Avalanche Forecast Glacier National Park

Sunday 3rd February 2019

Avalanche Danger Ratings Sun 3rd Feb 8:00AM Danger Ratings Alpine: Considerable Danger Ratings Treeline: Considerable Danger Ratings Below Treeline: Considerable Storm Slabs Storm Slabs Persistent Slabs Persistent Slabs

Parks Canada Forecaster: percy woods

Date Issued:

Valid Until:

The natural avalanche cycle is abating. Human triggering of avalanches is likely.

Weather Forecast

Cold air has invaded overnight bringing moderate Easterly winds light precipitation and temperatures in the -19C range. The cold air and Easterly flow are forecast to be here at least until mid week.

Snowpack Summary

At 1900m upwards of 70cm of storm snow in the past 72hrs with mod to strong S'ly wind. Wind is now shifted to NE mod. New snow sits atop hard wind slabs in the alpine and Jan 31 surface hoar at and below treeline. January 17 surface hoar is buried 90cm+ and is most reactive between 1400-1900m, and where it overlies a crust on steep solar aspects.

Avalanche Summary

Yesterday Grizzly Gulley ran across the normal skin track just prior to a group of skiers arriving. Avalanche covered approximately 150m of skin track 1m deep. Several new natural avalanches recorded in the highway corridor yesterday. Some of these slides were new on Feb 2nd while others likely ran on Feb 1st at the height of the storm.

Confidence

Due to the number of field observations

Storm Slabs Storm Slabs

Likelihood

Likely

Expected Size

1 - 3

70cm of storm snow has created a reactive storm slab problem. Strong S winds have now shifted to moderate NE wind reverse loading exposed areas. Expect the storm slab to be more reactive in wind effected areas.

Watch for whumpfing, hollow sounds, and shooting cracks.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

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Persistent Slabs Persistent Slabs

Likelihood

Likely - Possible

Expected Size

1 - 3

The Jan 17th Surface Hoar layer is now down 90cm+/-. This layer exists on all aspects, and is most problematic between 1400-1900m and on steep solar aspects where it overlies a crust.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

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