Avalanche Forecast

A stronger cold front will cross the Northwest on Sunday. Expect increasing strong alpine winds and significantly increasing moderate to heavy rain or snow on Sunday heaviest along the west slopes. Snow levels should lower to near the pass levels in the afternoon. 

This weather should transport snow and build new wind slab on lee slopes through the day. This should be mainly on N to E slopes in the above and near tree line bands. Watch for firmer wind transported snow and surface snow cracking from the tips of your skiis or snowmobile.

New storm slab should also build through the day in areas that rapidly accumulate snow. This avalanche problem may work its way down into the upper treeline by the end of the day. Rapid snow accumulation is generally more than an inch or 2 an hour for several or more hours.

New wind or storm slab layers could be very sensitive and easy to trigger where they build on the latest surface hoar layers such as seen in the northeast zone.

Dangerous avalanche conditions are expected by Sunday afternoon especially in the near and above tree line. Careful snow evaluation and conservative decision-making should be essential on Sunday.

The problem of loose wet avalanches will be left off the problem list on Sunday but watch for signs of significant wet snow at the lowest elevations.

Weather and Snowpack

Dry weather with the warmest temperatures of the winter occurred February 7-10th with temperatures climbing into the 50's in most areas east of the crest.

Snow in the northeast zone buried the crust with about 1.5-3 feet of snowfall February 11-20th.

Rain and mild temperatures were seen in the central east and southeast zones in mid February forming a newer crust in those areas. An active and cooler pattern buried the crust in the central and southeast zones with about 6-10 inches of snow in the near and above treeline February 17-20th.

Up to a few inches of additional snowfall fell east of the crest by Monday morning. E-SE crest level winds in places east of the crest Monday night and Tuesday may have redistributed surface snow to unusual west slopes in some places.

Sun and very mild temperatures were seen Wednesday and Thursday rising into the 40's or 50's. This fair and mild weather will have wet surface snow and night time melt form crust formation and helped to stabilize earlier wind slabs.

A weak front brought light amounts of rain and snow Friday night to Saturday morning.

Recent Observations

NWAC pro-observer Tom Curtis was in the Chiwawa River drainage on Wednesday and saw loose wet avalanches on most aspects and elevations. Signs of wind slab were seen on northwest to southeast slopes near and above treeline.

Tom was out again at Blewett Pass on Thursday and found cool wind transported snow on lee slopes near tree line that was not cohesive or reactive.

NWAC pro-observer Jeff Ward was out near Washington Pass on Thursday and found powder and good ski conditions on north to east slopes. Several loose wet avalanches up to size 1-2 were seen on on steep solar terrain. Surface hoar up to 15 mm was also seen on non-solar slopes. A large cornice release was seen in the Cutthroat Creek drainage.

The North Cascade Mountain Guides near Washington Pass on Thursday also found powder snow on non-solar slopes, surface hoar in the valley bottom and noted loose wet avalanches on solar slopes up to size 1-1.5.

Jeff was out again on Friday and reported numerous loose wet avalanches to size 1.5 on the south slopes of Delancy Ridge. He noted widespread 6-8 mm surface hoar on non-solar slopes.Good cool snow was also still found on non-solar slopes.

The North Cascade Mountain Guides on Friday at Washington Pass found an uptrack from Thursday partly buried by loose wet debris and settled powder on non-solar slopes.