textproduct: La Crosse

KEY MESSAGES

- A Blizzard Warning has been issued through 9 pm for southeast MN and northeast IA based on the latest radar and observations of whiteout conditions in snow and winds of 30-50 mph in southcentral MN. This will affect the commute and periodic whiteout conditions should be expected, more widespread in rural areas.

- Scattered to numerous snow showers with brief bursts of heavy snow are expected through evening hours (70-90%). Visibility could be rapidly reduced to /4 mile or less in the heaviest snow showers and travel could become slippery. Exercise caution if driving this afternoon and evening.

- Gusty winds continue through this evening with gusts up to 50 mph expected west of the Mississippi River.

- A brief dry period is expected Friday before snow potential increases for areas along and north of I-94 (20-40%) Friday evening into Saturday morning.

UPDATE

Issued at 401 PM CST Thu Dec 18 2025

Based on the number of accidents on MN roads per MN 511 and webcams, and an area of snow moving into southeast Minnesota and northeast Iowa, we felt the conditions warranted a short- term Blizzard Warning. Compounding the situation is the evening commute time and more travelers out and about. Observations in the wrap around snow in central MN are consistently 1/4mile or less and these conditions will move into southeast MN and northeast IA.

The higher-impact, more widespread whiteout conditions are not expected to move east into Wisconsin and therefore the Winter Weather Advisory will remain for less wind and isolated lower visibilities as the snow progresses east this evening.

Those using radar to estimate snowfall intensity should remember that away from the radar, the radar beam will be scanning over the snow and sampling a lighter reflectivity. It will likely be snowing harder than it appears on radar.

DISCUSSION

Issued at 202 PM CST Thu Dec 18 2025

Snow Shower Potential This Afternoon

A cold front shifts eastward through the area this afternoon and evening, currently extending from southern Minnesota into northwest Wisconsin. This front is supported by a tropospheric deep trough with the main surface low centered over northeast Minnesota. Forcing associated with this boundary in the form of 925hPa frontogenesis has been supporting a band of heavy snowfall across southern Minnesota that is expected to continue eastward, but should begin to diminish as it moves east of the Mississippi River. Visibilities of 1 mile or less have been reported with this band, but overall impacts have been minimal.

In the wake of the front, strong cold air advection moves into the region, steepening low level lapse rates. Lingering saturation within a deep DGZ and ample forcing associated with the wave overhead should provide for additional snow showers through the evening hours. Snow showers are expected to dwindle from west to east overnight as the frontal system shifts eastward.

Overall, expect snow showers through the evening hours which could provide brief bursts of heavy snow with accumulations around 1/2 inch. Gusty winds are expected to blow the snow around, enhancing visibility reductions. Roadways that become wet from the snowfall could also become slippery and travel could become hazardous. Exercise caution if driving this afternoon and evening.

Gusty Winds Through This Evening

A tightening pressure gradient on the backside the aforementioned wave will result in an increasing low level wind field across the Upper Midwest as it shifts eastward. The VAD Wind Profile from KFSD has indicated 40-45kts winds exist at 2000ft. These winds which combined with the steepening lapse rates have resulted in surface winds gusting to 35-50mph across southern Minnesota and northern Iowa. These gusty winds will continue spreading eastward this afternoon and evening, with gusts of 30-40mph expected across the region, up to 50mph for those west of the Mississippi River. The pressure gradient begins to relax after midnight as the wave departs, resulting in decreasing winds through the overnight hours.

Brief Dry Period Friday Then Increasing Snow Potential

Looking past this afternoon and evening, surface to 850hPa ridging quickly slides eastward through the region on Friday, leading to a dry period and clearing skies from the mid-morning through the early afternoon. This window of quiet weather will be short-lived for those along and north of I-94 though as another 500hPa surface wave deepens over southern Canada associated with the left exit region of a strengthening jet streak. Confidence is high (60-80%) that this wave primarily shifts eastward across southern Canada with little southward movement as a little variation in placement exists amongst the 18.12z GEFS/EPS/GEPS given upper level ridging in place.

Despite the northward trajectory of this wave, the Upper Midwest will not be spared from its influence. Southerly flow returns Friday afternoon, allowing for saturation in the mid to upper level. Forcing associated with this saturation in the form of isentropic ascent on the 290-300K surface should prove enough to provide some light snow to areas along and north of I-94 (20-40%), although dry air in the sub-cloud layer between 900-700hPa may hinder the overall amount of precipitation that is realized at the surface. Additional snowfall is then possible (10-30%) as the cold front moves into the region, but less confident in this solution with increased variation amongst the ensemble guidance.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 935 PM CST Thu Dec 18 2025

MVFR conditions associated with light snow and stratus continue to dissipate west to east as of issuance time. Snow should come to an end by 09z east of the Mississippi but low ceilings will remain for a few more hours after snow ends. VFR conditions are expected by 12z and thereafter. Northwest winds with gusts to 35 knots continue early in the period but these too should subside by 12z Friday. After speeds reduce to under 15 knots, winds will turn counter-clockwise to out of the south-southeast by 00z.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Winter Weather Advisory until midnight CST tonight for WIZ017- 029-032>034-041>044-053>055-061. MN...Wind Advisory until midnight CST tonight for MNZ086-087-094- 095. Winter Weather Advisory until midnight CST tonight for MNZ079- 088-096. IA...Wind Advisory until midnight CST tonight for IAZ008>010-018- 019-029-030. Winter Weather Advisory until midnight CST tonight for IAZ011- 030.