Avalanche Forecast

Issued: Mar 26th, 2015 4:00PM

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

jon stuart-smith, Parks Canada

Waterton Lakes.

Springtime snow, wind, rain, sun, and warm temps are continuing to create avalanche concerns. Monitor changes in weather and how the snowpack is becoming moist or wet before committing to a slope. Sunshine between cloudy periods could increase danger

Summary

Weather Forecast

A warm front passed through Wed night bringing warm temps and rain. Freezing levels will continue to climb to above 3000m on Fri. Cloud cover may help keep things shaded but the warm air will make all slopes moist up to ridgetop. Sat will cool slightly with 5mm of precip, likely rain with freezing levels dipping to 2000m. Sun cloudy but no precip.

Snowpack Summary

Rain and warm temperatures are penetrating the new snow we received over the last week. It was raining to at least 2500m on Thursday. The top meter is a mix of old wind slabs, rain crusts and sun crusts, all of which is becoming moist. The Feb 15 crust is now down about 110cm at 2100m. The snowpack BTL is dwindling: not much remains below 1800m.

Avalanche Summary

Avalanche activity has tapered off compared to last weekend with cooler temperatures on Tue/Wed. New snow translated into loose dry activity overnight Tue creating some large debris piles with up to sz 2 avalanches. Rain and warmth triggered snowballing and small loose wet activity only size 1 overnight Wed and during the day Thur.

Confidence

Timing or intensity of solar radiation is uncertain on Friday

Problems

Loose Wet

Warm temps and rain are weakening the snow we received over the last week. Although these may start as snowballs from trees and cliffs they can accumulate a lot of mass. If the sun comes out expect activity to spike on solar aspects.

Cornices become weak with daytime heating. Travel early before the heat of the day, and avoid big slopes in the afternoon.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Wet Slabs

The new snow over the last week is now becoming rain soaked and moist. As the surface layers become weak, rain or sunshine could trigger wet slabs, especially on steeper slopes.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

These layers from early season are still a concern on N aspects in the alpine. The warm temperatures and sunshine could wake up these layers, especially in shallow snowpack areas. Smaller surface avalanches could also step down to these deeper layers

Be aware of thin areas that may propogate to deeper instabilites.Avoid shallow snowpack areas where triggering is more likely.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 29th, 2015 4:00PM