textproduct: Louisville

KEY MESSAGES

* Milder temperatures and intermittent light rain chances are expected during much of the upcoming week.

* Unseasonably warm temperatures are likely around Christmas, with temperatures expected to be 15-20 degrees above normal.

* Mild weather continues into the first part of the weekend, but will gradually trend cooler by Sunday with a series of reinforcing cold fronts. There is low, but increasing potential for a stronger system Saturday night into Sunday that could bring strong to severe storms.

UPDATE

Issued at 833 PM EST Mon Dec 22 2025

A 40-50 knot low level jet really ramps up over the next 4-5 hours across the area. The isentropic lift created by this feature will allow for increasing coverage of light rain through that time, and then coverage will persist through dawn. From there, coverage slowly sinks south and eastward across KY on Tuesday as the low level jet core steadily lets go of the area. Although fairly decent coverage of at least some measurable rain is expected, amounts will be light and less than a tenth of an inch. Some locations across our far SE are most likely to stay dry or only see a trace through tonight. However, they will have better chances through tomorrow. Look for mild overnight lows in the 45 to 50 degree range for most.

SHORT TERM /THROUGH TUESDAY/

Issued at 320 PM EST Mon Dec 22 2025

Clouds have built back across the region this afternoon, but we have managed to warm into the upper 40s and low 50s thanks to a warm air advection regime. Regional VAD Wind Profiles, combined with SPC Mesoanalysis, show there being a southwesterly 35kt LLJ in the 850mb layer, which is located in the vicinity of a subtle sfc boundary. Sfc high pressure over Chesapeake Bay today also adds to the warm return flow.

Low level moisture transport is just now starting to creep into southern KY, and expect that to continue to strengthen over the next 6-12 hours as the LLJ continues to strengthen and isentropic upglide increases. By 06z tonight, the LLJ is expected to be around 45kts in the 850mb layer, with our moisture transport vectors maximized. This will lead to our PWATs to ramp up to around 0.9-1.0" overnight, per the HREF ensemble mean, and supportive for scattered gusty light rain showers across the entire forecast area tonight. PoPs peak between 00z and 12z, but this round of rain is one of those scenarios that feature high PoPs but low QPF.

Light rain looks to linger into tomorrow morning for at least some of the forecast area as the LLJ gradually shifts east. With unimpressive moisture in the mid-levels, total precip amounts around or less than a tenth or two is expected through tomorrow morning. Lingering low-level moisture trapped underneath an inversion through tomorrow, with model soundings indicating some drizzle possible.

With breezy southerly winds through the night, WAA remains in place, with temps only getting down into the mid-40s to near 50. Temps for tomorrow peak around 60.

LONG TERM /TUESDAY NIGHT THROUGH MONDAY/

Issued at 320 PM EST Mon Dec 22 2025

===== Christmas Eve through Christmas Day =====

Low overcast clouds and a few isolated light showers will be possible Wednesday morning as the sfc boundary will be situated across the area. However, most of the region should remain mostly dry through the day as mid-level ridging builds and moisture does not appear to be very deep. Temps will be well above normal for Christmas Eve, with forecast highs in the lower to mid-60s.

A subtle shortwave embedded within the progressive NW flow looks to bring a sfc low through the Great Lakes Wednesday night, lifting the warm front through most of the forecast area by Thursday morning. We'll see an increase in our PoPs for Christmas Eve night and into Christmas Day morning, as weak low-level jetting ramps up moisture advection and isentropic ascent. Best upglide lifting will be north of the warm front and over IN and OH, but still have good amount of PoPs across the northern half of the CWA.

On and off light rain chances will be possible throughout Christmas Day as we remain in that progressive NW flow. Despite the relatively high PoPs through this period, overall QPF will be quite meager, with total QPF under 0.10" possible. Temperatures are expected to be above normal once again, with highs reaching the mid to upper-60s. We'll end up short of the max temp records, but should be the warmest Christmas since 2021, which was the warmest Xmas on record for our climate sites.

===== Friday into Next Weekend =====

The upper flow flattens out on Friday, taking on a more progressive zonal flow pattern. However, low level WAA remains strong, and suppresses our diurnal range on temps. As a result, Friday morning low temperatures could end up breaking warm min records, with forecast temps in the upper 50s and low 60s. Given the relatively warm start, temps could end up pushing 70F on Friday, with mostly dry conditions and just some low-end PoPs.

Our next chance for rain comes over the weekend as another cold front approaches the region. A West Coast upper trough will eject across the Mountain West and quickly into the Plains before Sunday. It is possible we could see this system phase with the northern stream, but deterministic models have been slightly slower with the phasing today, which results in a less-amplified line of showers passing through on Sunday. Low confidence remains for the PoPs over the weekend as the guidance is too varied at this time.

There is higher confidence in temps falling behind the front, with Canadian high pressure building into the Ohio Valley by Sunday night and Monday. Temps Sunday night could drop into the 20s, with wind chills in the teens possible.

AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 651 PM EST Mon Dec 22 2025

Conditions have descended into the MVFR range at BWG/HNB, and the other 3 TAF sites will follow suit over the next few hours. Some very light rain has already begun in spots and this will also continue through the overnight. A warm front has lifted north over the area, today and steady to occasionally gusty SSW winds will take hold for tonight. When it isn't gusting, there is a brief LLWS threat thanks to a 40-45 knot low level jet.

Ceilings drop into the low MVFR range toward dawn, with some IFR possible by tomorrow. Winds veer to a more SW component by then generally around 10 to 15 mph. Some light vis restrictions in mist will also be possible into tomorrow, especially if/when ceilings lower into the IFR range.

LMK WATCHES/WARNINGS/ADVISORIES

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