Avalanche Forecast Sea to Sky

Date Issued: Valid Until:

Avalanche Canada ghelgeson, Avalanche Canada

Avalanche Forecast

Sat Mar. 16th ยท 4:21PM

Alpine

Danger Ratings Considerable

Treeline

Danger Ratings Considerable

Below Treeline

Danger Ratings Moderate
Wind Slabs Wind Slabs
Loose Wet Loose Wet

Alpine

Danger Ratings Considerable

Treeline

Danger Ratings Considerable

Below Treeline

Danger Ratings Considerable

Alpine

Danger Ratings High

Treeline

Danger Ratings High

Below Treeline

Danger Ratings Considerable
The heat is on and the game is changing. Direct sun and steadily warming temperatures are expected to destabilize the upper 30 to 50 cm of snow and a natural avalanche cycle is possible. Look up and avoid travel under avalanche paths and cornices.

Confidence

Low -

Weather Forecast

The first big warm up of the season really begins to flex on Sunday. Say goodbye to any kind of temperature driven overnight re-freeze for the next few days. This weather event is going to have a pretty significant impact on our snowpack.SATURDAY NIGHT: Freezing level rising to 2000 m, light west/northwest wind, no significant precipitation, no overnight re-freeze.SUNDAY: Clear skies, light variable wind, freezing level skyrocketing to near 3000 m, no precipitation, no overnight re-freeze.MONDAY: Clear skies, light southeast wind, freezing level holding at 3000 m, no precipitation, no overnight re-freeze.TUESDAY: Clear skies, moderate southeast wind, freezing level lowering to 2500 m, no precipitation, no overnight re-freeze.

Avalanche Summary

This MIN report from Thursday describes southwest winds promoting wind slab formation in the Whistler area, with ski cuts easily producing small 20-40 cm-deep slab releases on steeper slopes. Wednesday was an active day for avalanche activity. Loose wet releases were common on steep solar aspects to size 2. This MIN from Decker Meadows does a great job of showing just how quickly the very strong spring sun can produce avalanches with some great photos and a positive outcome. We suspect activity like that described in this MIN will probably pick up over the next few days as the region warms considerably. A size 2 natural wind slab avalanche was reported from a north facing feature at 1900 m. A size 1 remote triggered storm slab avalanche was also reported from a north facing feature between 2200 and 2000 m.Small loose wet avalanches were reported on Tuesday on south-facing slopes. There was also a size 1.5 remote-triggered avalanche reported at 1400 m.During the previous storm, there was an avalanche cycle to size 2.5. Operators noted some avalanches showed wide propagations.

Snowpack Summary

Another 15-20 cm new snow added to previous amounts to give storm totals in the range of 30-50 cm. Towards the end of the storm, winds shifted to the north, potentially creating some unusual wind slabs on south-facing slopes. Beneath the recent snow you may find hard wind-affected snow at higher elevations, soft faceted snow in shaded and sheltered areas, and crusts on steep southerly slopes. The middle and lower snowpack is well-settled.For Sunday, we're most concerned about the upper 30 to 50 cm of snow.The bigger questions are deeper in the snowpack. After Saturday night, we're not expecting an overnight re-freeze for at least a few nights. That's going to allow the snowpack to warm and start freeing up a lot of water which acts like lubrication. When it doesn't freeze overnight, this process gets turbo-charged. Could multiple hot days and warm nights wake up deeply buried weak layers that we haven't thought about for awhile? We're not sure, but now is probably a time to let the mountains do their thing from afar and check back in when the freezing level returns to seasonal norms which could happen by next weekend.

Problems

Wind Slabs

Wind Slabs

Clear skies & warm temperatures are expected to destabilize the upper 30 to 50 cm of snow which could begin failing naturally. If you're going riding Sunday, go super early, seek out higher elevation shaded aspects and make an early exit.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Back off slopes as the surface becomes moist or wet with rising temperatures.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Possible

Expected Size

1.5 - 2.5
Loose Wet

Loose Wet

Loose wet activity is expected to continue and the shaded aspects may start producing loose activity too, even at upper elevation. Cornices are going to begin to loosen up and you don't want to be under one of these monsters when they fail.

Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.Cornices become weak with daytime heating or solar exposure.Loose avalanches may start small but they can grow and push you into dangerous terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2