Maritime

Problèmes avalancheux

• 

  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Likely

  Taille

  1–2

  New snowfall over the last 24 hours has increased the avalanche hazard.  Human triggered avalanches are likely today involving the new snow.  Snowfall totals of 11 inches were recorded at Sugarloaf snotel @ 500' near the coast and 5 inches  at the Tsaina and Nicks snotel.  Snowfall totals are unknown at upper elevations but are estimated at 12-18 inches in the Maritime zone and 8-12 inches for Thompson Pass and North.  

  Expect instabilities to exist at the interface of this new snow as bonding is a process that takes time and does not happen all at once.  Human triggered avalanches are most likely within 24 hours of a snowfall event, which is the time frame we are currently in.  South aspects and low elevations previously had a melt-freeze crust that may take longer for bonding to occur.   There is a low probability that avalanches could be triggered at layers deeper in the snowpack on isolated terrain features below 3000' (see problem 2).

  Pay attention to how much new snow has accumulated and how much wind redistribution has occurred.  Small inconsequential test slopes and hand shear pits are helpful tools for quickly gathering information on how well new snow has bonded.  Watch for signs of instability, such as shooting cracks, collapsing, and recent avalanche activity, indicating the snowpack has the energy required to produce an avalanche.

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1.5–2

  There are currently 2 persistent weak layers on our radar, both are believed to be limited to terrain below 3000'.    There is a layer of buried surface hoar from Valentine's Day as well as weak snow below a decomposing rain crust from late January.  We have not yet seen any avalanche activity on either of these layers, however new snowfall has added stress over the last 24 hours that may make these potential weak layers reactive to human triggers.

   Buried surface hoar from 2/14 exists in previously wind protected areas from 1500 -2500 feet.  This layer is difficult to identify as it has only been found in a narrow elevation band and exists in terrain that was protected from the strong outflow (North) wind event that occurred in late January.  This layer has been found on average between 12-20 inches in depth.

  Below 1500 feet, a rain crust is buried 16-20 inches, and has shown propagation beneath the crust in snow pits as recently as 3/5.  Due to the limited extent of elevation, this layer is only a concern in a limited amount of terrain.  This layer could be a concern in steep low elevation canyons, or on steep unsupported slopes below 1500'.  

    To limit exposure to both of these layers avoid terrain traps and consider using conservative terrain while moving through low elevations..  There is uncertainty on the current and future reactivity of these two layers. We are keeping these on our list, as current weather conditions will continue to stress these layers.