Avalanche Forecast

Issued: Apr 5th, 2014 9:20AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Wind Slabs and Deep Persistent Slabs.

bcorrigan, Avalanche Canada

Purcells.

New snow amounts and rising temperatures are driving the hazard these days. Cornices will become weak as temperature rise.For more insight check out the latest Forecasters Blog:

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Synopsis: A series of frontal systems will bring precipitation into the interior of BC.Tonight:Â Cloudy with flurries. 5 to 10 cm of precipitation in the forecast, daytime freezing level around 1600m, winds light to moderate from the south west.Sunday: Sunny with cloudy periods, freezing level around 1600m, no overnight freeze, winds, moderate gusting to strong from the south west.Monday: Cloudy with flurries, light to locally moderate precipitation, freezing levels may climb to 2400 metres, winds light to moderate from the south west.Tuesday:Â Cloudy with flurries, 5 to 10cm possible, freezing level around 2500., winds moderate from the south west.

Avalanche Summary

Reports of avalanche activity has dropped off, with one operator reporting a two size 1.5 naturals on a west aspect. We expect to see natural avalanche activity rise with the precipitation and winds associated with the incoming storm system tonight ( Saturday ) along with periods of sun and increasing air temperatures later in the week.

Snowpack Summary

There is a highly variable snowpack throughout the forecast region, however...recent snow falls are are reported to be settling well and bonding to the variety of snow surfaces. Wind slabs have formed on the lee sides of ridge crests, mostly north and north east. Moist snow during the day on all solar aspects below 1800 metres, Sluffing in steep terrain. Surface facetting and surface hoar has been reported in protected north facing locations.Numerous crusts can be found in the upper snowpack on south facing slopes. A March 15 crust/surface hoar interface is down approximately 50-80cm in most parts of the forecast area. At 60 to 120cm below the surface you may find surface hoar and crusts that were buried at the beginning of March. This interface is still touchy in some areas, and continues to produce sudden planar failures in compression tests.The deeper facet/crust persistent weakness buried at the beginning of February, is now down 120to 180 cm, and still reactive in test pits. An avalanche on any of these deeper, persistent interfaces would be large and destructive. Weak basal facets exist in many areas, but triggering is unlikely, without a big load.

Problems

Wind Slabs

Incoming storms with strong south west winds will build wind slabs on north and eastern lee slopes. Solar aspects can be tricky in the afternoon. Cornices are a big concern with rising temperatures and recent strong winds.

Cornices become weak with daytime heating, stay well back from corniced ridges>Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid freshly wind loaded features.>

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

The February and March persistent weak layers could "wake up" if subjected to a large load ie: new snow, a cornice fall, or daytime heating on solar aspects

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Apr 6th, 2014 2:00PM