Humidity and storm chances return; I-80 bow echo
Plus: The meteorology of the Iowa to Chicago derecho
Minnesota is enjoying a postcard-perfect summer Tuesday.
Our trademark summer blue skies give way to more frequent clouds and higher dew points the rest of this week. Thunderstorm chances return, but coverage looks scattered until Friday when a more organized front brings widespread thunderstorm chances.
Warm front ahead
August is known for warm sticky air in the Upper Midwest. Our latest warm front pushes across Minnesota Wednesday. By Thursday, dew points return to the sticky 60s. Scattered thunderstorms will bubble up along the frontal zone through Thursday. But the most organized rains are likely Friday as another front approaches.
Air mass transition
Meteorologists watch dew point plumes in summer to gauge the sticky factor and thunderstorm chances. Watch how a plume of high dew point air returns to Minnesota Thursday. Dew points push the tropical 70-degree mark again Thursday close to home.
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August 80s
Highs in the 80s cover most of Minnesota the rest of this week.
A cooler puff of air appears ready to move in next week with highs in the 70s.
I-80 derecho
The derecho that blasted Iowa and Chicago ran along and north of the Interstate-80 corridor. Check out this fascinating radar sequence as the storm rolled eastward. Note the comma-shaped head and classic bow echo structure. Textbook.
Here’s (much) more on the meteorology behind the event and storm reports from the Chicago National Weather Service office.