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Hurricane Joaquin was upgraded to an "extremely dangerous" Category 4 storm Thursday afternoon, even as the East Coast was already preparing for potentially historic rainfall and flooding from another storm front.

Virginia, North Carolina and New Jersey were the latest states to declare emergencies, warning residents that the severe weather already predicted could be significantly worse if Joaquin whips northwestward.

The hurricane was packing 130 mph winds as it battered the central Bahamas, moving about 6 mph as of 2 p.m. ET

"We are not quite sure if this is going to be a single punch or a double punch," New Jersey Gov. Chris Christie told reporters Thursday.

But no matter which way Joaquin heads, an area of low pressure in the Southeast and a front stalled over the East Coast will pull moisture from the Atlantic Ocean, causing rain Thursday through at least Saturday, said Bruce Terry, lead forecaster for the government's Weather Prediction Center. The National Weather Service predicts as much as 10 inches for some areas.

For consecutive days we have seen HUGE 5 day rainfall 4casts. This is a HUGE story w/life threatening implications. pic.twitter.com/egEaeF6ydF — Jim Cantore (@JimCantore) October 1, 2015

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Different forecast models predict Joaquin will either ram into Virginia, Maryland or North Carolina this weekend, or skirt the East Coast entirely as it takes a more easterly track up the Atlantic. Overnight, the American model trended toward the European model in predicting that the storm would not make landfall in the United States.

Still, Georgia, the Carolinas and Virginia appear in line to be soaked by a separate storm pulling tropical air into the region. Between 10 and 15 inches of rain has been forecast over a 72-hour period from Friday through Sunday — with as much as 20 inches in some places. Parts of Maryland, Delaware and New Jersey are also expected to be drenched this weekend.

Heavy rain was already falling late Wednesday, and at least one person died in flash floods in Spartanburg, South Carolina, officials said.

Virginia Gov. Terry McAuliffe on Wednesday declared a state of emergency, while North Carolina Gov. Pat McCrory ordered state agencies to prepare for flooding. He also declared a state of emergency on Thursday.

"I cannot stress enough the imperative for Virginians to focus on the rainstorms that are headed our way [Thursday] and Friday, well before Hurricane Joaquin could potentially impact Virginia," McAuliffe said. "The forecast of up to 10 inches of rain in areas across Virginia could result in floods, power outages and a serious threat to life and property."

In Kitty Hawk, North Carolina, officials were hoping sandbags protect the town if the hurricane strikes the Outer Banks. "It could be some resemblance of what Sandy [in 2012] offered us, and we've learned some lessons from that," Kitty Hawk Mayor Gary Perry told NBC affiliate WAVY.

Gov. Christie on Thursday also declared a state of emergency in New Jersey, warning that he will order evacuations if necessary.

We are prepared. I need everyone to not panic. — Governor Christie (@GovChristie) October 1, 2015

In New York, Gov. Andrew Cuomo told reporters that emergency operations centers are staffing up and government departments will begin monitoring areas that have been prone to problems from severe weather.

Low-lying areas in New York and New Jersey were ravaged by Superstorm Sandy.

"I have learned the hard way that it is better to prepare for the worst, and in the past, we were not. We did not take worst-case scenario into full consideration and we paid the price," Cuomo said.

Disney Cruise Line rerouted a ship headed toward Nassau in anticipation of the hurricane, and said the vessel would go to Key West instead. Another Disney ship out of Port Canaveral will have its itinerary rerouted. Carnival Cruise Lines also modified the routes of two cruises, the company said.

Time to focus on dangerous flooding potential in SC/NC. Euro unimaginable amount of rain next 72 hrs. #NotJouquin pic.twitter.com/VeXTfyc1La — Bill Karins (@BillKarins) October 1, 2015

Authorities in the Bahamas fear storm surges, coastal flooding and up to 10 to 15 inches of rain, said Geoffrey Greene, a senior forecaster with the Bahamas Meteorology Department.

Capt. Stephen Russell, director of the Bahamas National Emergency Management Agency, said there were no major issues at 10:30 a.m. ET but some homes had flooded.

Hurricane Joaquin already flooding homes on Acklins Bahamas...Live shots.... pic.twitter.com/EfCMuXgiKu — Bahamas Press (@Bahamaspress) October 1, 2015

Isolated downpours of up to 15 inches are possible over San Salvador and Rum Cay through Friday, the agency warned overnight.