New York City is prepared to shut down its entire mass transit system if necessary Saturday as it braces for Hurricane Irene, officials said Thursday.

Nursing homes in low-lying areas received orders to evacuate completely Thursday. The monster storm with a wind speed of 90 mph coupled with heavy downpour is predicted to hit New York sometime Sunday.

Mayor Michael Bloomberg said Thursday it was very conceivable that he will order a mandatory evacuation of all low-lying areas of the city by Saturday, reported the New York Daily News.

The storm is predicted to be very dangerous, the mayor said.

Officials preparing for a worst-case scenario also will dispatch a fleet of police boats to patrol flooded areas.

Gov. Andrew Cuomo, declared a state of emergency on Thursday, activating all levels of state government to prepare for any situation that may be caused by Hurricane Irene.

The governors of North Carolina, Virginia and New Jersey also declared states of emergency.

Decisions regarding mandatory evacuation of highest-risk Zone A, which includes Coney Island, the Rockaways and Battery Park City in Lower Manhattan, will be made by Saturday morning, Bloomberg said.

About 250,000 residents of Zone A, which also includes South Beach and Midland Beach in Staten Island, are facing the risk of floods.

We are also notifying the other hospitals in the other Zone A areas as well as nursing homes and senior centers that they must - I repeat, must - evacuate beginning tomorrow and complete the process by 9 p.m. tomorrow night, the mayor said.

According to forecast reports, North Carolina will be the first to get hit by Irene on Saturday.

Detailed 7-Day Weather Forecast Released by NOAA

Zone Forecast: New York (Manhattan)

Overnight--Mostly cloudy. A chance of showers and thunderstorms before dawn Friday...then a slight chance of showers and thunderstorms. Lows in the lower 70s. Southwest winds 5 to 10 mph...becoming west. Chance of rain 30 percent.

Friday--Mostly sunny. Highs in the mid 80s. North winds around 5 mph...becoming east in the afternoon.

Friday Night--Partly cloudy in the evening...then mostly cloudy with a chance of showers with a slight chance of thunderstorms after midnight. Humid with lows in the lower 70s. South winds 5 to 10 mph. Chance of rain 30 percent.

Saturday--Partly sunny in the morning...then becoming mostly cloudy. A slight chance of thunderstorms. Showers likely...mainly in the afternoon. Humid with highs in the lower 80s. Southeast winds 5 to 10 mph. Chance of rain 60 percent.

Saturday Night--Showers...mainly after midnight. Locally heavy rainfall possible after midnight. Very windy and humid with lows in the upper 60s. East winds 25 to 35 mph with gusts up to 45 mph. Chance of rain 80 percent.

Sunday--Hurricane conditions possible. Showers. Locally heavy rainfall possible. Highs in the upper 70s. Chance of rain 90 percent.

Sunday Night--Tropical storm conditions possible. Mostly cloudy. Showers likely in the evening. Lows in the lower 60s. Chance of rain 60 percent.

Monday--Mostly sunny and breezy. Highs around 80.

Monday Night--Mostly clear. Lows in the mid 60s.

Tuesday--Sunny. Highs in the lower 80s.

Tuesday Night--Mostly clear. Lows in the mid 60s.

Wednesday--Sunny. Highs around 80.

Wednesday Night--Mostly clear in the evening...then becoming partly cloudy. Lows in the mid 60s.

Thursday--Sunny. Highs around 80.

The last hurricane to pass directly over New York, in 1821, caused tides to rise 13 feet in one hour, flooding all of Lower Manhattan up to Canal Street. According to official estimates, a storm similar to the great Long Island Express of 1938 would cause $40 billion in damage if it were to hit Long Island now.

According to meteorologists, areas like the Hamptons, the eastern Long Island haven for New York's affluent, are at the highest risk.

Flooding will be a major problem even if Irene spares the New York region as the tides are expected to be high in any case over the weekend due to a new moon.

If the storm followed the exact track of it, there could be considerable wind damage and tidal flooding out in those areas, James Aman, senior meteorologist with WeatherBug, told Reuters. There potentially could be some storm surge problems out around the eastern tip of Long Island, Rhode Island, Cape Cod, some of the areas around Boston that face Massachusetts Bay.

If Irene hits Long Island or southeast Massachusetts, the storm has the potential to be a $10 billion disaster, Weather Underground said in a blog post Wednesday.

Even the poshest homes in the region often lack hurricane-strength glass and wind shutters, which are standard in Florida, according to Michael Taylor, executive vice president for claims in the consumer unit at Chartis, the property insurance arm of AIG. These are things that will make homes a little more susceptible here if we do have high winds, he said.