Hurricane Iselle is coming from the east, so many residents on the Big Island are bracing for the first effects from this tropical cyclone.
As the powerful storm crossed over into central pacific waters Tuesday morning, many in Hilo were shopping up a storm.
"I've bought batteries, plywood and gasoline -- getting ready for the storm," said Orchidland resident Bob Ely.
Lines of vehicles filled gas stations, as folks filled up their cars, trucks and gas cans. Things were even busier inside stores.
"Early this morning the lines were all the way to the back of the building. People were mainly buying a lot of rice, water, toilet paper," said Mike Kelley, the manager of CostULess.
By Tuesday afternoon, some of the shelves were empty at stores as people piled up emergency supplies.
"Everyone's out of water!" exclaimed Hilo resident Jen Quinata.
Forecasters at the Central Pacific Hurricane Center say the ocean around the Big Island is a little warmer than the water ahead of Hurricane Iselle. Cooler sea surface temperatures help to weaken a storm. Forecasters don't believe that warm water around Hawaii will be enough to prevent Iselle from dropping to a Tropical Storm.
"While there is some warmer water, there's also a lot of wind shear. Wind shear is going to tear this system apart and weaken it quite a bit," said meteorologist Eric Lau, with the Central Pacific Hurricane Center.
The Big Island itself could also weaken Iselle. The massive mountains of Mauna Kea and Mauna Loa reach a fourth of the way up into the lower atmosphere - and could also make a big impact on Iselle.
"As Iselle approaches, there is real uncertainty as to what the results will be as it touches the 14,000 ft peaks of the Big Island. That is something we really do not know what is going to happen," said Lau.
Because of that uncertainty, even though many shoppers spent their day picking up disaster supplies, they hoped they will not need them.
"We're all hoping for the best. Last year, Flossie wasn't as bad as expected and we're hoping for the same," said Quinata.
While some Big Island residents are hopeful Iselle will be spared a direct strike, forecasters with the Central Pacific Hurricane Center said they are pretty confident Hawaii will be hit by Iselle as a tropical storm. Lau added what could change over the next two days is the exact location of where Iselle makes landfall.