Mobile, Alabama (CNN) - Heavy rain and wind gusts began punishing parts Alabama and Florida on Tuesday as Hurricane Sally slowly creeps toward the US Gulf Coast, where millions of people are preparing for "historic life-threatening flooding."
The center of Sally -- a Category 1 storm with maximum sustained winds of 80 mph -- was more than 50 miles south of Dauphin Island, Alabama, and moving toward land at only 2 mph, the National Hurricane Center said. That's slower than the average human walking pace.
Conditions were quickly deteriorating Tuesday, leaving piers destroyed along the coast and more than 18,000 customers without power in Alabama, Mississippi and Florida, according to PowerOutage.US.
"We are flooded in and cannot see the homes on the beach," Doris Stiers told CNN from a beach house near Gulf Shores, Alabama.
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Sally's center is expected to make landfall late Tuesday or Wednesday morning, forecasters say, but the storm is likely going to be moving over the same area for days.
"You could get four to five months of rain in just a matter of two to three days," CNN meteorologist Jennifer Gray said.
While some families in Mobile are waiting out the storm at home, Linda Duke was growing nervous and instead opted to drive to a motel.
"We are going to leave for the night" Duke, 75, told CNN. "We are only worried if we get a big storm surge because the ground is so wet and the house is so old, over 100 years old."
A hurricane warning is in effect from Bay St. Louis, Mississippi, through just east of Pensacola, Florida -- including all of coastal Alabama and the city of Mobile.
Sally's center is expected to move near southeastern Louisiana before hitting land -- perhaps near the Mississippi-Alabama state line, forecasters said.
Its slow movement should allow huge amounts of rain to pile up even ahead of landfall.
Hurricane conditions could arrive in the warning area Tuesday evening or early Wednesday, forecasters say. Outer rain bands already were hitting parts of coastal Alabama and the Florida Panhandle.
About 10 to 30 inches of rain are possible by storm's end from the Florida Panhandle to far southeastern Mississippi, forecasters say.
"Historic life-threatening flash flooding is likely," the NHC said in its latest advisory.
Tornadoes also are possible through Wednesday, especially in parts of southern Alabama and the Florida Panhandle, forecasters say.
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Katrina survivor prepares for Sally
As the storm approached Monday, Mississippian Mike Taylor prepared by filling and placing sandbags around his house in Long Beach, near Gulfport, to keep water out.
"Just got to prepare. That's all we can do," Taylor said.
Taylor lost his home 15 years ago during Hurricane Katrina. It sat just a few blocks from the beach front, he said. Taylor evacuated as the storm surge moved closer, and when he returned only a slab was left. One of the few belongings he found in the debris was a toy truck that he still keeps in his house.
Taylor isn't nervous about Hurricane Sally because he believes he has already experienced a worse storm, he said.
His 8-year-old nephew is not as confident. As he helped Taylor fill sandbags, he told CNN he's worried.
"I'm very nervous. The storm is coming at night and the wind can blow your house down," the boy said.
A lifelong Gulf Coast resident, 35-year-old Robert Higdon also filled sandbags in the Gulfport area. He said he is not terribly concerned about this hurricane but knows it's best to "prepare for the unexpected."
Gulf of Mexico storms can quickly intensify, he said, so he always assumes the hurricane is going to be a little worse than the official forecast predictions.
"I'd rather be prepared for the unexpected," Higdon said. "If it's a Category 2 or below we just bunker down. A lot of people are willing to ride it out."
Some of the storm's main threats, forecasters say:
• Dangerous storm surge, including 4 to 7 feet from the Mississippi-Alabama line to the Alabama-Florida line. Storm surge of 3 to 5 feet also is possible from the Louisiana-Mississippi line to the Mississippi-Alabama line, forecasters said.
The storm's sluggishness could mean lengthy surges -- perhaps multiple high-tide periods over 36 hours.
"You can just imagine the saltwater that's going to push in, as well as the freshwater coming down in the form of rain," Gray said.
• Heavy rain and dangerous flash flooding. The 10-30 inches forecast for some coastal areas would mean several months' worth of rain.
Flash flooding is possible not only there, but also well inland, forecasters say. About 4 to 12 inches of rain could fall in parts of southeastern Mississippi, central Alabama, northern Georgia and the western Carolinas though Saturday.
• Strong winds. Sally's slow pace means areas where the storm crosses land may experience winds of at least tropical-storm strength (39 mph and higher) for more than 30 hours, including hurricane-force winds.
Scientists believe climate change is influencing hurricanes and making their impacts worse, and Sally looks to be checking all their boxes -- including its slow forward speed.
Residents and visitors get ready in Alabama
In Bayou La Batre, a coastal Alabama town just southwest of Mobile, Ian Fields on Monday secured his boat on the bayou where he and his family plan to ride out the storm.
"We've got plenty of tie lines out. That's about as prepared as we are," he told CNN affiliate WALA.
Fields has ridden out past storms, though he has a backup plan just in case his family needs to leave this time, he said.
"I'm just waiting for it to come and go," he told the station.
Jerry Gunderson cut short his vacation on Alabama's Dauphin Island because of Sally, he told WALA. Still many hours from landfall, the storm was also complicating his evacuation.
"We had booked a home to go to in Mobile, and they just called and said that a tree fell through the house, so right now we're trying to find other accommodations," he said.
Evacuations ordered along the coast
The governors of Alabama, Louisiana and Mississippi have requested emergency federal assistance ahead of the storm and each has declared a state of emergency.
The Florida National Guard has activated 175 members and has 30 high-water vehicles on standby as the agency prepares for search and rescue operations, the Florida Division of Emergency Management tweeted.
Mandatory evacuations have been announced along the coasts of Louisiana, Mississippi and Alabama.
Residents in Louisiana's Plaquemines Parish, St. Charles Parish and parts of Jefferson Parish have been told to evacuate as flooding and storm surge are expected.
Those in low-lying areas of Mississippi have been advised to evacuate ahead of the storm, with mandatory evacuations ordered in Hancock County, about 60 miles east of New Orleans, for anyone living along the coast or near bayous, creeks, rivers, inlets or in mobile and modular homes.
Several shelters have been opened in the area to house evacuees. Some shelters were at reduced capacity to allow for distancing because of coronavirus, including in Alabama's Mobile County, CNN affiliate WPMI reported.