Avalanche Forecast

Issued: Mar 22nd, 2016 9:10AM

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

jlammers, Avalanche Canada

Northwest Coastal.

The Avalanche Danger may change quickly in the spring. Even brief periods of sun or rain can trigger pushy loose wet avalanches or promote destructive cornice falls.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Wednesday

Weather Forecast

On Wednesday expect 5-12cm of new snow with strong southwest ridgetop winds. Continued light snowfall (5-8cm) and decreased winds are forecast for Thursday. Clearing skies are expected on Friday as a dry ridge of high pressure develops over the province. Freezing levels should hover between 1100 and 1200m for the forecast period.

Avalanche Summary

Loose wet avalanches to size 1.5 were reported to have occurred in steep terrain on a variety of aspects. They failed in response to periods of solar warming or rain. New wind slab activity is expected in response to new snow and strong winds on Wednesday.

Snowpack Summary

Light amounts of snow fell on Monday night. The new snow overlies older wind slabs in exposed terrain and settled powder on shaded, sheltered slopes. Spring conditions have continued to develop. With that, lower elevation and sun-exposed slopes will likely appear moist or refrozen. A layer of surface hoar or melt-freeze crust buried on March 3 is down 50-80cm and has been on the radar of professionals in the mountains north of Stewart. A more widespread crust/facet layer buried in early February can now be found down over a metre. Both of these deeper layers have become less likely to trigger, but have the potential for large avalanches especially with a large trigger such as a cornice fall. I'd be increasingly cautious during periods of warming or solar radiation.

Problems

Wind Slabs

New snow and strong winds forecast for Wednesday will promote new wind slab formation in exposed high elevation terrain. New wind slabs are expected to increase in size and reactivity throughout the day.

Be cautious as you transition into wind affected terrain. >Be alert to conditions that change throughout the day.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Cornices

Natural cornice releases remain an ongoing concern for professionals in the region. During the past week, falling cornices have also triggered large avalanches on the slope below.

Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 5

Persistent Slabs

A few persistent weaknesses exist in the mid snowpack (see snowpack description). These potentially destructive layers may become reactive with spring warming or with a large trigger such as a cornice fall.

Conditions have improved, but be mindful that persistent instabilities are still present.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Mar 23rd, 2016 2:00PM