Avalanche Forecast

Issued: Jan 31st, 2022 4:00PM

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

Chris Gooliaff,

Glacier.

Sunday's overnight dump (50cm) sits atop surface hoar or a suncrust. These storm slabs will be reactive to human loads and may propagate widely.

Conservative choices are wise; even gladed tree runs aren't the usual safe havens.

Summary

Weather Forecast

Flurries and a mix of sun/cloud, followed by cold air Wed

Tonight: Cloudy with flurries, trace amounts, Alp low -15*C, gusty mod W winds

Tues: Mix of sun/cloud with flurries, trace amounts, Alp high -15*C, light N winds

Wed: Mix of sun/cloud, Alp high -19*C, light SW winds

Thurs: Cloudy with flurries, trace amounts, Alp high -9*C, light SW winds

Snowpack Summary

50cm from Sunday now buries the Jan 29 surface hoar (5-15mm) and crusts on steep solar aspects. Expect to find storm slab at all elevations, deeper in wind-deposited areas at Alpine and Treeline elevations. The Jan 20 surface hoar (2-4mm) is down 60-70cm. The Dec 1 crust/facet combo is down 1.5 - 2.5m.

Avalanche Summary

Artillery control Sunday night/Monday morning produced numerous avalanches to sz 3-3.5 in the park.

The natural avalanche cycle continues to be driven by mod/strong winds in the Alpine redistributing the new snow and overloading the Jan 29th surface hoar/suncrust layer. This layer exists at all elevations/all aspects and will persist for a while.

Confidence

Due to the number and quality of field observations

Problems

Storm Slabs

50cm of new snow and mod W'ly winds have buried the Jan 29 surface hoar (5-15mm), which is a crust on steep solar aspects and hard surfaces everywhere else. This layer will be easy to trigger and could step down to deeper layers.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Use caution on open slopes and convex rolls where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Loose Dry

The new snow has buried the Jan 29 surface hoar (5-15mm) and will likely be easy to trigger, especially in steeper, unsupported terrain. Manage your sluff appropriately, especially in gullies and with people above/below you.

Use caution above cliffs and terrain traps where small avalanches may have severe consequences.
Be careful of loose dry power sluffing in steep, confined or exposed terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

Several surface hoar layers in the upper snowpack may wake up with the new snow load. If triggered, there is potential to step down to the deeper Dec 1 crust/facet layer, resulting in a very large avalanche.

Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.
Avoid steep convexities or areas with a thin or variable snowpack

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 3.5

Valid until: Feb 1st, 2022 4:00PM