textproduct: La Crosse

KEY MESSAGES

- Very low chances (<15%) for rain showers across Southeast Minnesota and Northeast Iowa today. Better chances to stay west of the I-35 corridor.

- Chances for showers/storms return in earnest (60-90%) for Tuesday with heavy rain being the main concern.

- Dry conditions and near normal temperatures to prevail from Wednesday through the end of the work week.

DISCUSSION

Issued at 221 AM CDT Sun Sep 6 2026

Morning Fog & Storm Chances Staying West Today:

It'll be a foggy start to the day with light winds and stout surface moisture allowing for widespread patchy fog development across the region. To our west, across Western and Central Minnesota, showers and thunderstorms are expected to develop late tonight into the morning hours along the leading edge of some theta-e advection. Additional convection is expected to develop through the afternoon along an axis of instability just to our west. A stout layer of warm and dry air in the low levels across our area around 850 mb should keep areas east of the I-35 corridor capped enough to limit any convective development making its way into our area.

Increasing Rain Chances Through Start Of New Week:

By Monday, an upper wave will begin to eject out of the Pacific Northwest and into the Northern High Plains. At the surface, a low pressure center is expected to move out of the Northern Rockies and into the Canadian Plains, gradually occluding into midweek. As the upper level trough axis moves into the region, it will encroach on a very moist warm sector and provide some additional support aloft, setting off convection. 05.18Z ensemble soundings do not show a particularly unstable environment across our area with a strong cap in the low levels noted but pWats could very likely be in the 1.75- 2+ inch range so heavy rainfall along and ahead of the frontal boundary will be something to keep an eye on. Storm motion and overall boundary movement look to be progressive enough to limit any significant flash flooding concerns but 0.5-1 inch totals over a 6- 12 hour period are not out of the realm of possibilities. The heaviest rain should occur through the day on Tuesday with chances decreasing through the overnight hours as moisture gets scoured out by the frontal boundary early Wednesday morning.

Wednesday - Next Weekend: Drying Out, Near Normal Temperatures

As the upper wave/trough axis move east, the trailing frontal boundary from the occluding surface low well to our north in Canada will sweep through the region. This will finally usher in a drier airmass to the region as a whole with dew points falling back into the upper 50s. A weak surface high is expected to build into the Midwest by Thursday. This, in combination with zonal flow to weak ridging aloft, will keep conditions dry for the late week period. Temperatures behind the front won't be much "cooler" but they will be a bit closer to normal in the 70s to lower 80s Thursday and Friday. The next chances for rain look to come by the weekend as another upper wave looks to potentially swing through the upper Midwest.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 520 AM CDT Sun Sep 6 2026

While Dense Fog has remained east of both TAF sites, affecting KVOK, K82C, KY51, & KLNR, low level stratus causing LIFR-IFR ceilings at 06.12Z TAF issuance. Expect visibilities to drop near IFR before conditions improve after sunrise (~15Z). Subsequent additional Fog and overnight impacts possible Sunday night into early Monday morning.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Dense Fog Advisory until 9 AM CDT this morning for WIZ042-043- 053-055. MN...None. IA...None.