Glacier National Park Avalanche Forecast

Mar 6th, 2020 8:08AM

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

The Feb 22 Surface Hoar persistent weak layer (PWL) is becoming a low probability high consequence layer. Conservative route selection is a logical choice.

Summary

Weather Forecast

Scattered flurries with 5cm accumulation expected. freezing level rising to 1500m with an alpine high of -5C. Mostly light ridge wind with occasional gusts into moderate range.

Snowpack Summary

Storm snow is cloaking near surface windslabs in open terrain features at all elevations. Wind effect appears to be highly variable. Below these slabs, the Feb 22nd persistent weak layer is now buried down 60-70cm, and consists of 3-7mm surface hoar on all aspects up to 2450m, and a crust on solar aspects.

Avalanche Summary

No new natural avalanche activity observed in the highway corridor. A report of a size 1 skier accidental slab avalanche just above the up track skier's right of Frequent Flyer in the last 48hrs. The slab possibly released on the February 22 Surface hoar layer.

Confidence

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely - Possible

Expected Size

1 - 2.5

Recent wind has formed windslabs in open terrain features on all aspects in the Alpine and exposed areas of TL and BTL. If triggered these wind slabs have the potential to step down to the Feb 22nd surface hoar layer.

  • Be aware of the potential for wide propagations due to the presence of hard windslabs.
  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects:

All aspects.

Elevations:

All elevations.

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

1 - 3

The Feb 22nd SH is now buried 60cm+ deep, which is a likely depth for skier triggering, especially in shallower snow pack areas. Steep solar aspects harbor a crust under the surface hoar layer, which can increase the sensitivity of triggering.

  • Be aware of the potential for wide propagations.
  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Mar 7th, 2020 8:00AM