As Hurricane Sandy steadily approaches the East Coast, federal officials say that forecasts from the National Oceanic and Atmospheric Administration (NOAA) remain on track and that response teams from the Federal Emergency Management Agency (FEMA) have taken their places.

"Landfall is expected sometime tonight," Rick Knabb, director of NOAA's National Hurricane Center, said during a media call on Monday. "This huge overall storm system is going to continue to bring strong winds, elevated water levels in coastal areas and heavy rainfall over a very wide area -- both before, as we've seen during the day today, and after the circulation comes ashore."

Knabb said he anticipates storm surges of 4 to 8 feet above ground in many places, with areas around New York City likely to get the brunt of it -- up to 11 feet -- late Monday evening, due to the confluence of the surge and high tide. Meanwhile, mountainous regions of West Virginia could see up to 3 feet of snow.

The expected combination of extreme wind, rain, flooding and snow is "unprecedented" for the East Coast, he said.

FEMA administrator Craig Fugate added that his agency is "rapidly moving from preparing to being prepared to support response operations." Teams are readying emergency goods, including bottled water, meals, blankets and cots, as well as generators to run critical facilities such as water treatment plants and hospitals, he said.

Both Knabb and Fugate emphasized the storm's potential to linger, and said that could affect both the severity of its damage as well as the government's ability to deal with the wreckage.

"There will be that period where the storm is still impacting areas," Fugate said. "And that will have an impact on how quickly we can begin response-recovery operations."

Federal officials continue to urge residents to heed evacuation orders.

Knabb called Hurricane Sandy a "multi-hazard event," and warned that "time has either run out or is running out for preparations in many areas, especially coastal as conditions deteriorate before landfall tonight."