Avalanche Forecast

Issued: Apr 9th, 2015 9:09AM

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

ghelgeson, Avalanche Canada

Purcells.

The weather is changing Friday, so you need to stay alert to conditions that change with aspect, elevation and time of day. Watch for clues like a moist or wet snow surface that indicate its time to find colder snow or head for home.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

FRIDAY: Freezing level starting at 1500m rising to 2100m. Light SW winds at treeline, moderate SW winds at ridge-top. Cloud cover rapidly building to overcast by lunch. No significant precipitation during the day, 1 to 3mm of precipitation possible Friday night, less than 5cm total snowfall expected.SATURDAY: Freezing level hovering around 1600m. Moderate SW winds at treeline, Strong SW/W winds at ridge-top. 2 to 3mm precipitation, 2 to 6cm of snow possible. Overcast.SUNDAY: Freezing level starting at 1000m rising to 1500m. Light SW/W winds at treeline, Moderate W winds at ridge-top. Scattered cloud. Isolated flurries, no significant precipitation expected.

Avalanche Summary

Several cornice falls have been reported in the last few days, some of which have triggered slabs on slopes below, some which have not.

Snowpack Summary

Surface faceting is beginning to work on the 10 to 25cm cm generated by convective snow fall last weekend. The atmosphere has been unusually calm and wind effect is very isolated. This snow remains dry on north facing features above 2300m while corn is starting to form to ridge-top on south facing aspects. Moist snow is reported everywhere else. Just below this snow you will likely find the the late-March crust which is supportive to around 2000m. Moist snow underneath the late-March crust is ubiquitous in most of the region.Persistent weak layers in the mid-pack remain a lingering concern, although they seem to have gone dormant for the time being. In the north of the region, the mid-March crust/facet layer is down 40-60cm and the mid-February crust/facet/surface hoar layer is down about 80 cm. While weak layers formed earlier in the winter remain intact, they too are dormant at this time.

Problems

Loose Wet

There is potential for ongoing loose wet activity as clouds move into the region trapping warm air in the classic greenhouse effect. While slow moving, these avalanches cab be very powerful and you do not want to be caught by one.

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: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

Increased winds Friday should add to the already large cornices that loom over many features, possibly increasing the likelihood of failure. While unlikely, a large cornice failure may be able to trigger a slab release on slopes below.

Extra caution needed on slopes that are exposed to cornices overhead.>When traveling in the alpine, be SURE you're on the ridge, and not on a cornice.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 5

Valid until: Apr 10th, 2015 2:00PM