(CNN) Washington Gov. Jay Inslee declared a state of emergency Friday as the Pacific Northwest braces for a pounding snowfall, whipping winds and frigid air.
"Everyone in our state needs to focus on preparing for the snow and staying safe," Inslee said in a news release. "Weather forecasters predict this may be a storm unlike one we've seen in many years. I encourage everyone to stay off the roads if possible and plan ahead if you must travel."
The huge Seattle metro region could get six to eight inches in its second snowstorm of the week, forecasters say.
"The snow is expected to start as early as noon today with heaviest snowfall expected late this afternoon into tonight before gradually tapering off throughout Saturday morning," the National Weather Service said Friday.
More than 12 million people in the Northwest are under winter weather alerts Large amounts of snow are expected on the north slopes of the Olympics, about eight inches and more. Some isolated areas could get a foot.
Parts of western Whatcom County may get an inch, but it could also experience blowing snow. The coast could see as much as three inches. Portland, Oregon, and the Sierras will be affected as well.
Seattle, which averages 6.8 inches of snow over the course of an entire year, is under a winter storm warning. If Seattle does reach the predicted six inches of snow, it will only be the fourth time the area has seen that much since 1991.
Authorities in the densely populated Seattle region are getting ready to tackle the storm.
Schools are closing and officials are warning drivers to lower their speed and pedestrians to take care. A road could be icy and dangerous in the low temperatures, even if it appears to be clear.
"It could be really challenging. Might start thinking about adjusting your weekend plans if possible," the Washington Department of Transportation said in a statement. " ... If heavy snow is falling, there's only so much we can do and it will affect roadways. Roads will be slick, bridges/ramps/overpasses will be icy, collisions will increase and traffic will be challenging."
With the declaration of a state of emergency, the Federal Motor Carrier Safety Administration (FMCSA) is limiting the number of hours commercial vehicle drivers can be on the road. Only drivers collecting or delivering bulk milk products or de-icing road salt from FMCSA locations are exempt, the governor's release said.
The winds expected to accompany the storm could cause issues with blowing snow, as well as downed power lines and trees. The wind gusts could reach anywhere from 20-30 mph in the Seattle area, while the northern Puget Sound and Olympics region could see gusts of 60 mph.
Temperatures will drop below freezing Friday night and won't get back above 32 degrees until Sunday.
Those temperatures, combined with the wind, could make it feel like it's in the teens Saturday across the Seattle region.
If that wasn't enough, there's a possibility of more snow for Seattle Sunday into Monday.
The storm is affecting some planned activities, with a Friday appearance by Michelle Obama at the Tacoma Dome postponed to next month.
"With the snowstorm on its way into Tacoma, my biggest priority is making sure everyone stays safe -- and that's why we've decided to postpone my tour event to March 24th," Obama tweeted. "I can't wait to see you all next month, and in the meantime, stay warm and be safe out there!"
Several school districts in the Seattle metropolitan area are closing early Friday because of the threat of winter weather.
Seattle, Kent, Tacoma and Mercer Island are among the districts that have announced early release for students and faculty.
The University of Washington in Seattle said it is suspending operations at 12:30 p.m. (3:30 p.m. ET) Friday and all day Saturday. All classes and activities have been canceled.
The school is asking students and employees to "use caution when walking and driving on and around campus."
The Tacoma and Bothell campuses have also announced suspension of operations starting Friday through the weekend.
Earlier this week, another storm shut down Seattle and left some neighborhoods with about half a foot of snow.
Seattle Public Schools first announced Monday that classes would start two hours late for its 53,000 students. "But as the snowfall increased, it was determined that roads were too challenging with ice and snow," spokesman Tim Robinson said in an email.
More than 12,000 people were without power in Washington state due to snow-related outages.
The Department of Transportation said numerous spinouts were reported on interstates, and Interstate 5 through Seattle was shut down at times for snow removal and because of wrecks.