Avalanche Forecast

Issued: Feb 28th, 2017 4:58PM

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

istorm, Avalanche Canada

South Coast Inland.

Snowfall amounts may vary throughout the region. Localized areas receiving more than 30 cm of new snow may have a higher avalanche hazard and danger may rise to HIGH.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

WEDNESDAY: 15 cm (Duffy Lake Road) to 40 cm (Coquihalla) by Wednesday evening. Moderate to strong SW to W winds. Treeline temperatures remaining between -5 and -10 C.THURSDAY: 5 cm (Duffy) to 20 cm (Coquihalla) by Thursday evening. Moderate SW winds. Warming with treeline temperatures a getting close to zero.FRIDAY: Another 20 cm possible (Coquihalla) but dry further north (Duffy). Moderate SW winds. Temperatures starting to cool a few degrees.

Avalanche Summary

Only one slab avalanche reported: a size 2 on a South aspect in the alpine. Some loose dry sluffs reported from steep gullied terrain. Avalanche activity will increase with forecast snow, wind, and warming temperatures.

Snowpack Summary

10-35 cm of snow from the weekend is reportedly bonding poorly to facets and buried surface hoar, as well as crust on previously sun-exposed slopes. Reports from the Duffy Lake area on Sunday include easy whumphing and cracking observed at ridge top. The widespread mid-February crust can be found down 20-60cm and seems to be well-bonded, although is reportedly weakening. In the northern part of the region, a facet/surface hoar weakness buried early February, is now down 60-100 cm and remains reactive in snowpack tests. It is also suspected as the failure plane in at least one of two recent large persistent slab avalanches in the Hurley Pass area. In the Cascades (e.g. Coquihalla), the mid and lower snowpack are well settled and strong. Forecast new snow is likely to arrive with strong SW winds and warming temperatures.

Problems

Persistent Slabs

A possible pattern of persistent slab avalanche activity has emerged in the northern part of the region. Recreating in the mountains north of Pemberton suggests using more conservative terrain with additional caution on northerly aspects.

Be aware of the potential for large avalanches due to the presence of deep weak layers.Be cautious in shallow snowpack areas where triggering is more likely.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 4

Storm Slabs

Watch for wind slabs in the lee of exposed, higher elevation terrain features. Areas with 25 cm of storm snow, e.g. Coquihalla, are likely to develop more widespread storm slabs on steeper terrain features (even where wind protected).

Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.Be aware of increased wind slab danger in the south of the region.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 1st, 2017 2:00PM