Dangerous nor'easter targets East Coast with snow, rain, wind

BOSTON -- The Northeast is bracing for a powerful storm that will kick off the volatile month of March, bringing damaging winds, moderate to major coastal flooding, rain and snowfall, CBS Boston reports.

Heavy rain, intermittent snow and high winds with gusts exceeding 50 miles per hour are expected as the storm moves up the Eastern seaboard, beginning in New York and Connecticut on Thursday evening. Along the East Coast, authorities told residents of coastal communities to be prepared to evacuate if necessary in advance of Friday morning's high tide.

Boston weather forecasts and stories from CBS Boston

Meanwhile on the West Coast, a huge amount of snow is headed toward the Sierra Nevada, according to CBS Boston meteorologist Eric Fisher. Three to five feet of snow is expected across the Sierra. Across southern California, there's the risk of dangerous debris, flooding and mudslides. 

Ahead of the storm, many airlines have issued travel waivers to allow passengers to change their flights without penalty, CBS News' Kris Van Cleave reports.

Here's how the storm looks as of Thursday afternoon.

Massachusetts

For the first time since a blizzard hit the region in early January, New England will see "bombogenesis" -- signifying an intense and rapidly deepening storm, CBS Boston reports.

• What causes bombogenesis?
  

The storm has the potential to be a historic, crippling event for southern New England. With major coastal flooding, destructive winds and torrents of rain followed by a plastering of heavy, wet snow, the damage will be widespread and significant. Power outages will likely be numerous and lengthy.

The nor'easter will not have a quick exit, instead blocked by a large area of high pressure over Greenland. Combine a very slow moving storm with the highest astronomical tides of the month and you have the recipe for major coastal destruction.

From midnight to 6 a.m. Friday, rain is expected to arrive from south to north, starting as snow in western Massachusetts.

The storm will become an absolute monster southeast of Nantucket on Friday and only slowly pull away farther to the southeast on Saturday. There will be a large and powerful wind field, extending out several hundred miles from the storm's center.

Cape Cod and the Islands, as well as Cape Ann, are at greatest risk for widespread, damaging winds, ranging as high as 55-80 mph Friday and Saturday. The rest of eastern Massachusetts will see winds gusting 35-55 mph, enough to cause tree and property damage and cause some power outages.

The Massachusetts Emergency Management Agency director has urged residents in vulnerable coastal communities to evacuate, saying the powerful nor'easter is likely to destroy homes.

"It will be dangerous to remain in the homes," MEMA director Kurt Schwartz said. "Not only may rescue not be possible, but homes will be subject to significant structural damage. We expect to lose homes during this storm. If you're in one of those areas, you need to get out."

Massachusetts Gov. Charlie Baker said he has activated the National Guard. About 200 guardsmen will work with local and state officials during the powerful storm.

"I can't stress this enough. This isn't a snowstorm in eastern Mass, but the storm itself, especially along the coast, is shaping up to be more severe than the storm on January 4," said Baker. "While crews were able to perform rescues in between high tide cycles in January, it's possible first responders will be unable to reach all flooded areas at peak high tide tomorrow."

Coastal residents are warned that the storm's impact could be felt for several days. Residents should plan to have medicine, food, clothing, and money for an extended period.

"If you are in one of these typically effected areas do not ride out the storm in your home if you are told to evacuate," Baker said. "Rescue during the storm might not be possible. Staying in homes in flood prone areas puts yourself and first responders at risk."

Baker said the storm "will impact the entire state," though what impact is felt depends on location.

Snowfall is the biggest wildcard in the storm for some areas. In at least parts of New England, the first half of the storm will almost certainly be rain, followed by colder air Friday evening and overnight, changing the rain to a heavy, wet snow.

Snowfall in the hills of Worcester and in the Berkshires could easily top 6 inches before tapering off Saturday morning. Several inches are possible in the eastern part of the state Friday night. With the heavy, wet nature of the snow combined with strong winds, power outages may become a big issue.

Rhode Island, New York and Connecticut

The National Weather Service said all of Rhode Island will be under flood and high wind watches from Friday to Sunday morning, calling the situations "life threatening."

In Connecticut and New York City, rain is expected to begin on Thursday evening. Moderate coastal flooding in Queens and Long island is expected Friday.

The U.S. Coast Guard is advising boaters to exercise "vigilance and extreme caution" Thursday night through Saturday. Authorities recommend residents of coastal communities be prepared to evacuate if necessary in advance of Friday morning's high tide.

A flood watch is in effect from Friday morning through late Friday night for southern Connecticut and southeast New York.

New Jersey

High winds and flood watches have been issued around New Jersey, where most rains will begin Thursday afternoon, getting heavier in the evening. The storm will then usher in a wet and windy Friday, with gusts of up to 60 mph in Jersey Shore communities. Warning signs are posted at Wildwood beaches and some residents are already boarding up their homes there.

Officials in the state worried that the storm could take a chunk out of beaches just south of Atlantic City that are still being repaired because of damage from previous storms. The National Weather Service said flooding is possible Saturday. Waves of up to 12 feet are in the forecast at the shore in New Jersey.

Power outages are also a concern for coastal areas. Officials say Thursday's dry morning and afternoon hours are a good time for folks to get supplies and batten down the hatches.

Pennsylvania

In Pennsylvania, heavy rain, high wind and even some whiteout snow conditions are expected in the coming days. The National Weather Service says communities from Pittsburgh east to Philadelphia and the Poconos will be affected.

Rain will start in the state Thursday afternoon in most places and is expected to get heavier overnight. On Friday afternoon, the storm will usher in high winds, with gusts of up to 60 mph near Lancaster, and up to 50 mph in suburban Philadelphia and Allentown. Rain could turn to snow in parts of the Lehigh Valley and the Poconos, causing whiteout conditions with the high winds.

Pittsburgh is also under a flood advisory, and the same storm is expected to bring heavy rain and high winds to a swath of western Pennsylvania from Thursday and into the weekend.