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North Rockies Avalanche Forecast - March 11, 2021

The risk of an avalanche will increase slightly heading into the weekend.
North Rockies Avalanche

Thursday is a classic late winter day with cool temps & a few clouds. A warm storm arrives Thursday night, & then warming continues through the weekend. Peak warming may initiate a natural avalanche cycle, especially in the east where there are deeper concerns in the snowpack.

Thursday

Alpine - Moderate
Treeline - Low
Below treeline - Low

Friday

Alpine - Considerable
Treeline - Moderate
Below treeline - Moderate

Saturday

Alpine - Considerable
Treeline - Moderate
Below treeline - Moderate

Avalanche Summary

Our field team found some large and disturbingly wide avalanches in the Hasler Tuesday, lots of compelling images in their MIN report here. It's suspected that these are running on facets that are about 80 cm below the surface.

This adds to the tally of recent large avalanches they started collecting in Pine Pass on Monday. All of this activity leaves me feeling uneasy about a big warm up this weekend.

The warm temperatures last week triggered loose wet avalanches on solar (south through west) aspects. Strong winds triggered wind slabs naturally up to size 2 and explosive controlled avalanche (near Pine Pass) up to size 3.

Snowpack Summary

Strong south to west winds in exposed areas have scoured some slopes and built wind slabs on others. Freezing levels reached treeline last Thursday and Friday. It has cooled since so you will likely find 5 to 10 cm of new new snow on the surface or a crust at treeline and below.

About a metre of snow covers a weak layer of facets buried mid February. Slightly deeper there is a widespread persistent weak layer from late January/early February that consists of surface hoar. It is most prevalent around treeline elevations, but likely reaches into the alpine and in openings below treeline too. These layers are both significantly shallower in the east of the region.

Weather Forecast

A shot of cold snow Thursday night and then a pretty significant warm up this weekend.

THURSDAY - A few clouds, freezing level rising to about 1350 m in the afternoon, strong southwest wind, no snow expected during the day, 5 to 10 cm possible Thursday night.

FRIDAY - Broken cloud cover, freezing level climbing to about 1800 m, strong southwest wind, 5 to 10 cm of snow at upper elevations with rain at valley bottom.

SATURDAY - Scattered cloud cover, freezing level potentially climbing as high as 2000 m, strong southwest wind, no precipitation expected.

Travel and Terrain Advice

  • Be careful as you transition into wind affected terrain.
  • Avoid freshly wind loaded terrain features.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.