textproduct: Louisville

KEY MESSAGES

* This evening and tonight, strong to severe thunderstorms are possible, with the SPC putting us under a Slight Risk for severe weather. Damaging winds and isolated hail are the primary concerns.

* Temperatures are expected to warm into the mid 80s to low 90s for Sunday and into the beginning of next week. Some daily max temperature records could be challenged. * Tuesday and Wednesday, more showers and thunderstorms ahead of a cold front, dropping temperatures back to near normal for later this week.

MESOSCALE

Issued at 857 PM EDT Sat May 16 2026

Severe Thunderstorm Watch 208 was cancelled due to the atmosphere becoming more stable greatly reducing the threat of any additional severe threat. An area of convection that came out of southern IL into southern IN diminished rapidly as it worked eastward towards our CWA. Also went ahead and updated grids to update and reduce the forecast PoP grids especially as you work farther south.

Issued at 509 PM EDT Sat May 16 2026

Severe Thunderstorm Watch 208 has been issued until 1100PM EDT/1000PM CDT for all of our southern IN counties to as far south as Hancock, Breckinridge, Hardin, Nelson counties in KY and as far east as Trimble, Henry, Franklin, Henry and Trimble counties in north central KY. After the first round of storms from earlier today the atmosphere was able to destabilize quickly as we are well within the warm sector. Dew points are in the mid/upper 60s with in the watch. An MCV continues to move into the area with the bulk of the current convection taking place across southern IN into central IN. While we have good instability, steep low to mid-level lapse rates, overall shear profile seems a bit lacking. With this in mind we continue to see hail and gusty damaging winds as the main threats.

SHORT TERM /THROUGH TONIGHT/

Issued at 355 PM EDT Sat May 16 2026

Clearing skies across the area following this morning's showers and thunderstorms has allowed temperatures to rapidly climb into the upper 70s/low 80s. Temperatures will continue to grow into the low- to-mid 80s over the next few hours before a mid-level disturbance and a MCS moves through the area this evening. With robust southerly flow in place, dew point values have also rapidly rose into the mid- 60s, allowing for ample moisture as we prepare for another round of potentially strong-to-severe thunderstorms this evening.

Instability overall has quickly rose over the past few hours, with SBCAPE values ranging from 1500 to 2000 J/kg currently, and MLCAPE and MUCAPE values in the 1500-2500 J/kg range. With the strong diurnal heating, recent model guidance has us mixing up to near the 750 mb level, with fairly steep low-level lapse rates also present. As a result, this has also help increase our DCAPE values to over 700 J/kg, increasing as you go further south. An area of more robust bulk shear (>30 kt) has developed in SW Kentucky and will shift northeastward in the coming hours, helping set up our next round of showers and storms.

With our cloud bases from this morning and afternoon remaining fairly elevated, our main concerns for this upcoming round will mostly be damaging winds and isolated severe hail. The cells over time may form into a bowing/linear segment over time depending on the evolution of the system, which would then quickly transition our threat to mostly severe winds. With the wind shear that would be in place, a brief spin up tornado cannot be ruled out, but is very unlikely given the higher cloud bases/LCLs in place. This system will slowly move off the northeast during the overnight hours, exiting by Sunday morning. While near-surface capping will quickly develop after sunset as a result of an intensifying LLJ and the loss of diurnal heating, elevated instability will remain in place and allow the storng-to-severe threat to continue into the night for any storms that persist.

LONG TERM /MONDAY THROUGH SATURDAY/

Issued at 355 PM EDT Sat May 16 2026

Sunday - Monday...

Once the system departs to the east early Sunday, conditions for the next couple of days are going to be dry and very warm. With the ridge over the eastern CONUS becoming more amplified and the center of the surface high residing over the Atlantic, persistent southerly flow will allow ample WAA to move over the region. Temperatures will be in the upper 80s both days, with some locations getting above 90. LREF guidance gives most areas south of the Ohio River a 35-50% chance of reaching 90 on Sunday, with probabilities increasing to 40- 55% on Monday. Dew points both days will be in the low-to-mid 60s, so expect rather muggy conditions. A few weak perturbations may pass over the far western portions of the CWA, providing a quick shower or storm, though chances right now are currently low (10-20%).

Monday Night - Wednesday Night...

Off to the west, a robust shortwave trough ejects from the central Plains towards the Upper Midwest. The cold front from its associated surface low trails to the south and west, slowly moving towards the Ohio Valley and arriving late Tuesday. With southerly flow continuing ahead of the front, temperatures during the afternoon will again be very warm, with highs in the upper 80s/near 90. Once the front moves in, more widespread showers and scattered thunderstorms will continue through late Wednesday as the front slowly drifts southward. With the front overhead on Wednesday, a semi-decent temperature gradient will be in place, with southern Indiana in the upper 70s and south central Kentucky in the upper 80s.

Thursday - Saturday...

Rain chances will slowly decrease as the front departs to the south, and broad northerly flow will allow afternoon temperatures to be closer to normal for this time of year with highs in the mid 70s. The reprieve from drier conditions does not last long as a shortwave trough develops over the southern Plains and ejects to the northeast. This will help the previously mentioned frontal boundary lift back northward and set us up for another round of showers and occasional storms that would last until the end of the forecast period. Long-range guidance is not as certain on how far northward the front will lift given the preceding surface high pressure over our area to the north of the front. Temperatures each of the three days will be in the mid-to-upper 70s, with some places approaching 80 on Saturday.

AVIATION /06Z TAFS THROUGH 12Z MONDAY/

Issued at 156 AM EDT Sun May 17 2026

A much quieter period is expected with VFR conditions lasting through the forecast period. Skies will become mostly clear in the coming hours as winds remain out of the south.

LMK WATCHES/WARNINGS/ADVISORIES

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