Avalanche Forecast

Issued: Jan 29th, 2013 9:23AM

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

jfloyer, Avalanche Canada

Purcells.

Summary

Confidence

Fair - Wind speed or direction are uncertain

Weather Forecast

Synopsis: Continued northwesterly flow will bring light pulses of precipitation to the region interspersed with some dry patches.Tuesday night: 2-4 cm new snow.Wednesday: Flurries through the day. Treeline temperatures should peak around -2C. Northwesterly winds gusting to 40 km/h.Thursday: Flurries. Freezing level rising to around 1200 m. Light to moderate northwesterly winds.Friday: Dry. Temperatures around -6C at treeline. Light northwesterly winds.

Avalanche Summary

Small loose dry avalanches were reported on steep terrain on Tuesday. Explosive avalanche control on Monday produced loose avalanches that ran on the upper surface hoar layer and deeper slab avalanches (up to 100 cm deep) that ran on basal facets on very steep north-facing alpine slopes.

Snowpack Summary

Recent storm snow amounts over the past few days are 30 to 40 cm with as much as 60cm reported. Over the weekend, this low density 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 reported to be patchy. It is most likely to be preserved on shady slopes below treeline.

Problems

Storm Slabs

Recent storm snow overlies surface hoar at treeline and below. Wind slabs are likely and will build on south and east facing slopes in response to reverse loading by NW winds.

Avoid freshly wind loaded features.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>Dig down to find and test weak layers before committing to a steep line on open slopes at treeline and below.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Jan 30th, 2013 2:00PM