HONOLULU -- Hawaii is used to preparing for tropical storms - stock up on water, toilet paper and other essentials and wait. But actually getting hit with systems like the two approaching the islands? Not as much.
Though it's not clear how damaging the storms could be, many in Hawaii aren't taking any chances as they wait for a weakening Hurricane Iselle to make landfall Thursday, possibly as a tropical storm, and Julio, which strengthened from a tropical storm to a Category 1 hurricane on Tuesday, potentially hitting three days later. Stores are re-stocking shelves of bottled water, baby supplies and canned meat as soon as they empty as streams of shoppers fill their carts.
Storms are very common in Pacific Ocean waters around Hawaii, with an active season each year.
The Central Pacific Hurricane Center issued a hurricane warning for the Big Island of Hawaii as Hurricane Iselle approached, CBS Honolulu affiliate KGMB has reported. The storm with maximum sustained winds of 95 miles per hour was located about 542 miles east of Hilo and moving at about 16 miles per hour.
Julio, continuing its path behind Iselle, had maximum sustained winds of 75 miles per hour, according to the National Weather Service. The storm was located 1555 miles east of Hilo and was moving west-northwest at 17 miles per hour.
"Hawaii is a small target in the big ocean, so it just has to be really good timing and the conditions have to be right for us to get a direct hit," said Eric Lau, meteorologist for the National Weather Service in Honolulu.
Hawaii has been directly hit by hurricanes only three times since 1950, though the region has had 147 tropical cyclones over that time. The last time Hawaii was hit with a tropical storm or hurricane was in 1992, when Hurricane Iniki killed six people and destroyed more than 1,400 homes in Kauai, Lau said.
"We've been lucky so far. So we just need to really take this threat seriously and make sure everybody is prepared," he said.
When a pallet full of bottled water ran out at a Honolulu warehouse store Tuesday, shoppers loading up on supplies 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 constantly restock water and sold as much of it on Monday as it sold all last week, he said.
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 Charlie Gustafson, general manager of Tamura's Supermarket.
"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 is 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 "tropical storms are nothing to laugh at" and could bring heavy rains and sustained winds of 40 to 50 mph, he said.
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.
In the Atlantic Ocean, Tropical Storm Bertha continues to weaken as it moves northward, posing no direct threat to the U.S. East Coast. The storm's maximum sustained winds decreased to near 50 mph Tuesday evening with even more weakening expected over the next two days.
On Sunday, the storm buffeted parts of the Bahamas and the Turks & Caicos with rain and gusty winds, after passing over the Dominican Republic. Earlier, it dumped rain on Puerto Rico.
Ahead of this year's hurricane season, weather officials warned that the wide swath of the Pacific Ocean that includes Hawaii could see four to seven tropical cyclones this year.
Farther west, the Central Pacific Hurricane Center has also issued advisories on Hurricane Genevieve, located 1200 miles southwest of Hawaii. It's trajectory is expected to continue westward and cross into the Eastern Hemisphere, making it a typhoon.
Before Hurricane Iniki hit Hawaii in 1992, the last previous hurricane slammed the islands 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 were making sure to vote early in the primary elections, which are scheduled for Saturday. The elections include several marquee races, including primaries for U.S. Senate, governor and a U.S. House seat covering urban Honolulu.
Honolulu Mayor Kirk Caldwell planned to return two days early from a trip to Japan.