Southern Minnesota is bracing for its first round of severe weather on Monday, April 13, with storms expected to develop by late afternoon and intensify quickly across the Twin Cities and points south. The National Weather Service expects to issue both a watch and a warning as the weather turns dangerous between 3 and 11 p.m. ET.
Jacob Beitlich, a meteorologist with the Weather Service, said the timing is fitting because Severe Weather Awareness week starts the same day. He said the agency has high confidence severe weather will happen and wants people to be informed.
That is the lesson residents are supposed to take from the difference between a watch and a warning. A watch is issued one to two hours before storms develop and usually covers a large area, signaling that conditions could produce severe thunderstorms, hail, tornadoes or flash floods. It means storms are possible, not guaranteed, and people in the area should stay alert to changing conditions.
A warning is more urgent. It is issued when thunderstorms with high winds, lightning or hail 1 inch or more in diameter have been observed by trained spotters, or when a tornado is indicated by radar. Warnings cover specific counties or parts of them and usually include the cities in the path of the storm. When a warning is issued, people in the path should take shelter immediately.
As of 1 p.m. Monday, no watches or warnings had been issued in Minnesota, but a large stretch of the state from the southern metro to the Iowa border and east to the Wisconsin border was already under an enhanced risk of hazardous weather. That area includes Rochester, Winona, Mankato, Owatonna, Albert Lea and Austin, where hail 2 inches in diameter or larger, isolated tornadoes and damaging winds are possible.
A slight risk covers the north metro and cities including Worthington, Willmar, St. Cloud, Mora and Alexandria, while Fergus Falls, Bemidji and the Duluth-Superior area are in low-risk territory.
The Weather Service said other lessons during the week will cover safety during floods, tornadoes, hail and extreme heat. And while people often look to the weather map for the sound of sirens, those alerts are handled by cities and counties, not the Weather Service. Monday’s storm threat is expected to be the first live test of the difference between waiting and acting.