textproduct: La Crosse

KEY MESSAGES

- Strong to severe storms are possible this morning, primarily along and north of I-90. Large hail and damaging winds are the primary threats.

- Additional rounds of severe thunderstorms are likely this afternoon into this evening with very large hail, damaging winds, and tornadoes possible. Locally heavy rain is also possible.

- Another conditional threat for severe weather exists Thursday afternoon across northeast Iowa and southwest Wisconsin. All hazards including heavy rainfall are possible.

- Relatively quieter conditions are expected Friday through the start of next week with cooler temperatures and periodic chances for rain.

DISCUSSION

Issued at 1249 AM CDT Wed Jun 10 2026

This Morning: Strong to Severe Storm Potential

"Messy" is the word that comes to mind when thinking about how to best describe the evolution of today's severe weather potential.

Several rounds of severe weather appear possible today, but can largely be broken into two timeframes, the first being from early to mid morning. A warm front and associated 925-850hPa low level jet currently situated over eastern Nebraska/northwest Iowa lifts northward during the overnight hours with MUCAPE values of 1500-2500 J/kg building in along with it. HRRR/RAP soundings depict this instability largely residing above the warm nose in the 700-850hPa associated with the warm air advection ahead of the approaching front, suggesting that storms that develop should be elevated. The biggest uncertainty is if/where storms are able to form given on the capping in place. 700hPa temperatures in the 10.02z RAP sit around 12C which will act to suppress upward motions across much of the region. However, cooler temperatures above 700hPa will support mid-level lapse rates of 7.5-8.5 C/km, posing a threat for large hail and some modest DCAPE around 850-1000 J/kg would support damaging wind potential in storms that do develop. Effective bulk shear does appear to be fairly limited though, generally only 15-20kts, which would hinder the longevity of stronger storms that develop.

Currently thinking those areas along and north of I-90 will see the greatest risk for strong to severe storms with this initial round where forcing is maximized and capping is minimized. Some isolated cells may be able to develop across those areas south of I-90, but currently thinking capping will be too strong across these areas and will miss out on this first round entirely.

This Afternoon and Evening: Additional Rounds of Severe Thunderstorms

The second timeframe for severe thunderstorms is focused during this afternoon into this evening and will be the messiest from a development standpoint, but potentially the most impactful. Warm surface temperatures in the mid to upper 80s and dewpoints upwards of 70 degrees will support SBCAPE values of 2500-3500 J/kg through the afternoon and evening hours. 0-6km bulk shear will be on the increase through the day as well, becoming 35-45kts, although still somewhat displaced from model convection. Regardless, storms developing in this environment should quickly become severe. More interestingly is the low level shear, upwards of 25-35kts in the 0-3km layer as the low level jet increases across the region with low level curvature depicted in model hodographs which would support rotating updrafts as 0-1km SRH of 100+ m2/s2 exists through the afternoon. Mid-level lapse rates are also expected to be fairly steep, generally 6.5-7.5 C/km.

All hazards are on the table during the afternoon and evening hours. Given the steep mid-level lapse rates, large hail is expected to develop with storms that develop initially in a discrete to semi-discrete mode with the potential for tornadoes as well. However, the slightly displaced deep layer shear may result in storms quickly congealing into a linear mode supported by the 0-3km shear with damaging winds and embedded tornadoes the favored hazards. Heavy rain with rates of 0.5-1 inch is also possible, although widespread flooding is not anticipated.

Despite the favorable parameters for severe weather, plenty of disagreement exists amongst the various CAMs regarding the evolution of remnant outflows/MCVs from the morning's convection as these will be the primary catalysts for convective initiation, which reduces confidence in where these storms actually develop. The first area to watch is central Iowa as a line of convection is depicted to lift northward into northeast Iowa and southwest Wisconsin in the afternoon additional scattered development behind this line.

As we head into the evening, a surface cold front is expected to shift southeast across the region from central Minnesota providing another focus for convective development, which will be the second area to watch. The 10.00z HRRR is by far the most rambunctious with convective development along this front, and by the time the surface cold front moves into the region there is the possibility that the atmosphere is thoroughly worked over and any additional storms that do develop along the front will struggle to become severe. However, models continue to suggest SBCAPE upwards of 3000 J/kg will exist along the front with 40-45kts of 0-6km shear which would support severe thunderstorms in a linear mode. Damaging winds would be the primary hazards with the tornado threat largely dependent on how stable the near surface layer is by that point. However, tornadoes certainly can't be ruled out at this point, especially in bowing segments given a nearly perpendicular orientation of the 0-3km shear vector to the boundary.

Overall confidence in the evolution of this afternoon's severe threat remains low and likely won't increase until storms begin to develop along the aforementioned outflows/MCVs, but confidence in hazard type remains medium to high. Ensure you have multiple ways to receive warnings today!

Thursday: Conditional Severe Storm Potential, Heavy Rain

Additional severe storm potential presents itself on Thursday as a an area of low pressure ejects off the central Rockies before translating northeastward into the Great Lakes region. The favored trajectory of this feature brings it directly over our area with those in northeast Iowa and southwest Wisconsin within the warm sector. How far north the warm front makes it will largely be a function of how today's weather plays out as the cold front may be able to advance further south than currently depicted.

Regardless, MLCAPE of 1500-2000 J/kg build into those areas within the warm sector while 0-6km shear of 45-60kts is depicted in the 10.03z RAP, although this may work against storm development given the skinny CAPE profiles depicted in model soundings. Regardless, if storms develop in this environment, all severe hazards will be possible.

Heavy rainfall also looks to be favorable during this period. PWATs around 1.8-1.9 inches, above the 90th percentile of climatology combined with the skinny profiles previously mentioned, and warm cloud depths in excess of 10kft would support heavy rainfall. Mean 24hr QPF in the 09.19z NBM does suggest 1-1.5 inches of rain is possible through the day Thursday with an 20-30% chance for over 2 inches of rain, both of which are primarily focused over northeast Iowa into central Wisconsin.

Friday - Early Next Week: Periodic Rain Chances and Cooler

Relatively quieter conditions close out the week as the primary trough axis pivots into the eastern Great Lakes region, setting up zonal flow aloft over much of the northern United States. There is some potential for precipitation through the weekend, mainly on Saturday as the deterministic guidance resolves a surface boundary shifting southeastward through the Upper Mississippi River Valley associated with a 700hPa shortwave trough sinking southward from a vorticity maxima over Manitoba/Ontario. Probabilities of rainfall during this period sit around 30-60% in both the 09.19z NBM and 09.12z LREF with the highest confidence in rainfall potential located over northeast Iowa into southwest Wisconsin.

Behind this boundary, cooler temperatures look to arrive to start the new week as another shortwave trough sinks southeastward through the United States, setting up an area of lower heights across the Upper Midwest. Plenty of variation exists regarding timing and location of this upper level feature which leads to a fairly large temperature spread in the NWP/AIWP ensemble guidance, but the consistent trend amongst these suites is towards cooler temperatures.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1249 AM CDT Wed Jun 10 2026

MVFR/IFR ceilings are expected again overnight as low level moisture remains fixated over the Upper Mississippi River Valley. A line of thunderstorms currently over northwest Iowa/southwest Minnesota is expected to move northeastward over the next several hours, generally northwest of a line from KAUM to KMDZ. Gusty winds are expected throughout the day, generally 20-30KT from the south. Additional rounds of thunderstorms are expected throughout the afternoon and evening, but confidence in overall location/timing is fairly low. A cold front moves through the region towards the end of the TAF period, shifting winds to the west and bringing VFR conditions.

ARX WATCHES/WARNINGS/ADVISORIES

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