Avalanche Forecast

Issued: Nov 23rd, 2020 4:00PM

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

Aaron Beardmore,

Banff Yoho Kootenay.

Increasing wind will create fresh wind slabs in alpine by midday Tuesday. Snow fall coming in behind the wind event will raise the danger on Wednesday in the alpine.

Summary

Weather Forecast

Temperatures will remain the warm side of seasonal. Close to zero in the valley and -10 at the ridge. The wind is expected to pick up to the strong or extreme range starting tonight from the SW. This will be the biggest input inducing change in the near term. Snow amounting to about 10cm will start late Tues and continue into Weds.

Snowpack Summary

Wind slabs present at treeline and above from W-SW winds. At treeline 20-50 cm of storm snow sits over a layer of preserved stellars. The Nov. 5 facet/crust combo is down 50-80 cm and producing variable test results from easy to hard. The Nov crust extends up to 2500 m on N aspects and higher on solar aspects. Snow depths at treeline are 50-130 cm.

Avalanche Summary

No avalanches were observed or reported on Monday.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Tuesday

Problems

Wind Slabs

Little wind slab activity was observed today. However the winds are expected to increase tonight, producing fresh wind slabs in the alpine lee by midday on Tuesday.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

The Nov.5 crust/ facet layer exists up to 2500m on shady aspects, and higher on solar aspects. Where there is a dense slab overlying this layer, it remains a concern, and likely will be for the foreseeable future.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Nov 24th, 2020 4:00PM