Avalanche Forecast

Issued: Jan 10th, 2018 6:21PM

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

Avalanche Canada ghelgeson, Avalanche Canada

Up to 30 cm of snow is expected on Thursday with strong southwest wind. Take a very conservative approach to your day and avoid all avalanche terrain during periods of heavy loading.

Summary

Confidence

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

Weather Forecast

A significant weather system is expected to impact the Coast Wednesday night into Thursday. A ridge of high pressure will start to build over the Pacific starting Friday. On Saturday and Sunday a stagnant airmass with little in the way of precipitation will return to most of BC.THURSDAY: Overcast, freezing level beginning around 750 m rising to around 1100 m in the afternoon, strong southwest wind, 20 to 30 cm of snow possible at upper elevations.THURSDAY NIGHT: Overcast, freezing level near 1200 m, moderate south wind, 10 to 20 mm of precipitation expected.FRIDAY: Scattered cloud, freezing level around 1000 m, light variable wind, 1 to 5 mm of precipitation possible.SATURDAY: Overcast, freezing level beginning around 1000 m, rising to 2500 m throughout the day, light south wind, no precipitation expected.

Avalanche Summary

On Wednesday we received a fantastic MIN report of a size 1.5 skier triggered wind slab in the alpine. You can see it here. This report shows just how different the conditions are between the North Shore and the Squamish area. On Tuesday we received a report of a skier triggering a size 2.0 avalanche on the First Pump of Mount Seymour above the summer snowshoe trail. This is presumed to be the south facing slab at 1300 m, but this is not confirmed. On Monday storm slabs were sensitive to skier triggering to size 1.0 on northwest through southeast facing features with crowns 10 to 15 cm in depth.

Snowpack Summary

In the last 72 hours the North Shore Mountains have received about 91 mm of rain, and approximately 20 cm of snow with a rapidly fluctuating freezing level. A slight crust may have formed on the surface on Wednesday January 10th. Just below the surface, 10 to 20 cm of rain soaked snow now rests on the rain crust that formed Monday January 8th. Below the January 8th crust there is 15 to 30 cm of well settled rain soaked snow, that snow sits on the January 7th melt/freeze crust. The January 8th crust may not be present in the Alpine where temperatures are thought to have stayed cooler over the last few days. Significantly more storm snow is likely present in the Alpine, but we have few observations from that elevation band. Check out this great MIN report for an idea of current alpine conditions. Approximately 50 to 100 cm of moist snow are between the surface and a few prominent melt-freeze crusts that were buried mid-December, these crust layers have been reported to be bonding well to the mid-pack and are trending towards dormancy.The snowpack depth at 1000 m is about 150 cm and many early season hazards are still present.

Problems

Storm Slabs

An icon showing Storm Slabs
Thursday's storm is expected to deliver 20 to 30 cm of new snow with strong southwest wind. Widespread storm slabs are expected to develop on top of a buried crust.  Watch for increasingly touchy slabs to develop throughout the day.
Watch for signs of instability such as whumpfing, or cracking. Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.The new snow will require time to settle and stabilize.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Loose Wet

An icon showing Loose Wet
Loose wet avalanches are expected to be problematic Thursday, especially in steep terrain where precipitation is falling as rain or very wet snow.
Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Use extra caution on slopes where the new snow is wet.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 11th, 2018 2:00PM