Galena Summit & Eastern Mtns

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

  2–3

  Layers of weak snow can be found near the ground and in the middle and upper portion of the snowpack:

  1. Depth hoar exists near the ground on all aspects. This is the snow that we've been talking about all season long and seem to be destined to talk about for the remainder of the season.
  2. In the middle of the snowpack are several interfaces that have produced both avalanches and unstable test results in recent days. In this zone, these layers appear to be worst where they are accompanied by a crust.

  I went looking for these problems in this zone yesterday and found both of them. On Butterfield, near the mouth of Baker Creek, I found a thin snowpack with multiple buried weak layers (observation here, photo of snowpit here). These weak layers produced unstable snowpack test results and gave me no reason to want to enter consequential avalanche terrain. I also found both of these problems on Sunday, just to the south of this zone. Near Dollarhide summit, I dug snowpits on shaded slopes and those that face the sun and got poor snowpack test results in both locations (observation here, photo of snowpits here). As I continued upwards, I found a recent large, natural avalanche in a heavily wind-loaded location that appeared to have failed on a crust before stepping down to weak snow near the ground.

  You are more likely to trigger an avalanche on upper elevation, wind-affected slopes steeper than about 35 degrees. Triggering a wind slab (see Problem #2 below) could step down into these persistent weak layers, resulting in a much larger avalanche. Long story short, you can greatly reduce your risk of triggering a large persistent slab avalanche (or a wind slab avalanche for that matter) by sticking to terrain that is sheltered from the wind.

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

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

  Probabilità

  Likely

  Dimensione

  1–2

  Last night, 2-4" of new snow fell in this zone, accompanied by strong winds blowing out of the W/NW. Though 2-4" of new snow isn't that much, the wind is finding plenty of other ammunition in the snow that fell over the past 10 days. Fresh slabs on exposed, upper elevation slopes will be sensitive to your weight today, and triggering one of them is likely. I wouldn't be surprised to see that one or two had failed naturally overnight in the alpine portions of this zone (White Cloud, Boulder, and Pioneer crests). Thanks to the intensity of the wind, fresh slabs will extend down into middle elevation terrain as well. Today isn't a great day to be playing up high in the alpine—you'll find better skiing in sheltered terrain anyway.

  These fresh slabs are adding weight to the layers of weak snow buried in our snowpack, and you're more likely to trigger a persistent slab avalanche (Problem #1 above) on wind-affected slopes.