Salt Lake

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  3

  Triggering avalanches 1-3' deep on steep slopes facing west through north and east at all elevations remains possible. These avalanches are failing on a persistent weak layer (PWL) that formed during the January/February drought. Such warm weather can do weird things to our snowpack and become increasingly reactive to the additional weight. Over the next few days, we may begin to see the likelihood of triggering an avalanche on this layer increase again.

  Many of these avalanches are being triggered at the mid-elevations (8,000' - 9,500') and often in slight openings in otherwise dense trees. We've had many close calls throughout March on this weak layer and it's not time to let our guard down. Travel advice: Where the faceted snow is buried choose slopes less than 30° in steepness, with no overhead hazard.

  A few things to remember when dealing with these persistent weak layers:

  • You won't know exactly when and where you will trigger the avalanche, but you will probably trigger it from a distance. These types of avalanches are unmanageable.
  • Tracks on the slope offer zero signs of stability. Avalanches can take out multiple existing tracks.
  • If you do choose to ride slopes where this layer exists, stack the odds in your favor by choosing slopes with a clean runout zone free of trees and rocks that would cause trauma if you do trigger an avalanche.
• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2

  Overnight temperatures dropped just below or near freezing, that paired with clear skies should have allowed the snow surface to lightly refreeze this morning. However, another day of strong sunshine and warm temperatures will continue to produce wet, loose avalanches today once the snow surface begins to take on the heat. If you notice the snow surface becoming damp or unsupportable or see active roller balls cascading down, it's time to head home or change your aspect.

  Fortunately, this is generally a predictable avalanche problem where you can expect avalanching in the wet snow once it begins to soften. The main concern is having a naturally triggered slide come down onto you, especially if you are in a gully, couloir, or other confined terrain where avalanche debris can pile up deeper and you have no route for escape.

  Timing is key, once the snow surface becomes wet and unconsolidated it will be time to move off of and out from underneath any steep slopes. This weekend: Overall, forecasting wet snow is difficult. On Saturday and Sunday, we will continue to see very warm temperatures, clear skies, and likely more wet snow avalanches. With so many crusts, and facet interfaces we may begin to see some wet slab or glide avalanches as the facets and lower layers begin to get wet. The challenge is knowing when and if this change from more predictable wet loose avalanches, to more powerful wet slab avalanches will happen. See Drew's recent observation from Park City Ski Resort where he talks about some of the nuances of wet snow and free water movement in the snowpack. The good news is, even with wet slab avalanches, the same travel advice exists and timing is key. Avoid those slopes once the snow becomes wet and unconsolidated.

  In the photo below the Kool-Aid represents free water moving and pooling at suspect interfaces. You'll see the pink water pooling along with crust and facet/crust interfaces as denoted by the photo/blue lines. East facing slope at 9650' along the PC ridgeline.