textproduct: La Crosse

KEY MESSAGES

- Low snow chances late Friday night and Saturday, mainly north of Interstate 90.

- Another weather producer moves through the region Sunday afternoon and night as temperatures continue to warm, with higher probabilities (40-55%) of light snow falling near/north of Interstate 94. There are some lower chances (20-30%) that this system could have a light wintry mix in the I-90 to I-94 corridor.

- Above normal temperatures expected next week with little to no precipitation chances at this time.

DISCUSSION

Issued at 223 PM CST Thu Jan 1 2026

Saturday Morning Small Chance for Light Snow North of I-90

A weak system will brush the area in northwest flow (again) with very weak forcing it appears at this time. Some very weak frontogenetic signal is seen...but these systems are overachieving in northwest flow as of late. Will have to be ready to amp this one up. 01.12Z CAMS / HREF have some low reflectivity suggestive of the weak lift over the area. Soundings from 01.12Z deterministic models indicate mid-level saturation with a 3-5kft surface-based dry layer to overcome. Overall I think the lift would be more tied to the shortwave trough shifting through and if it can enhance frontogenesis like we saw today. Today's snow was very tied to the apparent shortwave trough moving through the northwest flow with a nice GOES water vapor darkening signal (over central WI at 18Z).

Sunday Wintry Mix Possible, Chances North of I-90 Currently

Longwave ridging continues to build across the central U.S this weekend and confidence per the 01.00Z LREF cluster is high on this pattern. On Sunday, a shortwave trough, ejected from the deep trough off the West Coast, rides the ridge through the northern states. Winds in the low-levels back to southwesterly and warm advection kicks in ahead of the trough. The 01.00Z LREF is in good agreement on an elevated warm layer above 0C moving northeast into the area Sunday afternoon with probabilities increasing (for >0C warm layer maxT) southwest of I-94. Surface T and Tw lag and remain below freezing making for the possibility of a wintry mix of precipitation as the trough moves closer. Right now northern WI, down to I-94 has higher probabilities for snow, with a mix south of there. The LREF probabilities suggest about a 30% (<10%) chance of 0.01" (0.05") of precipitation on I-90, increasing northward. North of I-90, precipitation probabilities increase, and there are clusters taking the precipitation completely north of the area (about 50% of the LREF members). The southern edge of the precipitation would need to be into the warm layer for non-zero probabilities of a wintry mix including ice pellets or possibly freezing rain. Predictability is still low on these details, but something to watch. The model trend over the past 12 hours of the ECMWF ensemble is southwestward and it looks like the system has light amounts (<0.10") for the area. Timing would be Sunday afternoon and evening right now, but figure that will change. NBM has trended toward low chances for freezing rain in the forecast as well in that I-90 to I-94 corridor area and thus have added that to the deterministic gridded forecast.

Temperatures Warming Into Next Week

The large scale flow will transition from northwest to zonal or slightly southwest with mid-CONUS ridging looking likely by next week. This will cause a warming trend across the area with probabilities for above normal temperatures quite high (90%). Interquartile max temperature spreads are around 5 degrees next week in the 01.00Z LREF which is moderate predictability. A majority of the guidance has a weather system moving through the northern states on Tuesday, which would be just west of the area. Overall, fairly quiet.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 537 PM CST Thu Jan 1 2026

MVFR to low-VFR conditions will continue through the evening as low- level moisture remains in place. However, these are expected to lift to some degree with probabilities for MVFR cigs diminishing to around 20-30 percent between 06z and 12z. VFR conditions are expected throughout much of the daytime hours on Friday with light winds from the northwest.

ARX WATCHES/WARNINGS/ADVISORIES

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