Avalanche Forecast

Issued: Mar 15th, 2015 9:01AM

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

Avalanche Canada rbuhler, Avalanche Canada

Lingering storm instabilities will provide tricky conditions in the alpine. Use a conservative approach to travel and avoid wind-loaded features.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

A ridge of high pressure should keep the region dry for the next three days. Mostly sunny conditions are expected for Monday with light alpine winds. Freezing levels should reach around 1500m or so in the afternoon. Overnight the freezing levels should fall below valley bottom. On Tuesday, a mix of sun and cloud is expected with light alpine winds and freezing levels reaching around 2000m. Conditions should be similar on Wednesday but with increased cloud cover.

Avalanche Summary

No observations were reported on Saturday due to the storm conditions. On Friday, widespread natural activity up to size 3 was reported in parts of the region. This was in response to very warm temperatures and strong sun. These avalanches were mainly in the alpine and were reported on all aspects. However, the largest avalanches were reported from north aspects. Much of this activity was releasing on the mid-February layer down 30-60cm. On Monday, touchy storm slabs are expected in the alpine and possibly at treeline. There is some uncertainty regarding the distribution of these storm slabs but they could be widespread. Thicker winds slabs associated with the storm are expected in leeward features and are the biggest concern for Monday.

Snowpack Summary

At higher elevations, new snow sits over a variety of surfaces including moist snow, crusts, wind affected surfaces, and/or old wind slabs which may still be reactive. Rain has soaked the upper snowpack to around treeline elevation. In the alpine, strong winds during the storm have redistributed the new snow into wind slabs in leeward terrain features. Prior to the storm, 30-50cm of snow was sitting over a weak facet/crust layer that was buried in mid-February. This layer has been quite reactive recently and may increase the likelihood of triggering a storm slab. The late-Jan crust/surface hoar layer (over 1m deep) and the mid-January surface hoar (around 1.5m deep) have been dormant for several weeks.

Problems

Storm Slabs

An icon showing Storm Slabs
A new storm slab sits over a weakness from mid-February and is reactive to human-triggering.  Thicker touchy wind slabs can be found in leeward terrain features in wind exposed terrain.
Avoid freshly wind loaded features.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Mar 16th, 2015 2:00PM

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