textproduct: Louisville

KEY MESSAGES

* Mainly dry and unseasonably warm starting today through the end of the week with temperatures 5 to 10 degrees above normal (upper 70s to low 80s)

* The best chances for showers and storms will come Friday through early Saturday. Another strong storm system could impact the area on Monday where a strong storm threat may develop.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 255 PM EDT Tue Apr 21 2026

Surface high pressure has kept skies mostly clear today and allowed temperatures to get into the mid 70s as a warm front moves through the area. Tonight, a low level jet will move over the area from the west causing some LLWS for aviation purposes. Light surface winds and clear skies tonight will allow sufficient nighttime cooling and drop temperatures into the mid to lower 50s.

A weak frontal boundary pushing eastward through north central Indiana into southern Ohio could trigger some scattered rain showers down to the I-64 corridor tomorrow morning. However, there is low confidence in these showers making it to the CWA due to the dry airmass in place. Otherwise, the warm temperatures continue with max Ts nearing 80 degrees.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/

Issued at 255 PM EDT Tue Apr 21 2026

Wednesday Night - Thursday Night...

Upper ridge axis builds over the area through mid to late week, and this will continue to keep us dry. Temperatures should be well above normal on Thursday with values mostly in the low 80s thanks to mostly sunny skies and light southerly winds. Overnight lows will also be mild, with mid 50s Wednesday night, and upper 50s to low 60s for Thursday night.

Friday - Sunday Night...

Friday morning likely starts out dry, however the focus will be upstream where a complex of showers and storms is expected to survive into our area ahead of an ejecting shortwave trough. Do expect a weakening trend as this complex approaches our area for a couple of reasons. 1.) We'll have an antecedent dry airmass in place, and the subsident upper ridge axis will only slowly be retreating. 2.) The overall trend with this system has been a bit faster, which would put arrival into the Friday morning hours across the area. Not a lot of time to re-destabilize in that scenario. All of that said, this complex could have a decent could pool pushing it into our area, and given the dry low level airmass do expect that our environment would be favorable to support some continued gusts into the region.

Our upper pattern flattens out to a zonal flow by Friday night, with a potential second shortwave ejecting out from the southern Plains. This feature may trigger a secondary batch of showers and storms across the area Friday night into Saturday. Given the overall faster trend of this system, it appears we may dry out by later Saturday.

Brief upper ridging once again builds in from later Saturday through Sunday night, where another dry stretch of weather is expected. Temperatures should continue to track just above normal in the 75 to 80 degree range for most.

Monday - Tuesday...

Monday continues to have an interesting look to it as shortwave energy ejects across the central Plains, and an associated (likely sub 1000 mb) surface low moves through the upper Midwest. From a pure pattern recognition standpoint, it does look like this could be a favorable setup for supercells 21/00z ECMWF upper wind field show exit region dynamics overspreading a developing warm sector in the Ohio River Valley region. Low to mid level speed shear also appears to be enhanced by a healthy 40-50 knot low level jet responding beneath the favorable exit region dynamics mentioned above. Exact timing is still in question, and there is a scenario where onset occurs a little too early and perhaps we don't get to destabilize. Nevertheless, the setup looks ominous, and there does seem to be some support from the SPC Day 7 Outlook, NSSL ML Severe probabilities in the 15-30% range, and the latest AI model suite trends showing an uptick in potential from yesterday. Right now, just keeping an eye on this day, but early on several boxes are being checked for a potential strong/severe storm type of a day.

For now, Tuesday looks dry and would be back in the post-frontal regime. Much of this does depend on the timing of the Monday system, so not too terribly confident just yet.

AVIATION /18Z TAFS THROUGH 00Z THURSDAY/

Issued at 107 PM EDT Tue Apr 21 2026

Currently, mostly clear skies across the area with 10-15kt SW winds. Stronger gusts have recently backed off on the latest obs. A low level jet will approach the area tonight causing LLWS at HNB/SDF/LEX/RGA with values near 40kts at 20kft. After a high cirrus deck moves through this evening, skies will clear again for tomorrow. Sites were kept dry however, there is a low probability of HNB/SDF/LEX seeing isolated rain showers tomorrow morning.

LMK WATCHES/WARNINGS/ADVISORIES

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