textproduct: Louisville

KEY MESSAGES

* Well-above normal temperatures continue throughout the upcoming week. A few temperature records may be in jeopardy tomorrow.

* Dry weather is likely to continue today and tonight (~90% confidence). The next chance for rainfall is expected Thursday, with some strong storms possible in the afternoon and evening.

* A stronger cold front will bring a chance for showers and storms again on Saturday. Another low-end threat for strong storms exists with this system.

SHORT TERM /THROUGH TONIGHT/

Issued at 349 AM EDT Wed Apr 15 2026

Mild conditions continue across southern IN and central KY this morning with temperatures in the upper 60s and low 70s as of 07Z. Scattered high clouds continue to stream across the region, with these clouds spreading east from overnight convection across the southern Plains. No significant weather is expected through sunrise, with mild temperatures and light S/SW breezes continuing across the area.

Today's forecast is pretty similar to the last few days as southeast US upper ridging and broad SW flow across the Plains and Midwest continues. Within this belt of SW flow, an unseasonably warm and unstable air mass will again be present just to the north and west of our area, with waves of strong to severe storms expected to continue this afternoon and evening. HREF paintball plots of reflectivity greater than 30 dBZ shows the vast majority of the convective activity remaining along and north of I-70 today, though there is a 10-15% chance that a stray storm could approach our northern row of IN counties later today. Otherwise, the main story today will be the continuation of well-above normal temperatures, with highs expected to reach the low-to-mid 80s this afternoon. SW winds of 10-15 mph with gusts of 20-30 mph are expected again today, along with a scattered stratocumulus field in addition to the high clouds.

An upper-level shortwave will begin to erode the southeast ridge tonight, with the greatest height falls across the Ohio Valley not expected until early Thursday morning. As a result, showers and thunderstorms should begin to push closer to the area after midnight, though it's unlikely that most of this activity will reach our western counties until the pre-dawn hours on Thursday. For most of tonight, expect another mild night with temperatures falling through the 70s into the 60s with light S/SW winds.

As convection approaches our area Thursday morning, it is expected to outrun the best instability axis. As a result, showers and storms should be weakening as they move across SW IN/W KY, and there's only a ~15% chance of thunder by the time activity reaches our western counties. After sunrise Thursday, rain showers should continue to weaken as they approach the I-65 corridor, with increasing clouds expected with this wave of showers. How long these clouds can remain over the area will determine the extent of the strong/severe storm threat Thursday, as lingering clouds could limit the amount of instability available for storms Thursday afternoon and evening. 0Z HREF progs show an axis of 1000-1500 J/kg MLCAPE nosing in from the southwest as sfc dewpoints should be in the upper 50s and low-to-mid 60s. 45-50 kt 500 mb flow should allow for roughly 40 kt of effective bulk shear, so organized multicells and perhaps a few bowing segments would be possible. The main severe hazard tomorrow afternoon should be damaging wind gusts, though if any of the higher- end instability progs verifies, severe hail would also be possible. The window for strong to severe storms should be between roughly 4 PM and 10 PM, with instability decreasing after sunset Thursday.

Once showers and storms dissipate Thursday night, clearing skies and light winds are expected through Friday morning. Any areas which receive rainfall could see patchy fog develop Friday morning. Low temperatures should fall into the upper 50s and low-to-mid 60s.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 349 AM EDT Wed Apr 15 2026

Friday and Friday Night...

Another upper trough ejecting across the Rockies and into the Plains during the day on Friday will cause ridging to flex northward into the Ohio Valley, though this episode of the southeast US ridging should be short-lived. Southwest flow should increase during the day on Friday, with another day of near-record temperatures expected as highs should reach the low-to-mid 80s. Upper ridging should be strong enough to keep most areas dry Friday into Friday evening, with waves of strong to severe convection again passing to the NW of the region. There is still a modest signal that a few showers could develop as the LLJ intensifies and pushes into the area Friday night, with the best chances for rain through Saturday morning expected west of I-65.

Saturday and Saturday Night...

Upper troughing over the Plains is expected to amplify as it crosses the Mississippi Valley on Sunday, with the trough expected to remain fairly open/positively-tilted as it approaches the Ohio Valley. The sfc low associated with this upper wave is expected to be over central Ontario by Saturday afternoon, with an extensive cold front stretching to the south-southwest into the Mississippi Valley. Ahead of the front, S/SW winds should allow for another warm day on Saturday, with sustained winds of 10-15 mph and gusts of 20-30 mph expected. Temperatures are expected to reach the upper 70s and low 80s Saturday afternoon, with increasing clouds and showers/storms limiting heating, especially west of I-65.

Uncertainty with how much destabilization will occur is again a limiting factor for the severe storm potential Saturday into Saturday evening. Current LREF 50th percentile SBCAPE values range from 400-800 J/kg across the area, with high-end (90th percentile) values around 1000-1400 J/kg. This will be sufficient for strong storms given the strong forcing along the front and ~40 kt of effective bulk shear; however, if there is more early-day showers and cloud cover, the overall threat would be reduced. Model soundings show fairly unidirectional shear profiles ahead of the front, and linear convective modes would be the most likely. As a result, continue to think that damaging winds would be the main threat with any strong storms. In the 0Z guidance, timing has remained fairly consistent, with the best chances for storms crossing the area between the early afternoon and just after sunset Saturday. By the late evening hours Saturday, winds are expected to veer to the W/NW, with temperatures tumbling into the 40s Sunday morning. Showers may linger across east central and southeast KY into the pre-dawn hours Sunday, with rapid clearing taking place to the NW.

Sunday into Early Next Week...

Seasonably cool and dry weather is expected for Sunday and Monday as the synoptic pattern remains progressive and upper troughing quickly crosses the region. Sfc high pressure should move over the area Sunday night into Monday morning, with this likely being the coolest morning over the next 7 days. There are 40-50% chances for low temperatures that would be support frost (<= 37F) Monday morning, so that's something we'll have to monitor in the otherwise quiet pattern. A warming trend is expected as we head toward the middle of next week, with NW flow keeping conditions dry through next Tuesday.

AVIATION /06Z TAFS THROUGH 12Z THURSDAY/

Issued at 127 AM EDT Wed Apr 15 2026

VFR conditions and south-southwest winds around 6-12 kt are expected through mid-morning, with occasional 15-20 kt gusts possible. As previous discussions have mentioned, there should be some marginal LLWS over the next few hours as a 40-45 kt LLJ resides just to the north of HNB and SDF. A fairly similar setup to the last few days is expected today, with winds and wind gusts increasing between 13-15Z as daytime heating begins. Expect sustained winds generally between 10-15 kt, with gusts of 20-25 kt likely. A SCT-BKN stratocu field should develop again today, with cloud bases between 5-7k ft. This evening, wind gusts should ease around sunset, with S/SW winds around 6-12 kt expected again tonight.

LMK WATCHES/WARNINGS/ADVISORIES

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