is low enough to keep out of the forecast for now.

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.