Glacier National Park Avalanche Forecast

Mar 9th, 2020 8:11AM

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

Happy Daylight Savings!

Give your minds extra time to assess slopes for the Feb 22nd weak layer.

We are into a period of lower probability/ high consequence!

Summary

Weather Forecast

A cold front is moving southward across the province and will reach Rogers Pass by Tuesday morning.

Today: a mix of sun and cloud. Light west winds. Alpine high -11*C.

Tonight: cloudy with clear periods, no precipitation. Moderate SW winds. Alpine low -11*C

Tomorrow: 19cm of snow with moderate SW winds. Alpine high -8*C and freezing level at 900m.

Snowpack Summary

25cm+/- of storm snow has been redistributed by moderate S'ly winds near ridgecrests in the alpine and exposed treeline. Below these slabs, the Feb 22nd persistent weak layer is now buried down 60-90cm, and consists of 3-7mm surface hoar on all aspects up to 2450m, and a crust on solar aspects. In some locations, this surface hoar sits on a crust.

Avalanche Summary

Numerous loose dry avalanches up to size 2.0 were observed yesterday on steep solar aspects, as well as several size 2.5 avalanches from the gullies of Mt. Macdonald.

On Friday, a snowmobile triggered size 2.5 slide occurred inside the E boundary of Glacier NP in the Bald Hills. Evidence indicated 2 sleds were involved and the group self extricated.

Confidence

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

Problems

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

1 - 2.5

The Feb 22 Surface Hoar/ sun crust layer is down ~90cm at TL in the W end of the park & 50-80cm in the east. It's a likely depth for skier triggering in shallower snowpack areas. This problem is decreasing in probability but remains high consequence

  • Be aware of the potential for wide propagations.
  • Avoid steep convexities or areas with a thin or variable snowpack.

Aspects:

All aspects.

Elevations:

All elevations.

Loose Dry

An icon showing Loose Dry

Likelihood

Likely

Expected Size

1 - 2

Unconsolidated new snow will be reactive to strong solar radiation, especially on steep, rocky features.

  • Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects:

South East, South, South West, West.

Elevations:

Alpine, Treeline.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible - Unlikely

Expected Size

1 - 2.5

Moderate to strong southerly winds this week have formed wind slabs in the alpine and exposed areas at treeline. If triggered, these wind slabs have the potential to step down to the Feb 22nd SH/ sun crust layer.

  • Use caution in lee and cross-loaded terrain near ridge crests.
  • If triggered the windslabs may step down to the Feb 22 SH layer with potential for large avalanches.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Mar 10th, 2020 8:00AM