Avalanche Forecast

Issued: Jan 18th, 2017 4:51PM

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

Avalanche Canada cam_c, Avalanche Canada

Heavy loading from snow and wind is driving avalanche danger up.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

THURSDAY: Flurries, accumulations 10-15cm, strong becoming moderate southwest winds, freezing level around 1300m.FRIDAY: Mainly cloudy with scattered flurries bringing up to 5 cm, light westerly wind and freezing level around 1200m.SATURDAY: Mainly cloudy with scattered flurries bringing up to 5 cm, light westerly wind and freezing level around 1200m.More details can be found on the Mountain Weather Forecast.

Avalanche Summary

Observations are still limited by the inclement weather, but reports of widespread storm slab avalanche activity are trickling in. In the southern part of the region, reports from Tuesday include stubborn soft storm slabs triggered with explosives and ski-cutting at alpine elevations, with just snowballing at treeline and below. However, reports from the northern part of the region on Tuesday include widespread natural and explosive-triggered storm slab avalanches up to Size 2.5 well below treeline.

Snowpack Summary

Rapid snow, wind and rain loading continues with fluctuating freezing levels. By Wednesday morning freezing levels had dropped, and another 30 cm or more of new snow fell as low as treeline elevations, with extreme southerly winds in the alpine. On Monday into Tuesday we had rain up to 2200m near Whistler, while in other zones like the upper Callaghan it was 35 cm or more of fresh snow. The rain (or snow high in the alpine) started to saturate and load a wide variety of previous surface conditions. Simply put, the upper snowpack is extremely variable: Last week we had very touchy wind slabs (5-40 cm thick) forming on southerly slopes near ridge crests and roll-overs. These slabs were the primary weakness of concern in the snowpack, giving easy sudden planar results in snowpack tests. Deeper in the snowpack, older snow is bonding fairly well to a variable surface consisting of a mix of soft wind slabs, hard wind slabs, sastrugi, faceted snow, and even some surface hoar. Snowpack layers below this interface are generally well bonded, and the lower snowpack is solid.

Problems

Storm Slabs

An icon showing Storm Slabs
New snow is bonding poorly to the previous snow surface. Expected avalanche likelihood and size to increase with increased snow and wind-loading. Slabs will be particulary deep and touchy on wind-loaded northerly aspects near ridge crests.
Minimize overhead exposure during periods of heavy loading from new snow, wind.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Valid until: Jan 19th, 2017 2:00PM

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