A dangerous winter storm is battering large swathes of the western US with residents in parts of California urged to shelter in place and prepare for power outages and a possible record 12ft of snow forecast to dump this weekend, amid gale-force winds and blizzard conditions.

Perilous conditions in the Sierra Nevada region are expected to get significantly worse over the weekend, with a high risk of whiteout conditions, near-zero visibility and avalanches across the mountain range, making travel impossible, according to National Weather Service (NWS).

“There is a high chance (over 70%) of substantial, long-lasting disruptions to daily life in the high elevations of the Sierra Nevada through Sunday where blizzard conditions and 5-12 feet of snow (and locally higher) are expected,” the federal agency warned.

Wind gusts of 75 to 100mph are possible and will “likely down trees and power lines, resulting in widespread power outages”.

On Thursday, Yosemite national park and several ski resorts closed and urged visitors to leave the area. By Friday morning, officials warned that the time window for safe travel was closed.

Atypically large quantities of snow are falling fast, with three to five inches an hour expected from Friday through Saturday in mountainous areas. Such extreme snowfall – with well over 100in forecast for just four days – is among the highest on record for the region.

A combination of the El Niño weather cycle and global heating caused by burning fossil fuels are driving historic storms that have battered California this winter, according to climate scientists.

The NWS in Sacramento issued rare blizzard warnings for the Sierra, Northeast Foothills, Motherlode and the western Plumas and Lassen area from 4am Thursday through 10am Sunday. Very unusually, the warning extends to the Lake Tahoe area, the expansive fresh water body which straddles the border of California and Nevada.

The rare blizzard and snowfall is causing perilous conditions but will also boost water supplies, bringing the Sierra mountain snowpack closer to long term average for this time of year.

As the snow storm, which began in the Pacific Northwest late Wednesday, continues to moves south throughout the weekend, much colder air will set in, with temperatures 10 to 20 degrees Fahrenheit below normal likely in parts of California.

Meanwhile in Texas, ferocious winds continue to hamper firefighters who are struggling to contain the state’s worst ever blaze which by Thursday night had razed one million acres, killing two people and herds of cattle.

Fueled by parched grasses, strong winds and abnormally warm temperatures, several fires have merged in the Texas Panhandle, destroying homes, farmland and livestock, spreading north into Oklahoma.

Conditions improved slightly on Thursday with some light rain and snow, but the Smokehouse Creek fire – the second largest in US history – is far from contained. Dry, warm conditions are forecast for the Texas Panhandle this weekend, posing a significant threat as firefighters battle with dozens of fires across the region.