Image credit: National Weather Service, Twin Cities/Chanhassen office
A strong weather system responsible for extraordinary tornado damage in Iowa also produced hail and damaging winds in Minnesota on Monday May 20 and Tuesday 21, 2024, as well as widespread heavy rainfall.
A wet weather pattern has been in place in Minnesota since late March, with frequent low-pressure systems passing through the region. Although spring has been much warmer than normal across the state, we have generally remained on the cooler side of most passing weather systems, leading to waves of steady, soaking precipitation, rather than muggy conditions and strong thunderstorms--which are often found on the warm side of these systems.
This time, the low pressure area tracked into central Minnesota, placing the south and southeastern parts of the state in a warm and humid air mass. Isolated strong and severe thunderstorms produced the state's first tornado of the year on Monday in Dodge County (southern Minnesota), and others produced quarter to half dollar-sized hail into Monday night across the southern third of the state. On Tuesday a wave of morning rain and thunderstorms was followed by a mid-day break, before much heavier and more widespread activity overspread the area.
Thunderstorms broke out over southern Minnesota during the mid-afternoon Tuesday and began spreading northward. Fast-moving and extremely intense thunderstorms swept across much of Iowa with destructive tornadoes and straight-line winds. Some of these dangerous thunderstorms made it into far southern and southeastern Minnesota, with a tornado reported south of Fairmont, and thunderstorm winds knocking out power, damaging trees, and flipping a semi truck, from the Albert Lea area through Wabasha, Winona, and Houston counties of far southeastern Minnesota. Although Minnesota has had isolated reports of hail and thunderstorm winds, Tuesday marked the first concentrated severe weather event of the year for the state, with widespread damage in the far southeast.
Widespread, non-severe thunderstorms spread over much of southern and central Minnesota, and persisted long after the severe storms had moved away. A steady, soaking rain, with waves of heavy downpours spread north of the thunderstorm activity as well, making it all the way into Canada by evening. In some areas, the steady to heavy rain lasted up to 8 hours, leaving all but the northwestern corner of the state with over an inch of rain for the event, and some areas with significantly more.
In general, the highest rainfall totals were oriented in southwest-to-northeast streaks scattered around western, central, southern, and southeastern Minnesota. The National Weather Service Cooperative observer at Milan recorded a storm total of 4.05 inches, with 3.72 inches falling on Tuesday. Numerous Cooperative and CoCoRaHS observers in the southern and eastern Twin Cities recorded 3-4 inches of rain, and even the northeastern Minnesota observers at Orr, Tower, and Wolf Ridge recorded over three inches of rain. Duluth recorded a total of 1.58 inches, International Falls saw 1.44 inches, and the Twin Cities recorded 2.55 inches, with 2.33 inches on the 21st--which was the largest daily total in nearly four years, since 2.37 inches fell on June 29, 2020.
KAB, May 22, 2024