textproduct: La Crosse

KEY MESSAGES

- Cold temperatures this evening and into tonight with wind chills ranging from 10 to 25 degrees below zero.

- Two clipper systems bring snow chances to the region on Tuesday and Wednesday. Minor accumulations of around a trace to a 1/2" are currently expected with each system.

- Additional cold air moves in Wednesday night and through Friday with New Years Day being very cold with highs in single digits to teens.

DISCUSSION

Issued at 145 PM CST Mon Dec 29 2025

Rest of Today - Wednesday: Cold Tonight, Slight Warm-Up Tuesday and Wednesday with Periodic Snow Chances

We can firmly say goodbye to our winter troublemaker this afternoon as the surface low associated with this system generally pushes east of the Great Lakes region today. As a result, the surface pressure gradient that has been responsible for our breezy winds and blowing snow will continue to weaken and thus we will continue to see wind gusts diminishing throughout the afternoon and evening. As we head into the overnight, northwesterly flow with surface high pressure develops into the region which in turn will allow for more efficient cooling with some clearing in sky cover and relatively lighter winds. As a result, expecting wind chills to remain in the 10 to 25 degrees below zero range this evening and into the overnight.

As we head into Tuesday, our attention then turns to a weak clipper system that pinwheels its way down into the region associated with a weak piece of warm air advection. As a result, the 29.12z HREF has high probabilities (60-90% chance) for measurable snowfall along and east of the Mississippi River on Tuesday afternoon and evening and gradually diminishing probabilities west of the Mississippi River. However, given the fairly weak forcing regime, not noting too much for more substantial accumulations as the 29.12z HREF has low probabilities (20-30%) for amounts of 0.5" or greater. One thing that will needed to be watched though given the weaker forcing regime will be if loss of saturation in the dendritic growth zone would occur. When looking at the 29.12z RAP/NAM soundings at KLSE both indicate some degree of saturation loss at -10C so cannot rule out a brief period of freezing drizzle as this system exits later on Tuesday afternoon/evening. The warm advection on Tuesday will allow temperatures to remain in the middle to upper 20s throughout much of the day and into the overnight as little modification to this airmass will be present.

By Wednesday morning, cold air advection associated with a passing upper-level shortwave trough to the east will push into the area resulting in temperatures trending colder during the day on Wednesday. Additionally, this provided forcing and very weak frontogenetic signal in the 29.12z NAM will be the instigating mechanism for some light snow chances to meander their way through the local area. Overall, the grand ensemble (GEFS/EC/Canadian ensemble) has medium probabilities (30-60%) for measurable snow and very low probabilities (10-20%) for 0.5" or greater at this time so really not expecting much for any accumulations or impacts at this point.

New Years Day - Friday: Trending Colder

Temperatures take a tumble to welcome in 2026 as the aforementioned cold air advection and ever present northwesterly synoptic flow keep a steady influx of cold air into the region late this week. As a result, highs on Thursday within the inter-quartile range of the NBM range anywhere from the single digits to upper teens. Additionally with overnight temperatures falling into the single digits above and below zero New Years Eve (Wednesday) night and into New Years (Thursday) morning, minimum wind chills will likely range from 10 to 25 degrees below zero. As a result, if you have any plans to head outdoors for New Years Eve and New Years, be sure to dress accordingly.

As far as precipitation chances are concerned, little signal really stands out after Wednesday as ensemble guidance does not depict any higher measurable precipitation chances through this weekend. That being said, given the northwesterly cyclonic flow with a upper-level troughing regime situated to our east, would not rule out the potential for some snow showers on days where low-level lapse rates are able to steepen. Either way, have held with a dry forecast for now as any snow shower potential remains very uncertain at this point and likely low impact.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1203 PM CST Mon Dec 29 2025

Main taf concern is lingering stratus deck of clouds and flurries early in the taf period. Low pressure over southern Ontario Canada continues to wrap low clouds and flurries into the area this morning. As low pressure system slowly moves northeast away from the region...pressure gradient relaxes and clouds will erode west to east across the area. Expect MVFR conditions to impact both the RST/LSE taf sites early in the taf period and conditions to slowly improve to VFR this afternoon. Next concern is another system tracking across the area Tuesday. Ceilings will lower possibly in MVFR late in the taf period. At this time...will leave mention since timing of MVFR conditions could be after taf period.

ARX WATCHES/WARNINGS/ADVISORIES

WI...None. MN...None. IA...None.