Salt Lake

Problemi valanghivi

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Possible

  Dimensione

  3

  Our PWL (persistent weak layer) of facets from the December drought is generally buried 2-5' deep and is easy to find by digging down with your shovel on west to north to southeast facing slopes. It is becoming more difficult to trigger this unstable combination in deeper snowpack areas, particularly in the upper Cottonwoods. Full avalanche mitigation efforts to open previously closed ski area terrain yesterday in upper LCC produced no results. Tests and observations like this one in White Pine of LCC on northwest facing terrain hint at a stabilizing snowpack.

  So what to make of the Davis Gulch avalanche? There are some similarities to the remotely triggered avalanche in East Bowl of Silver Fork from Wednesday the 24th. The predominant northwesterly winds have stripped and eroded many northwest facing slopes, making the slab thinner, the facets probably weaker and therefore more susceptible to triggering. My best guess is that the skier caught and carried (mind you, she was the third skier), found a thinner spot on the slab that triggered the avalanche where it then propagated into much more wind loaded terrain. The photo above shows this well. It was a close call.

  Bottom Line: it takes a LOT of homework - knowing slope history, knowing wind patterns, knowing which drainages have poor vs good structure, doing lots of probing and digging of snowpits and sharing of information to be able to ride steep terrain. And even then you may not get away with it. Human triggered avalanches are possible? No thanks.

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Very Likely

  Dimensione

  2

  With clear skies and warmer overnight temperatures, wet avalanches will start to run earlier today than yesterday, starting on east then south then west and eventually some northwest facing slopes. In steep, sustained and confined terrain, some of these wet avalanches will run fast and far and easily lead to significant debris piles. We had lots of reports of long running destructive avalanches in Tanners, the White Pine Chutes, Superior, even the Comma Chutes (NW facing) above the Bypass road in LCC etc etc. One wet avalanche took out a skin track in west facing White Pine (Tri-Chutes?) (Nick McEachern photo below). In some areas, much more destructive wet slab avalanches may occur, from either being pried out by wet loose sluffs from above, or - in some cases - melt water percolating down to structural interfaces (density changes and/or facets and crusts).

  Travel advice: If you see pinwheels and rollerballs and are finding the snow start to become unsupportable, move on to low angle terrain or cooler aspects.

  Though not technically wet avalanches per se, GLIDE AVALANCHES may start to release in the usual terrain of Stairs, Broads, Mill B South of BCC and the north side of Raymond in MCC. Probably best to avoid this terrain for awhile until it cools off...and even then give it a few days.