The threat for strong to severe thunderstorms is in the forecast for Wednesday afternoon through early Thursday morning. The current setup is showing a very warm air mass over southeastern Minnesota with dewpoints warming into the middle and lower 70s. A stationary boundary will sit just north of the KTTC viewing area will help create favorable conditions for thunderstorm develop.
The main threats Wednesday evening and Thursday morning will be heavy rain and strong wind gusts. Right now a “Slight Risk” for severe weather has been placed over the viewing area but that could easily be upgraded with new data coming in overnight.
Timing is a little difficult with this MCS (Mesoscale Convective System) moving through southeastern Minnesota. Current guidance suggests the MCS moving through during a 10 p.m. to 2 a.m. timeframe. Meaning late Wednesday evening and early Thursday morning. The problem is, we could have thunderstorm activity during the late morning and early afternoon hours Wednesday, which could impact the later MCS development.
Right now the forecast is calling for thunderstorm chances during the late morning and then late evening into early Thursday morning.
Once we are done with the thunderstorm chances, we have to deal with the extreme heat. There is an “Excessive Heat Watch” out for all of Iowa Thursday through Saturday evening. Right now that does NOT include our Minnesota counties.
Highs Thursday through Saturday will be in the upper 80s and lower 90s with heat index values jumping into the lower 100s.