Avalanche Forecast

Issued: Mar 1st, 2017 4:17PM

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.

cam_c, Avalanche Canada

South Coast Inland.

Snowfall amounts may vary throughout the region. In the Cascasdes, heavy snow is expected to result in HIGH danger, while further north, much drier conditions are expected to result in slightly lower danger.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

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.SATURDAY: A mix of sun and cloud with scattered flurries bring as much as 5-10 cm to some areas. Freezing levels around 1000 m and light southwesterly winds.

Avalanche Summary

No new avalanches have been reported since Monday, when 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

Another 15-25 cm of fresh snow adds to the 10-35 cm of snow from the weekend that is 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 at ridge top. The widespread mid-February crust can be found down 40-80cm 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 around a metre 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.

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

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 higher amounts of storm snow (e.g. Coquihalla), are likely to develop more widespread storm slabs on steeper terrain features (even where wind protected).

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 2nd, 2017 2:00PM