HOUSTON (Reuters) – Hurricane Sally drew closer to the U.S. Gulf Coast on Tuesday morning, threatening historic floods along the coast, the National Hurricane Center said, with more than two feet of rain expected in some areas.

The second strong storm in less than a month to threaten the region, Sally’s winds decreased to 85 miles per hour, and early Tuesday was 60 miles east of the mouth of the Mississippi River, the NHC said, moving at a glacial pace of two miles per hour.

It could wallop the Mississippi, Alabama and Florida coasts on Tuesday with massive flash flooding and storm surges of up to 9 feet some spots. Its slow speed recalls 2017’s Hurricane Harvey, which brought several feet of rain over a period of days in the Houston area.

Mobile, Alabama, Mayor Sandy Stimpson warned residents he expected a “tremendous amount of flooding” and said the city was barricading intersections likely to see high water.

Mississippi and Louisiana called for evacuations of low-lying areas and President Donald Trump issued an emergency disaster declaration for both states. Alabama closed the state’s beaches and recommended evacuations of residents in low-lying areas.

Ports, schools and businesses closed along the coast. The U.S. Coast Guard restricted travel on the lower Mississippi River in New Orleans to the Gulf, and closed the ports of Pascagoula and Gulfport, Mississippi, and Mobile, Alabama.

Energy companies buttoned up or halted oil refineries and pulled workers from offshore oil and gas production platforms.

The hurricane is expected to dump between 10 and 20 inches of rain on the coast, with isolated 30-inch downpours.

Mississippi appears more likely for landfall, but Sally’s biggest threat is that it will be a “rainmaker” across a wide swath of the Gulf Coast, with 3 to 4 inches in areas as far inland as Atlanta, said Jim Foerster, chief meteorologist at DTN, an energy, agriculture and weather data provider.

Sally is the 18th named storm in the Atlantic this year and will be the eighth of tropical storm or hurricane strength to hit the United States—something “very rare if not a record” said Dan Kottlowski, senior meteorologist at AccuWeather, noting that accurate data on historic tropical storms can be elusive.