Salt River and Wyoming Ranges

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–1.5

  The combination of new snow and wind has built slabs in terrain where the wind blows. I say this because as we know, this means many different features in the middle and upper elevations, and sustained west/northwest winds can craft slabs in abnormal locations.  Though winds remained light yesterday as my partner and I were riding in Strawberry Creek, evidence of old wind loading was everywhere. I'd expect fresh wind slabs to be on the smaller side, but given the weak snow surfaces they're forming on, they may remain sensitive to your weight. Recognize that wind-loading also adds stress to the weak layers buried in the snowpack (described in Problem 2 below). Any wind slab you trigger could step down to these deeper layers, producing a much larger, more dangerous avalanche. While come of these new slabs may remain small, they may be able to pick up steam as they travel downslope. Even small slides can have high consequences if they carry you through rocky, treed terrain.

  The new and wind-transported snow from the past 24 hours is now masking older wind slabs that formed earlier in the week. These older wind slabs have likely had time to stabilize, but given the increased chances of triggering a larger avalanche on wind-loaded slopes, it is prudent to avoid obviously wind-loaded avalanche terrain. 

  

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Unlikely

  Size

  2–3

  As days with small amounts of new snowfall continue to trickle in, the snowpack is getting time to slowly adjust to additional loading.  However, the possibility of triggering a slide on a deeply buried persistent weak layer will be on the table for some time to come. Yesterday up Strawberry Creek, my partners and I got propagating results near the ground in a snow pit test around 8,800' on a SE aspect. Instability lingers and though the probability of triggering these layers is low, the consequences would be high.

  Uncertainty is also high as to the tipping point of these layers. If you choose to enter avalanche terrain, be aware that at least one of these layers likely exists in the snowpack underneath you, particularly if recreating in terrain in the middle and upper elevations and on the southern half of the compass. Though not widespread, the layers most likely to produce large avalanches in this zone are found 2-4 feet deep and consist of well-developed facets near the base of the snowpack and crust+facet sandwiches. These prominent early-season facet layers are buried deeply, making it much more difficult, but not impossible, to trigger.

  In a nutshell: be alert to the consequence of being caught in a large avalanche in the terrain you are recreating in. 

  You are more likely to trigger an avalanche on upper elevation, "prime-time" slopes steeper than about 35 degrees. Most upper-elevation slopes have received additional loading due to wind over the past few weeks. While triggering a wind slab (Problem #1 above) is more likely, a wind slab avalanche could step down into these persistent weak layers resulting in a much larger avalanche.