Avalanche Forecast
Issued: Feb 20th, 2013 8:31AM
The alpine rating is Wind Slabs, Persistent Slabs and Cornices.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Fair - Due to limited field observations
Weather Forecast
Synopsis: A series of frontal systems is expected to affect the region over the next few days bringing steady precipitation and seasonal temperatures. Â Overnight and Thursday: Periods of snow â 10-20 cm. The freezing level is around 600 m. Winds are moderate to strong from the west-southwest. Friday: Moderate to locally heavy snowfall â 15-20 cm. The freezing level remains around 600 m and winds are strong from the west.Saturday: Cloudy with light snow. The freezing level is around 600 m and winds ease to moderate from the southwest.
Avalanche Summary
Natural avalanches activity has tapered off but some observers continue to report older (+48 hrs) natural slab avalanches up to size 3 from steep northeast facing terrain. These events may involve the basal weak layers.
Snowpack Summary
The previous storm snow seems to have settled and strengthened over the past couple days. Wind slabs have formed in exposed terrain in lee of ridges, in gullies, and behind terrain features. These wind slabs have not been reactive to skier triggers, even in steep unsupported terrain. There are a variety of old interfaces now down 40 - 100cm which include facets, crusts and isolated pockets of surface hoar. There is very limited information about the nature of this interface. I would stress the importance of digging down to find and test weak layers before committing to larger and steeper slopes.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow compared to averages; triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.
Problems
Wind Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Aspects: North, North East, East.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Feb 21st, 2013 2:00PM