DETROIT – As of 5 p.m., southeast Michigan is mostly dry. However, a potent line of storms across western lower Michigan is moving northeast. Some of this will impact the northern part of our area.
In addition, partial sunshine this afternoon is allowing temperatures to warm much more than on Friday, when it was clouds and rain all day. This additional warmth is further destabilizing the atmosphere, and additional scattered storms could pop up anywhere. The warmer temperatures also allow thunderstorms to grow taller, and this results in more intense storms. Combine this with a strong low-level jet stream aloft and increasing wind shear, and the storms could develop rotation.
Not every storm that rotates (called a mesocyclone) produces a tornado. However, interaction with other storms sometimes causes the surface wind flowing into the storm to shift counterclockwise, and that creates additional low-level wind shear that can spin up a brief tornado. This is my biggest concern this evening, along with damaging wind gusts. Obviously, these storms will have torrential downpours that could exacerbate our flood problems. And don’t take lightning lightly -- it’s America’s number two weather killer.
One final important piece of advice: if you happen to be outside and a storm is in the distance, remember that the damaging wind gusts associated with a severe storm typically flow out AHEAD OF the storm. So don’t wait for it to start raining before heading inside, as you could be caught in the middle of 60 mph wind gusts that hit almost without warning.
I’m working with Andrew Humphrey in the weather office -- we’re monitoring radar and will bring you updates on Local 4 and on Twitter (@PGLocal4 and @Local4Casters). Of course, you can track the storms yourself on the Local4Casters weather app’s real-time radar. The app also notifies you immediately about watch, warnings, lightning and even heavy rain headed your way (make sure notifications are turned on). If you’re one of the few who doesn’t have the app yet, just search the app store for “WDIV” - it’s right there. And best of all, the nation’s best weather app is free!