textproduct: Louisville

KEY MESSAGES

* Rain showers and a few thunderstorms possible Tuesday evening as a weak cold front pushes through.

* Wednesday night and Thursday, a strong low pressure system will bring a chance for strong to severe thunderstorms. The greatest risk for severe storms is expected in southern IN. Heavy rainfall and gusty winds (in and out of thunderstorms) are expected.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 320 PM EDT Mon Jun 15 2026

Tonight, as the surface high pressure pushes east winds will become very light if not calm in some locations. Partially clear skies will allow for radiational cooling, however some mid to low level clouds could linger in the southern part of the CWA limiting the cooling. Minimum temperatures overnight are still expected to be in the mid 50s.

Tomorrow, high temperatures are to warm into the upper 70s with partly cloudy skies during the day. During the afternoon and evening hours, a weak cold front will approach the Ohio Valley from the NW. A line of rain showers and a few thunderstorms will develop ahead of the front and move into the southern IN counties between 20z and 22z. No severe threat is expected as instability is very low and shear is marginal. PWATs will slightly increase with the frontal passage, however showers are still expected to be on the lighter side as drier air holds on in the lower levels. 20-25 mph wind gusts will be possible with daytime mixing.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 320 PM EDT Mon Jun 15 2026

Wednesday - Friday...

An active stretch of weather is expected across the region for the mid-to-late week period as an unseasonably strong upper trough and associated sfc low pressure system will move across the Great Lakes and Midwest Wednesday night into Thursday. At the beginning of the period, an amplified upper wave pattern is expected across North America, with broad troughing across the eastern CONUS and ridging extending from the eastern Pacific across the western one-third of the US. Between these two features, a 120+ kt upper-level jet streak within NW flow will eject across the northern Plains on Wednesday, with sfc cyclogenesis taking place as low pressure moves across the upper Midwest and into the Great Lakes Wednesday night. Ensemble mean MSLP fields suggest that the sfc low over the Great Lakes Wednesday night will be near the minimum of model climatology, with many progs showing a central pressure below 990 mb.

As the sfc low strengthens to the NW of the region during the day on Wednesday, S/SW flow should increase across the area, bringing greater low-level moisture and stronger wind gusts. The daytime hours on Wednesday should be warm and mostly dry, with temperatures expected to warm into the mid 80s. Gusty winds outside of thunderstorms should continue through Wednesday night, and we may be saved from advisory-level wind gusts across much of the area by a strengthening nocturnal BL inversion. Still, widespread wind gusts of 25-35 mph and occasional gusts of 35-45 mph will be possible from Wednesday night into the first half of the day on Thursday.

Wednesday evening into Wednesday night, strong to severe thunderstorms should be ongoing to the north of the area, with storms likely lining up along a trailing sfc cold front across northern MO/central IL/central IN. With the upper-level trough not expected to dig southward much if at all Wednesday night, the sfc cold front will be quite slow in its southward movement, and it will likely take some time for storms to make it into our southern IN counties as a trigger for convection will otherwise be lacking. The current thinking is that storms should arrive in southern IN during the early morning hours on Thursday. By this point, instability will have decreased due to the loss of daytime heating; however, with an 850 mb jet expected to be near the climatological maximum strength (50-55 kt), wind shear is expected to be very strong. The longer that storms take to reach our area Wednesday night into Thursday morning, the lower the overall severe risk will be. Given the strength of the low-level shear and curvature in the hodograph, tornadoes cannot be ruled out; however, would still expect damaging winds to be the primary severe hazard. Hail will also be possible in the strongest storms; however, decreasing instability will likely limit this potential.

During the day on Thursday, the cold front is expected to slowly sag south across Kentucky, with the upper trough now ejecting across the Appalachians and into the northeast US. As the trough ejects out, wind shear should progressively weaken from west to east, so while thunderstorms will again be likely across the area Thursday, the main organized/severe convection threat will be pulling off to the east of the area. A secondary upper cutoff low over the western Gulf will begin to advect more tropical moisture into the TN Valley Thursday afternoon and evening. Depending on the interaction between the quasi-stationary sfc front and the incoming tropical wave, enhanced rainfall totals and a higher flash flooding threat will be possible Thursday into Thursday Night.

The upper cutoff low over the Gulf states is expected to eject across the deep south on Friday, with NW flow aloft expected to push rain chances to the south and east of the area by Friday afternoon. As the sfc cold front finally sinks to the south, cooler, below- normal temperatures are expected on Friday, with highs only expected to reach the mid-to-upper 70s and low 80s.

Friday Night - Sunday Night...

Friday night into the first half of the weekend, NW mid- and upper- level flow is expected across the central CONUS, with upper level ridging gradually moving east from the intermountain west toward the Plains. Surface high pressure and subsidence aloft should combine with lower dewpoints to bring a largely dry stretch of weather from Friday evening through Sunday morning. Both GEFS and EPS ensemble mean temperature anomalies show below normal temperatures are likely for the first half of the weekend, with highs in the upper 70s and low 80s and lows in the upper 50s and low 60s.

By the second half of the weekend, a piece of upper-level energy ejecting across the Rockies will start to erode the ridge over the Plains, with more zonal flow aloft allowing for moisture to increase again into the Ohio Valley. Temperatures should also increase toward climo normals by Sunday into Monday. Rain chances are likewise expected to increase during the second half of the weekend, with the highest rain chances currently favored Sunday night into Monday. While thunderstorms will be possible, it is too soon to say what kind of strong/severe storm risk will exist with this disturbance.

AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 110 PM EDT Mon Jun 15 2026

VFR conditions are expected to continue through the forecast period. Mid level cumulus clouds are currently forming over the area, and are expected to stay VFR. Sites may see FEW050 throughout the night ahead of rain chances tomorrow evening. Winds will go calm for most sites tonight with partly clear skies. Winds will shift to SW by daybreak tomorrow with some low end gusts.

LMK WATCHES/WARNINGS/ADVISORIES

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