2:00 AM Update: The main line of storms is sinking more south than east, thankfully. However, the Storm Prediction Center has issued Severe Thunderstorm Watch #400 for extreme southwestern lower Michigan until 9am (PURPLE).
For Mid-Michigan, The slight risk still remains. Isolated severe storms are still possible as the night continues on.
This post will be updated as the night progresses, and outlooks change.
9:00 PM Update
The newest and most recent SPC outlook shows not much has changed, however, looking at the KGRB radar in Green Bay, WI we can see the storms firing, to eventually form a derecho along the line of instability.
This post will be updated as the evening progresses, and outlooks change.
6:00 PM Update
The Storm Prediction Center has increased our risk to Slight (YELLOW) and areas west Enhanced (ORANGE) and Moderate (RED). The main cause for concern is damaging winds in excess of 70 mph. Areas in the Moderate Risk have the potential to see winds of 85 mph+ per the NWS Grand Rapids.
Remain alert tonight for rapidly changing weather conditions, primarily in the 3am to 6am timeframe.
This post will be updated as the day goes on, and outlooks change.
1:00 AM Update
The Storm Prediction Center has placed areas north and south of I-69, and along/east of I-75 to Midland under a Marginal Risk for severe weather. Areas closer to Grand Rapids are under a slight risk. The main threats are Damaging wind gusts up to 60 mph for both risk areas.
The main scenario is as follows: Late tonight, into early Thursday morning, a mesoscale convective system is expected to move from northern Wisconsin, through mid Wisconsin, over Lake Michigan, and impact areas of western Michigan and Mid-Michigan, possibly scraping along a Traverse City to Sarnia line.
The line of storms is expected to move northwest to southeast at around 50 mph.
As stated above, the main threats appear to be Damaging Winds of 60 mph in the Slight and Marginal risk areas.