Avalanche Forecast

Issued: Jan 27th, 2013 10:08AM

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

Avalanche Canada jfloyer, Avalanche Canada

Summary

Confidence

Fair - Freezing levels are uncertain on Tuesday

Weather Forecast

Synopsis: Northwesterly flow will bring a series of low-intensity pulses of precipitation interspersed with short-lived periods of clear weather to the region through the forecast period. Temperatures will start out fairly cool but rise through Tuesday and into Wednesday to become mild.Monday: Flurries. Treeline temperatures around -7C. Light westerly winds.Monday night: Light snowfall, up to 5cm.Tuesday: Mainly dry during the day. Temperatures rising to a high of -3C at treeline elevations. Northwesterly winds, gusting to 30km/h at ridgetop.Wednesday: Light snowfall, up to 5cm. Treeline temperatures around -1C. Northwesterly winds gusting to 40km/h at ridgetop.

Avalanche Summary

Only two small avalanches (N and NE aspects) associated with explosive control were reported on Saturday, and none were reported Sunday. On Thursday and Friday, a small avalanche cycle produced avalanches up to size 1.5 running on the recently buried upper surface hoar layer.

Snowpack Summary

Recent storm snow amounts over the past few days are 30 to 40 cm with as much as 60cm reported. On Friday this snow remained mostly loose and powdery except for pockets of windslab behind ridges and ribs. Over the weekend, this storm snow started to settle into more of a cohesive slab, although little activity was reported through the weekend. Below the new snow is a suncrust on steep southerly facing slopes and a surface hoar layer at treeline and lower elevations (but it has a patchy distribution). Early January surface hoar is now around 60 - 80 cm deep and is also patchy and most likely to be preserved in shady slopes below treeline. Note, however, it may extend into the alpine in places.

Problems

Storm Slabs

An icon showing Storm Slabs
Watch for recent storm snow settling into a slab over a sun crust on steep southerly facing slopes or over surface hoar on shady wind protected glades. Also, pillows of windslabs likely in pockets behind ridges and cross-loaded gulleys.
Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Watch steep southerly facing slopes (buried suncrust) and shady sheltered glades (buried surface hoar)
Whumpfing is direct evidence of a buried instability.>Dig down to find and test weak layers before committing to a steep line in open glades.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Jan 28th, 2013 2:00PM