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KEY MESSAGES

- The passage of a strong cold front will spawn showers and thunderstorms across eastern MN and western WI today. Strong to severe thunderstorms are possible along and east of a line from Mankato to Mora, with the highest severe potential across western WI.

- Large hail and damaging winds are the primary hazards across eastern MN and points east. The risk of tornadoes increases over western WI, along with the intensity of each hazard.

- Much colder air is expected for the weekend with possibly a few snow showers but with no snow accumulation.

DISCUSSION

Issued at 304 AM CDT Fri Apr 17 2026

It's a quiet and mild start to Friday, as temperatures remain in the 60s following yesterday's beautiful weather conditions. As often seems to be the case in Spring, the taste of Summer will be short- lived as a strong cold front passes through the region today, ultimately ushering in much cooler air for the weekend. The frontal passage will be our primary focus for the development of strong to severe thunderstorms this afternoon. Temperatures will crash behind the front, sending Saturday morning lows below freezing across much of the forecast area -- widespread 24-hour temperature changes are forecast to run between 30-40 degrees!

As of 2 AM, surface observations reveal that the frontal boundary is on our doorstep. Current temperatures in the lower 40s paired with northwesterly surface flow at Morris and Madison suggests that the front has already moved into western MN. For reference, both locations observed highs in the mid to upper 80s Thursday afternoon and are both running ~40+ degrees cooler at this hour! Surface analysis shows two areas of low pressure, one located in the MN Arrowhead with a cold front extending to the SW to another surface low in western NE. Our focus will be on the surface low in western NE, which is forecast to translate east into IA as an upper trough strengthens over the northern CONUS today. The cold front will take a north/south orientation in response to the advance of the surface low. Warm advection ahead of the frontal boundary will work to establish a fairly potent warm sector across portions of the Upper Midwest. However, the early timing of the frontal passage is a key feature is evaluating today's severe weather threat locally -- Simply put, the farther east communities are in eastern MN/western WI, the higher the threat is. SPC's latest Day 1 Outlook featured little change in the risk areas: Enhanced Risk (Level 3/5) for the far eastern sliver of Eau Claire/Chippewa WI, Slight Risk (Level 2/5) along and east of a line from Freeborn - Goodhue - Barron (WI), and a Marginal Risk (Level 1/5) along and east of a line from Martin - Hennepin - Isanti. The greatest risk of large hail/tornadoes is located across the Slight & Enhanced Risk areas.

This will be an event that likely gets going in the first few hours after daybreak across south central MN. Recent CAMs have depicted isolated elevated convection blossoming on the leading edge of the northward surging plume of 60s Tds (currently sampled in eastern NE and forecast to advect northeast into southern MN). As these storms intensify, they will likely pose the threat of hail and damaging winds, but the elevated nature will limit tornadic activity. The initial round of convection is forecast to move towards the TC Metro/I-35 corridor around ~10/11 AM or so. The severe weather threat ramps up as the surface front moves into southeastern MN/ western WI early this afternoon, where more hours of surface heating and ongoing moisture advection will yield a warm sector characterized by MLCAPEs of 2000+ J/kg, steep lapse rates, and curved hodographs supported by slight backing of the surface winds and elongated by 40-50kts of southwesterly 850mb flow. It's this combination that will support the higher severe weather probabilities (including a greater threat of tornadoes) across our WI counties. Some uncertainty remains with regard to storm mode & how quickly cells will grow upscale into a linear system. That being said, the quick progression of the cold front will make the mid afternoon hours the most likely for severe weather across western WI, as guidance advertises that the front will be east of Eau Claire by 3 PM or so. For reference, the threat of large hail and strong tornadoes is even higher across central/southern WI, eastern IA, and northern IL.

Winds quickly turn northwesterly behind the frontal passage and are forecast to gust between 30-40 mph. Strong cold advection will drop temperatures into the 40s for most locations by mid to late afternoon. As referenced above, it looks like most locations are in for a night with temperatures below the freezing mark. Continued northwesterly flow will keep things cool and breezy this weekend, with forecast highs are in the 40s & 50s. Oh, and if that wasn't enough -- we could see a few snowflakes fly as the upper low/vort max pivots north of the International Border on Saturday. Fortunately, we're only talking about conversational snowflakes that will not accumulate.

We'll start to head back in the upward direction early next week as large scale western ridging/height rises build towards the Upper Midwest. Latest NBM features highs in the 60s Monday and the 70s Tuesday, Wednesday, & Thursday. Most of next week's warm up appears dry under the influence of high pressure and large scale subsidence. However, unsettled western troughing will become more of a focus by the end of next week and long term global ensembles advertise the return of wet weather during this time period.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 638 AM CDT Fri Apr 17 2026

Aside from low stratus this morning in far W/NW MN, only impacting AXN, VFR conditions are expected at the remaining TAF sites to start. Few more hours of LLWS conditions in eastern MN into western WI until deeper mixing allows surface winds to increase. High clouds will filter in from the west through late morning in advance of a low pressure center along a progressing N-to-S oriented frontal boundary. Convection is expected to develop over south-central MN by late morning then shift NNE along the front late this morning through the afternoon hours. Higher confidence in central-southern-eastern MN into western WI has allowed precip mention to be upped to TEMPO groups in lieu of former PROB30 groups. Have kept conditions no lower than MVFR but visibilities could/would be the first culprit in dropping to IFR should brief heavy rain cross any given terminal. Frequent lightning, strong winds and large hail may be possible from around MSP eastward during the middle part of the day. Going into the evening, MVFR ceilings will linger in the wake of the front while winds snap around from S to NW with the frontal passage with continued breezy/gusty speeds. Conditions return to VFR by sunset at the MN sites and by late evening at the WI sites.

KMSP...Still looking at the 15z-19z timeframe as the best timing for any convection. There is still a shot of frequent lightning, brief heavy rain and hail with the storms later this morning but the better chances for severe weather are east of MSP. Besides the precip/TS timing, the other issue is the timing of the strong wind shift. Wind speeds will still be breezy throughout, generally around 15G25kts, but the wind shift will occur between 15z-19z (essentially on the backside of the convection that moves through MSP). In addition, MVFR ceilings, including sub-2000ft ceilings, are expected mid-to-late afternoon.

/OUTLOOK FOR KMSP/ SUN...VFR. Wind NW 5-10kts. MON...VFR. Wind SE 5-10kts becoming S 10-15kts. TUE...VFR. Wind SW 5-10kts becoming NW.

MPX WATCHES/WARNINGS/ADVISORIES

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