Summary:
Our first severe weather threat of 2025 is now on the table for portions of Western Lower Michigan Friday evening into Saturday morning as a strong low-pressure system drives a swath of showers and storms, many of which will likely be severe, across much of the Midwest and Great Plains.
Discussion:
The Storm Prediction Center has outlined Marginal (level 1/5) and Slight (level 2/5) risks across parts of Southwest Michigan for Friday.
As we know, thunderstorms, and especially severe thunderstorms, generally need 4 key ingredients to mature and sustain themselves: moisture, wind shear, forcing for ascent, and instability. Sometimes, however, a lack of 1 or 2 of those ingredients can be overcome by an abundance of the other ingredients.
In this setup, Michigan and the Great Lakes region at large will generally be removed from the area of greatest moisture and instability, however, wind shear will be plentiful. This will allow for a non-zero severe weather risk across parts of our area in what is known as a "High-Shear-Low-CAPE" setup.
As the low-pressure system moves eastward, we will see wind shear across the area, which is more than favorable for the development and sustainment of thunderstorms and for the mixing of strong to even damaging wind gusts down to the surface. However, the lack of other key ingredients will hinder the initial development and overall longevity of thunderstorms, so our overall risk for severe weather is not overly concerning but is non-zero nonetheless.
