textproduct: Louisville

KEY MESSAGES

* Light precipitation in the form of freezing rain/drizzle and snow during the morning commute could result in slick and hazardous on untreated surfaces. Winter Weather Advisory in effect tomorrow morning for north of the Parkways along the Ohio River into southern IN

* A significant and impactful winter storm is expected over the weekend. Heavy snow and cold temperatures are possible, but forecast confidence in snowfall amounts and detailed timing remains low.

* Very cold temperatures along with snow for the weekend and continues into the start of next week.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 425 PM EST Tue Jan 20 2026

A weak shortwave trough working across the Dakotas, the Upper Midwest and into the Great Lakes overnight will help to track a weak sfc low and associated cold front into southern Michigan by tomorrow morning with the cold front stretching from Lake Michigan southwest towards St. Louis and into central OK. Pressure gradient will tighten allowing winds to remain fairly steady out of the south overnight around 10 mph. Ahead of the system a strong LLJ will advect warm moist air northward and model soundings indicate the column will start to saturate 850mb or around 4500ft up to the base of the DGZ. Hi-res models show a narrow area of precipitation associated with the leading edge of the LLJ arriving from the southwest between 09-11z. At onset, there will be plenty of of dry air below 850mb but with temperatures initially below freezing along with road temperatures, anything that falls will stick and/or freeze on untreated surfaces. As precipitation falls through the dry layer, wet-bulbing will occur, helping to saturate the lower layer and also keeping some temperatures below freezing through the first half of the morning. Given the timing of precipitation during the morning commute, temperatures below freezing along with road sfc temperatures in the 20s we went ahead and issued a Winter Weather Advisory for a wintry mix of snow and freezing rain along and north of the parkways and north towards the Ohio River. Untreated surfaces will easily become slick and hazardous as that will be the main impact.

Through the day, temperatures will continue to rise and top out into the low 40s. Any wintry mix of snow and freezing rain will eventually change over to all rain. Winds will increase and turn gusty, could see gusts of 20-30 mph. Most of the activity will push out by tomorrow evening, skies will clear out and temperatures will fall back into the 20s by Thursday morning.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 425 PM EST Tue Jan 20 2026

Thursday - Friday...

Forecast for the end of the week looks dry and turning colder as sfc ridging coming out of Canada will strengthen an anomalously strong arctic high builds over the Northern Plains and pushes a very strong cold front southward into the area. We will see a tight north-south temperatures gradient on Friday with low 30s for highs along the KY/TN border and low/mid 20s north of I-64.

Significant and impactful winter storm still expected this weekend...

The overall synoptic setup remains the same as we head into the weekend. As the aforementioned arctic sfc high continues to build southward from the Upper Midwest and Northern Plains into the Great Lakes and Ohio Valley, very cold arctic air will continue to advect southward. This will also increase drier air over across parts of southern IN.

Closed upper low coming in off the southern CA coast Friday night will get picked up by the southern stream of the jet. This will help to strengthen low-level SW flow and advect moisture from the Gulf through the Deep South into the Ohio Valley lifting it over the cold air associated with the arctic high to the north.

Synoptic scale ascent beneath the right entrance region of an intensifying jet streak will help to enhance the development of heavy snow bands. Location and development of these upper jet streaks will be crucial to placement of where the heaviest of snow will fall and just how far south the sfc high and dry air will reach.

Current thinking remains unchanged in a significant winter system impacting the region over the weekend. Snow continues to look like the primary precipitation type and confidence remains fairly high that locations will see impactful snowfall over the weekend. The winter Storm Severity Index has increased the probability of Moderate Impacts, or disruptions to daily life, to between 50-60%. We continue to see a shift of tails in the ECMWF Extreme Forecast Index around 1 across southern KY and a 2 across most of TN. Overall there continues to be high confidence in a winter storm impacting the region this weekend.

What remains in question, is overall storm track, timing or onset of precipitation, potential snowfall amounts given the continued model discrepancies in the deterministic. The ECMWF and Canadian seem to be more in line but differer on timing with the ECMWF still trending slower. After shifting northward with the 00z/06z runs the GFS has shifted back southward. Given that we will likely have a sharp snow amount cut off as we go north, small shifts north or south in storm track will result in significant changes in potential snow amounts over the area.

Along with the snow we will also have some very cold air in place over the weekend with highs in the teens on Saturday and low 20s for Sunday into Monday with lows in the teens and single digits.

AVIATION /00Z TAFS THROUGH 06Z THURSDAY/

Issued at 620 PM EST Tue Jan 20 2026

For the evening and overnight period, VFR conditions will be seen early in the period. Main concern overnight will be a low-level jet axis overspreading the region resulting in LLWS at the terminals after 21/05Z. Toward 21/10-11Z, batch of light precipitation mainly in the form of freezing rain will overspread the region. Precipitation intensity looks to increase with the freezing rain changing over to snow. MVFR cigs/vsbys will be possible here. Precip should exit the terminals by early afternoon with gusty southwest winds of 20-25kts being seen.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Winter Weather Advisory from 4 AM EST /3 AM CST/ to 11 AM EST /10 AM CST/ Wednesday for KYZ023>043-045>049-053. IN...Winter Weather Advisory from 4 AM EST /3 AM CST/ to 11 AM EST /10 AM CST/ Wednesday for INZ084-089>092.