textproduct: Louisville

KEY MESSAGES

* Showers and bands of storms will continue into the evening hours that bring a Marginal Risk for severe wind gusts and a small chance (2%) of a tornado.

* There continues to be a flash flood threat this evening as some storms could train over the same areas with localized rain totals tonight ranging 2-4+". Rain slowly winds down Saturday afternoon.

* Episodic bouts of showers/storms are expected to continue through the weekend and into the middle of next week. Localized excessive rainfall may result in flooding in some areas.

SHORT TERM /THROUGH SATURDAY/

Issued at 352 PM EDT Fri May 22 2026

Scattered showers are exiting our northern areas moving NE as convective showers and storms are rolling through our southern CWA. Everything is moving NE and will continue to bring heavy downpours along with the Marginal Risk of strong to severe wind gusts, small sized hail, and a small chance of a tornado (2%). A surface low has formed from the influence of a negatively tilted trough axis swinging through the Plains. A warm front associated with this low is near the Ohio River moving north creating the scattered storms across south/central KY. Through the rest of the evening, this surface low will pump in a surge of moisture with PWATs still in the 1.6 - 2.0" inch range. With the aid of dewpoints in the upper 60s to near 70, a southwesterly LLJ, and slightly increased instability, storms will continue to form within the warm sector.

In addition to the severe threat, there remains a flash flooding threat from these storms. A primary band of storms will push northward and begin to pivot near the surface low center trekking in our NW over southern IN later this evening. A weak boundary will form along the Ohio driven by the surface low creating a convergence zone at the surface to help maintain these storms in our western KY and southern IN counties closer to midnight tonight. Depending on the track of these storms and the location of the convergence zone later, a few locations could see repeated rounds of heavy rain. Latest HREF 6hr LPMM data suggests localized areas of 2-4" of rain is possible with these storms, hence the expanded Flood Watch area. We will monitor the progress of these storms and should concerns for localized flooding build, additional flood products will be issued.

The severe threat diminishes quickly just near or after sunset with the loss of daytime instability. The LLJ will remain overnight helping whatever convection is left but will trend towards general storms with rumbles of thunder tonight and sub-severe wind gusts. CAPE values also plummet near sunset as well, further supporting general showers and weak storms tonight. Lows tonight will be mild in the low to mid 60s.

Through the overnight, shower and storm coverage diminishes as the weak front from the surface low pushes to the northeast. Winds shift out of the WSW though PWAT values drop very little with dewpoints remaining in the low 60s. By Saturday morning, spotty showers are expected to drift towards the east along the weak boundary. This boundary will gradually slow and become near stationary, allowing an axis of weak lift with our mositure-rich atmosphere to spawn more showers or additional weak storms across central/eastern locations in our CWA. Highs on Saturday remain mild in the upper 70s. Eventually, rain should end for everyone by Saturday night. Rainfall totals by Saturday night have a 75% chance to be in the 0.75 - 2" range across the area, with locally heavier totals upwards of 4" inches possible with repeated storms that train over the same area.

LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/

Issued at 352 PM EDT Fri May 22 2026

Saturday Night...

The wave of low pressure responsible for our weather in the short term continues to lift northeast into southern Ontario Saturday night. A weakening sfc cold front will stall over the Ohio Valley. We will have another weaker mid-level shortwave trough lift northeast over the Lower Ohio Valley, but a drier overall airmass will lead to relatively drier conditions. Spotty, light rain cannot be ruled out overnight into early Sunday. Lows in the upper 50s and lower 60s should be common.

Sunday - Sunday Night...

A deeper upper level trough is forecast to swing northeast over Ontario and the Great Lakes on Sunday, with another upper level shortwave moving east over Texas. Synoptic scale ascent looks relatively weak over the Ohio Valley, but we will see another influx of moisture streaming northeast from the Lower MS Valley. Only weak low-level convergence is expected along the remnant boundary, but diurnally-driven showers and storms will be possible in the afternoon and evening.

Monday - Thursday...

A closed mid-level low will gradually rotate north from Texas into the central Plains Monday through the middle of next week. A west- east oriented axis of deep moisture pooled along a quasi-stationary boundary will slowly lift north over KY and southern IN Monday into Tuesday. PW values rise from 1.5 inches on Monday to 1.75 inches by Tuesday. Slow-moving, persistent showers and occasional thunderstorm activity will likely eventually lead to isolated flooding issues. Fortunately, the ground can likely soak up most of this weekend's rains in central KY due to drought conditions in recent weeks. We will need to monitor observed rainfall trends through the weekend, which will have an impact on the flooding potential next week.

AVIATION /00Z TAFS THROUGH 06Z SUNDAY/

Issued at 713 PM EDT Fri May 22 2026

Scattered showers are across the region, producing some heavy rain at times and reduced vis. Impacts to flight categories will continue through tonight, with mostly IFR cigs across the region. HNB has the best chance of LIFR cigs overnight and into tomorrow morning. Otherwise, we'll see sfc winds swing around as a sfc low spins through the area. Quite variable directions are to be expected during the period. Rain chances linger into tomorrow morning, with slightly more favorable trend for drier weather tomorrow. Could begin to see some slight improvements to cigs tomorrow as well, though most terminals will remain in at least a MVFR status.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Flood Watch until 5 AM EDT Saturday for KYZ030-031-034-040-048- 057. Flood Watch through Saturday morning for KYZ032-033-035>037- 041>043-049. IN...Flood Watch until 5 AM EDT Saturday for INZ077-078-090>092. Flood Watch through Saturday morning for INZ079.