Avalanche Forecast

Issued: Apr 13th, 2014 8:36AM

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

jlammers, Avalanche Canada

South Coast.

Avalanche danger can rise very quickly with warming and solar radiation. Be aware of changing conditions and overhead hazards.For more insight into spring danger ratings, check out our latest Blog Post.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Monday

Weather Forecast

Monday: Clear skies in the morning with increased cloud and light precipitation possible late in the day / Moderate southwest winds / Freezing level at about 2200mTuesday: Light to locally moderate snowfall / Moderate southwest winds becoming light and northerly / Freezing level at 1500mWednesday: Mix of sun and cloud / Light northerly winds / Freezing level at 1700m

Avalanche Summary

Observations from the region have been very limited; however, several natural cornice releases to size 3 were reported over the weekend in the Sea to Sky region. In a few cases, the cornice fall triggered slabs to size 2. I would expect continued loose wet activity and cornice fall with continued daytime warming.In recent days a very large (unknown size) persistent slab avalanche was observed on the northwest face of Mt Matier. The trigger is unknown; however, it demonstrates the potential for destructive persistent slab avalanches. See Wayne Flann's Avalanche Blog for a photo.

Snowpack Summary

A melt-freeze crust exists on all aspects up to 2200 m, and dryer snow can be found on high northerly aspects. The recent warmer temperatures have helped to strengthen and settle the upper snowpack, especially on solar aspects. Isolated wind slabs may still exist, although I suspect they're gaining strength. Surface hoar growth has been noted on shady slopes at higher elevations, and large sagging cornices are becoming weak with daytime warming.The February crust/facet layer is now deeply buried 150 250 cm below the surface. This layer is mostly inactive at this time, but could re-awaken with extended warming, solar influence and large triggers like cornice fall.

Problems

Loose Wet

Watch for loose wet avalanches with daytime warming on steep, sun-exposed slopes. Loose wet avalanches can be pushy and entrain mass quickly.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Cornices

With continued warming and intense solar radiation the likelihood of triggering a large cornice fall will increase dramatically. A cornice fall may also be what it takes to "wake-up" deep and destructive weaknesses which formed earlier in the season.

Extra caution needed around cornices with current conditions.>Cornices become weak with daytime heating. >

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

A recent large natural avalanche in the Duffey Lake area demonstrates that deep persistent slabs should still be on your radar. Deep and destructive persistent slab avalanches become more likely with intense daytime warming.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Large triggers like cornice fall could initiate a deep persistent slab.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 6

Valid until: Apr 14th, 2014 2:00PM