Turnagain Pass

Since yesterday morning we’ve had several hours of wind near 20mph with gusts to 47mph at the Sunburst weather station.  Winds as low as 12-15mph can transport low density snow.  Wind slabs continue to form in wind exposed areas throughout the region.  Where wind slabs exist on steeper slopes, it could be easy and likely for a human to trigger an avalanche.  Although we have a warming trend, the temperatures in the Alpine have remained below freezing helping maintain loose snow.  Our 3″ of new snow over night in addition to the snow from last week is still unconsolidated in most places and easily moves around with the variable winds.

It can be difficult to predict which slopes have formed wind slabs because the region has experienced winds from many different directions.  It’s essential to look for clues where wind slabs are forming, or have already formed.  If you see the winds depositing snow onto the lee of ridges or gullies, that’s a clear indicator a slab could be forming.  Scoured exposed areas can indicate loading to the leeward side.  Where visibility is low or you can’t see your entire route, remain aware of the snow beneath you –  you could be entering a wind slab if you feel stiffening of the snowpack, see rippling on the surface, see shooting cracks, or sense hollow drum-like sounds in the snow.  Choose routes with intention and don’t hesitate to adjust your plan.

Steady winds over the previous 30 hours capable of transporting loose snow.

This image is looking toward the northeast aspect of Magnum.  The visible scouring suggests easterly winds cross loaded many gullies on Magnum.  Winds from this direction could have easily loaded the common northwest uptrack.  2.3.2020  Photo: CNFAIC Archive

Cornices:  Cornices continue to form and could be touchy to human trigger as they build with new snow and wind transport.  As always, give cornices a wide margin.

Our snowpack structure contains weak layers formed before the storms last week.  We’re particularly keeping an eye on the MLK Jr facets and the NYE crust.  The incremental loading and wind transported snow naturally triggered avalanches last week – the MLK Jr facets and NYE crust were the suspected weak layers.  Our testing shows these layers are becoming more stubborn but it remains possible for a human to trigger a large avalanche in these layers 2-3′ down in the snowpack.  With time and our current warming trend, the chances increase for the top 2′ of snow to consolidate and become more cohesive.  These conditions could create a more distinct slab above these weak layers.

Additionally, If a wind slab is triggered, it could step down to initiate one of these layers deeper within the snowpack.

Loose Snow Avalanches:  On steep slopes with unconsolidated snow, watch for easily triggered loose snow sluffs.