Zimmerman, MN Weather

Key Messages

- Warm today, followed by a return to seasonal temperatures for much of the upcoming week.

- Multiple chances for rain through the middle of next week. Heaviest rainfall amounts expected across western MN.

Discussion

Issued at 250 AM CDT Sat Oct 24 2026

Slow-moving band of rain showers is exiting eastward across western WI, with a more recent batch trailing showers captured on radar over portions of central MN. These showers have developed within a 40- 50kt LLJ that spans from SW to NE across MN. Not anticipating these showers to be too heavy as latest ACARS data along with forecast soundings depict a very dry lowest 10k feet of the column along with a lack of elevated instability. Breezy southeasterly surface flow combined with cloud cover is working to limit cooling, so morning lows are on track to only dip into the upper 50s to lower 60s (this is ~5-7 degrees warmer than normal highs this late in October!).

One more warm day ahead, as the Upper Midwest begins the day located within the warm sector of a deepening surface cyclone positioned over south central Canada. The system is progged to rapidly lift northeast through the day and will send a trailing cold front southeastward across the forecast area. The front is progged to be near the border of the Dakotas and MN by daybreak, where showers and a few rumbles of thunder will be possible through the morning. The morning frontal position sets the stage for a 10+ degree high temperature gradient from western MN to western WI. The earlier frontal passage across western MN will limit heating and support highs in the lower 60s. Surface heating is forecast to be more efficient through the morning and into the early afternoon to the east of the front over much of east- central and southeastern MN as well as western WI. Filtered sunshine and ongoing WAA will yield highs in the low to mid 70s for locations that remain east of the front through midday. The band of rain showers will move east towards the I-35 corridor this afternoon and continue to drift eastward through the evening. Rainfall amounts will be the greatest across western MN (isolated tenth to quarter inch amounts possible) and decrease with eastward movement through the day (a few hundredths across southeastern MN/western WI). Winds turn northwesterly behind the frontal passage and will usher in much cooler air for Sunday. Forecast highs fall to more seasonal levels in the low to mid 50s. The mostly cloudy and cooler Sunday weather will also feature the potential for a few isolated raindrops.

Better chances for widespread rain (particularly across the western half of the forecast area) will arrive early in the work week as a compact upper-level shortwave lifts north through the Plains. Associated surface low is forecast to develop and track from central NE to northwestern MN Monday into Tuesday. This evolution will combine with PWATs 200-250% of normal to support a shield of heavy precipitation along the surface low track. A swath of 1-1.5" rainfall amounts appears most likely along the consensus low track from central NE to eastern SD into far western MN. While most communities will observe rain, overall amounts will lower as one moves east from far western MN. Continued cloud cover and rain spreading north results in cooler highs in the 40s across much of central/western MN on Monday.

The aforementioned upper-level shortwave is progged to shear out near the International Border as a more potent trailing wave digs across the northern CONUS Tuesday into Wednesday. This will spawn a surface cyclone near the International Border, once again placing the Upper Midwest on the "warm side" of the system. Temperatures should rebound into the 50s/60s on Tuesday prior to the passage of another front late Tuesday into Wednesday morning. Guidance varies on the timing and coverage of precipitation during this period, but the 30-50% PoPs early in the day on Wednesday tend to represent the forecast uncertainties well at this distance. Our latest forecast shows highs in the low to mid 60s following the early morning precipitation on Wednesday. We'll note that these temperatures may be too warm should the timing and evolution of upper-level and surface features slow down in upcoming forecasts.

The second half of next week features a return to large scale ridging over central CONUS, however influence from an active southwesterly jet may support occasional rain chances. In addition, the ridging is fueling a growing number of ensemble members (including machine learning ensemble counterparts) that feature a return to above normal temperatures heading into Halloween weekend. Should this become more of a "trend" we could see the NBM warm out of the upper 50s (which is already above normal) late next week.

Aviation

Issued at 1237 PM CDT Sat Oct 24 2026

Cold front over northern-western MN continues to make slow progress eastward across the state, but it still expected to do so through this afternoon and across western WI tonight. Swath of mainly -RA, with few-and-far-between CB/TS, over western MN will still progress eastward but will lose much of its energy thus no CB/TS is expected to reach any of the terminals and any -RA that does will likely have visibility hold at 6SM. Ceilings may well drop to MVFR with any rainfall this afternoon-evening then rise back to VFR levels overnight through tomorrow. Additional chances for rain return Sunday as the front stalls and enough lift tries to squeeze out moisture in the form of rain. Otherwise, mid-to-upper level ceilings will prevail. Winds will swing from SW to NW with the frontal passage, remaining near 15G25kt during the daylight hours today then gradually drop to the 5-10kt range this evening through tomorrow.

KMSP...Dry conditions are expected until late afternoon, then a few showers will try to drift across the field through the mid- evening hours. Little to no impacts are likely, outside of potentially some upper-range MVFR ceilings. Additional showers are possible mid-to-late Sunday afternoon, again with potentially MVFR conditions. Winds at initialization were 220 but the swap to W and NW winds are not too far to the west of MSP, so the wind shift looks to be fairly imminent. Winds will then remain NW from sunset through the overnight hours, and continue to slightly veer to NE during the day Sunday.

/OUTLOOK FOR KMSP/ MON...-RA/MVFR likely, chc IFR. Wind NE 5-10kts. TUE...Chc A.M. -SHRA/MVFR. Wind SE 10-15kts. WED...Chc A.M. -SHRA/MVFR. Wind SW 10-15kts.

Mpx Watches

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