Avalanche Forecast

Issued: Apr 6th, 2015 8:40AM

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

rbuhler, Avalanche Canada

South Rockies.

Snowpack and avalanche observations are becoming scarce. If you've been in the backcountry, please tell us what you've seen here on the Mountain Information Network.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

A ridge of high pressure moves over the interior on Tuesday and should be the dominant feature for the rest of the week. On Tuesday, a mix of sun and cloud is expected with light alpine winds and freezing levels reaching around 2000m in the afternoon. Isolated convective flurries are possible. Mostly sunny conditions with light alpine winds are expected for Wednesday and Thursday. Freezing levels are forecast to reach around 2000m on Wednesday and 2300m on Thursday.

Avalanche Summary

Observations are becoming very limited as we enter spring. If you're out in the mountains, please consider posting your observations to our webpage. In the Lizard range on Saturday and Sunday, loose sluffing was reported from steep features. Also in the Lizard on Saturday, ski cutting produced small soft slab avalanches in wind loaded features. With freezing levels rising and lots of sun expected on Tuesday, lots of natural sluffing is expected from steep sun-exposed slopes. Cornices will become weaker than they have been for the last week and may fail naturally. Wind slabs in the alpine are expected to be sensitive to human-triggering. Reverse loading may have occurred and wind slabs should be expected in leeward features on all aspects.

Snowpack Summary

10-20cm of recent snow overlies a widespread and supportive melt-freeze crust. Recent strong winds may have redistributed the surface snow resulting in wind slab formation in the alpine and exposed areas at treeline. Large cornices exist in the alpine and may become weak with daytime warming. The mid-March rain crust is down 35 to 70cm and has shown a good bond with snow above. Old persistent weak layers are still intact in the mid and lower snowpack and there may be potential for these layers to wake up with a big cornice fall, sustained warming and/or a significant rain event.

Problems

Loose Wet

Sluffing can be expected from steep sun-exposed slopes during the heat of the afternoon.

Be cautious of sluffing in steep terrain.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

Lingering wind slabs in the alpine may be sensitive to human triggers. Watch for triggering in the lee of ridge crests and in gullies.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.>Travel on ridgetops to avoid wind slabs on slopes below, but be careful with cornices!>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Large cornices at ridgetop may fail under the weight of a human-trigger. As spring conditions evolve, remember that destructive cornice falls become more likely during periods of warming and solar radiation.

Give cornices a wide berth when traveling on or below ridges. Remember that cornices become weak with daytime heating.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Apr 7th, 2015 2:00PM