Grocery stores are restocking shelves with water and bread, and supply stores are selling a lot of plywood and generators Monday as East Coast communities prepare for Hurricane Florence to strike hard later this week.
Florence has been upgraded for the second time Monday and is now a Category 4 hurricane, according to the National Hurricane Center. Florence has maximum sustained winds of 130 mph and is expected to continue growing as it heads toward the U.S. East Coast.
Further strengthening is expected, as Florence moves toward North and South Carolina, where it could unleash its fury as the most powerful storm to hit the area in three decades.
Tourists and residents were outside Sunday enjoying pleasant weather, but by Monday emergency management workers had been told to buckle up for what could be a very long week. "This storm gets stronger and stronger" and is on its way to a head-on impact on the Carolinas, CNN meteorologist Chad Myers said.
The National Hurricane Center forecasts Florence to hit the shore late Thursday night or early Friday morning.
Swells up to 15 feet high could reach the coast, Myers said, and the storm system is likely to stall when it crosses land, dumping up to 20 inches of rain in some inland locations.
Florence was about 625 miles southeast of Bermuda as of 5 a.m. ET Monday. The storm had maximum sustained winds of 105 mph and was moving west-northwest at about 9 mph, the hurricane center said.
The center of the hurricane was forecast to move between Bermuda and the Bahamas on Tuesday and Wednesday and approach the Southeastern US coast on Thursday as a Category 3 storm or higher, according to the hurricane center.
A Category 3 hurricane packs winds of between 111 and 129 mph, the hurricane center said. Florence could grow into a Category 4, with sustained winds of at least 130 mph as it crosses over the warm Atlantic waters.
"There is an increasing risk of life-threatening impacts from Florence: storm surge at the coast, freshwater flooding from a prolonged and exceptionally heavy rainfall event inland, and damaging hurricane-force winds," the hurricane center said. It warned people at the coast and inland from South Carolina to the mid-Atlantic region to monitor the storm's progress closely and ensure they have a hurricane plan in place.
Large swells generated by Florence are already affecting Bermuda and portions of the East Coast and will continue this week.
"These swells are likely to cause life-threatening surf and rip currents," the hurricane center said.
East Coast track
CNN senior meteorologist Dave Hennen said Sunday that computer models agree Florence is on track to make landfall in the Carolinas.
It would be the first Category 3 or higher storm to hit the East Coast since Hurricane Jeanne struck Florida in 2004.
Governors of Virginia, North Carolina and South Carolina have declared states of emergency.
"We are preparing for the worst, and of course hoping for the best," South Carolina Gov. Henry McMaster said, adding that his declaration would allow state agencies to deploy assets quickly to the coast. The state has begun enforcing a law against price gouging.
McMaster said Sunday that he has asked President Donald Trump for a federal disaster declaration. That would make state and local agencies eligible for Federal Emergency Management Agency reimbursement of some costs.
North Carolina Gov. Roy Cooper waived certain transportation restrictions so that farmers could harvest and move crops more quickly.
Cooper also urged people to learn what evacuation routes to take, and put fuel in their vehicles in case they're ordered to leave.
"Action today can avoid losses due to Florence," he said.
Lines at grocery stores
Crowds formed at supermarkets on Sunday as people tried to stock up on supplies.
"Checkout lines @Costco in Charleston running all the way to the back of the store. Hurricane #florence for the win! #chswx," Michael Livingston tweeted. "Wait was about 20 min - long but fast-moving. Prep is usual: foodstocks, fuel, cash, batteries, clean-up of property for high winds. Might buy a new board game or two. :)"
Erin Byrd checked in online from Publix in Apex, North Carolina.
"Water supplies being depleted. ... Bread and milk supplies still robust," she posted on Instagram.
"We don't panic, which is why we are amused that water was so depleted a week out. We still have water supply from last year here," she told CNN.
Alicia Buchanan posted on Instagram from Walmart in Rock Hill, South Carolina.
She just moved to the area two weeks ago from Northern Virginia and still doesn't have her furniture.
"So, I'm prepping with some bottled water, a couple puzzle books, and making sure all my electronics and back-up batteries are charged," she told CNN. "I plan to do most of my cooking on the grill."
Preparations for Florence come as the Atlantic hurricane season hits its peak. Two other storms also are churning in the Atlantic.
Hurricanes Helene and Isaac are not expected to hit the U.S. mainland.
Monday is the climatological peak date of hurricane season, the height of the eight-week period when the most powerful storms usually form, CNN meteorologist Pedram Javaheri said.
The Atlantic hurricane season officially began June 1, but cooler water and higher wind shear -- winds moving at different speeds and directions -- early in the season are less than ideal for tropical systems to gain and maintain strength.
Storms increase in frequency and intensity by mid-August and into September as temperatures in the Atlantic climb to their highest levels, Javaheri said.
"Take mid-August to mid-October, that period accounts for 87 percent of category 1 and 2 hurricane days and a staggering 96% of 'major' hurricane days -- (Categories 3, 4 and 5)," he said. "By late October, wind shear once again increases and the cooler autumn air filters farther south, allowing waters to begin their inevitable cooling process."
CNN meteorologist Gene Norman compared the conditions to boiling water on a stove, with the water taking a while to react to an increase and then decrease in the temperature of the element beneath it.
"Even though the season starts in June, the Earth is just beginning to warm up from the summer sun. By mid/late August, temperatures near their peak, like that pot on the stove starting to boil," he said.
"However, just as it takes a while to heat the ocean, it also takes a while for the latent heat stored there to dissipate, like that pot on the stove. This is why there can be strong storms lingering into October."