The city of Miami is preparing for its largest evacuation in more than a decade Thursday as the U.S. National Hurricane Cents warned that Irma, potentially the most powerful storm to hit the American mainland since 1992, is maintaining its category 5 wind speed as it bears down on the south Florida coast.

Miami Mayor Carlos Gimenez has issued a mandatory evacuation order for residents in some coastal areas of Dade County, the metropolitan area of Miami, to move inland and order local schools to be closed for the remainder of the week. The evacuation order, which is set to take effect at 7am eastern Thursday, is the first since Hurricane Wilma in 2005 and is expected to affect around 150,000 people.

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