Colorado: Avalanche center switches to spring mode

Zone forecasts end, statewide forecasts issued three times per week

Debris from a March 30 wet snow avalanche that killed a skier near Ophir, Colorado. PHOTO COURTESY COLORADO AVALANCHE INFORMATION CENTER.

By Bob Berwyn

SUMMIT COUNTY — The Colorado Avalanche Information Center has switched to a spring forecasting mode, ending zone-specific updates in favor of a statewide forecast emphasizing overall spring avalanche awareness.

The CAIC will continue to issue weather forecasts twice a day, through April 30, with statewide avalanche statements Sunday, Wednesday, and Friday, by 5 p.m. through the end of April and into May if conditions warrant.

CAIC director Ethan Greene said the change came a couple of weeks earlier than usual, prompted by a March snowpack meltdown that left many mountain areas nearly high and dry.

“We basically felt like we weren’t going to be able to write different forecasts … the other thing we looked at, with the nature of the problems that we’re having, need to do our field work early in the day,” Greene said.

But that doesn’t mean backcountry travelers should let their guard down, he added. Season-long instabilities persist at the base of the snowpack, leading to the potential for serious wet-snow avalanches on higher elevation northerly slopes, he said, adding that the chances of triggering those “lurking instabilities” are pretty small.

“What we’re seeing with the avalanche danger is, we still have this bad, deep depth hoar layer, mostly on north-facing slopes above treeline,” he said, referring to a persistent layer of large non-bonding faceted grains that can act like an unstable house of cards in the snowpack.

“We’re still biting our nails a little bit. That’s one of the things that worried me about going to springs operations,” he said. If there’s a big warmup that could lead to major avalanche cycle on north-facing slopes, or if there are other sudden changes to the avalanche hazard, the CAIC still can issue special warning bulletins.

So far, a major wet-snow avalanche cycle hasn’t materialized, although one backcountry skier died March 30 in a large wet snow slide near Ophir Pass, in the San Juans.

So far, seven people have died in avalanches this season in Colorado, with 30 deaths reported across the country.

The transition to spring-like conditions was so rapid that the snow started to melt before it got unstable, Greene said, adding that air temperature is only one of the factors affecting spring snowpack stability. Temperatures also cycled from warmer to cooler, helping preserve some of the snowpack’s integrity and strength.

Colorado’s snowpack was tricky from the beginning of the season.

“We saw some very unusual things … the structure of the snowpack that developed in October through December … -it was so much more fragile than we typically see. You could walk  in one to two feet of snow andsink through to the ground.

“Then it was  incredibly reactive in terms of avalanches once we started to get snow in mid-January, and when the upper part of the snowpack consolidated we started to get those big avalanches,” Greene said. “We had a bunch of events where we ran up to the line where we were going to go into a huge avalanche cycle, and then it eased off again,” he added.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s