Avalanche Forecast

Issued: Jan 26th, 2016 8:44AM

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

jlammers, Avalanche Canada

South Coast.

Touchy and dangerous conditions still exist in many parts of the region. With a warm, wet and windy storm on the way, conditions will continue to deteriorate.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Wednesday

Weather Forecast

Warm, wet and windy conditions will persist for most of the forecast period. Expect up to 15mm of precipitation on Wednesday with another 20mm possible Wednesday night. Winds on Wednesday will be extreme from the southwest while freezing levels will hover around 2300m. On Thursday, the region should see between 10-20cm of snow, strong southwest winds and freezing levels dropping from 1800 to about 1400m. On Friday continued snowfall is expected with accumulations ranging from 5-15cm. Winds should taper-off dramatically with freezing levels dropping to about 1000m.

Avalanche Summary

A widespread avalanche cycle to size 3 was observed last weekend in response to heavy snowfall, wind and warm temperatures. Many of these avalanches were persistent slab avalanches which failed on recently buried surface hoar. More recently, a skier-triggeredÂ size 2 persistent slab avalanche was observed in the north of the region around Birkenhead Lake. Check out the great Mountain Information Network posts that detail the touchy conditions in this area. Looking forward, continued warm, wet and windy weather is expected to spark ongoing wind slab activity in high elevation lee terrain, but warm temperatures and loading will also increase the likelihood of waking up any lingering persistent weaknesses that were not triggered by last week's storm.

Snowpack Summary

On Wednesday, moderate snowfall and strong winds will continue to form deep and dense storm slabs in high elevation terrain and cause substantial cornice growth. At treeline and below, rain is forecast to further saturate the upper snowpack. Heavy loading from last week's storm and the resulting avalanche cycle, has helped flush-out the mid and early-January surface hoar/facet layers now down 60-120 cm deep. However, these layers are still intact and reactive in many places and it may still be possible to trigger large slabs. The mid and lower snowpack is generally strong, with the exception of shallower snowpack areas that may be more faceted.

Problems

Persistent Slabs

Buried surface hoar remains primed for rider triggering in many areas including the Northern part of the region and Alison Pass. Forecast rain and wet snow will increase the likelihood of avalanches failing on this touchy weak layer.

Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Be wary of slopes that did not previously avalanche - even on low angle terrain.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 5

Wind Slabs

Continued precipitation, warm temperatures and wind on Wednesday will form dense new wind slabs in high elevation lee terrain. At lower elevations where rain is expected, loose wet avalanches are also possible.

Use ridges or ribs to avoid pockets of wind loaded snow.>Choose well supported terrain without convexities.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Jan 27th, 2016 2:00PM