The Storm Forecast Center is getting a little more confident about how strong and where thunderstorms may be this afternoon and evening. Part of southern Michigan has been warned of significantly severe weather.
The latest Storm Forecast Center (SPC) forecast, released at 8:24 a.m. this Monday, shows the highest probability of severe thunderstorms in a corridor in southwestern and southern Lower Michigan.
General forecast for a strong thunderstorm from 8 am on Monday to 8 am on Tuesday. The orange zone is called “increased risk”. (source: Storm Forecasting Center)
The orange shaded area south of the Muskegon line to Detroit is in what is called an area at increased risk of severe thunderstorms. The forecast for a severe thunderstorm can also be considered as a five-level forecast. Increased risk is the third level on this five-point scale.
The scenario we expect is a pile of thunderstorms unfolding this afternoon over southern Wisconsin. The storms are then expected to race southeast in southern Lower Michigan. This line of storms will probably be only a hundred miles from north to south. The storm line may have spots that receive what the Storm Forecast Center calls “destructive gusts of wind.”
Here is the forecast for the hard weather, broken down into specific types of hard weather.
The first forecast is for rectilinear gusts of wind. These strong gusts of wind come during the first 10 minutes of a thunderstorm. The black-shaded trail from Muskegon and the southwestern shoreline of Lake Michigan near Ann Arbor and Detroit has a chance of gusts of 75 mph or more. At 80 mph, gusts of wind cause significant damage to buildings and can even break windows. It is not a sure bet, but if thunderstorms become strong, they can cause short, very strong gusts.
Strong wind forecast for Monday afternoon and Monday evening. The black shaded area has a 10 percent chance of gusting at 75 mph or faster.
There is also a high enough risk of several tornadoes to be concerned, not just rectilinear winds. The same area with the highest risk of strong gusts of wind also has the highest risk of tornadoes.
Probable tornado forecast for Monday afternoon and Monday night.
High hail is possible, but it is not the main concern at the moment.
Forecast for high hail, showing a probability of hail with a diameter of one inch
THE TIME OF HEAVY THUNDERSTORMS
Thunderstorms are expected to enter western Lower Michigan sometime between 4pm and 7pm. We’re still not sure when it’s time. We will find out in the early afternoon. It will then take about three hours to track the storms in southern Lower Michigan.
Here are the cities with the highest risk of severe thunderstorms: Muskegon, Grand Haven, the Netherlands, South Haven, Benton Harbor, Grand Rapids, Battle Creek, Kalamazoo, Lansing, Jackson, Caldwater, Adrian and Ann Arbor.
North of Grand Rapids to the Flint area there is still a chance of a strong gust of wind, but it needs to be more isolated and less strong.
Storms may weaken some as they move through the Detroit area, but I will be watching that too.
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