Storms moving at ridiculously fast speeds will pose a damaging wind and tornado threat as they push through southern Minnesota and northern Iowa on Wednesday afternoon and evening.
The Storm Prediction Center has placed southern Minnesota and northern Iowa in a slight risk for severe weather, with parts of the Twin Cities in a marginal risk. It's what that the National Weather Service in the Twin Cities referred to in Tuesday morning's forecast discussion as a "rare weather setup."
According to the NWS, it's the first time any part of Minnesota has been under a slight risk for severe storms in December in 20 years. The last time it happened was Dec. 5, 2001. The latest a tornado has ever touched down in Minnesota is Nov. 16.
"Model forecasts are in reasonable agreement that convection will initiate nearer to the surface low to the west and north of Omaha around [3 p.m.]. A line is forecast to move quickly northeastward across western and northern Iowa into southern Minnesota during the afternoon," says the Storm Prediction Center.
The future radar simulation from the HRRR model shows storms moving through the Twin Cities between 6 p.m. and 10 p.m. You can see how dynamic the system is with strong storms blasting through southern Minnesota while wet snow falls on the back side of the system, and that snow will likely accumulate, though specific totals aren't clear yet.
Take a look at the lightning density simulation from the European model. This is from noon Wednesday until midnight. That won't be Rudolph's nose blinking, it'll be frequent lightning flashing as the storms race through southern Minnesota, including through the Twin Cities.
Storms are expected to weaken as they move into Wisconsin, but because they will be moving so fast – at 60 mph or faster – they will still have the ability to produce damaging wind gusts into the night, according to the NWS.
Winds associated with the low-pressure system will also be powerful. Not as powerful as the 60-70+ mph gusts eastern Nebraska and western Iowa could get, but still gusting over 40 mph for much of southern Minnesota, with far southeast Minnesota and western Wisconsin potentially getting 50-60+ mph gusts.
A high wind warning is in effect for Wednesday noon onwards for far southwestern Minnesota, where southwest winds 30-40 mph will gust up to 60 mph at times. A high wind warning is also in effect in far southeast Minnesota (including Rochester), southwest Wisconsin and all of eastern Iowa, where winds could gust over 60 mph.
The warning from the NWS says: "Damaging winds will blow down trees and power lines. Widespread power outages are expected. Travel will be difficult, especially for high-profile vehicles.
Anyone with unsecured property, including lightweight outdoor objects and holiday decorations, could be blown away as the storm system moves through.
Winds are expected to decrease by sunrise Thursday.