Avalanche Forecast

Issued: Jan 19th, 2015 7:48AM

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

Peter, Avalanche Canada

Northwest Coastal.

The storm track is aimed at the Northwest this week resulting in rising avalanche danger. Avoid avalanche terrain during periods of heavy loading from snow, rain or wind.

Summary

Confidence

Fair

Weather Forecast

Synopsis: The storm track looks like it will be aimed squarely at the Northwest for the next few days bringing a series of frontal systems. Expect 10-20 cm of snow on Tuesday, another 25-40 cm (or mm) Tuesday night through Wednesday, and it keeps coming down on Thursday. We should see a warming trend with freezing levels around 1200-1400 m on Tuesday, and 1500-1600 m on Wednesday/Thursday. Winds should be consistently moderate or strong from the S-SW.

Avalanche Summary

Most of the recent reported activity was from the north of the region. Numerous explosive triggered size 1-2.5 slabs were reported on Saturday and Sunday. Many of these were on wind-loaded N-NE aspects around 1400-1500 m. There were also a few natural cornice falls which triggered 10 cm deep slabs below. It's likely that southern sections also experienced recent natural avalanche activity but poor weather may have prevented observations.

Snowpack Summary

Strong winds have redistributed recent storm snow into wind slabs, and rain has saturated the surface of the snowpack to around 1000 m. If temperatures cool, the snowpack below treeline may gain some strength. Above treeline, a buried rain crust and/or surface hoar layer is down about 50 cm. Observations of the strength at this interface have been limited. The November crust near the bottom of the snowpack is generally well bonded, but may still be reactive in areas with a shallow snowpack, or with a very heavy load.

Problems

Wind Slabs

Fresh wind slabs will continue to build in wind exposed terrain throughout the week with forecasted snowfall and strong SW winds.

Travel on ridgetops to avoid wind slabs on slopes below.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Storm Slabs

Storm slabs may become sensitive to rider triggering as snow accumulates and temperatures gradually rise. Wet loose sluffs or wet slabs are possible below treeline if we start to see heavy rain at lower elevations.

Choose conservative lines and watch for clues of instability.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Jan 20th, 2015 2:00PM