Avalanche Forecast

Issued: Feb 4th, 2013 9:23AM

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

mpeter, Avalanche Canada

Sea To Sky.

If the storm arrives early, and there is more than 20cm by the afternoon, the DANGER ratings should be considered too low.

Summary

Confidence

Fair - Timing of incoming weather is uncertain on Tuesday

Weather Forecast

Tuesday: Expect flurries to build through the day, with more intensity in the southern part of the region. As much as 25cm are possible through the day. Expect moderate to strong southwest winds and alpine temperatures reaching -6.Wednesday: The storm continues with another 20cm possible. Strong southerly winds persists with temperatures reaching -8.Thursday: Snowfall should taper through the day, with winds turning more northerly and abating somewhat. Alpine temperatures should reach -6.

Avalanche Summary

No new avalanches. This will change as the upcoming storm intensifies.

Snowpack Summary

Currently (February 5th a.m.) isolated, stubborn wind slabs can be found behind ridges, ribs and on lee slopes (NW-NE). Sun crusts can be found on South and West facing terrain. The upper snowpack is showing continued settlement and gaining strength. Down 20-50 cm sits a persistent interface comprising of crusts, facets and surface hoar crystals. Recently, this layer has been reactive in very isolated, sheltered areas at treeline and below where surface hoar remains preserved. The mid pack is generally well settled with the average snowpack depth at treeline around 180 cm.As the storm arrives and develops, expect new windslabs to build on lee features and storm slabs will become reactive, first on south and west facing terrain where the suncrust is well developed.

Problems

Storm Slabs

As the storm arrives and intensifies, I expect the storm slab problem to to develop. New windslabs will form in lee features at treeline and in the alpine. Also, the new snow may initially bond poorly to the crusts present on many slopes.

Make observations and assess conditions continually as you travel.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Wind Slabs

Old windslabs exist in isolated locations. These will soon be buried by the storm snow.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Feb 5th, 2013 2:00PM