textproduct: Louisville

KEY MESSAGES

* Rain showers and a few thunderstorms possible this evening as a weak cold front approaches the area.

* 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.

* Excessive rainfall will be possible across south-central KY on Thursday as the cold front stalls across the region. There is some potential for flash flooding.

SHORT TERM /THROUGH TONIGHT/

Issued at 321 AM EDT Tue Jun 16 2026

Sfc high pressure is set up across the region this morning, which has kept us mostly clear and dry overnight. However, this sfc high will shift off to the east today as a cold front sweeps through the mid-Mississippi Valley today. Ahead of the front, steady southwest winds are expected, along with some afternoon gusts up to 25mph as lapse rates steepen. This will promote a WAA pattern this afternoon, with high temps topping out in the lower 80s. Clouds will increase through the day as the front approaches, and eventually should see a broken line of decaying showers and storms move into our southern IN counties by the mid to late afternoon hours. Low level dry air will help erode this precip line, but still expect to see at least some isolated to scattered showers and storms. Best chances will be along and north of the I-64 corridor in closer proximity to the front, but even an isolated chance will be possible through this evening down to the WK/BG Pkwys.

However, this sfc boundary is expected to get stalled out in the vicinity of the Ohio River and will not make a complete passage through the area today. It will likely lift back to the north as a warm front tomorrow, opening up the warm sector across the region before our next system. As such, temps will be much warmer on Wednesday. A few precip chances will linger beyond 00z tonight across the northern half of the area, but generally expect drier weather after 06z as instability wanes and moisture convergence along the front weakens. Lows for tonight will be slightly more mild south of the boundary with low to mid-60s south of I-64, though to the north of the boundary we could see temps drop into the 50s.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 321 AM EDT Tue Jun 16 2026

===== Wednesday - Friday =====

A strong, deepening low pressure system is expected to cross the Great Lakes on Wednesday, driven by an unseasonably strong upper trough over Canada. HREF and LREF probs indicate this sfc low could deepen below 990mb on Wednesday, which would be significant for June across the Ohio Valley. Based off the ESAT, the ECMWF MSLP is outside the Climate Forecast System Reanalysis (CFSR) across the Great Lakes region. This is considered a significant signal because this indicates that there are no other events in the reanalysis database with a sfc low this deep for mid-June between 1979 and 2009. For our forecast area, this translates to a return interval of less than 1 day every 10 years, so still quite a strong sfc pressure gradient for our area as the sfc low tracks to our north. As a result of this very strong sfc low, other parameters are pushed to the extreme ends of the CFSR in the ECMWF/NAEFS Percentiles. For example, mean integrated vapor transport is maxed out in the ESAT, indicating the ensembles are forecasting an IVT that exceeds the 1979-2009 climatology for this time of year. This also occurs in the ESAT for mean wind speed at the 850 hPa level.

What does this translate to? These signals are growing confidence in seeing very strong moisture advection into the area due to an impressive 50-60 kt LLJ over the area Wednesday evening into Thursday morning. Our PWAT values will likely soar above 2 inches, which would also be among the 99th percentile of climatology. Gusty sfc winds will mix down to the sfc on Wednesday, with gusts up to 30- 35mph possible. The HREF shows high probability (>80%) of wind gusts greater than 30 mph Wednesday afternoon, but lesser chances for greater than 35mph. By Wednesday night, there remains some uncertainty on how strong the nocturnal inversion could be, which plays into if we'll continue to see near advisory level wind gusts later into the night.

Most, if not all, of Wednesday will be dry, with the strong WAA regime helping to boost our temps into the upper 80s by afternoon. The increasing moisture advection will also increase our dewpoints, potentially reaching the low-70s in some areas. By the Wednesday night time frame, we'll see a line of strong to severe storms along a cold front across portions of MO/IL/IN. As mentioned in the prior discussions, this cold front will be slow moving, and likely will not make it to our area until during the early morning hours on Thursday. In terms of overall severe risk this would be good news, as our instability will be at the diurnal minimum. However, given the impressive strength of the LLJ, very strong shear will still be present, leading to large curved hodographs, SRH over 300 in the lower kilometers, and the risk of tornadoes. The greater risk area is across southern IN, with potential falling off as the line of storms moves southeast through the forecast area. As such, SPC maintains a Slight Risk across our far northern CWA, and a Marginal Risk primarily along and north of the WK/BG Pkwys in the D2 Outlook.

The focus then turns to Thursday with the risk for training convection along the very slow moving cold front. With such a high PWAT regime in place, there is a risk for excessive rainfall and potential flash flooding concerns mainly across south-central KY. These areas are still dealing with moderate to severe drought, so there remains some uncertainty on how much rainfall will be needed for hydro issues to arise. Main severe threat will be east of our area during the day, but a secondary mid-level disturbance will eject off the Gulf Coast and provide an additional surge of moisture into the TN Valley. Depending on the interaction between the quasi- stationary sfc front and the Gulf Coast disturbance, enhanced rainfall totals and a higher flash flooding threat will be possible Thursday into Thursday Night.

===== Friday into the Weekend =====

The sluggish sfc boundary will eventually exit by Friday morning, with lingering PoPs shifting out of the area by the afternoon. Upper ridging will be moving across the country, with sfc high pressure building to our west. This will support drier weather for the remainder of Friday and for Saturday.

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 /12Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 649 AM EDT Tue Jun 16 2026

VFR weather continues today, though mid-level clouds will increase ahead of an approaching weak cold front later this afternoon. Winds will primarily be from the SW today, with some afternoon gusts up to 20kts possible. Not all terminals will see precip today, with SDF, HNB, and LEX having the best chance. Otherwise, VFR continues tonight though with drier weather.

LMK WATCHES/WARNINGS/ADVISORIES

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