Avalanche Forecast

Issued: Mar 30th, 2018 5:15PM

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

mgrist, Avalanche Canada

South Coast Inland.

In the north of the region, wind slabs may sit on a weak layer of facets or surface hoar on shady aspects in the alpine and tree line. See Friday's Forecaster Blog for more details: goo.gl/8Z83CvAvoid sunny slopes if the sun comes out in full force.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

There may be some significant periods of sunny weather on Saturday before a weak system comes through on Sunday. Temperatures are staying cool for this time of year. SATURDAY: Cloudy with sunny periods / Light to moderate west wind / Alpine temperature -5 / Freezing level 1400m SUNDAY: A mix of sun and cloud with some flurries (3-5cm in the North and 5-10 cm in the South) / Light to moderate west wind / Alpine temperature -7 / Freezing level decreasing to 1000m MONDAY: Mix of sun and cloud and isolated lingering flurries / Light to moderate southwest wind / Alpine temperature -7 / Freezing level 1000m

Avalanche Summary

On Thursday, skiers triggered a size 2 wind slab that caught and carried a skier near Steep Creek in the Duffey zone. Slab thickness was 15-20cm. See this MIN post for more details. On Tuesday there was report of a skier triggered wind slab from the north of the region in the alpine near ridge top running on a layer of facets buried March 21. See this MIN post for more details. Reports on Monday from the north of the region show several skier triggered and natural storm slab avalanches size 1.5 to 2.5 running on either facets or surface hoar on north through east aspects in the alpine and tree line.

Snowpack Summary

The past two days have seen only 1-6cm of new snow in most areas (with some higher amounts in isolated areas of the Coquihalla). Winds have redistributed older snow to give a wide variety of surfaces: hard wind slabs, soft wind slabs and melt-freeze crusts. Snow from a week ago sits on a crust that is present at all elevations on sunny aspects as well as low elevation northerly aspects. On northerly and east aspects at treeline and alpine elevations the storm snow sits on a mix of large surface hoar and or facets.Deeper in the snowpack in the north of the region, north and east aspects are harboring cold snow and a surface hoar layer buried early March that is about 40-60 cm below the surface. This layer exists at alpine and treeline elevations, but it is not everywhere. This layer has produced large human triggered avalanches in the north of the region in the past week. In the south of the region, around the Coquihalla and in Manning Park, the last storm snow overlies a recent crust that caps a well settled snowpack.

Problems

Wind Slabs

Moderate to strong southwest winds (east in the Coquihalla) have built wind slabs. These slabs seem to be most reactive in the north of the region, specifically on shady aspects where they may be sitting on a layer of weak facets or surface hoar.

Watch for whumpfing, hollow sounds, and shooting cracks.Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Loose Wet

The sun really packs a punch this time of year - if you see it come out in full force, be prepared to adjust your terrain use accordingly.

Avoid exposure to sunny slopes.Watch for signs the snow warming up, like sluffing off cliffs and pinwheeling.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Mar 31st, 2018 2:00PM