textproduct: Louisville

KEY MESSAGES

* Winter Weather Advisory for counties along and north of I-64 for Saturday afternoon and night as another quick-hitting clipper system brings an additional 1-3 inches of snow.

* Cold Weather Advisory for majority of the region on Sunday as a very cold airmass will move into the region. Forecast lows will be in the single digits and highs on Sunday in the teens and low 20s. Minimum wind chills may bottom out in the 10 below to 5 above zero range.

* Temperatures will slowly moderate Monday afternoon through mid next week. Temperatures 10 to 15 degrees above normal expected by Thursday!

UPDATE

Issued at 1033 AM EST Sat Dec 13 2025

The freezing fog advisory was allowed to expire on time, as overall conditions appear to be gradually improving. Still going to see some patchy fog this morning with low stratus, but it does not appear widespread enough to keep the headline going. Regional radar mosaic shows some light radar returns moving into central and southern IN, which is light snow, mainly just north of the forecast area. Best forcing remains over central IL at this time, where negative EPV and an area of 700 mb frontogenesis is located and producing heavier snow rates. That area of forcing will overspread central IN later today, and we'll likely remain on the southern periphery of the best forcing.

Snow amount probs has trended down slightly since the morning package, with a 70% chance of exceeding 2 inches, and a 30% chance of exceeding 4 inches, specifically for Madison, IN. The need for a Winter Storm Warning for at least Jefferson County IN is still not out of consideration, but would want to see those probs much higher to have any confidence in verifying a warning there. Due to this, no changes to the headlines are planned for now. Additionally, overall forecast remains in good shape, with no major changes planned other than blending in some of the 12z hi-res guidance to adjust and tweak our hourly PoPs.

SHORT TERM /THROUGH TONIGHT/

Issued at 313 AM EST Sat Dec 13 2025

Pretty active stretch of weather in the near-term as we deal with some patchy dense freezing fog this morning, a quick hitting light snowfall later this afternoon and evening, and then bitterly cold temperatures and wind chills heading into Sunday morning. Buckle up!

First off, seeing some areas of dense freezing fog across east central KY at this hour. FTK, EKX, 6I2, AAS, DVK, and RGA are all reporting 1/4 mile and freezing fog with temperatures in the upper 20s to around 30F. Concerned about some black ice/slick spots combined with drastically reduced visibility. Please use caution in these areas if traveling this morning. Guidance does suggest some improvement with increasing cloud cover toward dawn, but so far have yet to see it. Current product goes through 13z.

Outside of that this morning, we should stay dry with increasing mid and upper clouds. Temps currently in the upper 20s and low 30s don't have a long journey through this afternoon as they are only expected to rise into the low and mid 30s across southern Indiana and central Kentucky ahead of the approaching arctic boundary. Southern Kentucky is expected to rise into the low 40s, giving a bit more of a diurnal range.

With that said, the stage will be set to accumulate some light snow amounts across our northern third of the CWA later this afternoon through the evening as another quick hitting clipper slides through the Ohio River Valley region. Like the Winter Weather Advisory placement along and north of the I-64 corridor as data has changed very little since the previous package. Perhaps a slight southward shift, and will consider adding some Louisville metro counties onto the current headline to account for a quick and fluffy .5" to 1". Farther north across southern IN and our northern Bluegrass counties a more solid 1 to 2" of fluffy dry snow looks pretty good. Perhaps some localized 3 or 4" amounts northern portions of our northern counties, depending on banding in those areas.

A look at cross sections/soundings for this event shows another setup with wonderful mid level frontogenesis beneath right entrance region jet dynamics. Noting another instance where more vertical theta surfaces in the mid levels suggest some WSS/CSI, and this is backed up by slightly negative EPV values. The end result should be some W/E oriented bands of moderate to briefly heavy snowfall at times embedded within the larger and broader light precipitation shield. Again, this should mainly be across our far northern counties in the Advisory area (think Madison county Indiana) where amounts more in the 2-4" range are more likely. Probabilities for at least 2" of snow in that county are between 70-80%, and probabilities of 4" of snow drop off to around 50%. Not far from needing a Winter Storm Warning for that county alone, but would like to see confidence around 80% before going with that upgrade, as the 2 to 4" range still fits in the Winter Weather Advisory nicely.

On the southern end of the advisory, plan on buffering the southern tier with an SPS mentioning a quick half inch of fluffy accumulation. It is worth noting that this system will be undercut by the shallow arctic airmass as snow is falling, so SLRs will actually improve during this event, opposite of the last event where they were lowering with time. Right now, it looks like we could start with 12-15:1 and end with 15-18:1, especially across the north where that healthier frontogenetical banding will take place. Will tweak the current headline, but will likely keep the same start and end time as they look pretty good. Will note that the system could end with some lingering flurries as very shallow moisture will still be enough to produce ice crystals with the arctic airmass settling in toward dawn on Sunday.

Speaking of the arctic airmass, that will be how the near-term portion of this forecast ends, and the long term discussion below begins. Cold Weather Advisory looks good for later tonight into Sunday morning as temperatures drop into the single digits north and low teens south along with a steady NW wind. The end result, will be minimum wind chills dropping down into the 10 below to around 0z range across the CWA. The colder values will be north, and may be exacerbated a bit by a fresh snow pack. Still, should stay within the Advisory criteria range. No changes planned there. Button up, but the good news is it won't last long. Check the long term discussion for info about going from 30 degrees below normal for this time of year to 10 to 15 degrees above normal in a 3 day span.

Forecast high temps could end up being near the cold max records for Dec 14 at SDF (15F, 1914) and BWG (21F, 1985).

LONG TERM /SUNDAY THROUGH FRIDAY/

Issued at 313 AM EST Sat Dec 13 2025

Sunday - Tuesday Night...

Arctic cold front will be clean through our area by sunrise Sunday, with any lingering light snowfall across our NE also likely shutting off by then. Some data does show just enough lingering low level moisture in the Bluegrass to warrant some flurries, but not ready to advertise this yet. Instead, will call for a cold/dry day with high temperatures only in the teens. Perhaps some KY/TN counties touch 20. For context, these highs will be a full 30 degrees below normal for this time of year. Folks should also remember that some locations (most likely southern Indiana) may not rise above Cold Weather Advisory criteria until Midday or so. So, be prepared for bitter cold temperatures and perhaps some lingering snow covered roads (I-64 and points north) if out and about Sunday AM.

The arctic surface high settles over our area by Monday AM, and this will actually bring colder over temperatures (0 to 10 above), however with little to no wind, wind chills will not be as low. Still, a cold morning, especially for the kiddos. Bundle up!

Monday highs begin to recover nicely under mostly sunny skies and a steady mild advection component thanks to a SSW wind on the west side of the departing surface high. Dry conditions continue through Tuesday Night, with temperatures continuing to moderate. Tuesday bring highs back into the 40s for most.

Wednesday - Friday...

The upper pattern will be in a progressive and zonal flow by mid week, and could bring a subtle shortwave through the area capable of some light precipitation across KY on Wednesday. Either way, the day should be mostly dry with continued milder temperatures rising into the upper 40s and low 50s.

Model data agrees fairly well in a strong trough axis swinging through our area around the Thursday time frame. This feature looks pretty strong and moist with widespread gusty showers a good bet. Good thing we're recovering from an Arctic airmass as dew points don't look to have enough recovery time to threaten a severe weather airmass. Still, this system will have plenty of wind energy and high PWATs so gusty showers and healthy rainfall totals could materialize. Something to keep up on as move closer. Thursday highs look to range in the 55 to 60 degree range, which will be about 10 to 15 degrees above normal for this time of year. Going from 30 below normal to 15 above normal in 3 days is pretty impressive. Right now, Friday looks to trend drier and cooler behind the departing cold front and trough axis.

AVIATION /12Z TAFS THROUGH 18Z SUNDAY/

Issued at 649 AM EST Sat Dec 13 2025

Seeing a mixture of IFR ceilings and vis this morning. Visibility will gradually improve through mid to late morning with ceilings also trying to climb back to MVFR. Steady SW winds will gradually go NW and then N as an arctic cold front approaches and passes through the period. Light snow begins later this afternoon, lasting through the evening. The most impacts will be at SDF/LEX/RGA where some reductions in vis and light snow accumulations are expected.

An arctic cold front approaches later in the period with surface winds shifting to a steady NW component between 10 and 15 mph. Expecting some impactful snow at the SDF/LEX, and possibly RGA TAF sites mainly in the 21 to 06z time frame. Steady NW winds and a return to VFR will occur in the pre-dawn hours of Sunday, lasting through the end of the period.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Winter Weather Advisory until 7 AM EST Sunday for KYZ030>037- 041>043-049. Cold Weather Advisory from 1 AM EST /midnight CST/ to 1 PM EST /noon CST/ Sunday for KYZ023>043-045>049-053>057-061>067- 070>078-081-082. IN...Winter Weather Advisory until 7 AM EST Sunday for INZ076>079- 091-092. Cold Weather Advisory from 1 AM EST /midnight CST/ to 1 PM EST /noon CST/ Sunday for INZ076>079-083-084-089>092.