textproduct: Louisville

KEY MESSAGES

* Drier weather expected this evening and tonight, though scattered showers will remain possible in the Lake Cumberland and Bluegrass regions this evening.

* Scattered showers and thunderstorms are possible on Sunday, with storms most likely during the afternoon and evening hours. Storms may produce locally heavy downpours, lightning, and gusty winds.

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

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 320 PM EDT Sat May 23 2026

Weakening sfc low pressure is now approaching Lake Erie this afternoon, with a stalling cold front draped southwest through central KY. The lead mid-level shortwave trough will continue to lift northeast into southern Canada this evening. Additional smaller scale disturbances will rotate northeast on the southern periphery of a deeper upper level trough that will lift ENE over the Upper Midwest and Great Lakes through Sunday. Locally, we'll see drier air aloft continue to advect in from the west this evening, helping to slowly dry things out from west to east. With the stalled, weak sfc boundary and deeper moisture still in place, scattered light to moderate showers will remain possible across south-central KY and up the I-75 corridor through this evening. A few thunderstorms will also be possible across the Lake Cumberland region, where instability is currently highest (~1000 J/kg MLCAPE). Brief torrential downpours will be possible in this area.

Low stratus has started to SCT out with deeper mixing, especially across south-central KY. This will allow temperatures to briefly top out in the mid 70s to near 80 this afternoon. This brief clearing trend should continue through early tonight, before additional cloud cover begins to spread in from the south early Sunday. With favorable low-level moisture and very light winds, the setup appears favorable for at least patchy fog overnight. Increasing clouds 06- 12Z Sunday will limit the overall fog potential, but we could certainly see some patchy dense fog tonight. Lows tonight will be in the upper 50s to lower 60s.

For Sunday, an upper level trough develops east across Texas with multiple smaller scale shortwave disturbances streaming northeast over the Ozarks, MS Valley, and Lower OH Valley. Deep SW flow will advect a plume of moisture from the Lower MS Valley northeast over the OH Valley, with PW values again climbing to 1.6-1.7 inches. Overall forcing for ascent is modest, but it appears scattered showers may lift north over the area during the morning hours. Modest destabilization appears likely, but thickening clouds and SCT precip will limit sfc heating. MLCAPE of 500-1000 J/kg seems reasonable, which would be enough for scattered convection in the afternoon and evening. Another weak sfc boundary will drift in from the northwest during the afternoon and evening hours, which should boost low-level convergence slightly. Weak SW flow aloft will limit deep-layer shear (25 kt), so organized severe convection is not expected. Stronger storms will be capable of locally heavy downpours, lightning, and gusty winds, however.

Temperatures will warm into the upper 70s and lower 80s Sunday afternoon. Shower and storm chances will gradually wane after sunset, with temperatures dropping back into the lower 60s early Monday.

LONG TERM /MONDAY THROUGH SATURDAY/

Issued at 320 PM EDT Sat May 23 2026

For much of the upcoming week, a fairly summer-like pattern is expected across North America with weak mid- and upper-level flow as the upper jet flexes northward into Canada. During the first half of the week, much of the weather conditions across the Ohio Valley will be associated with a cutoff low meandering over the southern Plains and lower Mississippi Valley. While this low is not expected to be particularly deep, cyclonic southerly flow on the east side of the low should bring a robust fetch of Gulf moisture into the region, with PWAT values rising from south to north on Monday. The richest moisture is expected to be in place from Tuesday into Wednesday, with LREF ensemble mean PWATs exceeding the 99th percentile of model climatology, around 1.8" over the area.

With the tropical setup in place across the Ohio Valley, daily chances for rain are in place for much of the week, with the highest PoPs expected when the richest moisture is in place Tuesday into Wednesday. Given weak forcing, precipitation coverage should vary with daytime heating patterns, with the greatest coverage in the afternoon and evening hours before tapering off during the late evening and overnight. A glance at sounding profiles does suggest that there may be enough instability for isolated storms, though coverage of storms should only be around 20-30% for much of the week. In general, deep warm cloud depths and "tall, skinny" CAPE profiles should support efficient rain-making in precipitation cores this week, further aided by the abnormally high PWATs. This deep moist profile and weak deep-layer shear (less than 15 kt for much of the week) suggests primarily garden-variety convection with a low severe weather risk.

By the latter half of the week (Thursday into Friday), a pattern shift is possible as an upper low over eastern Canada may try to retrograde back to the SW, with a shortwave trough swinging through the northeast US. At the same time, heights should build over central Canada, setting up an omega block by the end of the week. The question for our weather across KY and IN is how much the above- mentioned trough can dig back to the SW, allowing for sfc high pressure and cooler/drier air to filter in behind a backdoor cold front Thursday night into Friday. In general, ensembles do show some evidence for this occurring, as mean PWATs lower considerably from the north by Friday. On the other hand, LREF 500 mb height spread is very high on the western/southwestern flank of the low, and forecast uncertainty from Friday into next weekend remains medium-to-high.

The main impact from this week's weather pattern should be continued amelioration of drought across Kentucky. Ensemble most likely rainfall amounts of 1-3" are expected across the area through Friday, with convection likely leading to localized swaths well in excess of 3". Flooding will become a greater concern, especially in those aforementioned convective swaths and across southern IN where the antecedent conditions are not dry. Otherwise, fairly seasonable temperatures are expected, with highs in the mid-to-upper 70s and low 80s and lows in the 60s.

AVIATION /00Z TAFS THROUGH 06Z MONDAY/

Issued at 740 PM EDT Sat May 23 2026

Mainly VFR conditions are across the area, with some isolated slow- moving showers. Clouds will increase through the overnight as another wave of deeper moisture moves into the region, leading to cigs dropping to MVFR by tomorrow morning. We'll also see increasing rain chances throughout the morning, with a lower chance for some storms through the afternoon. Generally MVFR cigs are expected through most of the period.

LMK WATCHES/WARNINGS/ADVISORIES

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