UPDATE: Flossie Weakens Slightly, Landfall Expected Monday Morning

***Updated at 12:04 p.m. Sunday, July 28.***

Tropical Storm Flossie weakened slightly Sunday morning, and was located about 430 miles from Hilo at 11 a.m. Sunday morning.

At that time, the Central Pacific Hurricane Center in Honolulu said the storm was packing maximum sustained winds of 60 mph as it continued its westward track to the Big Island at a speed of near 20 mph.

A storm is considered a hurricane when its sustained winds reach 74 mph.

Storm-force winds extend outward up to 175 miles from the center of the storm.

That means at Flossie’s present speed, winds could begin picking up on the Big Island’s windward side early Monday morning.

Forecasters had predicted a gradual weakening of the storm as well as a slight slowing in its forward momentum.

A tropical storm watch issued Saturday for Hawaii and Maui counties was upgraded to a warning early Sunday, which meant that tropical storm conditions were expected within 36 hours.

This satellite image from the National Weather Service taken at 9:30 a.m. Sundayshowed Flossie east-northeast of the Big Island.

Forecasters say heavy rainfall and thunderstorms are expected to begin as early as Monday morning over the Big Island, and over Maui County by the afternoon.

Flossie was expected to produce rainfall in those areas of between six and ten inches, with the possibility of some areas receiving up to 15 inches.

Slightly lesser amounts of rainfall are expected as the storm makes its way up the island chain.

A tropical storm warning was issued late this morning for Oahu, which is expected to begin feeling the effects of the storm Monday night. A tropical storm watch was in effect for Kauai and Niihau.

Hawaii County Civil Defense officials were advising residents to begin preparing Sunday for high winds by securing loose objects, and to expect power outages and interruptions of telephone communications.

They said campers and those living in remote coastal areas should be prepared for surf heights of up to 15 feet on east-facing shores as early as Sunday night and the possibility of resulting road closures.

“Our advice is to pack up and move out if you can and no later than Sunday night,” Darryl Oliveira, head of the Hawaii County Civil Defense Agency, said in a briefing Saturday.

“In anticipation, the earliest we may see some of the storm effects may be Monday morning,” Oliveira said. “We would like them to plan on bugging out basically by Sunday night.”

The state Department of Land and Natural Resources on Saturday closed the Waimanu trail and campground, Pololu trail and the Ainapo trail and cabin. They will remain closed until conditions can be assessed once the storm passes, the department said.

Tornadoes and waterspouts are also possible within the storm, the National Weather Service said.

Posted at 6:14 p.m., July 26: 

Hawaii residents are being advised to prepare for the possibility of high winds, heavy rains and thunderstorms Monday as Tropical Storm Flossie approaches the state.

At 5 p.m. today, the storm was located about 1,295 miles east of Hilo and moving to the west-northwest at 18 mph.

According to the National Hurricane Center in Florida, Flossie was expected to continue that track for the next day or so and then turn gradually westward.

This graphic from the National Weather Service shows Flossie’s expected track (click to enlarge).

The center said the storm had maximum sustained winds of 60 mph with higher gusts.

However, while Flossie was maintaining its strength today it is expected to weaken by late Saturday.

While no advisories were in effect today, a flash flood watch or warning could be issued over the weekend, the National Weather Service said.

A low-pressure system becomes a tropical storm when sustained winds reach 39 mph, and a hurricane when they reach 74 mph.