(CNN) Hurricane Florence has weakened to a tropical storm but will likely strengthen again into a major hurricane and could threaten the US East Coast by next week.

Florence appears over the open Atlantic in an image from the International Space Station.

But increased wind shear over the open Atlantic -- the storm is about 1,500 miles from the East Coast -- weakened Florence to a tropical storm, with 65-mph winds as of 5 a.m. ET Saturday.

Wind shear will lessen over the weekend, and Florence should regain major hurricane intensity (Category 3 or greater) by early next week -- as the storm moves northwest, getting closer to the US coastline by the day.

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