Hurricane Irma: What We Know So Far

(CBS) -- Mighty Hurricane Irma blistered through the Caribbean and is taking aim for the U.S. mainland this weekend.

Here are five things we know about Irma on Thursday:

1) The most potent Atlantic Ocean hurricane ever, Irma weakened only slightly Thursday morning and remained a powerful Category 5 storm with winds of 180 mph, according to the U.S. National Hurricane Center.

2) At least 10 people have been killed, and the islands of Barbuda and St. Martin sustained massive damage.

3) Irma is taking aim for South Florida, Georgia and then South Carolina, likely as a Category 4 storm, starting this weekend. More than half of counties in those states (about 16 million people) could experience winds of at least 75 miles per hour.

4) South Florida will experience tropical storm force winds, starting on Saturday.

"The threat of direct hurricane impacts in Florida over the weekend and early next week continues to increase. Hurricane watches will likely be issued for portions of the Florida Keys and the Florida peninsula [Thursday morning]," the National Hurricane Center said.

5) Behind Irma, is Hurricane Jose, which is tracking farther north and east, comparatively.