It is rare for a tropical storm system to pass through Michigan.

Michigan and tropical storm systems don’t necessarily go together. Because the 45th parallel – the latitude that marks the midpoint between the equator and the North Pole – runs through the state, tropical systems rarely come this far north.

But that’s exactly what the remnants of Hurricane Beryl did this week, dropping up to six inches of rain in some parts of Michigan between Tuesday and Wednesday. It flooded roads in the areas that received the heaviest rainfall and put residents living near rivers and streams on alert.

One important difference is how meteorologists classify storms. Many are familiar with the classification of hurricanes, which is based solely on wind speed. A Category 1 hurricane begins with winds of 74 mph. A storm with winds of 39 mph to 73 mph is classified as a tropical storm. Similarly, a tropical depression is a tropical cyclone with winds of 38 mph or less.

All tropical cyclones, regardless of their strength, must have certain characteristics to be considered tropical. The most important characteristic is a “warm core,” meaning their energy is not associated with frontal systems.

After tropical systems move ashore, they often merge with “typical” weather systems and become “extratropical,” meaning they lose the specific conditions required for tropical conditions. Even with extratropical systems, high-impact weather events are still possible.

With that definition out of the way, let’s look at past tracks over Michigan. According to NOAA data, 18 different tropical or extratropical storm systems have been recorded moving through parts of Michigan. Beryl will likely be the 19th storm on record.

Of the 18 storms recorded, eleven were extratropical by the time they arrived in Michigan, six were considered tropical depressions, and one still had enough strength to be classified as a tropical storm.

The last time Michigan experienced a tropical/extratropical system was in 2020, when Tropical Storm Cristobal moved through the Upper Peninsula, which was already extratropical at the time. The tropical storm that moved through the state was Hurricane Connie in 1955. Connie had winds of 138 mph at times on the Atlantic! This storm moved through eastern parts of the state and brought winds of 45 mph.

Overall, Michigan is not a state known for its run-ins with tropical systems, but that doesn’t mean we never feel the effects of them, as Beryl clearly showed us this week.