Avalanche Forecast

Issued: Mar 29th, 2016 9:06AM

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

jlammers, Avalanche Canada

South Rockies.

An elevated Avalanche Danger exists on the east side of the divide where recent heavy storm loading occurred. Solar warming will drive the Avalanche Danger throughout the forecast period.

Summary

Confidence

Moderate - Due to the number of field observations on Tuesday

Weather Forecast

A well-embedded ridge of high pressure will maintain a mix of sun and cloud for the forecast period. Ridgetop winds will be generally light, while freezing levels will sit at about 2200m on Wednesday and Thursday, and then climb to about 2700m on Friday.

Avalanche Summary

At the time of publishing this bulletin on Tuesday there were some reports of smaller loose wet avalanches, although observations were very limited. The sun will become the main driver for avalanche activity throughout the forecast period. Although warming will promote settlement and strengthening within the recent storm snow, loose wet avalanches and cornice falls will become the most common avalanche type. Another concern, however, remains very isolated yet destructive releases on deeper weak layers which formed earlier in the season. Avalanches on these layers could run surprisingly long distances, and may be triggered by a cornice fall, a surface avalanche in motion or extended periods of warming.

Snowpack Summary

New snow and wind on Monday formed storm slabs which were especially deep on the east side of the divide. Reports suggest warming has promoted settlement and strengthening within the new snow. The current warming trend has also promoted a daily melt-freeze cycle on solar aspects at higher elevations, and on all aspects below treeline. About 15-60cm below the surface you'll likely find a widespread hard crust, although reports suggest a reasonable bond has developed between the crust and the overlying slab. Deeply buried weak layers near the ground are becoming hard to find, but may remain sensitive to triggering from significant warming or with large loads such as cornice fall. Large cornices overhang alpine slopes and will become increasingly weak with forecast solar radiation.

Problems

Cornices

Large fragile cornices threaten many slopes and will become increasingly touchy with solar radiation. A cornice fall could be the large trigger required to awaken destructive buried weak layers.

Stay well to the windward side of corniced ridges.>Do not travel on slopes that are exposed to cornices overhead.>Cornices become weak with daytime heating, so travel early on exposed slopes.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Loose Wet

Watch for pushy loose wet avalanches at all elevations throughout the forecast period. The combination of buried crusts and solar radiation may make conditions extra touchy on sun-exposed slopes.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Storm Slabs

On Monday, heavy storm loading was noted in areas east of divide (and south of the Crowsnest Hwy). Although warming has promoted strengthening within the new snow, I'd remain cautious in high elevation, wind-exposed terrain.

Avoid travelling in areas that have been reverse loaded by winds.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Mar 30th, 2016 2:00PM