textproduct: La Crosse

KEY MESSAGES

- Shower chances move west to east this morning into the afternoon, minimal overall accumulations expected.

- Heavy rain likely Monday through Monday night with flooding concerns where heavy rain bands set up.

- Rain chances return Wednesday, potentially lasting into the weekend.

DISCUSSION

Issued at 1245 AM CDT Sun Sep 13 2026

Today:

Shower chances through today will be tied to a mid level trough passage and positive mid level vorticity advection through the Upper Midwest. Overall limiting factor for coverage and amounts will be available moisture.

Rainfall Chances Monday Night:

Heavy rainfall spreads northeast through Monday morning, becoming widespread through of the rest of Monday and Monday night. The responsible closed upper level anticyclone on upper level water vapor imagery loops over the Pacific Northwest will rapidly advect east into southern Canada, drawing 90th percentile (TOP 13.00Z RAOB - Climatology) north through the Central to Northern Plains. Resultant local PWATs expected to near 2" by Monday Night (GEFS 12.18Z 30-60% ; EPS 12.18Z 50-90%). Initial, more widespread rainfall expected to progress east within the closing warm, moist sector advecting east across the Upper Midwest through Monday. Solidification of the low level frontal boundary and intensification of the low level jet with anomalous level moisture increases flooding concern primarily across the southern half of the forecast area Monday night. Exact location of the frontal boundary focusing the heavier rainfall rates as the parent low exits east will determine location of highest concern, varying from west-central Wisconsin, east-central Minnesota, and northeast Iowa in the available LREF (12.12Z). LREF (12.12Z) member mean precipitation spreads from 0.6" (GEFS) to 1.4" (EPS) with intermember interquartile spread from 0.25" (GEFS) to 1.2" (EPS), outlining the current forecast challenge in fine tuning location of highest impacts.

Rainfall Returns Wednesday:

Monday's frontal boundary expected to remain just south of the locale forecast area as passing anticyclonic low level flow mostly drying things out for Tuesday before a similar trajectory ejecting upper level low lifts northeast through the Northern Plains for Wednesday. While the anomalous moisture will remain on the southern doorstep of the local forecast area, meridional extent of the low's path leaves discrepancies and lower confidence for northern surge of moist air. Therefore, have kept NBM precipitation probabilities Wednesday through Saturday. The long duration of rainfall potential would increase additional flooding concerns through the week.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1245 AM CDT Sun Sep 13 2026

VFR conditions through the TAF period. Rain showers will move into the region, mostly along and south of I-90, around sunrise and push eastward. All rain chances subside by the mid- afternoon. CIGS hang around 10kft during the morning and early afternoon before clearing out for the rest of the TAF period. Northwest winds will be sustained at 5 to 10 mph into the evening.

ARX WATCHES/WARNINGS/ADVISORIES

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