A serious storm system that brought heavy snow, coastal rain and high winds within the mountains of California is constant a slow cross-country journey that is predicted to last all week, forecasters said on Sunday.
The storm is predicted to succeed in the Great Basin and the Desert Southwest by Monday, the Weather Service said, with those areas forecast to rise up to 2 inches of snowfall an hour, which could make travel difficult.
By Tuesday, forecasters with the service said, the storm could turn into a serious winter storm from the central High Plains to the Upper Midwest, which could end in “multiple days of great impacts to travel and infrastructure on account of snow, blowing snow and freezing rain.” The Weather Service emphasized that “travel may turn out to be unimaginable.”
Within the Sierra Nevada, snow fell at a rapid rate of roughly three inches per hour over the weekend, blanketing roads and creating “nearly unimaginable travel” and “near-zero visibility,” the service said.
As of Sunday, the Sugar Bowl Resort, within the skiing areas of mountainous Norden, Calif., reported nearly 4 feet of snow, the service said. Other parts within the region saw about two to 5 feet of snow, which caused some highways near mountains to shut.
In San Luis Obispo County, near the central coast of California, roadways were flooded and powerful winds with gusts of greater than 60 miles per hour brought down power lines, said David Gomberg, a meteorologist with the National Weather Service in Oxnard, Calif.
In Grover Beach, which is in San Luis Obispo County, all phone and 911 lines were temporarily down on Saturday night due to the winds. Service was restored early on Sunday, in accordance with town’s Police Department.
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Snow showers were expected to filter out for much of the Sierra Nevada by early Monday morning, said Hannah Chandler-Cooley, a meteorologist with the Weather Service in Sacramento.
Extreme winter hits the West over the weekend.
The storm system began to maneuver ashore Friday evening, bringing strong winds to the California coast. But within the mountains, that moisture became heavy snow.
Forecasters had predicted “extreme impacts” — the gravest warning on the Weather Service’s winter storm severity scale — across the Sierra Nevada over the weekend.
The California Department of Transportation warned residents on Sunday to be wary of dangerous road conditions and closures in affected regions. Maintenance crews were still working to clear snow from lanes on Sunday afternoon.
Because the low-pressure system moved ashore, it tapped into an atmospheric river — an area of moisture that flows through the sky like a river at a level of the atmosphere near where planes fly. The mixture allowed for the snowfall total to succeed in one to a few feet across much of the upper terrain.
Forecasters predict blizzard conditions across the Plains.
“We’re increasingly confident that we shall be coping with a fairly significant Northern Plains blizzard” this week, said Greg Carbin, the chief of forecast operations for the Weather Prediction Center.
The system will move out of the Rockies and start to strengthen, increasing the possibility of heavy snow and really strong winds through Wednesday across the Northern Plains. The wintry blast is feasible from Colorado, including Denver, and northeast across the Northern Plains. Across the Dakotas, not less than a foot is probably going, Mr. Carbin said.
“The potential does exist there for some really impressive amounts,” he added, as he expects this storm system will probably decelerate.
Severe storms, possibly with tornadoes, are expected across portions of the South.
It looks highly likely that severe storms, possibly capable of manufacturing tornadoes, will form on Tuesday across an area from eastern Texas to Arkansas, Louisiana and far of Mississippi, said Bill Bunting, the chief of forecast operations on the Storm Prediction Center.
“Most fall and winter severe weather events typically have several features in common,” Mr. Bunting said, “including a low-pressure system near or north of the realm of concern, a southerly flow of increasingly moist air from the Gulf of Mexico moving northward prior to the event and a chilly front moving east towards the realm.”
Tornadoes usually are not unusual this time of 12 months, but they’re less likely than within the spring and early summer.
“We average about 4 days in December per 12 months with not less than one EF-1” — rated on a 0-to-5 scale of tornado damage — “or stronger tornado,” said Harold Brooks, a senior scientist with the National Severe Storms Laboratory, a part of the National Oceanic and Atmospheric Administration. “There are about 100 days with an EF-1 or stronger tornado throughout the 12 months.”
Severe winter storms just like the ones predicted this week will be more dangerous than ones that form during peak severe weather season, in May and June.
“Because days are shorter,” Dr. Brooks explained, these storms are “more prone to occur after dark.” This “makes them more dangerous” because people in harm’s way cannot spot them as they approach, he said.
“Additionally they usually tend to occur within the mid-South and Southeastern United States, which have greater rural population density than the Plains and have the next fraction of manufactured housing and poverty,” he added. “Thus, the impacts will be greater.”
Snowfall within the Northeast.
Some snow fell across southern Latest England and upstate Latest York on Sunday. In Albany, N.Y., there have been about five to seven inches of snow, said Bob Oravec, a meteorologist with the Weather Service.
About eight inches of snow fell within the Berkshires, Mr. Oravec added, and Hartford, Conn., recorded between 4 and 6 inches.
Boston and Windfall, R.I., each had one or two inches of snow.
“Some areas may not have had much snow yet this winter,” Mr. Oravec said. “So any time you get snow, it’s all the time impactful.”
Christine Chung and April Rubin contributed reporting.