textproduct: La Crosse

KEY MESSAGES

- Widespread precipitation chances return to the local area Tuesday evening, lasting through Wednesday mid-day. Initial rainfall switches to snow overnight Tuesday through Wednesday morning.

- Thursday night into Friday brings another chance for precip primarily east of the Mississippi.

DISCUSSION

Issued at 206 PM CDT Sun Mar 8 2026

Precipitation Chances Return Tuesday & Wednesday

Benign conditions will prevail for the start of the work week as upper level flow becomes more zonal in nature by 00z Monday. This won't last for long however as a closed, cutoff low, currently sitting just off the coast of the Baja California peninsula, starts to slowly slide east into the Southern Rockies late Monday into Tuesday. Around the same time, a shortwave trough will work its way across the Northern CONUS, deepening as it reaches the upper Midwest by Wednesday. How these two systems will phase together will play a significant role in our forecast. Both the NBM 08.13z and 08.00z LREF Grand Ensemble (EC, GEFS, Canadian) are showing a 75-95% chance of measurable precipitation across the area but there remains significant differences in the ensembles as to amounts and to a lesser degree precipitation types. These significant differences stem from how the ensemble member is handling the phasing of the upper level systems. The EC members are lagging the phasing until much later on Wednesday with the GFS comparably much more aggressive with how quickly they phase together. With the EC keeping the systems unphased for longer, we really only see the influence of the northern stream shortwave and it's much weaker. The GFS ensemble members tend to highlight a much stronger northern shortwave as it moves into our area with the southern stream trough more completely in sync. As such, the GFS ensemble members have higher precipitation amounts, especially in regards to snow Tuesday night into Wednesday. The GEFS is highlighting 20-40% probabilities for 3+ inches of snow, mainly east of the river across West Central Wisconsin with the EC much less enthused at less than 10% probabilities of 3+ inches of snow across our area, keeping the higher probabilities well to our north. Both are showing precipitation starting as rain late Tuesday with a gradual transition to rain/snow mix as colder air starts to work its way in behind the cold front. Eventually, much of the area should see a complete transition to snow. The main differences between the models in regards to precipitation types are in how quickly this transition to all snow happens with the GEFS being faster and the EC a tad slower. Given that the evolution of the upper level pattern will play a key role in how our forecast pans out, hopefully more clarity will be gained once these systems are able to be more accurately sampled as they start to move onshore later tomorrow.

Regardless of how the systems phase, the southern stream shortwave is expected to eject out of the Rockies and into the Plains. Out ahead of it, a weak surface low will start to take shape and allow for more abundant deep moisture to work its way into the Mid Mississippi River Valley late Tuesday into Wednesday. With increased lift from the surface low and divergence aloft ahead of the shortwave, a significant swatch of showers and thunderstorms will likely form across the Central US. Fortunately, we should largely stay clear of any severe threat as by the time ample instability is realized, much of the area should be behind the cold front. This will need to be monitored closely over the next couple days as changes in timing could increase the risk for thunderstorms. Currently, the Day 3 Marginal Risk area just clips Grant County with the higher risk areas to our south and east.

Unsettled Pattern Continues Late Week

We'll see a brief break in precipitation Wednesday night into Thursday before chances for precipitation return yet again with northwest flow becoming the prevailing pattern across the region. With this pattern, weak shortwave troughs and clipper systems are more likely to trek across the region. One of interest looks to come right on the heels of the mid week systems late Thursday into Friday as PoPs are already in the 50-70% range. Precipitation type is likely to start as a cold rain with temperatures in the 40s and strong warm southerly flow into the region. Some locations could see a rain/snow mix where temperatures are allowed to cool more readily (North Central Wisconsin) but these details remain fluid and subject to change. Looking towards the weekend, more clipper systems/shortwaves look possible but these are much less resolved and look weaker overall.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1100 PM CDT Sun Mar 8 2026

VFR conditions will prevail over the TAF period with concerns focusing on potential for LLWS and low level turbulence over the first 6 hours of the period. For valley locations, relativelylower wind speeds and tendency for a bit more of a southerly component will lead to a good amount of low level shear with winds aloft out of the west-southwest ramping up to 45-50 knots. Meanwhile, ridgetop locations and those outside of the Mississippi Valley will see surface gusts to 25-30 knots during the same period, enough for some low level turbulence and shear, but too low for a mention at RST. Next potential flight rule reductions look to occur well beyond this period on Tuesday evening.

ARX WATCHES/WARNINGS/ADVISORIES

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