textproduct: La Crosse

KEY MESSAGES

- Heavy rain looks to possible through Thursday night. At this time, the greatest threat looks to be south of Interstate 90.

- Weak shear and CAPE profiles will likely minimize severe weather threats from late this afternoon into Thursday evening.

DISCUSSION

Issued at 316 AM CDT Wed Jun 11 2025

Through Tonight

At 3 am, surface cold front near the Interstate 94 corridor will gradually move south this afternoon and evening and it will be located just north of Interstate 80 by morning. South of this front, most unstable CAPES means are in the 1000 to 1300 J/kg range. As the cap near 800 mb gradually erodes in the warm sector, convection should initiate in northwest Iowa and southwest Minnesota early in the afternoon and move into northeast Iowa and southeast Minnesota by late afternoon or early evening.

With soundings showing a very skinny CAPE, hail should be generally less than 1 inch in diameter. While the sub-cloud layer remains dry, the winds aloft are generally less than 30 knots. As a result, the threat for damaging winds look to be on the low side (up to 5 percent). While the 0-3 km hodographs show some slight curvature for storms near the front, the high LCL heights are not that favorable for tornadoes. SPC has a marginal (level 1 out of 5) risk south of Interstate 90 and that looks reasonable.

With precipitable water values between 1.3 and 1.7 inches and warm cloud layer depths up to 4 km, the showers and storms south of Interstate 90 will be efficient rain producers. 11.00z HREF mean ranges from 0.5 to 1.5 inches across southeast Minnesota, northeast Iowa, and southwest Wisconsin. The highest totals look to be in northeast Iowa. The ensemble localized probability- matched means are in the 3 to 5 inch range in northeast Iowa and 1.5 to 2.5 inches in southwest Wisconsin. WPC has this area under a marginal (less than 5 percent) risk of excessive rain.

With the HRRR indicating that there will be some increase in surface smoke just north of the cold front in southeast Minnesota and west-central Wisconsin tonight, smoke was added to the forecast grids.

Thursday through Thursday Night

As a low pressure area moves east along the North Dakota and South Dakota border, the front will move back to the north. With cool air and clouds north of this front, there is some uncertainty on how far north this front will be able to move. Like today, the mean most unstable CAPES will climb into the 1000 to 1300 J/kg range in the warm sector of this system. Soundings continue to show skinny CAPES and weak shear. The winds throughout the sounding are much lower than they are today. As a result, the severe weather threat look to be very low.

Precipitable water values remain in the 1.3 to 1.7 inch range and warm cloud layers are up to 4 km. This again will result in showers and storms being highly efficient rain producers. The 11.00z HREF have 24-hour rain totals ranging from 0.25 to 1.5 inches south of Interstate 94 with the highest totals in northeast Iowa. The ensemble localized probability-matched means are in the 3 to 7 inch range in northeast Iowa and 1.5 to 2.5 inches in southwest Wisconsin.

Friday and Friday Night

The low pressure area will move slowly east across the area and into the southern Great Lakes. With the better moisture shifting east of the area and weaker 925 and 850 mb moisture transport into the area, the threat for heavy rain looks to be east of the forecast area. Up to an additional inch of rain will be possible. The highest totals will be along and north of I-94 where there will be the best moisture and convergence.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 545 AM CDT Wed Jun 11 2025

VFR conditions are likely throughout much of the TAF period as increasing mid-level clouds move in this afternoon. As we head towards the evening hours, showers and some isolated storms will move through the region. In more robust showers/storms, some MVFR vsby reductions may be possible (10-20% chance), however did not include any category reductions or TS mention in the TAF at this due to low confidence on how any convection will develop near and north of I-90. Otherwise, winds will remain between 5-10 kts throughout much of the TAF period and will shift from northerly to easterly later this evening. Some MVFR cigs may be possible near or just after 12z as the 11.06z HREF has some increasing probabilities (30-60%) during this time period.

ARX WATCHES/WARNINGS/ADVISORIES

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