MOUNT VERNON — Winter has been under way for only a week and already it has affected those who choose to venture outdoors for recreation.

Sudden and unpredictable weather shifts have turned seemingly perfect environments into treacherous going.

“For the next two days at least, I would stay out of avalanche prone areas,” said Mark Moore of the Northwest Weather and Avalanche Center. “The conditions we have now in the mountains is very reminiscent to those in 2007 where we had five avalanche fatalities. It’s a very similar snowpack.”

That snowpack is causing havoc across the West.

A young snowmobiler died Monday in Utah after being caught in an avalanche 500 to 600 feet wide. He was buried in 6 to 7 feet of snow.

In Fernie, B.C., search teams recovered the bodies of eight snowmobilers after they were swept away by back-to-back avalanches in Canada’s backcountry. Three survived.

Closer to home, a snowmobiler was killed Sunday in an avalanche in Brown Bear Basin near Harts Pass in Okanogan County. Despite traveling with a group of experienced snowmobilers equipped with avalanche beacons and probes, the man couldn’t be saved by his three companions.

Four people died in Utah as a result of avalanches in December.

In Colorado, avalanches have claimed four lives. In Wyoming, a skier was killed and a restaurant at Jackson Hole Mountain Resort was damaged when an avalanche slammed into the structure. Snow exploded through doors, plowing into tables and chairs.

According to the Northwest Weather and Avalanche Center, avalanche danger is based on three variables: snowpack, weather and terrain.

And in the North Cascades, the three variables are colliding.

“It’s bad and getting worse,” Moore said of the deteriorating conditions. “The situation continues to escalate in regards to avalanche danger and it’s going to get worse in the next couple of days.

“The snow that fell early in December to what has fallen up until say the 24th has led to a very weak snowpack structure. We had the continental snowpack and then maritime snowpack. That’s a very bad combination. Then it began to snow again. That is how we reached this point.”

Continental snowpack is thin, cold and weak. Maritime snowpack is thick, warm and strong.

This type of snow structure is called faceted snow.

Faceted snowpacks are derived from angular snow with poor bonding createdby large temperature gradients.

Faceted snowpacks cause the vast majority of avalanche fatalities in North America.

“Faceted snowpacks are a little different,” said Moore. “They are comprised of re-crystalized snow grains that have no bonds. That leads to persistent weak layers.”

And that makes for dangerous conditions in the backcountry of the North Cascades.

“We’ve begun to bridge over that weak snow structure,” said Moore. “But we aren’t there yet. And as we add another 1 to 3 feet (of snow) over the next two days, there is going to be the possibilities of some big avalanches because those weak layers of snow are going to become very stressed.”

That stress will be released in avalanches large and small.

“We will see natural slides first,” said Moore. “Then those natural slides could trigger larger avalanches.”

A slide such as these occurred Wednesday on Shuksan Arm near Mount Baker.

“That was a 6-foot natural slab,” Moore explained. “A lot of snow came down. We expect to see more events like that one and possibly much larger avalanches. We expect to see 2 to 4 foot natural as well as human-caused avalanches (today) and maybe even 6 to 10 feet.”

The problem with the delicate snowpack could be persistent.

“It can come back to haunt you in the spring,” said Moore.

In the meantime, staying informed is import.

“Stay aware of the forecasts,” he said. “Conditions can change dramatically in a very short period of time.”

For avalanche forecasts, go to http://www.nwac.us.

Vince Richardson can be reached at 360-416-2181 or by e-mail at .