Avalanche Forecast

Issued: Mar 31st, 2014 10:21PM

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

Tim Haggarty, Parks Canada

Waterton Lakes.

Watch for periods of solar heating to cause an increase in the hazard beyond the posted Danger Ratings.

Summary

Weather Forecast

No precip is expected for the period. Winds will slowly increase on Wed and again for Thurs to SW 30 G 70. Good overnight recoveries but temperatures will also increase with freezing levels reaching near 2000m Wed and Thurs. The sun will be the major factor for this period: with only partly cloudy skies forecast it will exert significant heating.

Snowpack Summary

Surface Crusts below 1500m and to ridgelines on solar aspects. 25 to 40 cm now over the 0325 interface that behaves as a soft slab. The 0314 crust is found to ridgelines on S aspects and the 0310 rain crust goes to about treeline on shaded aspects. The Feb facet layer is generally very deep or under a crust in all but thin, high elevation areas.

Avalanche Summary

We are into a predictable cycle of daily heating that creates loose wet avalanches on solar aspects. The size of these events will vary with the significance of the heating and the depth of the crust that gets broken down by that heating. The slabs to size 2 that have been seen indicate a reactive slab exists in open areas on shaded aspects.

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Storm Slabs

Recent warm temps and wind have contributed to the formation of a soft slab that has failed naturally over the last few days. This slab will become more sensitive to triggering with heating and could be triggered in steep or unsupported terrain.

Dig down to find and test weak layers before committing to a line.Be cautious as you transition into wind affected terrain.

Aspects: North, North East, East, South East, South.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

Daily heating and the sun will create moist snow at low elevations and on solar aspects. Intense periods of radiation will trigger avalanches or cause cornice failures that could trigger avalanches as well.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Avoid avalanche terrain during periods of rain.

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Valid until: Apr 3rd, 2014 4:00PM