Nicholas Filipich of Biloxi, Miss., shovels sand for sand bags into his grandfather’s truck on Friday May 24, 2018. Filipich was helping his grandfather prepare for expected heavy rains over the weekend. (John Fitzhugh/The Sun Herald via AP)
A pair of fishermen walk out on a pier in Pass Christian, Miss., on Friday May 24, 2018. Heavy rains are expected over the Memorial Day weekend in south Mississippi. (John Fitzhugh/The Sun Herald via AP)
A cyclist tries to stay dry along Collins Ave. in Miami Beach, Fla., Friday, May 25, 2018. Rain from Subtropical Storm Alberto is expected to will drench the Memorial Day weekend. (Jim Rassol /South Florida Sun-Sentinel via AP)
Empty beaches and low-hanging clouds are shown, Friday, May 25, 2018, at Fort Lauderdale Beach in Fort Lauderdale, Fla. A storm kicking up in the Caribbean Sea is threatening to bring heavy rainfall and flash floods to parts of Mexico, Cuba, Florida and the eastern U.S. Gulf Coast this weekend and possibly beyond. (AP Photo/Wilfredo Lee)
MIAMI — A storm moving slowly through the Gulf of Mexico is threatening to bring heavy rainfall, storm surges, high winds, and flash floods to the U.S. Gulf Coast this holiday weekend.