Avalanche Forecast

Issued: Nov 20th, 2017 8:09AM

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

ian gale, Parks Canada

Glacier.

The new snow needs time to become less reactive. If triggered, avalanches could run to valley bottom today.

Summary

Weather Forecast

Today will be a lull in the stormy weather we've been seeing. Expect a mix of sun and cloud, with no snow forecasted and freezing levels around 1500m. Wind will be light from the south. A significant storm will affect Roger's Pass Tuesday-Thursday bringing heavy precip and very high freezing levels, up to 2800m on Wednesday!

Snowpack Summary

Another 25cms fell overnight in the Alpine. Thats an average of 20cms's a day for the last 5 days. This recent snow with moderate South winds has built widespread storm slabs. The Halloween crust is the layer we're watching and it's down approx 80-100cm. The snowpack is still very thin below 1700m

Avalanche Summary

In the Highway corridor this morning forecasters observed fresh debris to size 2.5 that ran into avalanche path runouts. There was also a report of a size 3 avalanche off of the East aspect of Grizzly Peak in the Connaught drainage. This increase in avalanche activity can be attributed to recent snow loading and strong winds in the alpine.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Storm Slabs

Heavy snow loading and strong alpine winds have created a reactive storm slab. Yesterday shooting cracks were observed in the alpine. The storm slab will be most reactive in unsupported terrain and features exposed to wind loading.

Minimize overhead exposure during periods of heavy loading from new snow, wind.The new snow will require several days to settle and stabilize.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

The Halloween Crust layer is buried down approximately 100cms. With the recent loading from heavy snow and strong winds we could see this layer become reactive. If it does "wake up" the resulting avalanches would be large!

Minimize exposure during periods of heavy loading from new snow and wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Nov 21st, 2017 8:00AM