Snow, rain and flooding pummel US coast to coast

San Bernardino County fire department captain Don Whitesell prepares to drive a snowcat in Lake Arrowhead, California, on March 10. (Will Lester/Inland Valley Daily Bulletin/SCNG/Getty Images)

Officials in California's San Bernardino County said they are preparing for the possibility of a significant runoff in their county from an approaching atmospheric river system.

The San Bernardino County mountain communities were heavily impacted recently by unprecedented snow from a series of winter storms that led to residents being trapped in their homes for days, CNN previously reported.

The National Weather Service has increased the coverage of flood watches across California to around 30 million people.

The most recent flood watches issued include Santa Barbara County, Ventura County and Los Angeles County. Major cities in flood watches include San Francisco, Oakland, Sacramento and Los Angeles.

Rainfall totals through Wednesday are forecast to be 2 to 5 inches across coasts and valleys, with the highest amounts along the coast of Santa Barbara County. Higher elevations and mountains could see between 4 to 8 inches and rainfall rates could reach an inch per hour. Flood watches continue into the day on Wednesday.

More than 220,000 customers are without power in the Northeast as of 9:30 a.m. ET due to inclement weather, according to PowerOutage.US.   

New York and Massachusetts have some of the most outages:

More than 8,000 utility crews have been pre-deployed to handle power outages across New York state as a winter storm is expected to generate heavy snow, winds and coastal flooding across the US Northeast, according to New York Gov. Kathy Hochul.

At least 4,000 power outages have already been reported in New York’s capital region, Hochul said on WAMC Radio Tuesday morning. She added that an emergency operations center has been open in Albany and crews have been out salting the roads throughout the night.

Most roads across the state are currently open, but Hochul encouraged residents to stay off of them. Tractor trailers have been banned from driving with empty cargo, given the greater risks of accidents with lighter loads, Hochul said.

There have not yet been any reports of anyone trapped or needing rescue, Hochul said. She added that the New York state legislature is closed Tuesday due to the weather. 

CNN’s Gili Remen contributed to this report.

Over the past few days, snow amounts have been highest in New England and the Sierra Nevadas in eastern California — as well as northern states like Minnesota and Wisconsin.

Use the map below to explore what areas have seen the largest snowfall levels:

And here's where snow is expected to build up by the end of the week:

LaGuardia Airport (LGA) in New York City is currently under a “ground delay” due to winter weather, according to the Federal Aviation Administration.

The “ground delay” is in effect until at least 11:59 a.m. ET Tuesday, and there are average flight delays of about two hours. Flights that are departing LGA are being sprayed with deicing fluid to remove snow and ice, the FAA added.

The FAA also said that ground stops at nearby Newark and JFK airports are “possible” later on Tuesday, but no official announcements have yet been made.

A general view shows flooded streets in Pajaro, California, on March 11. (Josh Edelson/AFP/Getty Images)

Another atmospheric river is creeping into storm-ravaged California, pummeling communities with more rain, prompting fresh evacuation alerts and putting rescue teams on notice as residents work to recover from last week’s flooding storm.

More than 30 million people across the state were under flood alerts as the West’s 11th atmospheric river of the season pushed into Northern California and aimed Tuesday toward central and Southern California, battering ground saturated by the last round of rain and overflowing rivers.

The storm comes on the heels of another deadly atmospheric river – a long, narrow band of moisture that can carry saturated air thousands of miles like a fire hose. This round could bring up to 8 inches of rain – falling as fast as 1 inch per hour – in some places, with melting snowpack due to worsen flooding.

And after this system, another atmospheric river is forecast next week, the National Weather Service said. From severe flooding to long droughts, water-related disasters have gotten more intense in the last two decades as global temperatures climbed to record levels, new research shows.

Now, evacuation alerts are in place across California, including in Monterey County, where residents along the Salinas River were ordered to flee. Los Angeles and Santa Barbara counties issued evacuation warnings Monday night ahead of the atmospheric river’s arrival in the south, with Santa Barbara officials saying the warnings will become orders in the morning.

People view the wreckage of a bridge over the Tule River that was destroyed in a flash flood on March 10 in Springville, California. (David McNew/Getty Images)

Facing the latest storms’ one-two punch, over 600 Californians have taken refuge in 32 shelters across 13 counties, and California National Guard troops have been helping with swift-water rescues. Roads across the state are closed, and a key river levee has been breached.

“We weren’t expecting it to be as bad as we’re seeing it,” Monterey Mayor Tyller Williamson told CNN Monday.

Trucks plow snow in Worcester, Massachusetts, Tuesday morning. (WHDH)

Heavy snow rates of more than two inches per hour can be expected over the next several hours, the weather service in Albany, New York, warned Tuesday morning, adding that this will make travel very difficult. These high snowfall rates will lead to snow totals exceeding 7 inches in the Hudson Valley by 10 a.m. ET, and one to two feet in higher elevations. 

Much of the interior Northeast and New England is or will experience similar heavy snow on Tuesday. Western Massachusetts is reporting up to a foot of snow has fallen overnight and much of the surrounding region has reports of 2 to 6 inches. 

Additional snowfall accumulations of 6 to 12 inches are expected for many areas of upstate New York and New England, with even more for in the higher elevations.

Rain and strong winds are in place along the East Coast Tuesday morning, including Boston. Rain changed over to snow in Worcester, Massachusetts, this early morning and is beginning to quickly accumulate, CNN Meteorologist Derek Van Dam noted. Snow is expected to overtake the rain closer to the coast later today. Winds gusts will also increase to up to 65 mph along the New England Coast. 

More than 150,000 customers are already without power in New York, Massachusetts, New Hampshire and Vermont from the storm, according to poweroutage.us, and that number will likely grow today.

A ground stop has been issued at New York's LaGuardia Airport ahead of Tuesday's nor'easter. 

The first nor'easter of the season is expected to hit parts of the Northeast and New England with areas around New York City expected to feel the storm's effects later today.