Avalanche Forecast

Issued: Apr 6th, 2015 4:00PM

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

tim haggarty, Parks Canada

Waterton Lakes.

The new snow that fell with another blast of winter over Easter will quickly be affected by periods of heating expected on Tuesday and more so on Thursday. Expect an increase in avalanche activity as the sun comes out on these days.

Summary

Weather Forecast

Winds should return to westerly Tuesday limited clear patches, freezing levels should reach 2000m. Wednesday winds should diminish allowing for convective flurries to produce a limited amount of snow with a freezing level near1800m. Clearing and light winds Thursday will allow for significant heating with freezing levels expected to reach 2200m.

Snowpack Summary

Early last week, a solid crust could be found everywhere but above 2400m on North Aspects. At the end of last week West winds built windslabs with 5 to 10 cm of new snow TL and above over this crust. Since Saturday NE winds have brought an additional 20 cm of snow with a bit more yet to come Monday night. Cornices have seen some fragile new growth.

Avalanche Summary

Visibility has been poor over the last few days however neighboring areas are reporting that the new snow is failing as loose dry avalanches to size one. This activity can be expected to continue heating causes a transition to loose wet activity instead.

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Wind Slabs

Slabs up to 50cm deep have formed over the crusts with the recent snow. These soft slabs have formed with winds from unusual directions and are likely to be found along ridge crests and in cross loaded features within a slope.

Use caution in lee areas in the alpine and treeline. Recent storm snow has formed touchy slabs.The new snow will require several days to settle and stabilize.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Dry

The new snow is likely to fail easily in very steep terrain naturally however travelers will experience sluffing in steep terrain as they travel through. Manage your group carefully to prevent being caught by these sluffs especially above cliffs.

Be very cautious with gully features.On steep slopes, pull over periodically or cut into a new line to manage sluffing.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2

Loose Wet

As the sun comes out on Tuesday expect moist snow to develop and fail naturally first on solar slopes and then on lower elevation shaded slopes. This should be more serious on Thursday with clear skies and a higher freezing level expected.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Cornices become weak with daytime heating.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Apr 9th, 2015 4:00PM