Flathead Range & Glacier NP

Lawinenprobleme

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Likely

  Größe

  1–2

  Today is the third consecutive day of warming temperatures and sustained sunshine, resulting in a Wet Loose problem. Fortunately, modest daytime highs and well below-freezing readings overnight have limited wet snow instabilities to the near-surface on aspects facing the sun. 

   A surface crust of varying thickness is found on sunny slopes up to 7000 feet or higher. As the crust deteriorates through the day, the danger will rise. Shady slopes harbor loose, dry snow, which has so far escaped warming. If today's warming exceeds forecasted readings, wet loose activity may develop on aspects not receiving direct sun.

  The threat of natural Wet Loose avalanches on sunny slopes below 7000 feet is diminishing but triggering a slide in mushy surface snow remains likely as the day heats up. A crust that cannot support you or your machine indicates instability. Rollerballs and pinwheels are precursors to a wet slide. If you can make a snowball in the surface snow, this signifies that the surface has become moist. These are signs directing you to move to a different aspect. Stay ahead of the sun today, or select lower-angle slopes to enjoy the corn-like conditions. Choose a route that does not expose you to steep overhead westerly aspects on your exit. Limit time above terrain traps where even a small slide can pile up deep. Northerly aspects should remain safer and hold higher-quality snow.

   

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Unlikely

  Größe

  2–3

  Several weak layers capable of producing a large destructive avalanche can be found throughout our snowpack.

  • Faceted snow formed in November near the bottom of the pack responsible for the recent snowmobile-triggered slide in the northern Whitefish Range and the natural slide on Elk Mountain earlier this week (Photo above/to the right).
  • Weak snow resting on the Christmas crust.
  • A weak layer from mid-January is responsible for most of the Persistent Slab avalanches recorded this season. This layer is generally found 2-4 feet below the surface.

  The Persistent Slab has become a low-likelihood high-consequence problem. With relatively deep snow depths across the area, these layers are generally buried at a depth that a rider is unlikely to affect. However, as recent avalanches signify, thin areas in the snowpack are likely trigger points. These include rocky outcroppings and wind-swept or scoured locations where the weak layer is closer to the surface.

  Terrain selection is the most straightforward way to deal with this issue. Choose slopes with a deep, uniform snowpack without a peppered rocky appearance. When in doubt, defaulting to lower-angle slopes is the best choice.