Hikers found the woman's dog, named Blue, on Sunday. The animal is now back with Yu's relatives, West said.
It was the first avalanche fatality reported in Washington this season, according to the Northwest Weather and Avalanche Center in Seattle. Nationwide, 16 others have died in avalanches this season, according to the Colorado Avalanche Information Center.
The Northwest Weather and Avalanche Center said the avalanche danger in the area Monday was "considerable" above 4,000 feet.
Kenny Kramer, director of Northwest Weather and Avalanche Center, said 20 to 30 inches of snow fell over the weekend. All that new snow was weakly attached to the old snow crust, making it more unstable, Kramer said.
Avalanches during the spring aren't rare, he said, noting that there's a secondary peak of landslides during this time because the Northwest still sees heavy storms, which can include snow. When that snow falls in the spring, it often warms up quickly, creating unstable conditions, he said.