Avalanche Forecast

A stronger system should impact the area on Wednesday, with the heaviest precipitation loading expected in the afternoon and evening hours. Rain at lower elevations and the potential for a wintry mix once again in the Cascade passes should do little to change the avalanche danger.   

Increasing S through W ridge-top winds Wednesday afternoon should begin to build new wind slab in the near and above treeline zones on lee NW thru E aspects. If precipitation rates of the new snow accumulation becomes heavy enough Wednesday afternoon, watch for new snow instabilities late in the day. 

 

 

 

The last significant storm crossed the area last Thursday, initially producing rain or wet snow before transitioning to snow at lower elevations. New snow amounts varied from north to south and with elevation. Upper elevations in the north received about 20-30 cm (8-12 inches) of new snow with lower elevations and areas in the south getting about 10-20 cm (4-8 inches).

Sunny weather with increasingly warm temperatures were experienced over the weekend except where easterly flow maintained locally cooler temperatures near the passes. Small loose wet snow avalanches were also reported on solar aspects over the weekend, releasing easily on the slick underlying crust. 

Reports indicate mainly favorable profiles in the new snow and good bonding of the most recent storm snow to older wet snow. The mid and base pack mostly consists of stable layers of crusts and rounding or melt forms due to warm periods in late December and early January.

The exception was where the new snow bonded poorly to a slick rain crust. On this past Saturday sensitive storm and wind slab released in at least 2 different human triggered incidents. A climber triggered 2 separate slides and was caught in a 1 foot storm or wind slab in the east facing bowl below Chair Peak near Snoqualmie Pass at about 5500'.  The climber was not seriously injured.

A skier also triggered but was not caught by a 1-1.5 foot storm or wind slab on a south facing slope on Mt Herman near the Mt Baker ski area at about 5700 feet. The bonds here may not have been as good between the recent and old snow with the old crusted snow acting as a bed surface. Sunshine may have helped to activate this slope.

Surface hoar formed with clear cool nights this weekend in the lower elevations of the cooler Cascade passes and on shaded aspects throughout the west slopes. This surface layer should have been destroyed by the warming temperatures Monday night and Tuesday along with rain at lower elevations and freezing rain/mixed precipitation in the passes.  Generally light amounts of new snow at mid and higher elevations received Tuesday and Tuesday night should have bonded well to the old snow surface.

There will be less danger in areas that received less recent snow such as Hurricane Ridge and Crystal Mountain. The avalanche danger will continue to be low at lower elevations due to less recent snow and a low snowpack.