When it comes to potential tracks of Hurricane Joaquin, designated a Category 3 storm Wednesday night, "the range of possible outcomes is still large," including a possible "major hurricane landfall in the Carolinas," the National Hurricane Center said Wednesday.

Though the storm could still turn east and out to sea, recent conditions indicate "an increased threat to the mid-Atlantic states and the Carolinas," the center said.

Even if the system gives Long Island a pass, the area could still see rainfall, winds, erosion and coastal flooding, forecasters say.

"Whether Joaquin directly impacts the East Coast or not, tropical moisture from Joaquin is expected to increase the potential for heavy rainfall," said the National Weather Service's Upton office late Wednesday afternoon.

"Additional rounds of heavy rain are possible late this week through this weekend, which could bring flooding concerns," said the weather service, which in its five-day rainfall forecast through next Tuesday put Long Island in the area looking at an added 5 to 7 inches.

Coastal flooding is expected later in the week, likely to continue through the weekend, the service said. "Heavy surf and beach erosion are likely."

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Heeding the lessons from superstorm Sandy, both Suffolk and Nassau counties have started putting plans in place. The Nassau County Office of Emergency Management "has begun implementing its 120 hour plan," should the storm approach the area, with vital supplies placed in communities ready for quick dispatch if needed, according to county executive Edward Mangano. Residents south of Sunrise Highway and north of Route 25A, are advised to make plans to find shelter with friends or family outside those zones, should evacuation become necessary, he said in a statement Wednesday.

Suffolk County Fire Rescue and Emergency Services has been directed to open the Emergency Operations Center, monitor hurricane conditions "and coordinate our preparedness efforts with local fire departments and emergency service providers," said county executive Steven Bellone.

"As we learned with superstorm Sandy, it is better to be overly cautious and to have a plan in place," Bellone said in a statement.

Indeed, despite the longer-term track uncertainty, as well as possibility for hitting the mid-Atlantic coast, "we must treat it as if it could get here as a Cat 1 hurricane or strong tropical storm sometime Monday just in case," said Bill Korbel, News 12 Long Island meteorologist.

A key issue of uncertainty involves the potential for a weak trough stretching from the Great Lakes down to Florida to be strengthened, as another trough drops down from the upper Midwest, said Brian Colle, professor in Stony Brook University's School of Marine and Atmospheric Sciences. That could "help guide the storm more towards the North or South Carolina coast," he said.

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Also, with much riding on timing and strength, he said, a ridge of high pressure that's forming over Quebec could block the storm from turning to the east, one of the scenarios that played out with Sandy, leading to its hook left into New Jersey.

If landfall does occur near the Carolinas, he said, "we dodge worst-case scenario," but we still may experience some minor to moderate coastal flooding and some heavy rainfall. However, if the track brings the storm further up the coast, and it heads left onto land north of Delaware, that puts New York City and Long Island "on the north side of the storm, with strong winds from the east that can pile up water," a similar scenario to what was seen with Sandy.