textproduct: La Crosse

KEY MESSAGES

- Slightly warmer temperatures expected Friday compared to Thursday as precipitation chances increase overnight through Saturday.

- Overall confidence in heavy rain remains low (<25%), albeit higher than severe storm potential (<15%) through the weekend.

DISCUSSION

Issued at 1240 AM CDT Fri Aug 28 2026

Slightly Warmer For Friday, Rain Chances Increase Overnight:

Slightly warmer temperatures expected through Friday compared to Thursday as the colder low level air slowly exits east and return flow ramps up through the evening hours. Upper level water vapor imagery loops place the responsible upper level ridge axis over the Rocky Mountain West overnight, abating strongest low level moisture advection upstream of the local forecast area through southern Minnesota into the Missouri River Valley. Initial sprinkles will be possible overnight with first lobes of low level moisture advection with eventual phasing of the upstream extratropical cyclone east increasing widespread heavy rain chances through much of Saturday across the Upper Mississippi River Valley

Weekend Heavy Rain Potential:

Highest confidence in heavy rain being the main impact as PWATs of 1.5" to 2" (GEFS/EPS) are well above 90th percentile RAOB climatology (SPC) as subsequent extreme phasing of the low level trough abandons the accompanying low level frontal boundary through the weekend. While local annual climatology places the main threat for flooding earlier in the calendar year, a secondary annual maxima during the late summer months into early autumn can be attributed to similar setups with lingering low level moisture and a quasi- stationary frontal boundary. Therefore, although overall NBM precipitation forecast probaConfidence remains low (around 30 percent) along thebilities remain low (<24%) through the weekend and given the disallowment of forecasting away from the NBM, repeat storms forming over the same areas may raise flooding concerns and will be a forecast detail/impact to remain cognizant of.

Weekend Severe Storm Potential:

While lower NBM precipitation probabilities (<24%) limit overall confidence in storms affecting the forecast area, LREF joint probabilities for 0-500mb bulk shear of 30+ kts and SBCAPE/MUCAPE of 500+ J/kg of 70-95% increase local severe storm concerns Sunday into Monday. Accompanying LREF sounding plumes suggest a low level temperature inversion will limit widespread storm initiation as well as severe storms should/could remain elevated in nature. While low level wind signal doesn't suggest a concurrent low level jet, location of a quasi-stationary frontal boundary may be sufficient forcing to initiate short window of storms should severe ingredients temporally coalesce.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 547 AM CDT Fri Aug 28 2026

IFR to LIFR valley fog will continue in the Wisconsin and the Mississippi tributaries through 28.15z. Meanwhile, there will be some low stratus in the Mississippi mainstem. Otherwise VFR conditions are expected.

ARX WATCHES/WARNINGS/ADVISORIES

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