Ogden

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2

  There were pockets of wind-drifted snow before this storm, and another fresh 6-10 inches fell with wind during it. Drew found small, dense wind slabs when he visited Snowbasin yesterday. Winds stayed at perfect loading speeds yesterday, meaning you can find two types of wind slabs:

  1. New, more reactive slabs will freshly built from the new snow.
  2. Older, more stubborn pockets will be harder to identify as the new snow covers the older, textured snow surfaces.

  You will be able to trigger both new and old wind slabs at mid- and upper-elevations on all aspects. These will be most likely at upper elevations, near ridgelines and on exposed mid-slope catchment areas like gullies and convex rolls on slopes facing SE-E-NE. These can be as small as a pocket around your machine's ski, or big enough to wipe a rider off a slope. These may propagate wider than expected and be triggered from a distance if they fail down into the weak faceted snow from January (DJL)—more on that below.

  New snow: In areas with higher accumulations, be aware of the possibility of triggering loose, dry sluffs of new snow that may run far and fast on crusts. In protected mid- to low-elevation areas, know that slabs of new snow may develop and possibly propagate widely if deposited on weaker snow or slick old crusts.

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2

  This season's been nothing but irregular, and the Dry January Layer (DJL) is no exception right now. The weak, old snow that sat out during January is still there, and has become damp to wet in some locations with the warmer weather in the recent days. The layer is trending more stubborn since it's first loading event in recent weeks, but wet facets do weird things.

  On Cutler Ridge on Wednesday, the wetted DJL to propagated with easy force (ECTP3) on our first test—see the surprising video below—before not being able to get the layer to propagate at all in the next 4 tests we conducted (ECTN). This just shows the irregularity with the snowpack this year, and how high our uncertainty is wtih more loading. This wet, warm, and weird setup is going to be a bit of a puzzle in how exactly it reacts to a sizeable loading event.

  As we add more load and stress to this layer with new snow today, know it is still possible to trigger a slab on the PWL on mid- (NW-N-E) and upper elevation (W-N-E)slopes up to 3 feet deep. Any new snow or wind slab avalanches have the potential to step down into this weak, old snow and create a much larger slide than modest new snow totals might make you expect. This possibility is more likely in and along thinner, rocky snowpack areas.

  I would approach any steep slope that harbors this layer of facets with caution.