textproduct: La Crosse

KEY MESSAGES

- Isolated light showers continue through the morning hours, mainly west of the Mississippi River.

- Drier conditions are expected tonight through Monday before rain chances return Tuesday through the rest of the week.

- Temperatures will remain seasonal in the 60s to 70s.

DISCUSSION

Issued at 1243 AM CDT Sun Sep 27 2026

Today - Tuesday: On and Off Chances for Rain, Dry Periods

A weak upper level shortwave trough overhead is interacting with relatively deep moisture west of the Mississippi River creating some isolated light showers. Additional development is expected through the early morning hours as additional mid-level moisture makes its way into the region. With generally drier air east of the river, most activity will remain across SE Minnesota and NE Iowa through the morning hours before dissipating as synoptic lift from the exiting upper trough weakens. Generally dry conditions will prevail for late Sunday through Monday with temperatures ranging from ranging from the mid 60s to the mid 70s.

For the early portions of the work week, our area will be in between two primary weather systems: a low pressure system across the northeastern US and strong trough across the Southwestern CONUS. This will leave our area in a realm of increasing southwesterly flow aloft. Deep moisture is also expected to be on an uptick moving into Tuesday as it surges northward ahead of the trough. This deep moisture combined with embedded shortwave impulses will allow for the development of showers and potentially thunderstorms across the region Tuesday through Tuesday night. Precipitable water values could certainly exceed 1.75 inches, maybe even nearing the 2 inch threshold, through the course of the event. Current WPC forecasts show QPF amounts generally between 0.5-0.75 inches for much of the area with some locations approaching or even just barely exceeding the 1 inch threshold from 12Z Tuesday to 12Z Wednesday. While the 90th percentile rainfall amounts from the LREF do highlight the potential for some locations to see an inch or more, confidence in this occurring is still fairly low as appreciable low level forcing might be hard to come by (certainly hard to make out at this time) and moisture quality will be a factor.

Rest of Next Week: Daily Rain Chances May Continue

The remainder of this forecast period is highly uncertain as it will depend upon the evolution of the low pressure center associated with the synoptic scale trough as well as how this feature combines with the remnants of now Hurricane Polo. Ensemble guidance along with deterministic forecast models indicate plenty of differences in timing and location in the axis of better rain chances for Wednesday and beyond. This is shown really well in the NBM PoP values, which keep at least low to medium (20-50%) chances for rain through Friday. The current expectation is that the heaviest rainfall will stay south of the Upper Midwest, but there are outlier solutions that produce 2+ inches of rainfall during the later half of this upcoming week. Temperatures are forecast to remain near average to end the month of September.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1243 AM CDT Sun Sep 27 2026

Scattered showers and perhaps a rumble of thunder will continue overnight, mainly along and west of the Mississippi River, although some light rain is possible across Wisconsin as well. Along with these showers, MVFR conditions are expected with ceilings possibly falling below 1kft across southeast Minnesota and northeast Iowa later this morning, a 20-40% chance per the 27.00z REFS/HREF. Light southerly winds continue this morning, becoming variable this afternoon.

ARX WATCHES/WARNINGS/ADVISORIES

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