textproduct: Louisville

KEY MESSAGES

* Above normal temperatures expected Thursday.

* Gradient wind gusts of 35-40 mph are expected on Thursday ahead of a strong cold front. Widespread showers and a few thunderstorms will be possible. The risk of a stronger storm or two looks limited.

* Quick shot of colder air will arrive late Thursday behind the front and continue into Friday. Temperatures will then trend warmer through the weekend and into next week.

UPDATE

Issued at 939 PM EST Wed Dec 17 2025

Regional radars showing some shower activity down in the Lake Cumberland region of south-central Kentucky. This activity will continue to trek on northeastward this evening. Have updated to forecast to put in some PoPs down that way. Otherwise, remainder of the forecast appears to be in good shape. Went ahead and did a quick refresh of the other weather elements to bring them in line with current obs. Updated products will be available shortly.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 419 PM EST Wed Dec 17 2025

Currently, mostly zonal flow is in place overhead with surface high pressure sitting to our southeast. To the west, a small upper trough in the zonal flow has developed with a surface low near the Alberta/Montana border. The resulting pressure gradient over the Lower Ohio Valley has driven warm air advection by generally southern gusty winds. High temperatures have overachieved, pushing into the low to mid 50s.

Tonight, the aforementioned upper trough will continue to strengthen as it pushes towards the Midwest, developing into a closed low. The system's surface low will track towards the western Great Lakes, dragging its cold front towards east towards the Missouri Ozarks. The increasing pressure gradient will cause winds to increase overnight from around 5-10 mph early in the night to 10-20 mph Thursday morning. Cloud cover is also expected to increase during the night as the front approaches. These things should limit falling temperatures in most places to the low to mid 40s.

Tomorrow, ahead of the approaching front, very strong isentropic lift will begin moving into the CWA from the west around 12z with rain chances expected to begin shortly after. This will be driven by a strong low level jet with winds reaching around 50-65 knots with the higher values over southern Indiana and northern Kentucky, but the heaviest rain arrives during the afternoon and evening hours closer to the front and its extra forcing. Rain will come to an end around 02z in Dubois County, IN to around 06z Thursday night in the far eastern Bluegrass and Lake Cumberland area counties.

Model soundings show very impressive deep layer shear with 0-6km shear in the 50-70+ knot range with 50-60 knot winds only 2-3,000 feet off the ground, but with low level inversions in place for most of the day. Some of this wind could have trouble reaching the ground. This is expected to limit gusty winds to 35-40 mph. A gust over 40 mph isn't out of the question, but currently leaning just short of 40 mph for most places.

With the front not arriving until near sunset, WAA is expected to lift high temperatures during the day into the mid to upper 50s, but behind the front with CAA, temperatures dive into the 20s by Friday morning. Any remaining water should be expected to freeze, but with winds staying elevated behind the rain and before freezing temperatures arrive, most surfaces should see a decent amount of drying.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 419 PM EST Wed Dec 17 2025

Friday, the axis of the upper trough continues to move east away from the CWA as surface high pressure, behind the front, slides from east Texas towards the Tennessee Valley. This keeps CAA in place through the day, limiting highs to the low 30s to low 40s, but as the high passes east of the region Friday night, WAA returns to the region. After a cool night Friday night with lows in the 20s, temperatures rebound into the 50s under mostly sunny skies for Saturday.

Saturday night, as a low pressure system passes east, north of the Great Lakes, its trailing cold front pushes southeast through the Lower Ohio Valley. This front will separate two surface high pressure centers. It will likely only bring some passing cloud cover the the region and more CAA. Sunday's highs get limited to the 40s to near 50.

Zonal flow will push the surface high over the Midwest east across Indiana, bringing WAA back to the CAA. Highs return to the 50s and maybe a few 60s across southern Kentucky by Tuesday and Wednesday. Some additional chances of light precipitation are possible during this time, but there remains a lot of uncertainty in the guidance.

AVIATION /00Z TAFS THROUGH 06Z FRIDAY/

Issued at 627 PM EST Wed Dec 17 2025

We are dry and VFR this evening, but we'll see our next round of rain chances during this forecast period as a strong cold front approaches the region. Ahead of any rain, LLJ will strengthen out ahead of the front, causing LLWS to ramp up during the overnight hours. Rain and lowering cigs will move into the area as the LLWS phases out tomorrow, leading to flight cats to drop to MVFR progressively from west to east throughout the early afternoon. Gusty sfc winds will accompany the rain showers, with gusts up to 30ks possible from the south. HNB has the best chance of dropping into IFR with the frontal boundary passing through by the end of the period. Impacts to flight ops are expected to continue through the end of the forecast period, except for SDF, where they will return to VFR in the extended time frame.

LMK WATCHES/WARNINGS/ADVISORIES

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