Severe Tornado Watch Issued for Parts of Iowa, Minnesota and Wisconsin; Hail to 3 Inches Possible

“URGENT - IMMEDIATE BROADCAST REQUESTED.”

With that headline, the National Weather Service’s Storm Prediction Center on Monday issued Tornado Watch Number 103 for a broad stretch of the Upper Midwest, warning of an unusually high-end spring severe weather setup with the potential for “a couple intense tornadoes” and hail up to 3 inches in diameter during the busy late-afternoon and evening hours.

The watch, issued at 3:10 p.m. CDT Monday, is in effect until 10 p.m. CDT. It covers portions of northern Iowa, southern Minnesota, central Wisconsin and part of Lake Michigan. The Storm Prediction Center, known as SPC, describes the watch area as approximately along and 50 miles north and south of a line from about 30 miles west-northwest of Fairmont, Minnesota, to 20 miles east-northeast of Oshkosh, Wisconsin.

Forecasters are highlighting a combination of hazards: tornadoes, very large hail and damaging straight-line winds. In the watch product, SPC states that “a few tornadoes [are] likely with a couple intense tornadoes possible,” along with “widespread large hail and isolated very large hail events to 3 inches in diameter likely” and “scattered damaging wind gusts to 70 mph possible.”

The agency’s probability table underscores that this is not a low-end or routine watch. SPC assigns a 70% probability of two or more tornadoes within the watch area and a 40% probability of at least one strong tornado, rated EF2 to EF5 on the Enhanced Fujita scale. For hail, the center lists an 80% chance of 10 or more severe hail events and a 60% chance of at least one hailstone larger than 2 inches in diameter.

Hail to 3 inches in diameter, roughly “teacup”-size, is capable of shattering windows, damaging roofs and vehicles, and harming crops and infrastructure.

In its summary of expected storm evolution, SPC says: “Thunderstorms are expected to rapidly develop this afternoon along a warm front across the watch area. Supercells capable of very large hail and tornadoes are possible. A strong tornado is possible.” The mean storm motion is listed as 26030, indicating storms moving generally from west to east.

A Watch Status Report issued later in the afternoon emphasized that the threat was ongoing, stating that “THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA” between 5:25 p.m. and 6:40 p.m. CDT.

April is prime severe-weather season for the central United States. As temperatures warm and stronger storm systems move through, states such as Iowa, Minnesota and Wisconsin typically see an increase in organized severe thunderstorms and tornadoes, with activity often ramping up further into late spring and early summer.

The current watch focuses on atmospheric conditions rather than confirmed impacts. The SPC watch product and its status message list elevated probabilities and detailed threats but do not confirm any tornado touchdowns, damage or injuries. Any such reports would be documented later in SPC storm reports and in post-storm surveys by local National Weather Service offices.

SPC includes standard guidance on what the watch means: “REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings.”

A watch covers a broad region where dangerous storms could develop. If radar or spotters indicate that a tornado is imminent or occurring, local National Weather Service offices — including those in Des Moines, the Twin Cities, La Crosse, Milwaukee and Green Bay — will issue tornado warnings for specific counties or communities.

For aviation interests, SPC notes that “tornadoes and a few severe thunderstorms with hail surface and aloft to 3 inches” are possible, with “extreme turbulence and surface wind gusts to 60 knots.”

Residents and travelers in the watch area are urged to monitor local forecasts, weather radio, apps or media outlets for updated information and any warnings that may be issued as storms evolve into the evening.