Marginal Risk of a Severe Storm

Bill’s Blog

Posted: Aug 24, 2020 / 02:32 AM EDT Updated: Aug 24, 2020 / 02:21 PM EDT

Thunderstorm (cumulonimbus) over Central Iowa 8 23 20

The Storm Prediction Center has much of Lower Michigan in a Marginal Risk Area for later tonight and also for Tuesday PM/night:

The map above is for this Monday PM/Night. Thunderstorms are expected to form in Minnesota and move east-southeast into Wisconsin. SPC says:

"...a swath of potentially damaging wind gusts across parts of central/southeastern Minnesota through western/southern Wisconsin by late this evening. It is possible severe weather probabilities could be increased across parts of this region, once lingering uncertainties become better resolved."

Storms that come through Wisconsin may cross Lake Michigan after midnight. They may be in a weakening trend by then. (top picture of Iowa thunderstorm – cumulonimbus – from Austin Hamilton).

This is the Day 2 (Tuesday PM/night) Severe Weather Outlook Map. There is a large Slight Risk Area from Ohio into the Northeast. SPC has introduced a small Enhanced Outlook Area that includes from Washington D.C. up into New Jersey. West Michigan is in a Marginal Risk Area that extends pretty much all across the country from Oregon to the Atlantic Ocean. There are also a rare Slight Risk Area for Idaho and western Montana and Marginal Risk Areas in Arizona and in Southern Louisiana with Hurricane Laura coming onshore. SPC says:

"Storms may be ongoing at the start of the period across portions of the Wisconsin/Lower Michigan vicinity, with limited/lingering severe potential possible with one or two of the stronger convective clusters. 

The threat is for isolated strong winds and hail.

Severe Weather OUtlook Area for Wednesday PM/Night

This is the Severe Weather Outlook Area for Wednesday.There’s a Slight Risk Area from Lower Michigan to nearly the Atlantic Coast, surrounded by a Marginal Risk Area. Again the greatest threat for us will be isolated wind damage.

A Final Note from the Storm Prediction Center: “…convective/severe risk could evolve across the Upper Great Lakes Day 5 Friday.” Storms are not expected over the coming weekend in Michigan.

Links: The latest SPC convective (thunderstorm) outlooks, current severe thunderstorm and tornado watches, current mesoscale discussions. Great Lakes radar:

Central Great Lakes sector loop
Go to: Most Recent Image

Grand Rapids radar:

Click for latest Base Reflectivity radar image from the Grand Rapids/Muskegon, MI radar and current weather warnings

Here’s current Michigan weather observations and a Michigan weather map. Grand Rapids, Kalamazoo, Battle Creek, Ionia and Mt. Pleasant have all reached 90 degrees this PM.