Avalanche Forecast

Issued: Feb 1st, 2016 8:35AM

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

jlammers, Avalanche Canada

Purcells.

Recently formed wind slabs and touchy persistent weak layers are making for tricky conditions. Conservative terrain selection remains important.

Summary

Confidence

Moderate

Weather Forecast

On Tuesday and Wednesday morning expect a mix of sun and cloud and light northwest winds. By Wednesday evening a Pacific system will make its way inland bringing 3-5cm of new snow and strong southwest winds. Freezing levels will stay at valley bottom for the forecast period.

Avalanche Summary

On Saturday a size 3 sledder-triggered avalanche occurred in the Gorman Creek riding area near Golden. According to the report, 4 people were involved in the incident; however, all of the party member survived. Hats off to the sledders who responded to the incident in a calm and organized manner. Check-out the great Mountain Information Network report for details. On Monday, a size 2 wind slab was accidentally triggered by a skier in the backcountry around Golden. The individual was carried to the bottom of the slope, but was not buried or injured. Recently formed wind slabs and a reactive persistent slab are both expected to remain sensitive to human-triggering on Tuesday.

Snowpack Summary

40-60cm of snowfall has typically accumulated over the past week and weaknesses may still exist within or beneath this snow. Southwesterly winds have recently built wind slabs on the leeward side of ridge crests and behind terrain features on cross-loaded slopes. The persistent weak layer of surface hoar buried in early-January is now typically down 60-90 cm and has recently produced some large, destructive avalanches in the region. The layer is slowly getting harder to human trigger but is still quite reactive in snowpack tests and has the potential for wide propagations. In general, the lower snowpack below this layer is well settled and strong.

Problems

Wind Slabs

Recently formed wind slabs are lurking below ridge crests and behind cross-loaded terrain features and are expected to remain sensitive to human triggers. Cornices have also recently been reported to be large and fragile.

Avoid freshly wind loaded features. >Use ridges or ribs to avoid pockets of wind loaded snow. >Be cautious as you transition into wind affected terrain. >

Aspects: North, North East, East, South East, South.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

The likelihood of triggering buried surface hoar is slowly dropping but if triggered, this layer can still produce large, destructive avalanches. A cornice failure or a small avalanche in motion has the potential to step-down to a deeper weak layer.

Be cautious around open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Be aware of the potential for remote triggers and wide propagations due to a layer of buried surface hoar. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Feb 2nd, 2016 2:00PM