textproduct: Twin Cities

KEY MESSAGES

- Severe thunderstorms likely tonight with damaging wind gusts the primary hazard. The highest threat is across southern Minnesota.

- Another round of thunderstorms is likely Monday night. Severe thunderstorms are possible across southeast Minnesota & western Wisconsin.

DISCUSSION

Issued at 257 AM CDT Sun May 17 2026

Isolated rain showers have developed on cue overnight, driven by forcing on the nose of strong low & mid-level warm advection from the low-level jet. These showers are expected to dissipate after sunrise as the low-level jet wanes in intensity, but another region of showers & thunderstorms is likely to continue over southeastern Minnesota & west-central Minnesota as a MCV from overnight convection across Iowa moves through the area.

The main trend to watch this morning & afternoon will be how our temperatures & dewpoints respond through the day. We are currently sitting under strong northeasterly flow, & will remain cool & dry until winds become more southeasterly & allow for dewpoints to rise into the upper 50s & 60s. Confidence is high that we'll see these more unstable conditions develop across southern Minnesota, but it's more uncertain how far north into central Minnesota & western Wisconsin we'll see temperatures in the 70s & dew points near 60 extend by late afternoon. Widespread cloud cover through the day will put a limit on the extent of solar heating this afternoon, so watching where winds become southeasterly this afternoon will be key on identifying where the environment for severe weather exists later this evening.

Thunderstorms are expected to develop late this afternoon across the astern Dakotas, near the triple point of a low forecast to track northeastwards from the central plains into Minnesota & Wisconsin. These storms will likely become supercellular given the impressive environment for severe weather over the Dakotas & central plains, but will likely merge into a linear MCS and/or multiple line segments as they move into western Minnesota around 7-9 PM this evening. All modes of severe weather will be possible with these initial supercellular storms, with very large hail (2-3" in diameter) & a few tornadoes accompanying a damaging wind threat. As the discrete storms transition to a MCS or line segments, damaging wind gusts will becoming the predominant severe threat, although a few QLCS tornadoes are also possible given the southeasterly flow ahead of the storms generating impressive low-level wind shear & helicity. As mentioned above, where southeasterly wind develop & allow more instability is going to be key for determining where the severe threat from these thunderstorms is going to continue into the evening as storms move eastwards across Minnesota & Wisconsin. High-resolution ensemble guidance really highlights southern Minnesota for the greatest severe environment, up to the latitude of Marshall/Mankato/Red Wing, where we see the potential for surface-based CAPE values approaching 1000 J/kg. However, we could still see a low CAPE/high-shear environment extend northwards into central Minnesota & western Wisconsin as long as storms are still able to tap into some sort of surface- based instability. Various high-resoluton model solutions tend to depict the highest concentration of damaging wind gusts & QLCS tornado potential mainly occurring across this region of southern Minnesota, but some potential still exists farther to the north & east. Timing- wise, high-resolution models are generally in agreement with moving the thunderstorm complex reaching western MN through 7-9 PM, central MN & the metro between 9-11 PM, & western WI between 11 PM - 1 AM.

The thunderstorms will begin weakening around midnight as instability wanes, likely reducing the threat for severe weather across western Wisconsin. Showers & thunderstorms will still be ongoing into the overnight hours, with the precipitation mostly over across our area by sunrise. For Monday, we will likely be dry through the day but will have to monitor where any outflow boundaries or remnant from MCVs from the overnight storms set up during the day. Another round of showers & thunderstorms is likely Monday night, but we will likely remain north of the best synoptic environment for severe weather across Iowa & southern Wisconsin. Can't rule out something interesting happening if we get a mesoscale boundary to set up across our area Monday evening, but otherwise we're looking at mostly a rain event. Rainfall-wise, we'll see our first soaking rainfall of the month with most of the area expected to see at least 1-2" between the thunderstorms tonight & Monday night. Localized amounts of 3-4" look possible based on individual high- resolution model runs, depending on which areas get the slowest- moving thunderstorms.

By Tuesday, seasonably cool & dry weather returns as the Upper Midwest returns to a pattern of troughing aloft. The next round of disturbances & precipitation arrives Friday, with additional chances for showers & thunderstorms later on the Memorial Day weekend

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 714 AM CDT Sun May 17 2026

Breezy northeasterly winds will prevail this morning for all sites with gusts ranging between 22-27kts. Prior to the passage of a cold front this evening, winds become southeasterly by the afternoon. VFR cigs will gradually fall into MVFR/IFR categories as storm development begins initiating across western MN early this evening. With some uncertainty of the northern extent of precip coverage, have maintained prob30 mentions for TSRA mainly between 00- 06z. It is anticipated that tighter tempo and prevailing grouping will be introduced next routine issuance. After the front passes, winds will shift northwesterly tomorrow morning.

KMSP...Another breezy day with northeasterly winds shifting southeast by this afternoon between 10-15kts with gusts as high as 22-27kts. Early AM -SHRA has cleared north of the field and now dry conditions are expected for much of the day before storms redevelop this evening. As of now, maintained prob30 mention of TSRA between 02-06z. Cigs will slowly drop to MVFR by this afternoon and then IFR this evening prior to precip arrival. Once the storms and frontal boundary passes, winds will then shift to westerly near 10kts.

/OUTLOOK FOR KMSP/ MON...-SHRA/-TSRA likely, IFR/MVFR. Wind N 10-15 kts. TUE...MVFR cigs. Wind NW 10-15G25kts. WED...VFR. Wind NNW 5-10kts.

MPX WATCHES/WARNINGS/ADVISORIES

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