Warm, muggy, spotty storms Thursday

With high dew points and a meandering frontal boundary, expect isolated to spotty showers and thunder to pop up for some in western and southern Minnesota Thursday. Highs will range from the 80s south to the 70s north.

Unsettled in parts of Minnesota Thursday

Muggy air with light winds and a frontal boundary moving back and forth across the region will create the recipe for at least a few spotty showers and thunderstorms Thursday. They should mainly be in western and southern Minnesota.

Great Lakes breathing?

You’d be forgiven for thinking Lake Superior (and the other Great Lakes) appears to be ‘breathing’ in this dew point forecast loop.

We have high pressure centered north of Lake Superior the last couple days and over the Great Lakes Thursday still. Air flows outward and clockwise around areas of surface high pressure since air is descending and stable. That outward flowing, cooler and drier air has been creating low cloud banks and fog (like this imagery from Tuesday below).

This is also why the dew point dropped from the low 70s to the low 60s in the Twin Cities Tuesday night into early Wednesday before going back up in the afternoon. Dew points took another drop for many areas of northeastern and east-central Minnesota, along with northern Wisconsin again last night into early this Thursday morning.

You’ll note there appears to be a “back and forth” in the dew point loop. That’s because the movement of the drier and cooler air is diurnal, or different day versus night. During the day the sun warms the ground and that allows the air to expand and the muggy air fills back in. During the night, the cooler, drier air can make some headway inland as high pressure gives the air momentum.