SEATTLE -- A powerful, "dangerous" storm began its march through Western Washington, pummeling the region with snow and strong winds -- and triggering warnings of blizzard conditions, deep accumulations of snow and a message from troopers to stay home on Saturday night.

The snow began on the coast Saturday morning, spread to the South Sound and north to the central Puget Sound area, where flakes began falling by mid-afternoon. Winds picked up in the foothills of the Cascade Mountains, including Enumclaw, North Bend and Maple Valley.

The snow prompted a warning from the Washington State Patrol, urging drivers to stay home if at all possible. Roads in Pierce and Thurston counties are slick and covered with ice, and troopers can respond only to blocking and injury collisions, the State Patrol said.

Forecasters said that by the time the storm passes through the region on Sunday, it will drop 4 to 8 inches of new snow along the Interstate 5 corridor north of Tacoma, including Seattle and Everett.

Heaviest snow will occur on the Kitsap Peninsula, along Hood Canal, and from Olympia and Chehalis west to the central coast near Ocean Shores. Ten to 18 inches of snow is expected near the Hood Canal, with other locations in the area getting 5 to 12 inches of snow.

Forecasters said the storm will bring winds gusting to 90 mph to communities in the foothills of the Cascade Mountains, Enumclaw, North Bend and Maple Valley.

Meteorologists said Sultan and Gold Bar also could see wind gusts of 70 to 90 mph, with the storm expected to bring steady winds of 50 to 70 mph from 7 p.m. Saturday to 7 a.m. Sunday.

In the mountains, a blizzard warning is in effect until 1 p.m. Sunday.

"The combination of heavy blinding snow and east winds gusting locally in excess of 75 mph will create blizzard conditions in the passes through early Sunday afternoon," said a severe weather alert.

The combination of heavy snow and high winds will cause whiteout conditions that could disorient anyone driving or caught outdoors. Wind chill values are expected to range from zero to 25 below zero. Storm totals in the mountains will reach 1 to 2 feet.

In Spokane, meteorologist John Fox said the same storm will bring 3 to 6 inches of new snow to Eastern Washington. Spokane has had 25 inches of snow during the past three days.