Avalanche Forecast Northwest Coastal

Date Issued: Valid Until:

Avalanche Canada ghelgeson, Avalanche Canada

Avalanche Forecast

Sat Apr. 13th ยท 3:16PM

Alpine

Danger Ratings Considerable

Treeline

Danger Ratings Moderate

Below Treeline

Danger Ratings Low
Storm Slabs Storm Slabs

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Moderate

Below Treeline

Danger Ratings Low

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Moderate

Below Treeline

Danger Ratings Low
Winter is coming... back and new snow should improve riding quality, especially in the alpine. But, new snow and wind are likely forming fresh slabs, so you need to carefully check out the bond of the new snow before committing to your line.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Winter is coming, back, at least to the alpine for the next few days. These storm systems are pretty convective which makes it difficult to pin down accurate snowfall amounts, but the weekend storm should offer a nice reset for alpine riding quality. There is a bit of a lull Sunday and Monday before another shot of precipitation looks to make landfall Monday night into Tuesday.SATURDAY NIGHT: Freezing level around 800 m, mainly light west/northwest wind, potential for moderate winds near ridgetop before dawn, 2 to 8 cm of snow.SUNDAY: Overcast, freezing level around 1000 m, light to moderate west/northwest wind, trace to 8 cm of snow possible. MONDAY: Broken cloud cover, freezing level rising to around 1200 m, light to moderate south/southwest wind, trace of snow possible.TUESDAY: Overcast, freezing level around 1200 m, moderate to strong south/southwest wind, 5 to 15 cm of snow possible.

Avalanche Summary

We received a great MIN report on Friday. It details a few avalanche occurrences including a size 3 on an east facing slope and lots of loose wet activity from steep terrain.On Thursday small loose wet avalanches were observed in steep terrain. Control work produced a few storm slab avalanches to size 2 on northeast facing slopes between 1800 and 2000 m.On Wednesday, reports indicated several natural slab releases and a cornice failure up to size 2.5. Slab avalanches were remotely triggered (from a distance) by riders up to size 1.5. We suspect these avalanches were running on the April 4th crust interface. Daytime warming produced loose wet avalanches on solar aspects up to size 2.

Snowpack Summary

The region is receiving a bit of new snow, but as of Saturday afternoon amounts are less than 10 cm. As we enter into mid-April we're dealing with a classic warm snowpack. At and below treeline the snowpack is becoming isothermal. We're entering a cooler period for the next few days, so a surface crust is expected to remain supportive. This supportive crust is what the new snow will come to rest on in most locations. The exception is high elevation north facing features where 20 to 80 cm of cold dry snow sits above the April 4th crust which may have some surface hoar or facets above it. Digging deeper, north facing alpine terrain also has a layer of facets down approximately 100 cm below the surface which are thought to be dormant at this time.

Problems

Storm Slabs

Storm Slabs

Watch for fresh slab development, especially in high elevation north facing features where human triggering is most likely near ridgecrest. High elevation south and west slopes could produce heavy sluffing as the new snow slides on a crust.

Recent new snow may be hiding windslabs that were easily visible before the snow fell.Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Possible

Expected Size

1 - 2