textproduct: La Crosse

KEY MESSAGES

- Showers and storms are likely (60-80%) Wednesday, primarily during the afternoon into the overnight bringing heavy rainfall. Amounts of 1 inch or more possible (30-50%) with localized amounts of 2-3 inches.

- Strong to severe storms may accompany the heavy rainfall Wednesday. Damaging wind gusts will be the primary threat.

- Seasonable temperatures are expected throughout much of the week with highs in the low to mid 80s before warming through the weekend and into next week.

DISCUSSION

Issued at 156 PM CDT Tue Jul 7 2026

Rest of Today

Fairly quiet conditions are expected to linger throughout the remainder of the afternoon and into this evening as weak upper ridging remains situated across the region. There does appear to be some low potential for a stray shower or storm mainly along and north of I-90 ahead of sunset given a few hours where MLCAPE reaches 1000-1500 J/kg per RAP/HRRR/RRFS soundings. The main uncertainty regarding this potential is the lack of a definitive forcing mechanism for convective initiation. Currently thinking any convective development sits at a 10-15% chance.

Wednesday - Thursday: Heavy Rain and Strong to Severe Storms

More zonal flow takes hold late this evening into the overnight hours, allowing several shortwaves to translate eastward and spark convective development across portions of central Minnesota and northern Wisconsin. CAM guidance and short-range ensembles such as the 07.12z REFS/HREF suggest the bulk of convective activity will remain to the north along a surface boundary that currently extends from South Dakota across Minnesota and into northern Wisconsin and along with it, the heaviest rainfall. However, towards the morning hours, showers and storms should begin to move into Taylor and Clark Counties (30-60%) bringing a period of heavy rainfall.

The aforementioned boundary begins to slide southeastward through the Wednesday as another leading to showers and storms across the Upper Mississippi River Valley. Heavy rainfall is expected to continue along this boundary given favorable PWATs in excess of 1.7 inches, above the 90th percentile of climatology, and warm cloud depths of 10-12kft. Boundary relative flow is somewhat parallel rather than orthogonal such that the risk of training is slightly reduced. That said, there is still some decent probabilities for amounts greater than 1 inch of rain in the 07.13z NBM which sits at 30-50%. The 07.12z HREF/REFS 24hr LPMM also suggest some pockets of 2-3 inches are possible along and north of I-90 which would lead to some flooding concerns, especially over southeast Minnesota where the greatest rainfall amounts occurred last week. There is also some flooding concern for areas that see multiple rounds of rain such as north-central Wisconsin. That said, the progressive nature of the boundary should help keep mitigate some of the flooding risk.

On top of the heavy rain threat, storms that develop Wednesday may become strong to severe. MLCAPE on the order of 1500-2500 J/kg would support stronger updrafts, although shear is the biggest uncertainty regarding organized convection. There is a few hour window where stronger 500hPa flow aloft elongates hodographs in the 3-6km layer, resulting in shear values of 30-35kts which would support some supercellular structures in storms that initially develop. This would result in a short period where hail could pose a threat, but given the previously discussed warm cloud depths and a WBZ height above 10kft, hail is a lower end threat. However, this upper flow quickly diminishes with time resulting in wind shear being confined to the 0-3km. This would suggest the severe threat would transition to damaging winds as cold pool development and upscale growth to more of a linear mode occurs.

Friday - Early Next Week: Warmer Temperatures Return

Over the weekend, mid to upper level ridging begins to build across the United States which is noted in most/all of the deterministic and ensemble guidance. Heights associated with this ridge are expected to be fairly impressive, reaching 594-600dam at 500hPa, which the 07.00z NAEFS highlights as near or exceeding the maximum heights within climatology. Surface temperatures trend warmer this weekend into next week in response to these rising heights. There's still quite a bit of spread within the various ensemble suites regarding what the temperatures will ultimately be, but interquartile spreads suggest highs in the upper 80s are favored, but possibly reach into the low 90s. Dewpoint temperatures also increase during this period as the 07.07z NBM suggests a 30-60% probability to exceed 70 degrees highest over northeast Iowa, translating to apparent temperatures in the 90s. Will need to continue monitoring trends, but a return to warm and muggy conditions looks to be on the horizon.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1219 AM CDT Wed Jul 8 2026

VFR conditions throughout much of the overnight give way to shower and storm concerns throughout the morning through evening hours for Wednesday. Will have to watch to see if storms in north-central WI shown in the CAMs early this morning could make their way to the I-90 corridor (under 20% chance), however the bulk of the CAMs keep the I-90 corridor storm free until afternoon. MVFR to IFR reductions are to be expected with any storms and a few storms may be strong to severe with gusty to locally damaging wind gusts. Cigs will remain predominantly VFR outside of any storms but will lower to low-VFR and perhaps MVFR north of I-90 towards 06z Thursday. Winds will remain from the southwest throughout much of the day at around 6-12 kts.

ARX WATCHES/WARNINGS/ADVISORIES

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