Avalanche Forecast

Issued: Apr 30th, 2013 8:15AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs, Storm Slabs and Loose Wet.

sylvia forest, Parks Canada

Glacier.

This is the last regular bulletin of the season for Glacier Park. Bulletins will be updated periodically as conditions change. Springtime conditions can change rapidly, from hot and sunny to snowy and cold. Be aware of changing danger levels.

Summary

Weather Forecast

A mix of sun and cloud will dominate for the last week of April and beginning of May. Typical springtime patterns of sunny breaks, combined with convective snow flurries means you should plan for anything. A ridge of high pressure is expected for the end of the week. Freezing levels will range from 1300 m to as high as 2600 m by the weekend.

Snowpack Summary

Springtime conditions: snow flurries continue to deposit new snow in the alpine and treeline, with freezing levels near 1300m. Moderate to strong winds continue to create hard and soft slabs in wind exposed areas. Much of the snowpack is isothermal - freezing overnight, and becoming soft whenever the sun pokes out. Cornices are large.

Avalanche Summary

Deep large avalanches are are still possible. On April 29, a near neighbor reported a size 3.5 on a SE aspect. Few details given, but this likely failed on a deep PWL. In Glacier Park, moist storm snow avalanches continue to be noted at lower elevations. Glide cracks appear stagnant for the moment, but should be treated with caution.

Confidence

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

Problems

Wind Slabs

Sustained southerly winds and new snow available for transport are creating wind slabs and loaded pockets of snow at higher elevations.

Be careful with wind loaded pockets near ridge crests and in terrain depressionsBe cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Storm Slabs

Storm snow continues to accumulate with unsettled weather and convection, creating slabs on lee features. This overlies moist, isothermal snow and crusts. Riders may trigger sluffs in steep terrain that can gain significant mass in heavy, moist snow.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

Expect loose avalanches at all elevations, especially when the sun pokes out. Watch for "pin wheels" from your skis or board which can gain mass rapidly.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Make your travel plans to take advantage of overnight freezing.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Valid until: May 1st, 2013 8:15AM