A major storm system which could bring several feet of snow to the West and blizzard conditions to On Friday evening, the Northern Plains approached West Coast at the start of a Forecasters predicted that a slow, cross-country journey would last all week and continue into the weekend.

Forecasters with the National Weather Service said that Friday’s storm system crossed the Northern Pacific and will continue to push into California during the weekend. Weather Prediction Center of the National Weather Service said on Saturday. The storm will continue to Bring snow from the mountains and rain from the coast to The West.

On Sunday, wintry precipitation will reach the Northeast from the Great Lakes Region. Thunderstorms and heavy rain could reach the South.

Computer modeling has made it possible for forecasters to predict what risks will occur as the storm moves across the middle of the United States. Here’s what forecasters think is likely to happen.

The storm system was created to Strong winds will bring you to the shore Friday evening. to California’s coast. Rainstorms at lower elevations can lead to flooding. to flooding.

However, the mountain areas have seen this moisture increase. to Fall as heavy snow

“The impacts will be widespread from north to south with numerous winter weather-related advisories in effect,” The Weather Prediction Centre said on SaturdayAdd that “the heaviest snowfall is expected for the Sierra Nevada” With several feet expected.

Forecasters forecast “extreme impacts” — the gravest warning on the Weather Service’s winter storm severity scale — across the Sierra Nevada this weekend.

Snow was falling in the Sierra mountains region. a According to Saturday afternoon, the rate was six inches per an hour to California Department of Transportation “Travel is difficult to impossible with whiteout conditions,” the department said on Twitter.

As this low-pressure system moves ashore, it will tap into an atmospheric river — an area of moisture that flows through the sky like a river at a Atmosphere near airports. Combining these two factors will enable snowfall total to Reach one to Most of the higher terrain is three feet in width.

Parts of the Sierra Nevada are likely to receive more than five feet in snow. forecasters at the Prediction Center wrote.

“We are increasingly confident that we will be dealing with a pretty significant Northern Plains blizzard next week,” Greg Carbin, chief of forecast operations for The Weather Channel, said: Weather Prediction Center.

The system will eventually move out the Rockies to begin to The chance of heavy snowfall and strong winds across Wednesday’s Northern Plains is increasing, according to Weather Underground. The wintry blast could be seen from Colorado, Denver, and northeastern across the Northern Plains. At most, the Dakotas. a According to Mr. Carbin, foot is possible.

“The potential does exist there for some really impressive amounts,” He also said that he expected this storm system to slow down.

The Central Rockies and Arizona mountains could have snow. a By Sunday night, foot

According to Bill Bunting, chief of forecast operations at Storm Prediction Center, severe storms that could produce tornadoes are very likely to form in an area extending from eastern Texas through Arkansas, Louisiana, and most of Mississippi on Tuesday.

“Most fall and winter severe weather events typically have several features in common, including a low-pressure system near or north of the area of concern, a southerly flow of increasingly moist air from the Gulf of Mexico moving northward prior to the event and a cold front moving east towards the area,” Explained Mr. Bunting.

“A similar setup is expected early next week,” He said: “which gives us confidence regarding the potential for a focused area of severe thunderstorms and possibly tornadoes.”

Although tornadoes can still occur at this time of the year, they are much less common than in spring and early summer.

“We average about four days in December per year with at least one EF1” — rated on a 0-to-5 scale of tornado damage — “or stronger tornado,” Harold Brooks a Senior scientist at the National Severe Storms Laboratory (part of the National Oceanic and Atmospheric Administration). “There are about 100 days with an EF1 or stronger tornado during the year.” 

Severe winter weather storms such as those predicted next week could prove more dangerous than severe storms that develop during peak severe-weather season, which is May and June.

“Because days are shorter,” Mr. Brooks explained, “they’re more likely to occur after dark,” He spoke of the storms. This “makes them more dangerous” because people in harm’s way cannot spot them as they approach, he said.

“They also are more likely to occur in the mid-South and southeastern United States, which have greater rural population density than the Plains and have a higher fraction of manufactured housing and poverty,” He concluded. “Thus, the impacts can be greater.”

Forecasters stated that snow was expected to fall in the southern New England, interior Northeast, and central Appalachians on Sunday.

“Moderate snow totals between 3-4 inches are possible inland for higher elevation locations like the Berkshires and Catskills, and 1-2 inches are possible further south into central Pennsylvania,” The forecast stated.

By Sunday night, rain and snow will be falling in interior northeastern New Jersey and the lower Hudson Valley. New York City could experience snow Thursday.

April Rubin Contributed reporting