San Francisco tornado warning and ice, snow, rain for much of the US

On December 15, 2024By Littum

Following a tornado warning Saturday morning, the Bay Area still faced the threat of flooding while other parts of the United States braced for ice, rain and snow.

The National Weather Service issued a tornado warning Saturday morning for downtown San Francisco and San Mateo County just before 9 a.m. ET/6 a.m. PT. It was lifted soon after. This is believed to be the first recorded tornado warning in the area, the National Weather Service told USA TODAY.

But severe weather remained a threat in the region with an atmospheric river event expected to bring gusty winds and very heavy rain, with the potential for flooding, to northern and central California throughout Saturday, the weather service said.

San Francisco has also been hit with power outages due to storm impacts, according to the San Francisco Department of Emergency Management, which issued an update on the social network Xearlier Twitter, just before 10 a.m. ET/7 a.m. PT.

The weather event is also expected to bring heavy mountain snow to the Coastal Ranges and Sierra Nevada, where winter storm warnings were issued by the National Weather Service.

Gusts of 40-60 mph are likely along the California coast and in the mountains of northern and central California — as well as western Washington and British Columbia, thanks to an additional storm, according to AccuWeather.

Rainfall of 2-4 inches is expected in San Francisco to Redding and just east of Sacramento. “Rain will pour into low elevations across northern California and southwestern Oregon from Friday into Saturday,” AccuWeather Senior Meteorologist Adam Douty said in a forecast.

In the low elevations of central California, 1-2 inches of rain could bring “a risk of mudslides, other debris flows and landslides, and road washouts,” according to AccuWeather. “Motorists should be prepared for flooded roads in places that typically drain poorly.” The storm is unlikely to bring rain to Southern California, where firefighters continue to battle Malibu’s Franklin fire.

Winter Weather Advisory for the Western United States

The same weather system is expected to bring rain and snow to parts of Idaho, Wyoming, Utah and Montana. Lower elevations will get rain and a limited amount of snow. Heavier snow is forecast in the mountains, including central Idaho and western Wyoming, where winter snow warnings are in effect for snowfall of 5-10 inches, with 12 inches or more possible locally. National Weather Service said.

A winter weather advisory is in effect through Sunday morning in Idaho, with up to six inches of snow expected above 4,500 feet in the Camas Prairie, Boise Mountains and West Central Mountains.

Another winter weather advisory in effect through Sunday afternoon covers Utah’s Wasatch Mountains and western Uinta Mountains, with up to 15 inches of snow possible in the Ogden area mountains and Bear River Range.

A winter weather advisory is also in effect late Sunday afternoon and Sunday night for parts of Montana, with 4-8 inches of snow predicted for areas near the Idaho border and in the Henrys Lake and Centennial areas. Another advisory – for central and eastern Montana, including Carter, Custer, Fallon and northern Rosebud counties – predicts a wintry mix of 1-2 inches of freezing rain turning to snow.

The chance for precipitation – including a wintry mix – will spread eastward into the Northern High Plains Saturday night, at National Weather Service said.

Snow and freezing rain in and east of the Midwest

The threat of a wintry mix with accumulating freezing rain also led to many winter weather advisories from the upper Midwest to the Mid-Atlantic through the weekend.

With the likelihood of a “potentially impactful wintry mix with freezing rain” expected The National Weather Service issued a ice storm warning Saturday for parts of Iowaeast and north of Des Moines. The entire state was under a winter weather advisory until Saturday afternoon, along with parts of Minnesota, Wisconsin, South Dakota, Nebraska, Kansas, Missouri and Illinois.

In the areas under the ice storm warning, travel could be “nearly impossible,” and the storm is expected to cause power outages and tree damage, the NWS said.

Freezing rain left a glaze over the roads in Omaha, where a local resident posted a short video on X of how the street had become a hockey rink.

This “surge of wintry precipitation” will move into the Great Lakes region late Saturday, eventually reaching places like Green Bay, Wisconsin and Traverse City, Michigan, according to AccuWeather.

A winter weather advisory is also in effect through Sunday afternoon for a swath of the Mid-Atlantic, including northwestern North Carolina, southwestern Virginia and southeastern West Virginia, along and west of Interstate 77. Freezing rain expected from midnight to early Sunday, with snow and sleet in the mix, could lead to ice accumulations.

A forecast of snow, sleet and ice has led NWS to issue winter weather advisories until early Monday morning for western and north central Maryland, the panhandle and eastern West Virginia, and northwestern and western Virginia.

It’s not rain, ice and snow everywhere in the U.S. Most of the country will have high temperatures at or above average this weekend, with some of the hottest spots in Texas and the southern plains where highs could enter the low 80s is and the desert Southwest and Florida, which will see temperatures in the 70s, the weather service said.

This story has been updated with new information.

Follow Mike Snider on X and Threads: @mikesnider & mike carvers.

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