West Slopes Central

Avalanche problems

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1–2

  Strong sun and high freezing levels (8000'!) will make for wet avalanche problems on Sunday. Unlike the firm snow conditions that came with sunny skies in late January, 1-2 feet of new snow can be found near and above treeline. This soft snow will be more susceptible to warming and produce natural loose wet avalanches. They are most likely on slopes directly facing the sun, but signs of instability like rollerballs and even small avalanches could be seen in shadier terrain.

  Anticipating and reducing your exposure to loose wet avalanches is fairly simple. Is the snow surface becoming wet, mushy and unsupportable? Are you observing extensive roller balls or small avalanches? When you see the above signs it’s time to stay off and out from under steep terrain on similar aspects. 

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  Numerous human triggered slab avalanches - almost all in wind loaded terrain - were reported on Sunday in West North Most were small and released at a weak interface in the new snow less than a foot deep. Others were large (D2) and deep enough to catch and carry those who triggered them. These avalanches were almost all triggered on unsupported terrain features steeper than 40 degrees. Precipitation totals from the last storm were higher in the West Central than other zones so this avalanche problem could be even more pronounced.

  The current surface of dense snow makes it a bit harder to distinguish areas of wind slab. Hand shears and adding weight to the uphill side of skin or snowmobile tracks might be the best way of identifying and evaluating wind slab reactivity as you travel. Approach wind loaded slopes with caution and use areas of lower angle, supported terrain to navigate around steeper areas where you are more likely to trigger an avalanche.  

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1.5–2.5

  The January dry spell created weak snow layering of sugary facets and old crusts that are now buried two or more feet deep. We have not seen many avalanches at these layers, but one large snowmobile triggered avalanche was reported today in addition to two remotely triggered slides in the last week. Reports of extensive whumphing and other signs of instability were noted farther east in West North. Snowpack test results at these layers vary widely, which points to an uneven distribution of where these layers could make for a large avalanche. In simpler terms, this means you probably won't trigger it in most areas, but there are some in which you still could. Observations have narrowed the area where you could trigger one of these avalanches down to upper elevation aspects that do not receive direct, strong sun.

  Persistent avalanche problems are tricky - there is a low likelihood of triggering but if you do trigger and get caught? The outcome is not good.  So what to do about it? First don't ignore obvious signs of instability like whumphing, shooting cracks, or signs of similar, previous avalanche activity. Minimize your exposure to steep avalanche paths at upper elevations. When assessing terrain, factor in not only the possibility of triggering a large avalanche but also the consequences in the terrain below if you are.  Finally, remember that ultimately you are the one responsible for determining your risk in avalanche terrain.