HONOLULU -- When a pallet full of bottled water ran out at a Honolulu warehouse store Tuesday, shoppers loading up on supplies ahead of a hurricane and tropical storm barreling toward Hawaii hovered around until a worker refilled it. Then, it quickly emptied again.
"Days like today, in a situation like this, we just throw open the doors and hold on for the ride," said Scott Ankrom, assistant general manager of the Costco. The busy store near downtown has had to continually restock water and sold as much of it on Monday as it sold all last week, he said. People also stocked up on paper towels, toilet paper, baby supplies and rice.
Two big storms so close together is rare in the central Pacific, and Hurricane Iselle could make landfall by Thursday and Tropical Storm Julio could hit three days later, officials said.
It's unclear how damaging the storms could be, but people throughout the islands weren't taking any chances. Judy Castillo of Oahu said she wanted to make sure her family was prepared before big crowds flooded stores and shelves emptied.
"Two storms in a row? It's like, hello," she said, pushing a cart with two cases of water and other items from a drug store to her car.
A grocery store in the coastal Oahu community of Waianae opened 15 minutes early Tuesday because people were already lined up to buy supplies. Bottled water and cans of Spam and Vienna Sausage flew off the shelves, said Tamura's Supermarket general manager Charlie Gustafson.
"Just about every shopping cart I see has at least one case of bottled water. Some as many as eight," he said. "It's all flowing out very fast."
Chris Pruett of Waikiki was anticipating the silver lining that comes from bad weather: good waves.
"We're just getting water and preparing ourselves, too, because it could be bad," he said. "Of course we're not looking for a storm ... but it tends to generate good waves."
The second storm system heightened the urgency to prepare, Hawaii County Civil Defense Director Darryl Oliveira said Tuesday. His county, also known as the Big Island, was expected to see Iselle first.
Hurricane Iselle was expected to weaken to a tropical storm when it hits the Big Island on Thursday afternoon and then sweep over the other islands, said Brian Miyamoto, spokesman for State Civil Defense/Hawaii Emergency Management Agency.
But he said "tropical storms are nothing to laugh at" and could bring heavy rains and sustained winds of 40 to 50 mph.
The outlook for Julio is more uncertain -- it could hit the islands by Sunday, Miyamoto said.
The clustered storms are rare but not unexpected in years with a developing El Nino, a change in ocean temperature that affects weather around the world.
"It's something that doesn't happen very often," said Eric Lau, meteorologist for the National Weather Service in Honolulu. "Conditions are favorable because we're entering El Nino temperatures."
A hurricane last hit Hawaii in 1992, and before that, in 1982.
"The central Pacific doesn't see nearly the activity that the Atlantic sees," said James Franklin, chief of hurricane specialists for the National Hurricane Center in Miami.
In preparation, some people in Hawaii are making sure to vote early in the primary elections, which are Saturday. It includes several marquee races including primaries for U.S. Senate, governor and a U.S. House seat covering urban Honolulu.
Honolulu Mayor Kirk Caldwell plans to return two days early from a trip to Japan.