textproduct: La Crosse

KEY MESSAGES

- Below normal temperatures for the remainder of the week, warming back to around average on Saturday.

- The risk for near freezing early morning temperatures continues for Thursday and Friday, focused mainly east of the Mississippi River.

- A few rounds of light showers pepper the area through the end of the week, but the vast majority of the forecast period through Saturday afternoon looks dry.

DISCUSSION

Issued at 149 PM CDT Wed May 6 2026

Today: Quiet and Cool

A substantial cloud deck has formed across the Upper Midwest early this afternoon, keeping temperatures on the cool side in the 40s. As this is expected to persist into the evening, have lowered high temperatures for this afternoon to adjust for this trend. Any sort of clearing will help temperatures briefly recover into the upper 40s but not anticipating widespread 50+ degrees anymore. As a weak shortwave passes through the mid-levels just to our north, this might set off some showers later this afternoon as it interacts with more abundant moisture aloft and some elevated weak instability. A continued inverted-V signature on area soundings highlight the dry air in the low levels so much of the shower activity may not even reach the ground and present more as virga. Most showers should remain to our north across far northern Wisconsin but a few sprinkles will be possible for some of our North Central Wisconsin counties later this afternoon.

While the cloud cover is expected to continue through the afternoon, these are expected to mix out by later this evening. However, another deck of clouds is expected to move in late overnight with yet another shortwave impulse passing overhead. This cloud cover is expected to limit the severity of radiational cooling tonight, even with very light winds and a dry low level airmass in place. As such, have opted for a Frost Advisory for WC/SW Wisconsin, and eastern portions of SE Minnesota and NE Iowa as these areas will have a little more time to cool before the clouds move in. Low temperatures should be tempered by these clouds so most areas outside of the notorious cold drainage areas should stay right around freezing and not drop into the 20s like last night.

Thursday - Friday: Warmer with Some Passing Showers

As previously mentioned, another shortwave impulse is expected to propagate through the northwest flow aloft tomorrow as the western periphery of the longwave trough remains over the Upper Midwest. This is expected to provide a focus for shower development early tomorrow morning through the afternoon hours. The main question continues to be about the mid-level moisture plume expected with this passage. Global models and the grand ensemble of the LREF continue to show a more widespread footprint of moisture and overall QPF return. The hi-resolution models have remained less enthused about the overall chances with more meager moisture return. As such, NBM probabilities for measurable precipitation have decreased to less than 20% for areas along and east of the river. Have generally continued with the previous forecast in capping PoPs at 20-30% given this lack of confidence in significant enough moisture depth to effectively overcome the substantial dry air at the surface. In any case, showers should be very light with minimal impacts expected.

Temperature wise, highs finally start to climb out of the 50s and into the 60s across the region, more seasonal for this time of year. Will need to monitor the potential for yet another frost/freeze headline Friday morning as sub-freezing temperatures look possible for WC Wisconsin. Current NBM probabilities of sub freezing low temperatures sit in the 10-30% range but this jumps significantly when looking at the LREF grand ensemble (ENS, GEFS, GEPS) to 40-80%. This would mainly be for the Chimney region but some locations further south could certainly get close to freezing, necessitating a Frost Advisory. Will need to see how quickly the upper wave moves through and if/how this will impact potential cloud cover.

This Weekend - Early Next Week: Warmer to Start, More Rain Chances

As the dome of cold air aloft finally gets shunted to the east by this weekend, we'll likely see our warmest temperature of the forecast period on Saturday. A lobe of 850mb thermal ridging is expected to work its way into the Upper Mississippi Valley with some low level warm air advection out of the west/southwest. High temperatures look to climb into the upper 60s to low 70s for most, a pleasant reprieve for the 40s today. However, this will be short lived as a cold front extending from a weak surface low to our north in Western Ontario will start to push southeast into the region. The low level southwest flow will allow for some moisture return, resulting in some slightly increased pWats across the area (still low by seasonal standards but more than what we've seen for much of this past week). Because of this slight increase in moisture, some low chances for showers and maybe even a few thunderstorms will be possible later in the day on Saturday along and ahead of the front. There's still some synoptic uncertainty in regards to this system so will leave the blended solution with slightly higher PoPs (30-40%) confined to SW Wisconsin and NE Iowa. The more time an area can have for moisture return ahead of the frontal passage will help with rain chances so the timing of the front will likely play a big role in forecast QPF amounts. These details will be ironed out over the coming days.

Behind the front, skies will clear out as a surface high pressure drops south out of Canada. This will keep conditions dry and temperatures seasonal for the area into early next week. It isn't until Tuesday next week that we see more widespread rain chances return as a ridge builds over the western CONUS, putting our region under more cyclonic flow aloft. This will also coincide with more robust moisture return, allowing for more substantial rain chances.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1230 PM CDT Wed May 6 2026

BKN-OVC skies continue through the afternoon hours today, although these ceilings remain VFR given bases of 4kft or greater. Northwest winds also continue through the afternoon hours with gusts to 25KT, strongest west of the Mississippi River. Winds diminish with sunset, becoming light overnight and backing to the south-southwest before veering to the northwest again for Thursday. Some clearing is expected overnight ahead of another bout of clouds around 5-10kft that moves through the region late tonight into Thursday morning. Thursday afternoon brings some potential for isolated showers along and east of the Mississippi River, but confidence in showers is low, with the 06.12z HREF only painting 10-30% probabilities for measurable precipitation.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Frost Advisory from 1 AM to 8 AM CDT Thursday for WIZ017-029- 032>034-041>044-053>055-061. MN...Frost Advisory from 1 AM to 8 AM CDT Thursday for MNZ088-095- 096. IA...Frost Advisory from 1 AM to 8 AM CDT Thursday for IAZ010-011- 029-030.