textproduct: La Crosse

KEY MESSAGES

- Muggier today with numerous showers and storms, producing widespread rainfall amounts of 1-2 inches with locally higher pockets exceeding 3 inches.

- Increasing heat and humidity into mid-week. Highs in the low 90s are likely (70 to 90% chance) for Tuesday and Wednesday but recent forecast runs have trended a smidge cooler.

- Increasing likelihood for a severe weather event, potentially significant, Wednesday afternoon-evening with large hail, damaging winds, and tornadoes possible. Many forecast details still uncertain.

- Conditional severe weather risk in our far southeast on Thursday depending on how Wednesday's event evolves.

DISCUSSION

Issued at 100 AM CDT Mon Jun 8 2026

Today: Muggy with Showers and Storms, Locally Heavy Rain

A shortwave trough lifting in from the southwest combined with weak low level moisture transport will contribute to renewed fairly widespread shower/storm chances across the area today into this evening. As the moisture transport axis becomes more south-north oriented, a rich plume of precipitable water will increase overhead this morning to around 2 inches, with dewpoints climbing to around 70. It is noteworthy that warm cloud layer depths today are also on the increase to around 4km, so the deep saturation through the column along with tall/skinny CAPE profiles will favor heavy rainfall potential with any more robust convection.

Storm motion should be a little faster compared to yesterday due to the shortwave pushing through, so it is less likely to have heavy rain stall over an area. However, if storms repeat over any areas, particularly those in northeast Iowa and southwest Wisconsin that were recently saturated by heavy rain in the past 72 hours, there could be a quicker runoff response that could potentially lead to localized flooding. HREF max 24 hour rainfall suggests pockets of 2 to 5" rainfall is not out of the question, mainly over western Wisconsin. Given the limited instability (up to 1000 J/kg SBCAPE) and weak shear profiles, severe storms are not expected from today's convection.

Tue - Wed: Heat and Humidity Briefly Build In

Upper level ridging will build behind the departing shortwave trough beginning Monday night and continuing through Wednesday. This sets us up for the long-advertised but brief hot spell Tuesday into Wednesday. Recent NBM runs have shown a slight downward trend in the potential for max temps reaching 90+ owing to some questions around cloud cover and Wednesday's precipitation chances. But by Wednesday the NBM mean has widespread low to mid 90s. GEFS and ENS both lend very high confidence (>90%) for dewpoints nearing or exceeding 70 for the majority of the area Tuesday and especially Wednesday, creating sticky, humid conditions. Heat indices on Tuesday look to reach into the 90s with values of 95-105 for Wednesday, again conditional on how clouds and storms unfold.

Wed Afternoon/Evening: Severe Storms, Potentially Significant

The heat and oppressive humidity will break heading into Thursday, but not before a potentially significant severe weather setup Wednesday afternoon-evening. Deep longwave troughing digging into the Northern Plains and eventually Upper Mississippi Valley will drive a strong cold front into the region heading into Wednesday evening. The magnitude of severe weather will hinge on the exact timing of this front and resultant impacts on available instability. Frontal passage in the late afternoon to early evening hours would encounter SBCAPE on the order of 2500-3000+ J/kg (per GEFS/GEPS), whereas a delayed arrival into the evening would mean less instability to work with.

There does look to be ample deep layer shear near the front of 40+ knots to support supercells with hodographs showing pronounced clockwise curvature in the 0-1km layer. All severe storm hazards will be in play, but their likelihood will depend on storm mode details that will be pinned down over the next couple days. Will also have to watch to see if any convection Tuesday night into Wednesday morning might spoil the severe weather setup for later in the day.

Thursday: Conditional Severe Weather Threat in NE IA & SW WI

By Thursday morning, the cold front will stretch from the Central Plains into the Upper Great Lakes with potentially a developing surface low riding northeast along it. This should focus the bulk of convective activity just to our southeast, but far northeast Iowa and southwest Wisconsin could be on the fringes depending on exactly where the front sets up. By afternoon, our southern tier of counties could be on the SBCAPE gradient with rich deep layer shear in place, supportive for some additional severe weather potential. In short, Thursday's severe potential will be conditional, hinging on how Wednesday's event evolves.

End of the Week into the Weekend: Cooler

Periodic small shower and storm chances dot the extended forecast into the weekend, but by Sunday into next week deep upper troughing looks to bring a flip to below normal temperatures.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 100 AM CDT Mon Jun 8 2026

Widespread showers and isolated thunderstorms move through the region through mid to late afternoon today. Ceilings fall to MVFR/IFR during this time, with the higher probabilities of IFR ceilings (50-70% chance) west of the Mississippi River before 15Z today. Pockets of IFR visibilities will occur with any of the stronger showers. This system departs in the late afternoon and evening, and depending on how fast clouds depart, a widespread IFR/LIFR fog looks to develop overnight into Tuesday morning. Winds through midday will be from the southeast at 5-10kts, become lighter and more variable during the afternoon into the overnight.

ARX WATCHES/WARNINGS/ADVISORIES

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