textproduct: Louisville

KEY MESSAGES

* Windy conditions are expected through Wednesday, with widespread wind gusts of 25-35 mph and isolated gusts to 40 mph likely.

* A cold front will bring rain to the region tonight into Wednesday. Precipitation will transition to scattered snow showers and flurries Wednesday night, with light accumulations and slick spots possible Thursday morning.

* A more significant wintry system is possible Thursday night into Friday morning, which could bring accumulating snowfall to portions of north central KY and southern IN.

* Another shot of colder air arrives this weekend.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 423 PM EST Tue Dec 9 2025

Mostly sunny skies, breezy S/SW winds, and milder temperatures are observed across the area this afternoon as the region sits in between high pressure over the southeast US and deep low pressure over the Dakotas. For the rest of this afternoon and evening, relatively mild and breezy conditions will continue, with winds becoming a bit less gusty around and just after sunset as the boundary layer becomes more stable. While clouds will increase from the north later this evening, dry conditions are expected to continue until early Wednesday morning.

Tonight, the upper level shortwave associated with the deep low over the Dakotas will drop to the SE toward Lake Michigan. The pressure and height gradient over the Ohio Valley will continue to strengthen overnight, leading to the development of a 60-70 kt H85 jet which will move across southern IN and northern KY during the pre-dawn hours. While breezy winds will continue at the surface through the nighttime hours, model soundings show poor lapse rates between the sfc and the LLJ, suggesting that mixing of faster winds aloft will be limited overnight. With this being said, chances for rain showers will increase after 06Z Wednesday, and often times stronger winds will be brought down to the surface with the initial wave of precipitation. As a result, wind gusts should generally range from 25 to 35 mph overnight, but isolated 40+ mph wind gusts will be possible in heavier rain showers. With strong southerly winds and increasing cloud cover expected overnight, temperatures will struggle to cool, with temperatures remaining fairly steady in the upper 30s and low 40s.

Precipitation amounts with this system will be fairly light overall, as access to Gulf moisture will be limited, as is typical with clipper-type systems. Hi-res model guidance suggests that most of the showers should be concentrated along or just ahead of the cold front, moving across the area Wednesday morning. During the afternoon and evening hours, cold advection and steepening low-level lapse rates should lead to showers becoming more scattered, with cooling aloft gradually increasing the likelihood of showers mixing with or changing to snow. Highs tomorrow should be reached during the late morning and early afternoon hours, with temperatures falling later in the day as winds swing around to the NW. Winds will remain gusty during the day on Wednesday, with better mixing leading to continued 30-40 mph wind gusts until late afternoon.

Wednesday evening into Wednesday night, low-level moisture will linger with the upper trough still spinning overhead. Where pockets of deeper moisture exist, there will likely be bands of flurries or light to moderate snow showers. Coverage of these snow bands will be isolated to scattered, with the greatest coverage likely occurring across the Bluegrass region; however, within the heavier bands, a quick coating to half inch of snowfall will be possible. With temperatures falling into the mid-to-upper 20s Thursday morning, any locations which receive snow Wednesday night could see slick road conditions during the first part of the day on Thursday.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 423 PM EST Tue Dec 9 2025

Thursday should be the transition period between the clipper system which moves through the region tomorrow and a subsequent clipper system which is expected to dive through the area Thursday night into Friday. Any lingering flurries or light snow showers should dissipate by late Thursday morning as the upper trough axis pushes east of the Appalachians. Temperatures should remain cool on Thursday, with highs in most locations expected in the 30s. With little in the way of return flow, clouds are likely to stick around through much of the day on Thursday, with mostly cloudy skies expected.

Thursday night into Friday, another clipper system will drop across the Ohio Valley within the broader NW flow pattern. A NW-SE oriented band of precipitation is expected to develop on the cold side of the effective sfc warm front, with isentropic upglide and broad rising motion downstream of an upper-level shortwave serving as sources of lift. As with the mid-week system, moisture with this system will be somewhat limited as SW low-level flow limits access to Gulf moisture sources. In spite of this, there will likely be a stripe of light to moderate precipitation which results in accumulating snowfall across portions of the Ohio Valley. Exactly where that occurs is still uncertain, and the cutoff between areas which receive significant accumulations and areas which see no snow is expected to be fairly sharp. The most consistent signal for accumulating snowfall has been along and northeast of a line extending from Jasper to Louisville to Richmond, in other words, mainly across southern IN and northern KY. While most likely snowfall amounts within this band of precipitation are generally in the advisory-level range, this amount of snow could lead to detrimental impacts to travel conditions during the first half of the day on Friday, so it bears watching over the next few days.

Later in the day on Friday, precipitation should clear the region as the system moves off to the east of the area. Surface high pressure will begin to nose in from the northwest Friday night; however, the onset of the heart of this cP air mass continues to look to be slower to arrive, with temperatures gradually easing downward over the weekend. Another system may try to swing through the region Saturday into Saturday night before upper troughing and sfc high pressure finally settles into the region on Sunday; however, a consistent picture is yet to be depicted in medium-range guidance, and confidence is still low. If we were to see precipitation during this time period, mixed precipitation types would be possible, with better chances of wintry weather to the north and greater likelihood of rain to the south.

Saturday night into Sunday, high pressure is expected to sink into the region, with temperatures tumbling into the 20s and low 30s for the day on Sunday. Low temperatures Sunday night are currently expected to be in the upper single digits and low-to-mid teens, some of the coldest air of the season thus far. During this time period, dry weather is more likely, though as mentioned above, forecast confidence is pretty modest at this lead time.

AVIATION /18Z TAFS THROUGH 00Z THURSDAY/

Issued at 1248 PM EST Tue Dec 9 2025

VFR conditions are expected through most of the current forecast period, though ceilings should gradually drop tonight into tomorrow morning. The main impacts to operations should be due to gusty S/SW winds and LLWS tonight as a strong low pressure system moves to the north of the region. Confidence in wind gusts is a bit lower overnight as there are uncertainties with how much mixing will be able to occur. Scattered rain showers will be possible, mainly after 06Z tonight, though impacts from these showers should be relatively minor. By Wednesday morning, a cold front will move through the region, causing winds to veer from S/SW to W/NW. Wind gusts of 30 kt are possible Wednesday morning, especially at SDF, LEX, and RGA. Ceilings may also drop to MVFR levels by the end of the forecast period; however, confidence in this is still moderate.

LMK WATCHES/WARNINGS/ADVISORIES

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