By Steve Gorman and Brendan O'Brien
LOS ANGELES (Reuters) - California, reeling from a month-long string of late-winter storms, braced for another bout of heavy rains, wind and snow on Monday, while most of New York state and New England girded for a powerful Nor'easter.
The leading edge of the latest Pacific storm swept into northern California and was expected to intensify late Monday night through Tuesday as it spread through central and southern parts of the state still sodden from weekend flooding.
Emergency crews preparing for the season's 11th "atmospheric river," an airborne current laden with dense tropical moisture from the ocean, renewed sand-bagging operations and round-the-clock patrols of levees and rain-swollen riverbanks.
Mandatory evacuation orders remained in effect for residents in 10 California counties, according to the Federal Emergency Management Agency.
The National Weather Service (NWS) posted flood watches for much of the state, along with warnings for gale-force winds and extensive uprootings of trees.
"With the ground already saturated from the previous storm and river levels well above average, another round of major and life-threatening flooding is likely" along California's coast, the Sierra Nevada foothills and the state's vast Central Valley farm region, the NWS said.
Some of the heaviest rain, as much as 10 inches (25 cm), could fall in the Santa Barbara and San Bernardino mountains of Southern California, state climatologist Michael Anderson told reporters on Monday.
The rainfall was likely to hasten the melting of snow left on the ground from recent blizzards in mid-level mountain areas, adding to heavy runoff and flood hazards downstream, as it did over the weekend, forecasters said.
But the new storm was also expected to dump another 3 to 5 feet (1-1.5 meters) of snow at higher elevations, above 8,000 feet (2,400 meters), in the Sierra range, according to the NWS.
Anderson predicted additional precipitation from the looming storm, and one or two more still forming behind it in the Pacific, would likely push the southern Sierra snowpack to all-time historic levels, surpassing a 1969 record.
Nine atmospheric rivers lashed California in rapid succession from late December through mid-January, triggering widespread flooding, levee failures, mudslides and punishing surf. At least 20 people perished.
'SAD FOR ALL THE PEOPLE'
The 10th atmospheric river system of the season struck on Thursday and Friday, sending rivers and creeks spilling over their banks in several low-lying areas, most notably along central California's coast.
Drone footage above Monterey County showed entire neighborhoods inundated by muddy, brown waters after a levee on the Pajaro River failed. Evacuation warnings and orders across the county of 430,000 residents remained in place on Monday.
One evacuee from the flood-stricken community of Pajaro, farm worker Pedro Rangel, 42, attempted to return to his home on Monday but said he could not penetrate the mud and water surrounding his residence.
"It's sad for all of the people who live there. You lose everything," Rangel told Reuters at an evacuation center in nearby Watsonville.
About 140 miles (225 km) to the south, public works teams in San Luis Obispo County were monitoring stream levels and reinforcing a rain-weakened earthen levee along the Arroyo Grande Creek with sandbags in hopes of stemming renewed flooding.
"Now the creek levels are so high that it's really not going to take a lot to cause flooding," said Rachel Monte Dion, the county's emergency services coordinator.
Across the country, a Nor'easter storm was forecast to dump as much as 16 inches of heavy snow and whip winds of up to 45 miles per hour from Pennsylvania and New York state up into Maine starting on Monday night and into Wednesday, the NWS said.
Heavy, wet snow from the storm was likely to topple trees and power lines, causing power outages, while also diminishing visibility and making road travel extremely dangerous, forecasters said.