Avalanche Forecast

Active weather and avalanches should be seen this weekend!

A front will approach the Northwest Saturday morning and should cross the Cascades Saturday midday. This will cause increasing winds and moderate to heavy rain or snow with warming on Saturday. A change to rain or snow showers should be seen following the front Saturday afternoon and night.

This weather will build generally upside down snow layers of increasing density near the surface and snow may also change to rain in some areas. Up to about a foot of upside down snow should be seen along the west slopes in especially in the higher terrain bands by late Saturday.

This snow will load the January 3rd and January 11th persistent slab layers were they exist along the Cascade west slopes. This could produce natural or triggered avalanches that could be remotely triggered, propagate around terrain features and bury, injure or kill.

New wind slab will also be very likely mainly on lee north to east slopes but on more varied slopes in the Cascade passes.

New storm slab due to the warming trend is also very likely on varied aspects where winds are lighter and snow rapidly accumulates to deeper than a few inches.

Avalanches releasing in near surface layers on Saturday may entrain previous snow producing large avalanches.

It has been hard to decide whether or not to extend the high danger to below tree line along the west slopes on Saturday. This issue was discussed with several pro patrol members at ski areas along the west slopes today. There was general agreement that natural avalanches due to persistent slab, wind slab and storm slab will be likely to below treeline on Saturday.

Deep storm snow that fell during mid-late December is well settled, homogeneous and has stabilized so the current avalanche danger focus will be on the upper snowpack.

Fair weather over the New Year caused extensive surface hoar and near surface faceted snow. This was buried by about 4-15 inches of snowfall along the west slopes from about January 3-6th.

Another fair weather period was seen from about January 7-10th. Surface hoar and near surface faceted snow formed again in many areas during this period.

The latest period of snowfall has been from about January 11-15th with about 7-20 inches along the west slopes.

There has been unexpected dangerous avalanche activity along the west slopes Thursday and today. It looks like persistent layers buried about January 3rd and and January 11th are beginning to get active due to loading from the past couple storm cycles.

From a combination of  reports from the Mt Baker pro patrol and the NWAC Observations page, a 2-3 foot slab was remotely triggered Thursday at about 5500 feet on the north side of Shuksan Arm. A phone report from the Mt Baker pro patrol to the NWAC indicated the persistent January 11th layer.

NWAC Pro observer Lee Lazzara was near Mt Baker on Thursday and above 5000 feet on W-N-E aspects found 30 cm of snow over a 2 cm think layer of surface hoar buried on January 11th. He was able to trigger this persistent slab with a cornice test and snow pit tests gave easy results indicating propagation. He also noted pockets of wind slab over the same persistent January 11th layer.

A solo ski tourer in Silver Basin near Crystal Mountain today triggered a 40 cm slab on a west aspect at about 6600 feet that released on the persistent January 11th layer. This skier was caught and and sustained minor injuries.