East Slopes North

Problèmes avalancheux

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Unlikely

  Taille

  2–3

  There was a remotely triggered large avalanche likely occurred on this layer on Wednesday near Harts Pass. The crown was up to 3ft in depth and broke along a convexity in unsupported terrain. Before that, the last reported avalanche on this layer occurred on March 3rd, also near Harts Pass. A week between avalanche occurrences is not unusual when considering deep persistent slab problems. It may just indicate that avalanches on these deeply buried weak layers are becoming more difficult to trigger, making them challenging to manage. The best way to approach this low likelihood, high consequence avalanche problem is to limit your exposure to steep, complex terrain. Also, remember that large triggers such as cornice falls, smaller avalanches, or snowmobiles increase the potential to trigger deep persistent slabs. Since the storm on February 26th through March 1st, snowpack tests show that the weak snowpack structure remains unchanged. You can find the late January weak layer (facets sandwiched between two crusts) 3-5' below the surface. Snowpack tests can help you identify the layer of concern. Sudden or propagating results have remained consistent during periods when avalanches have become difficult to trigger. East of Washington Pass, the snowpack is likely much more shallow. This interface may be nearer to the snow surface, potentially making avalanches easier to trigger. 

  While the structure exists throughout the East North zone, the Harts pass area seems to be the focal point of avalanche activity on this layer. Therefore, extra caution and conservative terrain choices are warranted if recreating near the Harts Pass area.