Avalanche Forecast

Issued: Mar 7th, 2018 4:03PM

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

pgoddard, Avalanche Canada

Purcells.

Southern areas may get extra snow on Thursday. Choose conservative terrain if it's snowing heavily.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

THURSDAY: Cloudy. Around 10-15 cm snow. Treeline temperature near -4. Moderate southerly winds.FRIDAY: Mix of sun and cloud. Treeline temperature near -3. Light winds.SATURDAY: Mainly sunny. Treeline temperature near -1. Light winds.

Avalanche Summary

Wednesday was pretty quiet. A natural cycle of wind slabs and storm slabs to size 2.5 was reported on Sunday/Monday/Tuesday. Recent explosives testing has mostly produced storm slabs or wind slabs, and one persistent slab on a north aspect.

Snowpack Summary

Solar aspects have developed new sun crusts, which new snow may sluff easily on. Recent storm snow and wind slabs continue to settle. A couple of layers buried in mid-late February (down around 50-100 cm) are variably reactive, but both have the potential to create surprisingly large avalanches if triggered. Initially, these interfaces were most reactive on solar aspects, where they present as buried sun crusts. However, persistent slabs have been triggered on shady aspects too, where surface hoar and/or facets exist.Deeper persistent weak layers from January and December are generally considered dormant, but could wake up with forecast warming, a surface avalanche stepping down, cornice fall, or a human trigger in a shallow or variable-depth snowpack area. These layers consist of sun crust, surface hoar and/or facets. Facets linger at the base of the snowpack.

Problems

Wind Slabs

New snow and wind may build new wind slabs. Stay well away from large looming cornices.

Use ridges or ribs to avoid pockets of wind loaded snow.Extra caution needed around cornices with current conditions.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Persistent slabs are most likely to be triggered with a large load like cornice fall; or by a person in a thin or variable-depth snowpack spot.

Pay attention to overhead hazards like cornices which could potentially trigger the persistent slab.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3

Valid until: Mar 8th, 2018 2:00PM