Avalanche Forecast

Issued: Mar 21st, 2015 10:19AM

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

ghelgeson, Avalanche Canada

South Rockies.

It's still winter at and above treeline and the current avalanche problems dictate careful terrain selection.Check out the new video by the South Rockies Field Team in our blog section: www.avalanche.ca/blogs

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain on Monday

Weather Forecast

Sunday: Clear skies in the morning, cloud cover increasing throughout the day. Strong winds out of the SW at treeline, NW at ridgetop, backing off as the day goes on. Freezing level starting at 800m, rising to 2300m.Monday: Overcast skies. Light variable winds at all elevations. 5 to 15cm of snow possible. Freezing level starting at 600m, rising to 1500m in the afternoon. Tuesday: Scattered cloud. No significant precipitation expected. Light variable winds at all elevations. Freezing level starting at 600m, rising to 1500m in the afternoon.

Avalanche Summary

No new avalanche activity to report from Friday. A widespread natural avalanche cycle to size 2.5 occurred on Monday during the storm. These were primarily storm slab avalanches but several stepped down to deeper persistent weak layers or to the ground in steep unskiable terrain. At lower elevations, loose wet avalanches up to size 2.5 were reported as well as isolated wet slabs. Natural avalanches quickly tapered off during the storm but touchy conditions existed through the week. Winds increased on Thursday and wind slab formation has been ongoing since.

Snowpack Summary

A moist or wet snow surface is expected on all aspects to around treeline and on sun-exposed slopes into the alpine. Dry snow can likely still be found on sheltered high elevation slopes. Ongoing strong SW winds are redistributing the surface snow in exposed high elevation terrain.Â A weak rain crust from last weekend is down 30-50cm and has a good bond with snow above. There are a couple older persistent weak layers in the midpack that are still intact and have the potential to wake-up with substantial warming or heavy loading. Cornices may become fragile with afternoon warming.

Problems

Wind Slabs

Ongoing strong winds are likely continuing to form fresh wind slabs in wind exposed terrain at and above treeline. Warming temperatures Sunday afternoon could increase the reactivity of said slabs.

Avoid freshly wind loaded features.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Loose Wet

Loose wet avalanches can really pack a punch at this time, especially below treeline as the temperature rises above freezing.

Watch for terrain traps where small amounts of snow will acumulate into deep deposits.>Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

A crust/facet layer down 90 to 150cm still has the potential to produce very large avalanches with a heavy trigger like cornice failure or a surface avalanche in motion.

Be aware of thin areas that may propogate to deeper instabilites.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 6

Valid until: Mar 22nd, 2015 2:00PM