textproduct: La Crosse

KEY MESSAGES

- Apparent temperatures warming into the single digits below zero this afternoon will be short lived as apparent temperatures drop from -20 to -35 overnight into Sunday morning. Therefore, the ongoing Cold Weather Advisory for northern half of the forecast area will cover entire forecast area overnight into Sunday morning. More normal temperatures return for Tuesday with daytime highs in the 30s. - Subsequent widespread preciptiation chances Wednesday night of a wintry mix with no precipitation type being ruled out across the forecast area.

DISCUSSION

Issued at 1230 PM CST Sat Dec 13 2025

Cold will be the main forecast concern through the weekend as freezing temperatures progressed as far south as the Red River Valley along the TX/OK border and the Chattooga/Tugaloo River Valleys along the SC/GA border this morning. The anomalous cold seen locally in single digit above and below zero surface temperatures. Off surface observations from ACARs, 12Z RAOBs, and POES/GOES paint the collocated low level minima, near record anomalous -20C isotherm at 925mb, from the Northern Plains through Wisconsin into the northern Great Lakes. Expect this main vein of Arctic air to continue south of the forecast area through tonight as the wrapped upper level low over southern Ontario on GOES water vapor imagery perpetuates upstream troughing.

A synoptic upper level ridge over the Pacific West Coast on GOES WV imagery returns /more/ normal, albeit a few degrees cool still yet, temperatures on Monday as low level warm air advection ramps up Sunday night into early Monday morning. While temperatures will be increasing, a tightening low level isoheight gradient will also increase wind speeds, persisting below zero wind chills through Monday morning.

Similar to previous forecasts, confidence in coldest apparent temperatures from 20 to 35 below zero locally tonight due to proximity of anomalous Arctic airmass. Exit of the coldest airmass through Sunday concurrent with passage of the low level ridge axis keeping wind speeds low keeps confidence for ending ongoing Cold Weather Advisory high. Confidence for above zero surface temperatures in HREF increases through Sunday, maximizing from 40-80% during peak diurnal heating. LREF Cluster analysis has continued agreement for daytime high temperatures in the 20s for most of the area on Monday.

Precipitation Chances Increase Wednesday Night:

Glancing synoptic lows wavering east/southeast near the International border mean precipitation chances cannot be completely ruled out in central Wisconsin counties Sunday night or area wide Monday and Tuesday nights. Current confidence is minimal, <15%. Regardless, the passing lows increase local moisture ahead of subsequent synoptic cyclogenesis initiated from remnants of early week reintensification to the ongoing Pacific Northwest Atmospheric River. Resultant widespread precipitation potential impacts the Upper Mississippi River Valley Wednesday night through Thursday. Current confidence is low as a quasi- zonal mid/upper level pattern in clusters and individual ensembles will undergo quick changes to cause cyclogenesis across the central CONUS. Ensemble member spread in low tracks is vast due to differences in exit behavior of early week low tracks and varying solutions to the subsequent synoptic upper level jet streak intensification.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1112 AM CST Sat Dec 13 2025

VFR conditions are forecast through the TAF period with mostly few to bkn high clouds throughout the next 24 hours. There are some small probabilities (10-30% chance) for some MVFR cigs to reach either KRST or KLSE this evening in the 13.12z HREF, however confidence was not high enough to include any mention at this point. Winds will increase for the afternoon to around 10-15 kts from the northwest before diminishing to around 5-10 kts overnight and into Sunday morning.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Cold Weather Advisory from 6 PM this evening to 10 AM CST Sunday for WIZ054-055-061. Cold Weather Advisory until 10 AM CST Sunday for WIZ017-029- 032>034-041>044-053. MN...Cold Weather Advisory until 10 AM CST Sunday for MNZ079- 086>088-094>096. IA...Cold Weather Advisory from 6 PM this evening to 10 AM CST Sunday for IAZ008>011-018-019-029-030.