Avalanche Forecast

Issued: Mar 30th, 2016 11:11AM

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

jlammers, Avalanche Canada

South Rockies.

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

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Thursday

Weather Forecast

A well-embedded ridge of high pressure will maintain a mix of sun cloud for the forecast period. Freezing levels should hover around 2400m for Thursday, and then jump to about 2900m on Friday and Saturday. Ridgetop winds will remain generally light throughout the forecast period.

Avalanche Summary

At the time of publishing this bulletin on Wednesday there were reports of several loose wet avalanches to size 2 on variety of aspects. A few older size 2 wind slabs were also noted in exposed alpine terrain. The sun and warming have become the main driver for avalanche activity throughout the forecast period. Although warming has promoted settlement and strengthening within the recent storm snow, loose wet avalanches and cornice falls have become the most common avalanche type. There is also concern for 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 in areas east side of the divide. Reports suggest warming has promoted settlement and strengthening within the new snow, but the current warming trend has also promoted a daily melt-freeze cycle on all but the highest north facing terrain. About 25-60cm 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 in the mid and lower snowpack are becoming hard to find, but may become 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. Loose wet avalanches may be surprisingly large in areas east of the divide where recent storm totals were the greatest.

Travel early before the heat of the day, and avoid big slopes in the afternoon.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Mar 31st, 2016 2:00PM