Hurricane Dorian

Shoppers stand in line waiting to check out at Costco ahead of Hurricane Dorian on Thursday in Davie, Fla.

MIAMI • Florida residents picked the shelves clean of bottled water and lined up at gas stations Thursday as an increasingly menacing-looking Hurricane Dorian threatened to broadside the state over Labor Day weekend.

Leaving lighter-than-expected damage in its wake in Puerto Rico and the Virgin Islands, the second hurricane of the 2019 season swirled toward the U.S., with forecasters warning it will draw energy from the warm, open waters as it closes in.

The National Hurricane Center said the Category 1 storm is expected to strengthen into a potentially catastrophic Category 4 with winds of 130 mph and slam into the U.S. on Monday somewhere between the Florida Keys and southern Georgia — a 500-mile stretch that reflected the high degree of uncertainty this far out.

“If it makes landfall as a Category 3 or 4 hurricane, that’s a big deal,” said University of Miami hurricane researcher Brian McNoldy. “A lot of people are going to be affected. A lot of insurance claims.”

President Donald Trump canceled his weekend trip to Poland and declared Florida is “going to be totally ready.”

With the storm’s track still unclear, no immediate mass evacuations were ordered.

Along Florida’s east coast, local governments began distributing sandbags, shoppers rushed to stock up on food, plywood and other emergency supplies at supermarkets and hardware stores, and motorists topped off their tanks and filled gasoline cans.

Some fuel shortages were reported in the Cape Canaveral area.

Josefine Larrauri, a retired translator, went to a Publix supermarket in Miami only to find empty shelves in the water section and store employees unsure of when more cases would arrive.

“I feel helpless because the whole coast is threatened,” she said.

Tiffany Miranda of Miami Springs waited well over 30 minutes in line at BJ’s Wholesale Club in Hialeah to buy hurricane supplies. Some 50 vehicles were bumper-to-bumper, waiting to fill up with gas.

“You never know with these hurricanes. It could be good, it could be bad. You just have to be prepared,” she said.

As of Thursday evening, Dorian was centered about 330 miles east of the Bahamas, its winds blowing at 85 mph as it moved northwest at 13 mph .

It is expected to pick up steam as it pushes out into warm waters with favorable winds, the University of Miami’s McNoldy said, adding: “Starting tomorrow, it really has no obstacles left in its way.”

The National Hurricane Center’s projected track had the storm blowing ashore midway along the Florida peninsula, southeast of Orlando and well north of Miami or Fort Lauderdale.

But because of the difficulty of predicting its course this far ahead, the “cone of uncertainty” covered nearly the entire state.

Forecasters said coastal areas of the Southeast could get 5 to 10 inches of rain, with 15 inches in some places, triggering life-threatening flash floods.