Hurricane Sandy will move northward through the Bahamas on Friday,...

Hurricane Sandy will move northward through the Bahamas on Friday, bringing tropical storm conditions to the east coast of Florida. (Oct. 26, 2012) Credit: NOAA

Long Island was bracing Saturday for Sandy, an immense storm that forecasters expect to batter the region next week with destructive winds and flooding.

The Town of Islip ordered a mandatory evacuation for Fire Island to be completed by 2 p.m. Sunday. Supervisor Tom Croci declared a state of emergency for the town beginning at 8 a.m. Saturday.

Long Island's residents likely will see some rain and wind by Sunday night and feel the brunt of the storm late Monday into early Tuesday, said David Stark, a National Weather Service meteorologist in Upton.

Sandy, upgraded to a hurricane again Saturday just hours after forecasters said it had weakened to a tropical storm, left 43 dead across the Caribbean and was projected to make landfall Tuesday morning over Maryland.

"It's going to be a very large and powerful storm," Stark said. "Even if that landfall shifts 50 miles one way or other, the effects will be the same."

As Sandy churned off the East Coast, federal, state and local governments, transportation providers and utility companies began advising the public of plans for a worst-case scenario, which could include sustained hurricane-force winds of 50 mph and coastal flooding.

As of 8 p.m. Friday, National Hurricane Center forecasters said the storm was about 400 miles south-southeast of Charleston, S.C., with maximum sustained winds of 75 mph.

Some dubbed the moisture-laden mass a "Frankenstorm." It could mix with a cold front coming from the west, and that front, in turn, was just ahead of a low-pressure trough angled in such a way that it draws Sandy in a westerly direction toward the coast. The potential result: a nor'easter with an extra-dangerous punch.

Gov. Andrew M. Cuomo declared a state of emergency for the state and advised New Yorkers to take "common-sense steps" such as clearing yard debris and stocking up on food.

"There's no reason to panic," Cuomo said at a Hauppauge news conference, adding that it was early in storm preparations and "better to err on the side of caution." The declaration will free officials to make emergency decisions, help make equipment and personnel available from the National Guard and clear the way for a federal disaster declaration, if needed, he said.

Nassau County Executive Edward Mangano said residents of flood-prone areas south of Sunrise Highway or north of Route 25A should be prepared to evacuate their homes as early as 3 p.m. Saturday.

"Objects should be removed or tied down in backyards, and they should have battery-operated radios for the latest updates on the storm," he said, adding that the county's website also will have updates.

Joseph J. Lhota, chairman of the Metropolitan Transportation Authority, warned that the impending storm could force the second systemwide MTA shutdown in history if sustained winds of 39 mph and above are imminent. The first shutdown occurred in August 2011, in advance of Tropical Storm Irene.

"We are hoping for the best but preparing for the worst," Lhota said.

The Long Island Rail Road began its pre-storm preparations by clearing drains, securing work sites against high winds, fueling equipment and making plans to move gear and supplies away from low-lying areas.

Nassau's bus system, NICE, advised riders to expect delays and service interruptions because of flooded roads that could become impassable. NICE also is making buses available for evacuations.

The Long Island Power Authority said it was coordinating preliminary preparation efforts with state, New York City, county and local emergency management organizations, ensuring that all LIPA and National Grid personnel are ready to respond, securing additional utility and tree trim crews, testing communication and information systems, and making sure that supplies and equipment were fully stocked.

Long Island hospitals and the Nassau and Suffolk health departments said they have been gearing up to make sure they have enough staff and supplies -- and to make sure hospital beds are available in case some nursing homes and hospitals have to evacuate, as they did during Tropical Storm Irene.

Nassau County Health Commissioner Dr. Lawrence Eisenstein said he has urged hospitals and nursing homes in the county to send home those patients who can leave. "It's always safer to move people in a more controlled way," he said.

Sam Kille, the American Red Cross' regional communications director for Long Island, said the agency was talking to partners to determine where shelters will be opened and how many volunteers and supplies will be needed.

"Once it's determined where we're opening shelters, we will release information through the media," said Kille, who advised residents to check the Red Cross website and download its free emergency preparedness mobile application.

Joe Williams, commissioner of Suffolk County Fire and Rescue, which includes the Office of Emergency Management, said county officials had begun meeting with representatives of agencies at all governmental levels as they prepare for Sandy's impact.

The county is focused on its "120-hour plan," which includes a to-do checklist, from the "small things like making sure all generators in the county are topped off with fuel, to the more serious ones like calling for evacuations," he said.

Officials are concerned about the county's coastline from Babylon to Montauk, and on the South and North shores. Williams said no decision on evacuations would likely be made until Saturday.

"When a storm strikes south of us, all that water is going to be coming into all our bays, all our inlets," Williams said. "We're definitely going to have some beach erosion, some flooding."

George Gorman, deputy regional director of New York State Parks, said he is particularly worried about Robert Moses State Park, which saw considerable erosion on its eastern end during Irene.

"So, right now we have a very short beachfront," he said. "If the storm does have a major impact, we could see severe erosion."

Lisa Hodes, owner of Sweeties Candy Cottage shop in Huntington, said she fears the effects of the storm on her business, which lost power during Irene.

"We can't afford to close," Hodes said. "But I will batten down the hatches outside. I am crossing my fingers."

With Rick Brand, Sid Cassese, Mark Harrington, Patricia Kitchen, Ridgely Ochs and Nelson Oliveira