textproduct: La Crosse

KEY MESSAGES

- Light snow expected today with some locations potentially (30-80%) reaching an inch of accumulation north of I-90. Small (15-20%) chance for brief freezing drizzle in central WI before precip ends this evening.

- More notable snow possible Saturday night with a decent (25-50%) chance for at least 4" of accumulation in northeast Iowa.

- Multiple periods with snow potential next week.

- Cold, wintry temperatures continue over the next 7 days.

DISCUSSION

Issued at 344 AM CST Fri Dec 5 2025

Light snow today, low potential for freezing drizzle

Today, upper wave over the Dakotas as of 08z swings southeastward, passing over Lake Michigan around 06z Saturday. In the interim, this should provide enough lift to generate light snow across a good portion of the CWA, particularly north of a latitude defined by the IA/MN border. Aside from the upper disturbance, forcing for ascent is weak and so thinking most areas will only see minor accumulations, with potential (30-80% per 09.00z HREF) for an inch along and north of I-90 with best chances in Clark/Taylor Counties and northern Buffalo/Trempealeau/Jackson.

Of note, progged soundings in HRRR/RAP suggest that west central WI may see a brief period where saturation in the DGZ is lost while ascent in the low levels continues this evening. Should this occur, a brief period of freezing drizzle would result. However, signal for continued ascent in the saturated near-surface layer has not been consistent between runs of short-term guidance and, in any case, FZDZ would occur for only an hour or two, so current thinking is that potential for impacts is low (15-20%).

Snow Saturday night

Saturday into Saturday night, stronger shortwave dives southeast from MT to E IA. Stronger forcing with the wave itself and potential for an axis of 850mb frontogenesis should lead to higher snow totals compared to Friday's snow, with remaining questions focusing on where exactly moderate to heavy snow will occur and how far north this will spread. 09.00z GEFS/EPS are in relative alignment and focus heaviest snows - perhaps upwards of 6" - in central IA to the south of our CWA. Taking a look at probabilities to reach 3", these are generally 35-90% along and southwest of a Lake City MN to La Crosse to Platteville WI line. GEFS/EPS disagreement focuses on how far north/east impactful snows will occur, with a bit higher probability that these could occur as far northeast as I-94. Given strong cycle to cycle continuity seen in the EPS, am leaning toward this solution for now. In any case, interests in NE IA could very well (25-50%) see an additional 4" of snow.

Periodic snow next week

Persistent northwest flow aloft will keep the area vulnerable to additional snow from clipper systems beyond Saturday night. Operational 05.00z runs suggest two clippers will occur somewhere in the upper midwest in quick succession Tuesday night and then again Wednesday night into Thursday but disagree on placement and exact timing. Given the wide range of clipper trajectories and timings seen across operational and ensemble guidance, have elected to stick with blended guidance values which are broadly illustrative of the periodic snow potential next week.

Cold continues

The calendar flipped over to December a few days ago, the first month of meteorological/climatological Winter, and temperatures have certainly reflected that and then some, remaining well below normal for early December. This continues over the next week with the best shot (40-70% per 09.07z NBM) at subzero lows appearing to center on Sunday night into Monday morning, when a post frontal surface high and concomitant clear skies and light winds look to become centered in our CWA around midnight. Relative relief may occur Tuesday afternoon, when temperatures could (20-60%) reach above freezing briefly. However, with northwesterly flow aloft continuing for at least the next 7 days (hints at a central CONUS ridge seen a couple days ago have vanished), a notable warm up is not expected.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 539 AM CST Fri Dec 5 2025

VFR conditions give way to IFR conditions late this morning as a disturbance will bring light snow near and north of I-90 for much of the afternoon today. Consequently, probabilities for IFR cigs and vsbys increase dramatically (40-70% chance) by around 16-18z. Much of the CAMs generally keep snow continuing through much of the afternoon before exiting to the east during the evening hours. Overall snow accumulations generally will be around an inch or less near and north of the I-90 corridor. Cannot rule out (~20% chance) a very brief period of FZDZ across portions of west-central WI late this afternoon and evening as snow exits. Winds will begin the TAF period from the south at around 8-12 kts but will shift to northwesterly with a frontal passage this evening.

ARX WATCHES/WARNINGS/ADVISORIES

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