textproduct: Louisville

KEY MESSAGES

* The risk for heavy rainfall and flash flooding continues this evening across southern IN and central KY. Rainfall amounts of 1 to 2 inches are possible, with locally higher amounts due to training storms. Isolated significant flash flooding is possible.

* Summer heat remains in place his week with a strong ridge overhead. Highs will be in the mid to upper 90s and feels like temperatures will range 100-110 beginning Monday.

* Independence Day looks to not as hot, though highs remain in the low 90s.

SHORT TERM /THROUGH TONIGHT/

Issued at 440 PM EDT Sat Jun 27 2026

The threat of a significant rainfall and flash flooding event continues this afternoon through tonight as another round of showers and thunderstorms develops off in western Kentucky, southern Indiana, and southern Illinois. Per the latest SPC mesoanalysis, an area of at least 2" precipitable water extends ahead of a cluster of showers and storms off to our west and will push eastward over the coming hours. While the elevated LLJ that was in place during our initial round of showers and thunderstorms has drifted off to the east, a new shortwave coinciding with the previously mentioned showers and storms have aided in the redevelopment of active weather. Another 25-30 kt LLJ will develop this evening just behind the current cluster of showers and storms that will allow new showers and storms to develop tonight in what will still be an area of rich moisture.

As the surface frontal boundary shifts ever so slightly to the south, the main track of the showers and storms for this afternoon and evening will also push south some. The WPC has our southern and southwestern CWA in a Moderate Risk in their Excessive Rainfall Outlook, highlighting the more likely higher amounts in our southern counties. Per the 12z HREF LPMM guidance for 24 hour precipitation, there are multiple swaths of higher rainfall amounts across southern Kentucky. The NBM also paints an area of 1-2" rainfall across southern Kentucky, especially south of I-64. For this area, ex expect to see an additional 1-2" of rainfall through tonight's event, though areas of 3"+ in southern Kentucky will be possible with heavier downpours and/or training showers and storms. As a result, the threat for flash flooding will continue for this area through Saturday night into early Sunday.

Another thing to look out for this afternoon and evening is a lower- end severe weather threat for the far western portions of the CWA. For areas that have had a reprieve from this morning and afternoon's rainfall have destabilized some with semi-clearing skies. This has allowed MLCAPE values to rise to over 2000 J/kg in western Kentucky, acting as a spark for the ongoing showers and storms in that area. With that said, the persistent showers and storms that most of the area has experienced so far today has left an area of very stable air in its wake. While some destabilization could occur in the coming hours, there should be enough stable air in place to limit the extent of severe convection mainly to the western CWA. Damaging winds will be the primary concern with the strongest thunderstorms, though a brief isolated tornado cannot be completely ruled out.

LONG TERM /SUNDAY THROUGH SATURDAY/

Issued at 440 PM EDT Sat Jun 27 2026

=====Sunday - Tuesday===== Despite some leftover showers in the morning, Sunday features a large change in the synoptic weather pattern that will last for most of this week. Any additional rainfall will be light just after sunrise and will dissipate quickly ahead of a strong ridge of high pressure moving over the Gulf states. WAA from SW flow, strong subsidence, and plenty of sunshine will boost temperatures above normal this week. With clouds clearing, highs on Sunday will be in the mid 80s and low 90s, with the hottest temperatures in the SW where clearing will occur the earliest in the day.

The largest weather story will be the feels like temperatures soaring into the 90s and 100s this week. On Sunday, feels like temperatures will be in the 90s to low 100s near Heat Advisory criteria. Dewpoints from this SW flow will be in the upper 70s, meaning this new air mass expected coming in Sunday afternoon will bring very stuffy, oppressive heat and the hottest air of the year thus far. Climatological 850-500mb height values from the latest HREF guidance indicates this high will strengthen and barely move this week, reaching the 95th percentile by midweek. Lows remain warm Sunday night from these elevated dewpoints in the low to mid 70s. Considering this, and the amount of rain KY/south IN has received, there could be isolated areas of fog Sunday morning with mostly clear skies overnight.

If not for Sunday, then Heat Advisories will be needed for Monday and Tuesday as the ridge axis and center of the high comes right overhead. Highs on both days with mostly clear skies will be in the mid 90s with feels like temps ranging 100-110 degrees during the day. This is potentially dangerous heat and warrants those working outside to take longer breaks, drink plenty of water and find ways to cool down when possible. This week is a good time to check on those who may not have AC in their home and check on your neighbors during the day when you can.

=====Wednesday - Weekend=====

Heat Advisories may continue to be issued for Wednesday and Thursday this week but there's a catch. With continued SW flow and the ridge axis just sliding off to the east, there may be enough moisture in the air to form afternoon convection providing some heat relief. Forecast certainty is low for these storms, though spotty coverage of some brief downpours can't be ruled out. Highs will still be warm in the mid 90s with feels like temps still in the 100-110 range.

Into next weekend, the ridge is expected to weaken some, though will remain stationary over the Gulf keeping temperatures warm heading into Independence Day. For now, the forecast for the holiday is hot with highs in the low 90s and a continued chance of spotty afternoon convection.

AVIATION /18Z TAFS THROUGH 00Z MONDAY/

Issued at 231 PM EDT Sat Jun 27 2026

Multiple rounds of showers and thunderstorms continue to move across southern Indiana and central Kentucky Saturday afternoon. Showers and storms that produce heavy downpours could cause reductions in visibility, which was observed recently with the earlier rounds of showers and storms. Lightning will also be possible with these waves, and were included in the TAF as PROB30 groups. While there is currently a slight decrease in activity, this will quickly ramp back up in the next couple hours, lasting into the overnight period. Coverage of showers and storms will finally begin to decrease late Saturday night, though low MVFR ceilings will linger into Sunday morning. There is the potential for IFR cigs Sunday morning, though confidence was too low to include in the TAF. By the end of the TAF period, winds across most terminals will predominantly be out of the southwest at 5-8 kt.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Flood Watch until 8 PM EDT this evening for KYZ030>043-049. Flood Watch through Sunday morning for KYZ023>029-045>048- 053>057-061>067-070>078-081-082. IN...Flood Watch until 8 PM EDT /7 PM CDT/ this evening for INZ076>079-083-084-089>092.