textproduct: Louisville

KEY MESSAGES

* A line of strong to severe storms is expected to develop ahead of an approaching cold front today. These storms may bring strong gusty winds and marginally severe hail in areas generally west of I-65.

* More active weather arrive later this week as multiple rounds of showers and scattered thunderstorms are possible going into Memorial Day weekend and into early next week.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 323 AM EDT Tue May 19 2026

Area radars show that earlier convection continues to diminish across the region. In its wake, partly to mostly cloudy skies were noted across the region. Temperatures were generally in the upper 60s to the lower 70s. A few mid 70s were noted down in far southern Kentucky. For the remainder of the overnight period, generally quiet weather is expected. We could see a few light rain showers transverse southern Kentucky over the next few hours. Overnight lows will be in the upper 60s to the lower 70s.

For today, the upper level pattern will start off in a trough in the western CONUS with a ridge centered off the southeast coast. From the southern Plains through the Ohio Valley, a broad southwest flow will be seen. Within this broad southwest flow, a shortwave trough axis and associated 75-85kt h5 jet streak will move into the upper Midwest/western Great Lakes. A surface low will move into southern Ontario with a stretched out cold front extending southwestward through the Mid-MS Valley.

Ahead of this front, warm advection within the broad southwest flow combined with partly sunny skies will allow surface temperatures to warm into the upper 80s with a few spots touching 90 again. It will fell humid out there today as dewpoints will remain in the mid-upper 60s. This combination of temps and dewpoints will allow surface based instability to develop with SBCAPE values rising into the 2500- 3000 J/kg range. While instability will be plentiful for strong/severe convection, environmental wind fields are not impressive as bulk shear values will remain in the 20-25kt range with higher values off to our west. Enough instability and shear will be available to generate organized convection along the cold front. Based on model soundings and the instability/shear profile, the forecast soundings support mainly multicellular convection that may be able to grow upscale into small linear segments capable of producing damaging winds.

Convection looks to move into our western areas later this afternoon/evening. However, the storms are likely to outrun the instability/shear axis out to the west and weaken as they cross the I-65 corridor and head into the Bluegrass region. The highest risk of severe will be generally west of the I-65 corridor where damaging wind gusts look to be the main threat. Some isolated marginally severe hail may occur in some of the stronger cores early in the convective cycle. However, the severe threat will rapidly diminish after sunset with the loss of heating and the better synoptic forcing remain well displace from our region. The surface cold front will push into the region overnight and slowly stall out. While there will be some diminishing of convective coverage overnight, at least scattered shower/storms will linger into the early part of the overnight hours. Lows are expected to drop back into the mid-upper 60s.

For Wednesday, surface frontal boundary will remain in the vicinity throughout the day providing a focus for renewed convective development. Overall convective coverage may be slightly higher across our eastern areas. Model soundings again show marginal instability (likely limited by ongoing cloud cover) and weak shear. Gusty winds and marginally severe hail could occur in some of the stronger cores. However, greater instability and better lapse rates will be found to our east across the Mid-Atlantic region. Highs on Wednesday will be cooler with temps remaining in the mid-upper 70s west of I-65 with upper 70s/lower 80s east of I-65. Lingering convection will be possible into the early part of Wednesday night before diminishing. Lows will be in the upper 50s to the lower 60s.

LONG TERM /THURSDAY THROUGH MONDAY/

Issued at 323 AM EDT Tue May 19 2026

For the long term period, it appears that the aforementioned cold front from the short term period will gradually sink to the south for the LMK CWA and yield a slightly drier pattern for Thursday. Blended PoPs look too high here and are probably being help up by the spatial differences in the model fields. Best chances of any shower/storm activity would be across southern and southeastern KY. Highs will be cooler here with readings in the lower-mid 70s. Lows Thursday night will drop back into the upper 50s to the lower 60s.

Looking into the upcoming Memorial Day weekend, stalled out frontal boundary to the south looks to lift northward on Friday. An approaching mid-level perturbation within an increasing southwesterly flow pattern will lead widespread showers and storms across the region for Friday. Overall risk of severe looks fairly marginal here given poor low-mid level lapse rates and weak shear. Highs on Friday look to warm into the upper 70s and the lower 80s. Overnight lows will be will be in the mid-upper 60s.

Moving into the Sat-Mon period, a southwest flow pattern will remain in place across the Ohio Valley with multiple perturbations moving through within the mean flow aloft. This will lead to episodic bouts of showers and storms through the period. Afternoon highs will likely top out in the upper 70s to the lower 80s with overnight lows in the mid-upper 60s. Given the rather moist airmass that is expected to be in place this weekend, bouts of heavy rainfall will be possible. Total rainfall amounts over the next 7 days across the region will vary, but a swath of 3-4 inch rainfall with locally higher amounts look possible. This rainfall will be beneficial given the recent dryness across the region.

AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 625 AM EDT Tue May 19 2026

VFR conditions will be seen at the terminals this morning. Winds have already shifted to the southeast and will veer a little more to the southwest after sunrise. Look for winds to come up this morning and become gusty through the afternoon. Sustained winds of 12-15kt with gusts of 20-24kts will be possible through the afternoon hours.

Cold front out to the west of the region will be on approach this afternoon. Convection is forecast to develop out ahead of this feature. Timing among the latest CAM guidance is starting to tighten up a little bit, but overall confidence in timing is still below normal here. For now, plan to introduce TSRA at HNB/SDF after 19/22Z and then over into LEX after 20/00Z. Coverage down south is questionable and for now have left PROB30 in at BWG, but current thinking is that if guidance continues to tighten up, we probably can run TSRA at BWG between 19/22-20/02Z or so.

LMK WATCHES/WARNINGS/ADVISORIES

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