Avalanche Forecast

Issued: Apr 6th, 2015 8:26AM

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

Kootenay Boundary.

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 1800m in the afternoon. Isolated convective flurries are possible. Mostly sunny conditions with light alpine winds are expected for Wednesday and Thursday. Freezing levels are expected to reach around 2000m on Wednesday and 2200m on Thursday.

Avalanche Summary

Observations are becoming more limited as we enter spring. If you're out in the mountains, please consider posting your observations to our webpage. On Sunday, natural and human-triggered wet sluffing was reported. This was limited to size 1 and was sliding on the late-March crust layer. On Saturday, explosives triggered small wind slabs and thin storm slabs that ran on the crust. 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

Melt-freeze surface conditions exist on sun-exposed slopes. On shaded slopes, 10-20cm of recent snow overlies a thick supportive melt-freeze crust. At higher elevations these accumulations have been blown around by variable winds and thin wind slabs may exist on a variety of aspects. The mid-March crust/facet complex is buried around 50cm below the surface. This layer is generally considered dormant while the cooler temperatures prevail. The mid and lower snowpack are strong and well settled.

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, Treeline.

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