Avalanche Forecast

Issued: Mar 23rd, 2019 3:59PM

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

ghelgeson, Avalanche Canada

Sea To Sky.

Even if the skies are cloudy you should avoid slopes that have wet and mushy snow. Check out this LINK to see how easy it is to trigger a loose wet avalanche.

Summary

Confidence

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

Weather Forecast

We're moving into a weather pattern more in keeping with seasonal norms. Monday night's storm should offer a nice refresh at upper elevations and temperatures should remain cool, at least through Wednesday morning.SATURDAY NIGHT: Light south/southeast wind, freezing level around 1500 m, no significant precipitation expected. SUNDAY: Clear skies in the morning building to broken cloud cover by sundown, light southeast wind, freezing level holding around 1700 m, no significant precipitation expected.MONDAY: Broken cloud cover, light southeast wind, freezing level holding around 1800 m, no significant precipitation expected during the day. The freezing level drops to about 1000 m Monday night with 3 to 8 mm of precipitation expected. This will likely start as rain at lower elevations and should produce a trace to as much as 10 cm of snow above treeline, stay tuned for more details.TUESDAY: Overcast, moderate west/southwest wind, freezing level around 1000 m, 10 to 15 cm of snow possible.

Avalanche Summary

In the north of the region on Friday loose wet avalanche activity to size 3 was reported on solar aspects. Sporadic natural slab avalanches were also reported in the alpine and treeline, but no activity was reported from north aspects. Very little activity was reported from areas closer to Whistler.On Thursday, several loose wet avalanches up to size 1 were reported from steep solar terrain at lower elevations. Explosive control produced a size 2.5 loose wet avalanche on a southwest aspect between 1750-2050 m. It ended up triggering three slabs that failed at the ground. Active cornice control using explosives also produced a size 3 cornice failure which did not pull a slab avalanche from the slope below.

Snowpack Summary

Snow surfaces are variable. On higher north aspects above 2000 m you may find some dry, faceted snow. Some of this has been redistributed by southwesterly and northerly winds which may have formed isolated wind slabs. On solar aspects (south and west) at and above treeline the snow surface is expected to have a supportive crust by Sunday Morning. There are still a handful of melt freeze crusts, surface hoar and facets in the upper snowpack, but all of these layers appear to have gone dormant for the time being. We're expecting a good overnight refreeze on Saturday night and increasing cloud cover Sunday which should allow the upper snowpack to solidify.`

Problems

Loose Wet

A good overnight re-freeze Saturday night and increasing cloud cover Sunday should curtail loose wet activity, but it may still be possible to trigger loose wet avalanches at lower elevations where the snowpack remains soft and mushy.

Loose wet avalanches may be small but they can gain mass and push you into a terrain trap.Back off slopes as the surface becomes moist or wet.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Cornices

Large weak cornices loom over many ridgelines and you don't want to be on or under one of these monsters when they fail.

Cornices often break further back than expected; give them a wide berth when traveling on ridgetops.Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.Cornices become weak with daytime heating.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 24th, 2019 2:00PM