West Slopes North

Problemi valanghivi

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

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

  Probabilità

  Possible

  Dimensione

  1–1.5

  Wednesday observers reported wet, sticky snow surfaces up to 5400ft on all aspects. Rollerballs were frequent, and a few wet loose avalanches occurred. This happened on all aspects, not just limited to the south, because of large amounts of cloud cover. Expect similar conditions Thursday. If it remains cloudy, expect the wet loose problem to exist on all aspects, especially northerly and upper elevations where the layers were previously dry. If skies clear, the problem might stay on southerly slopes. 

  Pay attention to how soft snow surfaces get. Search for obvious signs of weak surfaces such as rollerballs or recent wet loose avalanches. If you’re sinking several inches down, or noticing snow already sliding down, avoid steep slopes and terrain beneath those slopes. 

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

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

  Probabilità

  Unlikely

  Dimensione

  1.5–2.5

  Avalanche danger is remaining Moderate because every few days we’ve seen a large avalanche occur on a persistent weak layer. The most recent one was far out on the Arm in the Baker backcountry. It probably occurred sometime Tuesday, and was reported to be around 2 feet deep, spanning 600ft, and producing a “big pile” on the valley floor. The following is what we know about avalanches on the persistent weak layer:

  • The snowpack structure is inherently weak.
  • The layers are still reactive above 5000’ on aspects that did not receive strong sun in late January.
  • Reported natural and human triggered avalanches occurred at the same aspects and elevations.
  • They mostly occurred where there are 2 or more feet of new snow over the crust-facet layering.
  • Snowpack tests produce inconsistent results at the crust-facet layering, sometimes even in the same snowpit.
  • Many steep slopes - some very near avalanches that released in the same layers - have been ridden and skied with no results.

  The conclusion so far is that there are very few places where you could trigger one of these avalanches, but it would also not be surprising if another one occurred. If you venture onto steep terrain in these areas you are assuming a bit more risk than if the layering was not present.