Updated at 10:27 p.m. ET
Hurricane Sally will likely make landfall on Tuesday or Tuesday night with sustained winds of at least 110 mph, making it a strong and dangerous Category 2 storm, the National Hurricane Center said.
Some coastal areas in Louisiana, Mississippi, Florida and Alabama are already seeing floods from the slow-moving storm, with Sally meandering over the north-central Gulf of Mexico. Its forward speed will slow even further as it heads northwest and finally north toward landfall.
The surge could be as high as 11 feet in some areas. The storm will also bring a huge amount of rain — from 8 to 16 inches, with up to 24 inches in isolated areas of the central Gulf Coast and the western Florida Panhandle.
"Slow movement means more rain," National Hurricane Center Director Ken Graham said in an online briefing. "These rainfall totals are dangerous."
As of Monday night, Sally was about 100 miles east of the mouth of the Mississippi RiverBiloxi, creeping west-northwest at 5 mph. Its maximum sustained winds were measured at 100 mph. It would need to develop winds of at least 111 mph to become a Category 3 storm — a major hurricane.
"Impacts of an extremely dangerous and life-threatening storm surge, hurricane-force winds and torrential rain with flash flooding from Sally will likely begin later today," the National Weather Service said on Monday.
The National Oceanic and Atmospheric Administration and Air Force Reserve Hurricane Hunter aircraft confirmed that Sally had strengthened into a hurricane, the National Hurricane Center announced at noon ET.
"Additional strengthening is forecast during the next day or so," the center said.
Forecasters said conditions are too unstable to predict exactly where the storm will arrive. Current projections show Sally coming ashore east of Gulfport, Miss. The predicted track has shifted consistently eastward in the past 24 hours, bringing a measure of relief to people in southwestern Louisiana, which is still recovering from Hurricane Laura in late August.
Sally's effects are already being felt in Florida, where it was expected to create flash floods across the peninsula Monday, the hurricane center said. The storm is adding to major flooding already happening across western and central Florida, the agency said.
Sally is one of five named storms the agency is tracking – tying a record from September 1971 for the most tropical cyclones at one time, according to senior hurricane specialist Eric Blake of the hurricane center. The newest is Tropical Storm Vicky, which developed late Monday morning.
Hurricane Paulette made landfall on Bermuda early Monday, bringing sustained winds of at least 90 mph with higher gusts, the hurricane center said. At around 5 a.m. local time, the entire island was inside the storm's eyewall. The storm's center is now moving north-northwest away from the island, but dangers persist from strong winds and heavy rain that are still to come.
"Please stay hunkered down Bermuda," the Bermuda Weather Service said Monday morning.
People in Bermuda should remain indoors until at least Monday afternoon, the National Hurricane Center said, warning that "winds will increase suddenly from the southwest."
The massive amount of water Sally brings will pose a perilous threat from its storm surge and heavy rainfall. Heightening that risk, the storm is expected to continue to move slowly, increasing the impact of its rainfall.
"Life-threatening flash flooding is possible and widespread minor to isolated major flooding on area rivers is likely along and just inland of the Central Gulf Coast," the National Hurricane Center said.
A storm surge warning is in effect from Port Fourchon, La., to the Alabama-Florida border, including several lakes and Mobile Bay. A hurricane warning is in effect from Morgan City, La., (west of New Orleans) to the Mississippi-Alabama border.
Parts of Mississippi and Alabama will also see the risk of significant flash and urban flooding through the middle of the week, the National Hurricane Center said.
"Life threatening surf and rip currents have begun along our beaches this morning," said the National Weather Service office in Mobile, Ala. "Waves will continue to increase throughout the day and DOUBLE RED flags are flying at all of our beaches. Stay out of the water!"
"The window of time you have left to get ready is quickly closing," Louisiana Gov. John Bel Edwards told residents Sunday night. Edwards declared a state of emergency over the weekend; he has also asked President Trump to declare a federal emergency.
"The storm is expected to impact New Orleans, where the state is currently housing more than 12,000 Hurricane Laura evacuees in hotels," NPR member station WWNO reported.
Overall, the hurricane center is tracking seven systems — the five named storms and two disturbances that have only small chances of developing over the next 48 hours.
Tropical Storm Teddy formed in the distant Atlantic Ocean overnight and is expected to become a major hurricane – but its forecast path veers northward away from the Caribbean and over the open water, and it's not yet certain what dangers it could bring to any populated areas.
At this early stage, Teddy is expected to follow a similar path to Paulette's, although with a sharper turn to the north.
The other named storm is Tropical Storm Vicky – which formed Monday but is expected to devolve quickly. Rene is experiencing a similar fate; it was declared a tropical depression over the Atlantic on Monday.