textproduct: La Crosse

KEY MESSAGES

- Measurable snow (potentially 1-4 inches) likely between Interstate 90 and 94 late tonight through Tuesday morning. A Winter Weather Advisory is in effect for portions of SE Minnesota and West Central Wisconsin from 1 AM through noon tomorrow.

- Rain later in the week (Thursday night and Friday) is looking far less likely, so transitioned the forecast drier.

DISCUSSION

Issued at 206 PM CST Mon Nov 17 2025

Today - Tuesday: Rain/Snow Expected for Most

Bit of a messy forecast over the next 30 hours or so. A weak upper low is ejecting out of the North Central Rockies with a surface low taking shape to its south in the lee of the Colorado Rockies. These are expected to trek east into the Mid/Upper Mississippi River Valley over the next day or so. As moisture transport begins to resaturate the lower levels of the atmospheric profile across the region, showers will start to move in from the southwest later this afternoon and evening. This should start off as all rain before things take a turn for the more complicated.

As we move into the 00-06Z timeframe, we'll see a signficiant 850- 700mb fgen band move in and drape itself across the tri-state area. Around this time, we should also see an increase in synoptic lift from the left exit region of the upper jet which will be located around the base of the upper low. As temperatures begin to cool and wet bulb temperatures begin to approach freezing, we'll start to see a transition to a rain/snow mix. How long this transition takes is still a point of contention among guidance. The favorable dynamics may allow the transition to mostly snow happen faster than the current late overnight timeframe. Unfortunately, with the 17.12Z HREF soundings showing largely isothermal profiles through 750 mb around 0 deg C, the slightest shift in temperature will impact what is seen on the surface so near term updates in when and where the transition happens will likely be needed. For now, have introduced the rain snow mix after 06Z with snow becoming more dominant closer to 12Z generally between the I-90 and I-94 corridor as latest hi-res guidance has indicated a slight northward shift in the band of snowfall. Snowfall rates look to peak around 0.5 in/hr with very low (less than 10%) chance of seeing rates at or above 1 in/hr. Snow ratios will be lower than normal around 6-8:1 so it will be a heavy, wet, and slushy snow. This is also expected to fall overnight and into tomorrow morning, likely impacting the morning commute. Totals look to hover in the 1-4 inch range but this is highly dependent on when the transition to mostly snow occurs. If it occurs earlier than currently expected, these totals might be too low. If the transition occurs later, or not at all, these totals will be too high. This is a particularly finicky forecast with lots of emphasis placed on a narrow range of temperatures that could easily fluctuate. Even this close in time, details are subject to change so stay tuned for any needed forecast updates.

As the low and subsequent fgen band slide to the east, precipitation will quickly come to an end through the late morning and early afternoon. With the potential for a light snowpack and continued cloud cover across the region, temperatures will struggle to reach the 40 degree mark tomorrow afternoon with most locations staying in the mid to upper 30s.

Wednesday - The Weekend: Some Rain Chances, Near Normal Temps

The forecast gets a bit less hectic as we move into the mid to late week timeframe. Wednesday should be dry with continued cool temperatures in the upper 30s to mid 40s. A longwave trough is expected to move across Canada by late in the week, dragging a trailing cold front through the area Thursday. Temperatures will have rebounded into the mid 40s to low 50s by then so precipitation should stay as all rain.

Yet another upper low across Southern California is expected to pivot northeast Thursday into Friday. Latest guidance has trended this low further south than the past couple days which would keep precipitation across our area to a minimum with only areas along and south of I-90 seeing any sort of chance during the day on Friday. Overall, chances for rain both days are limited to the 20-30% range. A surface high moves in behind these systems to keep the forecast dry for the weekend. Temperatures should remain near normal in the mid 40s to low 50s.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1208 PM CST Mon Nov 17 2025

VFR conditions continue through the afternoon and evening hours today with ceilings between 5-10kft and southeast winds of 10kts or less. Overnight, a low pressure system moves eastward through the region, resulting in a messy winter weather scenario through Tuesday morning. Rain moves northward into the area tonight, transitioning to snow after 06z, although confidence in exactly when this transition occurs is low. Once it does occur, snow/wintry mix is expected to continue through Tuesday morning, generally along and south of a line from KMSP to KSTE, ending west to east toward the end of the current TAF period. Widespread IFR conditions are expected for these same areas through the day Tuesday associated with the snow/wintry mix, but areas west of the Mississippi River may see LIFR ceilings develop by the late morning. Otherwise, winds will shift to a more easterly direction overnight into Tuesday, generally 10kts or less, although some gusts to 20kts are possible in northeast Iowa overnight.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Winter Weather Advisory from 1 AM to noon CST Tuesday for WIZ029-032>034-042>044. MN...Winter Weather Advisory from 1 AM to noon CST Tuesday for MNZ079. IA...None.