September is generally a comfortable, rather dry and peaceful weather month in these northern latitudes far from the hurricane tracks. But not so this year.
Rain has been plentiful and followed a very wet August. My backyard rain gauge has measured 4 inches of rain through the first half of the month. And we have had some severe weather.
Now are into a warm, muggy period. Afternoon temperatures this Monday afternoon have risen into the 80s across all of Minnesota except the much cooler areas near Lake Superior. Dew points have reached well into the 60s in eastern Minnesota while it has climbed into the July-like low 70s across the western half of the state.
Sultry Tuesday with storms
Tuesday will be another very warm and humid day. A morning low temperature in the Twin Cities near 70 will be close to what a normal high temperature would be for Sept. 17. High temperatures should reach the 80s for most of Minnesota.
An atmospheric wave from the west seems likely to spread thunderstorms from South Dakota into western Minnesota Monday night after midnight and then northeastward to east-central and northeastern Minnesota on Tuesday. These storms are not likely to become severe.
Stronger storms likely Tuesday night
A vigorous wave aloft accompanied by a cold front will bring stronger, possibly severe storms across Minnesota Tuesday night and into Wednesday morning. The Storm Prediction Center has posted a marginal risk of severe weather for mainly Tuesday night into early Wednesday morning.
The “Day 2” label on the graphic is indicating a 24-hour “day” that ends at 7 a.m. on Wednesday. The position of this marginal risk has been shifted farther eastward in Minnesota than was indicated in earlier outlooks and includes Redwood Falls, the Twin Cities, St. Cloud, Brainerd and Grand Rapids.
The high moisture content of the atmosphere this week could contribute to rather heavy rains from these storms.
Behind the cold front
Drier, somewhat cooler air will flow in from the northwest courtesy of Canada on Wednesday and Wednesday night.
Chances of more storms later this week
Forecast models show a low-pressure system likely to bring thunderstorms late this week, mainly Friday and Friday night. We could easily see one more day of very muggy dew points on Friday.
Our weather looks likely to return to its normal mid-September comfortable, rather dry and peaceful state by Sunday.