Weather changing as cold air mass heads toward Bay Area

SAN FRANCISCO -- If forecasters are correct, a cold air mass arriving in the Bay Area on Tuesday will be a dramatic weather changer from California to the Atlantic Ocean.

The winter storm will impact millions this week, from coast to coast, with heavy snow, dangerous winds, possible blizzard conditions and for some, the coldest temperatures of the season.

And it begins with the front's arrival in the Pacific Northwest on Monday and moving to California on Tuesday before heading out across the country.

"This system will be dynamic and providing several impacts to the Bay Area and the Central Coast: strong wind gusts, cold temperatures, rain, snow, and even the slight chance for a thunderstorm," the National Weather Service Bay Area office warned. "Winds will start to increase Tuesday morning as the system approaches and increase in magnitude through Tuesday evening."

A wind advisory goes into effect from 1 p.m. Tuesday to 1 p.m. Wednesday for gusts up to 55 mph.

Temperatures will also take a plunge.

"The far more impactful outcome to these temperatures will be how cold it gets overnight and into the morning hours," forecasters warned. "Widespread interior areas will reach the mid 30s, with only the coastal and bay shoreline areas remaining in the low 40s."

"Thursday and Friday mornings, widespread temperatures in the 30s with interior valley areas seeing 30 to 50 percent chance for dropping below 32 Fahrenheit, and those probabilities jump to 70 to 90 percent for the interior East Bay, North Bay, and Southern Salinas Valleys."

Showers also will be a feature of the weather shift.

"Between Wednesday and Saturday morning, the total rainfall amounts around the Bay Area  and the Salinas Valley would be 0.75 to 1.00 inches, with the higher elevations of Santa Cruz Mountains seeing 1 to 2 inches, locally up to 3 inches," the weather service predicted.

And a dusting of local snow.

"Lastly, and it has generated a lot of buzz on social media, the chance for snowfall," forecasters said. "The highest confidence remains in elevations greater than 1500 feet seeing snow."

In Tahoe, the weather service has issued a winter storm advisory from 10 a.m. to 10 p.m. on Tuesday.

"Total snow accumulations of 3 to 5 inches, except 4 to 9 inches above 7000 feet," the NWS office in Reno predicted. "Winds gusts in lower elevations up to 50 mph, with wind gusts as high as 100 mph along the Sierra crest."

The heavy snow and extreme cold will then move into the Rockies and Midwest, where the storm could have its biggest effects.

Blizzard warnings are in place for southern Wyoming, where nearly two feet of snow and winds gusting more than 70 mph will create blinding conditions. The weather service also warns of wind chills falling to 25 degrees below zero.

The storm releases its fury on the Midwest Tuesday through Thursday, with two rounds of snow. The first round on Tuesday will bring four to six inches of snow to much of the region.

The big problems come in for the second round Wednesday night into Thursday. This is where we could see up to two feet of snow across the Midwest, along with 50 mph wind gusts. Travel will be nearly impossible during this time frame.

With the storm still a few days away, the weather service is still fine-tuning the details.

Thursday will also bring a swath of icy weather for some big cities, including Chicago. Ice could also be a problem for parts of the Ohio Valley, yet pinpointing exactly where it will occur is challenging this far out. Stay tuned with the forecast if you live in these areas, because freezing rain and sleet could halt your travel plans and even cause power outages.

While the northern half of the storm will be all snow, the southern half will be heavy rain. We could see strong storms develop on Wednesday for places like Dallas, Little Rock, Shreveport and Memphis. The Storm Prediction Center has highlighted the area as a region with the potential for large hail, damaging winds and possible tornadoes.

The storm does make it to the Northeast and New England by the end of the week. As of now, it looks like New York City is left out of the snow once again, however, Boston could get a couple of inches.