textproduct: Louisville

KEY MESSAGES

* Shower and storm chances (50-70%) return Wednesday night into early Thursday. There is a low risk for severe weather west of I- 65 in Kentucky and localized flooding across areas west of I-75.

* Very slight (15-24%) shower and storm chances linger through Saturday across areas mainly east of the I-75 corridor, but most locations look to stay dry.

SHORT TERM /THROUGH THURSDAY/

Issued at 358 AM EDT Wed Aug 19 2026

Looking across the region this morning, central Kentucky and northern Indiana continues to be under an area of surface high pressure. The surface high is slowly drifting off to the east, allowing relatively light winds to shift to the south. Satellite imagery reveals mostly clear skies across the region, with very patchy fog developing in areas near Lake CUmberland that will dissipate by sunrise. Another feature of interest is the first of multiple disturbances that will move over the region in the next 36 hours, currently trekking eastward over Missouri. This system will slowly dissipate as it moves towards the Ohio Valley later this morning, thanks in part due to very limited instability, wind shear, and low-level moisture. There's a slight chance for a few light showers for places in southern Indiana and west of I-65 in Kentucky, with very little appreciable precipitation expected. Most places across the area will remain dry during the daytime hours on Wednesday, with highs in the low to mid 80s forecast north of I-64, and in the mid to upper 80s for areas south. Mid-level cloud cover will build as the day progresses as this first disturbance moves over the region, with the HREF suggesting some clearing will be possible by the evening hours (~90% cloud cover by midday decreasing to ~25%).

Chances for widespread precipitation will increase Wednesday night as a shortwave trough begins to move over the Ohio Valley. Current HiRes guidance has the feature entering the western counties of the CWA around 12 AM EDT, exiting off to the south and east during the mid-morning hours on Thursday. This features will be accompanied by a modest LLJ (HREF mean 850 mb wind of 30-40 kt) and deep-layer shear (35-45 kt 0-6 km shear), as well as decent PW (1.8-1.9") ahead of the system. Three of the biggest limiting factors though will be decreasing instability as the night progresses (>1000 J/kg mean SBCAPE around 8 PM EDT dropping to <500 J/kg after 12 AM EDT), weaker mid-level lapse rates, as well as limited time for low-level moisture recovery. The Storm Prediction Center has placed a Slight Risk for severe weather in our far southwestern CWA since instability will be somewhat modest as it passes over that area, but chances for strong to severe storms will decrease rapidly as the system moves eastward. Damaging winds and isolated severe hail would be the primary concerns west of I-65. There is a very low-end threat for a tornado to develop, and would likely need better thermodynamics to be realized over our region. Another concern with this system would be heavy downpours resulting in localized flash flooding. The most recent HREF 6 hour LPMM does show a couple swaths of rainfall amounts greater than 2.5", so this will need to be monitored is areas get persistent heavy rain from training thunderstorms especially.

As the bulk of the shortwave departs to the southeast Thursday morning, one last shortwave trough and accompanying frontal boundary will pass over the region during the daytime hours. Chances for rain will be slightly elevated (20-40%) for southern and eastern Kentucky through midday, with slight chances (<35%) of isolated showers to develop ahead of the front as it moves through. Temperatures will be below normal for this time of year, with highs in the low to mid 80s forecast.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/

Issued at 358 AM EDT Wed Aug 19 2026

Once the front departs to the south Thursday night, surface high pressure and dry low-level air will build in over the region, allowing for a mostly calm stretch of weather to close the workweek and start the weekend. Temperatures will remain below normal, with forecasted highs in the mid 80s and lows in the mid to upper 60s Friday morning and in the low to mid 60s Saturday morning. A few slight chances for rain are possible east of I-75, but most places will remain dry during this stretch. The upper trough over the eastern CONUS will dig southward on Saturday, with the trough axis swinging over our region as well. A shortwave will accompany this pattern chance, providing another chance for showers and isolated storms to develop. With fairly dry low-level air in place, chances for appreciable rainfall are fairly low (<20%).

Once the trough axis swings through late Saturday, bringing in reinforced dry air and surface high pressure, the rest of the weekend into the start of the following workweek looks to be dry and mild, continuing the trend for afternoon temperatures in the 80s. The very end of the forecast period is a little uncertain, as the sturdy ridge over the western CONUS becomes less amplified, causing the4 upper trough over us to shift to the east. The spread in deterministic and ensemble solutions does present some uncertainty in precip chances after Monday, though antecedent low-level dry air should keep probabilities low for the rest of the forecast period (<25%).

AVIATION /06Z TAFS THROUGH 12Z THURSDAY/

Issued at 156 AM EDT Wed Aug 19 2026

VFR conditions will prevail through the daytime hours on Wednesday, with building mid-level cloud cover to OVC skies as the day progresses. A few light showers are possible near HNB during the midday hours today, with a Prob30 group included for that timeframe. Otherwise, all other terminals will remain dry into the early evening hours. A broad cluster of showers and storms will begin to enter the region after 03z, impacting SDF, BWG, and HNB through the end of the TAF period. While ceilings should remain VFR, heavier downpours could result in brief reductions in visibility.

LMK WATCHES/WARNINGS/ADVISORIES

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