Avalanche Forecast

Archived

Nov 16th, 2011–Nov 17th, 2011

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Sea To Sky.

This bulletin is based on limited data. Local variation in conditions and danger levels are likely to exist. To produce more accurate forecasts, we need information. Please send an email to [email protected].

Confidence

Poor - Due to limited field observationsfor the entire period

Weather Forecast

Thursday: Expect another 5-15cm of new snow as the storm tapers off. Freezing levels should lower to around 300m and winds should ease off becoming light to moderate westerlies.Friday: Isolated flurries bringing light amounts with freezing levels as low as 200m and light northwesterly winds.Saturday: Relatively clear, dry and cold with light northwesterly winds.

Avalanche Summary

No reports of avalanches, but I suspect wind slabs and any new storm slabs will be susceptible to human triggering. The size of the ensuing avalanche depends on slab thickness, with slabs thicker than 30cm generally producing avalanches sufficiently large to bury or injure a person.

Snowpack Summary

Total snowpack depth at treeline is around 80-100cm. Expect to find deeper pockets of wind-blown snow immediately down-wind of terrain features and ridge crests. A rain crust from last week is 70 or 80 cm off the ground at treeline and lower alpine elevations, and is heavily faceted faceted in some locations. Watch this weakness as it gets more load.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.