HONOLULU (AP/Meredith) — Hawaii residents rushed to grocery stores Tuesday to stock up on bottled water, ramen and toilet paper as they faced the threat of heavy rain, flash flooding and high surf from an erratic hurricane whose path is uncertain.

The National Weather Service issued a hurricane watch for Hawaii, Maui and other smaller islands, meaning tropical storm-force winds could arrive within 48 hours. It's possible Oahu and Kauai may later be included in a watch.

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Hurricane Lane "is forecast to move dangerously close to the main Hawaiian islands as a hurricane later this week, potentially bringing damaging winds and life-threatening flash flooding from heavy rainfall," the weather service's Central Pacific Hurricane Center warned.

The storm had been moving west but is expected to turn northwest toward the state Wednesday. There's some uncertainty to Lane's path — whether it moves north or south, meteorologist Gavin Shigesato said.

[Related: Hurricane Lane is the biggest weather threat to Hawaii in decades]

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"It is much too early to confidently determine which, if any, of the main Hawaiian islands will be directly impacted by Lane," the weather service said.

Even if the center of Lane doesn't make landfall, the islands could be walloped with rain and wind. Officials were urging residents to use Tuesday and Wednesday to prepare.

"People are getting ready, which is exactly what we want," Maui County spokesman Rod Antone said. "I know people are taking trips to Costco, buying ramen, rice, the usual. Toilet paper."

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He reminded people to have emergency kits ready and to "withdraw cash. Remember, if the power goes out, ATMs aren't going to be working."

Some customers were buying cases of bottled water Tuesday at Island Grocery Depot in Kahului, Maui, manager Brian Arakaki said. He planned to call in more workers to cope with an expected afternoon rush.

On the south side of the Big Island, workers at Mizuno Superette in Pahala also were bracing for a busy afternoon.

[Related: Photos: Residents in Hawaii prepare for Hurricane Lane]

"Right now, it's nice, everybody's calm," said Carla Andrade, a store clerk. "When everybody finishes work, they'll have time."