Avalanche Forecast

Issued: Mar 20th, 2018 5:25PM

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

swerner, Avalanche Canada

South Rockies.

Pay close attention to how the new snow is bonding to the old snow surfaces, especially where it sits on surface hoar and buried crusts.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

Wednesday: Mix of sun and cloud. Alpine temperatures near -2 and freezing levels near 1900m. Ridgetop winds light from the South.Thursday: Snow amounts 5-10 cm, accompanied by strong ridgetop winds from the southeast. Freezing levels near 1700 m.Friday: Cloudy with isolated flurries. Alpine high of -11 and freezing levels near 1500 m. Light to strong gusty southwest winds.

Avalanche Summary

On Tuesday, one size 1 wind slab was reported, entraining moist snow during warming. A few natural loose dry avalanches up to size 1.5 occurred on Monday.

Snowpack Summary

Up to 25 cm of low density snow fell Sunday overnight into Monday, combined with last weeks snow, this brings the total amount 30-40 cm. This new snow sits on a wide variety of old surfaces: a melt-freeze crust on sunny aspects, isolated old wind slab in the alpine near ridge crests and predominantly dry snow or surface hoar (up to 20mm in size) on north aspects above 1500-1800m.A weak layer of surface hoar buried mid-February exists in parts of the region around 50 to 80 cm deep. The lower snowpack is weak with a combination of crusts and facets near the bottom of the snowpack that are widespread.

Problems

Storm Slabs

Watch for signs of poor bonding of the new snow with underlying surfaces, especially the March 18th crust, which can be found almost everywhere except high north facing aspects. Dry loose sluffs may run fast and far on slippery crusts.

Use caution in lee areas in the alpine and tree line, especially south / west facing slopes.Observe for signs of instability, such as cracking, whumpfing, and avalanche activity.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

If the sun comes out on Wednesday, expect the new snow to become reactive and/or slide naturally, especially from steep solar aspects.

Watch for signs that the snow is moistening such as pin-wheeling and point-releases below cliffs.Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.Avoid exposure to sunny slopes

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 21st, 2018 2:00PM