textproduct: La Crosse

KEY MESSAGES

- A compact, but potent, band of snow affects mainly northeast Iowa into southwest Wisconsin tonight into Friday morning. There is a 20- 40% chance that the heaviest snow rates exceed 1"/hr per hour and total snow amounts could exceed 6" in a few locales (20-30% chance).

- The exact placement and snow amounts remain a challenge of the forecast. The northern side of the snow band is especially sensitive as there will be a sharp cutoff in snow amounts and impacts over just a few miles.

- "Colder", aka near or slightly below normal, temperatures move in for the end of the week and early next week. These temperatures look to rebound somewhat for next Tue/Wed.

- Light snow moves through for the weekend, otherwise no major weather systems of note are on the docket through at least the middle part of next week.

DISCUSSION

Issued at 241 AM CST Thu Feb 19 2026

Tonight - Friday Morning: Snow Band Details

The upper level shortwave responsible for our band of moderate to heavy snow later tonight into Friday morning made landfall across the northern California coast about 6-12 hours ago and is now being sampled by the upper air network. This has resulted in the previously diverse suite of solutions converging quickly on the southeastward side of the ensemble envelope, taking the snow band across northeast Iowa and into southwestern Wisconsin. This PV lobe, very evident in water vapor imagery, is progressing rapidly along the southern flank of the mean longwave trough and reaches the High Plains by midday and the mid-Missouri River Valley this evening. A lee cyclone already taking shape along the Colorado Front Range peels off across Kansas and the Lower Missouri River Valley this morning, reaching around Keokuk, IA by this evening and into lower Lake Michigan by sunrise Friday.

A stout deformation zone/frontogenesis band develops along the northwest flank of the low within a region of enhanced upper tropospheric divergence in the left front quadrant of a 170-kt jet streak. Ample Gulf moisture is progged to wrap around the low with upper level specific humidity values around the 90th percentile of climatology. The mean QPF forecast within this band is over half an inch with 20-30% of the ensemble members painting a narrow corridor of precipitation values around or just over 1". The question of course is: where will the snow fall and how much?

Starting with the position of the band--the 00Z ensembles have come into much better agreement with the previously noted southeastward shift in the QPF/snow axis, and have trended the official forecast in line with this shift. This places the corridor of heaviest snow along a rough line from Independence, IA to Boscobel, WI and then towards Wisconsin Dells. This corridor is still likely to wobble over the next 12-18 hours given the fast motion and dynamic nature of the wave. There will be a sharp cutoff in snow amounts on either side of this snow band, particularly the northern side where individual models show snow amounts going from 6" to dry in the span of 10 to 15 miles.

Now, how much snow could fall within this deformation band is a bit trickier to unpack. On face value, the QPF amounts from the various deterministic and ensemble members is rather scary. The omega profiles through the DGZ resemble a classic cross-hairs sounding with an impressive maximum near or slightly under the DGZ. However, the snow system is fast hitting--in and out in about 6-9 hours. To achieve the higher end snow amounts progged by some of the guidance, we would need to see 1-2" snowfall rates for nearly the entirety of the event. Historically, this rarely happens in these environments characterized by higher liquid content and lower snow ratios. The DGZ is also not overly deep (50-100 mb), another limiting factor for excessive snow amounts. It will still snow quite heavily for a period and there is a 20-30 percent chance that a given location in northeast Iowa and southwest Wisconsin sees 6 inches of snow, but some of the outlier solutions of 10-15 inches just seem very far fetched given the setup.

There is also the possibility of seeing freezing drizzle north of this snow band as shown in some soundings that lose ice with lift still present, but the window of opportunity for this to occur is rather narrow and confidence is only about 10-20% in there being any impacts. Will need to monitor trends throughout the day and see if this risk becomes more defined.

We're now at 24 hours from the event, so while the forecast remains fluid and subject to change, have gone ahead and issued a winter weather advisory for where confidence is highest for impactful snow. There will likely be adjustments made to the footprint of the advisory throughout the day/evening and the possibility of a narrow warning needed if confidence increases for a 6+ inch band.

The Weekend: Colder, Light Snow

Polar air lurking over the western Dakotas this morning finally starts to filter southeast in the wake of tonight's system, but given the complex upper level trough pattern and an upstream trough deepening as it moves across the Rockies, there will not be a cohesive push to bring this colder air into the region until later in the weekend as the trough moves through. The end result will be a steadily cooling for Friday through Sunday, with highs in the low to mid 20s for Sunday and lows Monday morning in the single digits. The passage of this aforementioned upper level trough is also the focus for a round of light snow Saturday night and Sunday. Impacts at this time look to be light (1-2" of snow at the most) and mainly east of the Mississippi River.

Early Next Week: Warming and Mostly Dry

Synoptic longwave ridging across the western CONUS flattens and shifts eastward for the start of next week, which will have the effect of shunting our cooler air back to the north. However, how this ridge breaks down remains less certain and will play a role in our temperature and precipitation forecast for midweek and beyond. There is good agreement that a Pacific airmass spreads across the High Plains and into the region for Tuesday, resulting in high temperatures returning to the mid 30s to around 40 (possibly influenced by where we have snow on the ground). The interquartile temperature spread increases to 10-15 degrees beyond Tuesday (20-25 degrees for the 10th to 90th percentiles), a function of how quickly the ridge flattens and how far south it sinks later in the week.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 540 AM CST Thu Feb 19 2026

MVFR to high IFR stratus lingers for much of the area north of an OVS to OLZ line this morning. Current trends indicate little in the way of improvements prior to our next system arriving this evening, which will bring continued widespread MVFR to IFR conditions with visibility reductions of less than 1sm in heavy snow affecting sites along a somewhat narrow line from OLZ to OVS to DLL overnight. This snow starts to clear at the end of the TAF period and continues to exit Friday morning. Winds will be light from the west to north this morning, increasing from the NNE this evening at 5 to 15 kts, with gusts up to 25-30 kts overnight as winds back to the northwest.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Winter Weather Advisory from 8 PM this evening to 6 AM CST Friday for WIZ042>044-053>055-061. MN...None. IA...Winter Weather Advisory from 8 PM this evening to 6 AM CST Friday for IAZ011-029-030.