Avalanche Forecast

Issued: Nov 28th, 2015 3:00PM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Loose Wet, Wind Slabs and Deep Persistent Slabs.

bcorrigan, Avalanche Canada

Purcells.

Warm temperatures on solar aspects in the alpine are the prime concern these days.Use caution on sun affected slopesIf you are traveling in the backcountry, share your observations through the MIN

Summary

Confidence

Fair - Due to the number and quality of field observations

Weather Forecast

An arctic high continues to dominate the weather pattern over western Canada and is not forecast to move out of the area until Tuesday or Wednesday next week. In the meantime, an above-freezing layer (AFL) of air will pass through the region between 1500 and 3000m bringing temperatures in that elevation band to as high as +5°c., especially on solar aspects. Arctic air pooling in the valley bottoms will keep the temperatures well below freezing until the next storm system flushes out the cold air.

Avalanche Summary

Loose snow sluffing in steep north facing terrain has been reported. No reports of wind slab avalanche activity from yesterday.

Snowpack Summary

The snowpack is extremely variable at this time. Wind scoured north facing slopes exist at treeline and above from the recent strong winds associated with the arctic front. South facing slopes with wind slabs at tree line and above may be hiding surface hoar from the previous spell of cold clear weather. Surface facetting has observed in the region as a result of the recent cold weather and clear skies, and surface hoar is forming in sheltered locations. There are a number of surface hoar layers now buried in the snowpack that at present appear to be unreactive, the most recent having been buried on Nov 24th. In shallow snowpack areas, especially on northern aspect, there may be a weak facetted layer at the base of the snowpack. Recent warming at upper elevations will change the snowpack on all aspects, and especially those facing to the south.

Problems

Loose Wet

Intense solar radiation on south facing slopes may create a hazard. Use caution when traveling on or under slopes affected by the sun and warm temps.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Wind Slabs

Strong north winds have built wind slabs in places where we are not used to seeing them. South facing slopes below ridges may be loaded by arctic winds.

Avoid freshly wind loaded features.>Use caution in lee areas in the alpine. Recent wind loading may have created wind slabs.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

Facetted snow from early in the season has been reported on northern aspects, especially in shallow snowpack areas.

Avoid shallow snowpack areas where triggering is more likely.>Now is a good time to dig a snow profile (or two) and figure out how the snowpack changes with aspect and elevation.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

2 - 5

Valid until: Nov 29th, 2015 2:00PM