textproduct: La Crosse

KEY MESSAGES

- Light to moderate rain continues this morning, with a 60-80% chance of renewed thunderstorm development later this afternoon and evening over NE Iowa and SW Wisconsin.

- An additional 2 to 4 inches of rain possible with these afternoon thunderstorms in NE Iowa and SW Wisconsin, which could lead to renewed flooding concerns.

- Additional light rain possible (20-30% chance) Monday night into Tuesday, but the bulk of next week looks cooler and drier.

DISCUSSION

Issued at 630 AM CDT Sat Sep 19 2026

This Morning: Ongoing Heavy Rain and Flooding Concerns

Our well-advertised heavy precipitation event dropped upwards of 6 to 7+ inches of rain along a 10-15 mile wide band from northwest of Albert Lea, MN, through northern Mower, Fillmore, Houston and western Vernon counties with additional corridors of heavy rain across portions of northeast Iowa, in particular Fayette and Clayton counties. Multiple reports of flooding have been received and several rivers are rising close to flood stage. Recent radar trends have shown a slow by steady downward trend in rainfall rates as the LLJ weakened after 09Z, with this trend expected to continue through the morning hours.

This Afternoon: Continued Heavy Rain Threat in NE IA/SW WI

As a shortwave over the Siouxland ejects eastward and lower level moist advection increases later this morning, there is a short window for far southwest Wisconsin and adjacent parts of northeast Iowa to find themselves south of the surface front. Thus, as the shortwave approaches, additional showers and thunderstorms will likely (60-80%) develop there. With PWATs still near 2", efficient rain rates are once again favored. Of particular concern is the potential for this round of rain to overlap with where heavy rain occurs overnight. Should this occur, flooding concerns would be heightened. Finally, while highly unlikely given the tendency for lower tropospheric temperature profiles to be moist adiabatic, the window with surface-based thunderstorms introduces a risk (1%) for a stray tornado as sfc-500m helicity values look to reach around 100-150 m2/s2.

Next Week: Cool and Drier

The lower tropospheric baroclinic zone slides to the south of the region by Sunday morning, taking the bulk of the rainfall risk with it. Cannot fully rule out some stray elevated showers scraping parts of east-central Iowa during the day, but most of the region will stay dry with some sun poking out as we move through the afternoon. The mean longwave trough/cutoff low currently over the Inter-Mountain West slides eastward for Monday night into Tuesday, bringing with it the next potential for wider coverage showers. However, with the deeper moisture displaced well to the south of the region, any impacts from this rain will be low. Eastern flow off a Great Lakes/Ontario high will keep temperatures seasonably cool and mostly dry for the remainder of the week.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 630 AM CDT Sat Sep 19 2026

Widespread IFR to LIFR ceilings this morning will only lift a few hundred feet today with most locales seeing IFR ceilings for much of the day, which fall back to LIFR/IFR for tonight. Higher elevations may see fog at times as a result of these very low ceilings. Periods of showers will also result in reduced visibilities through this evening, mainly south of a AEL to DLL line. Winds slowly back from the east to the NNE through the day at 5 to 10 kts with a few gusts to 15 kts.

HYDROLOGY

Issued at 630 AM CDT Sat Sep 19 2026

Minor flooding is ongoing over the headwaters of the Cedar, Root, and Turkey Rivers rivers with minor flooding still possible over the Kickapoo basin.

A second round of heavy thunderstorms will likely occur (60-80%) in far southwest Wisconsin and adjacent parts of northeast Iowa. Additional flash flooding and rises on streams and creeks would occur if these thunderstorms develop with heightened concerns for flash flooding should these storms track over the same areas that saw heavy rain over the last 12 hours.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Flood Watch until 1 PM CDT this afternoon for WIZ053. Flood Watch through this evening for WIZ054-055-061. MN...Flood Watch until 1 PM CDT this afternoon for MNZ094>096. IA...Flood Watch until 1 PM CDT this afternoon for IAZ008>011-018- 019-029. Flood Watch through this evening for IAZ030.