Flathead Range & Glacier NP

Problèmes avalancheux

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1.5–3

  Up to 3 feet of new snow over the past few days likely amounts to 5–6'+ of wind-drifted snow in start zones that face NW-E-SE. This load is stressing the January Drought Layer (JDL—surface hoar and facets on a crust), which was still producing large and destructive avalanches prior to this storm cycle. This layer now sits roughly 3–6 feet below the surface in sheltered terrain, and even deeper on wind-loaded slopes. With a deep weak layer and a tapering storm, the likelihood of triggering a persistent slab avalanche will decrease, but the consequences are severe.

  Two main scenarios could produce an avalanche on the JDL today. The biggest concern is a slide that begins in the recent storm snow and steps down several feet to the JDL, producing a large and destructive avalanche. The other possibility is triggering an avalanche from a thin spot—often near rocky outcrops, the bases of trees, or locally wind-scoured areas—where the weak layer sits closer to the surface. Either scenario could produce an avalanche that would be difficult to walk away from.

  Avoidance remains the best strategy. Stick to low-angle terrain without steep slopes overhead. Fortunately, excellent riding conditions exist in this type of terrain, allowing you to enjoy the new snow while staying clear of this lurking dragon.

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Likely

  Taille

  1.5–2.5

  Avalanches in new and wind-drifted snow are likely today. Continued loading, fresh north and east winds, and cold temperatures will keep slabs sensitive to a rider’s weight. While problems may exist in sheltered terrain, the most sensitive areas will be wind-loaded start zones where two types of wind slabs are the primary concern.

  Flavor 1: New Wind SlabsFresh wind slabs will form in real time today, especially on slopes that are usually wind-scoured, such as those facing west. If you see blowing snow, assume slopes downwind are being actively loaded. Shooting cracks are a clear sign of instability, but if a slope is being loaded, that’s reason enough to move on to another slope.

  Flavor 2: Older Wind SlabsWinds have eased significantly since their apex overnight Wednesday into Thursday, allowing softer, lower-density snow to cover older, harder wind slabs on slopes facing NE–E–SE. This softer snow may hide the usual visual clues, like textured surfaces or pillowy deposits. You can dig a quick hand pit to feel for a buried harder slab capping softer snow. Because these slopes also host the persistent slab problem, the safest choice is to avoid steep start zones on shaded aspects.

  Dry Loose:

  Expect sluffs in the new snow if you are riding on steep slopes today. With a lot of soft snow on the surface, some of these could grow large as they descend.