ATLANTA -- Categories are the key to understanding just how severe a hurricane actually is – something that’s essential with tracking a major storm.

The Saffir-Simpson scale is how those categories work. In short, it places hurricanes in five classifications. The weakest of these includes hurricanes with winds as slow as 74 mph. Meanwhile, a Category 5 hurricane has winds over 156 miles per hours.

In addition to wind speeds, these storms can create different amounts of storm surge based on their category. The largest of them have a surge of over 18 feet.

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Category 3 and up have the highest potential for storm-related damage and loss of life, with that category being considered “devastating” and the two above it being labeled “catastrophic.”

Hurricane Michael moved up to Category 3 Tuesday afternoon and was expected to remain at the same level when making landfall.