Updated at 5:00 a.m. ET Friday
The National Hurricane Center says Irma is now a Category 4 storm. It has maximum sustained winds of 155 mph.
Updated at 11 p.m. ET
Hurricane Irma continued its northwestward sweep Thursday evening, losing little steam as it skirted the Dominican Republic and Haiti and bearing the full force of its 165-mph winds down upon the southeastern Bahamas and away from the Turks and Caicos islands. Forecasters upgraded their alert for South Florida to a warning.