Avalanche Forecast

Issued: Apr 7th, 2015 9:06AM

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.

jlammers, Avalanche Canada

South Rockies.

Daytime warming and solar radiation will be driving the avalanche danger over the next few days. Watch for conditions that change with aspect, elevation and time of day.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Generally sunny skies are expected for the forecast period as a dry ridge sets up over the region. Increased cloud and light snowfall are possible on Friday evening. Ridgetop winds should remain light for Wednesday and Thursday, and then become strong from the southwest by Friday night. Daytime freezing levels should hover around 2000m.

Avalanche Summary

Observations are becoming more limited as we enter into spring. If you're out in the mountains, please consider posting your observations to our webpage using the Mountain Information Network. With freezing levels rising and lots of sun expected on Wednesday, lots of natural sluffing is expected from steep sun-exposed slopes, especially in areas where cold, dry snow is exposed to solar radiation for the first time. Cornices will become weaker than they have been for the last week and may fail naturally. Wind slabs in the alpine may be sensitive to human-triggering. Reverse loading may have occurred and wind slabs should be expected on a variety of aspects.

Snowpack Summary

10-30cm 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

Over the next few days, watch for pushy loose wet avalanche activity on sun exposed slopes. Loose wet avalanches are most likely in areas where dry snow is exposed to solar radiation for the first time.

Minimize exposure to sun exposed slopes when the solar radiation is strong.>Be cautious of sluffing in steep terrain.>Be alert to conditions that change with aspect, elevation and time of day.>

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

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Apr 8th, 2015 2:00PM