Avalanche Forecast

Issued: Mar 17th, 2019 3:45PM

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

Avalanche Canada ghelgeson, Avalanche Canada

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The heat is on and the game is changing. The strong spring sun and increasingly warm temperatures are expected to further destabilize the upper 20 to 30 cm of snow and a natural avalanche cycle is very likely. Even deeper avalanches are possible.

Summary

Confidence

Low -

Weather Forecast

Hot days & warm nights look to be with us through at least Thursday. Say goodbye to any kind of temperature driven overnight re-freeze for the next few days. This weather event is having a pretty significant impact on our snowpack.SUNDAY NIGHT: Clear skies, light northerly wind, freezing level rising to around 2500 m, no precipitation, no overnight re-freeze.MONDAY: Clear skies, light variable wind, freezing level holding at 2500 m, no precipitation, no overnight re-freeze.TUESDAY: Clear skies, light southeast wind, freezing level fixed at 2800 m, no precipitation, no overnight re-freeze.WEDNESDAY: Clear skies, moderate southeast wind, freezing level fixed at 2800 m, no precipitation, no overnight re-freeze.

Avalanche Summary

Saturday (which was colder and cloudier than Sunday) initiated a natural avalanche cycle that featured loose moist avalanches to size 2.5 on south and southeast facing slopes between 1400 and 1600 m as the old storm snow slid on a crust before stepping down to basal (deep) weak layers.On Friday a couple of small wind and storm slabs were reported on northeast, east and south facing slopes. These avalanches were failing on the facet/crust combo just under the most recent snow, this activity likely picked up on Sunday and is expected to be even more active on Monday.

Snowpack Summary

Solar aspects (south and west) were sporting a new crust Saturday. Sunday's blast of heat has likely eliminated any trace of cold snow, but you may still find some on high elevation north features. Wind slabs are likely done at this point, zapped of their strength by time and warming.We're not expecting any overnight re-freeze Sunday night, and we're very concerned about the upper 20 to 30 cm of snow that sits on a mix of facets and crust.The bigger questions are deeper in the snowpack. We have at least three prominent weak layers in the upper meter and we're not expecting an overnight re-freeze for the foreseeable future. That's going to allow the snowpack to warm which starts freeing up a lot of water which lubricates the upper snowpack. It also allows the upper snowpack to start creeping downhill at an accelerated rate. When it doesn't freeze overnight, this process gets turbo-charged. How many hot days and warm nights will it take to wake up the more deeply buried weak layers? 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

Persistent Slabs

An icon showing Persistent Slabs
A warm night followed by another day of clear skies & hot temperatures is expected to further destabilize the upper 20 to 30 cm of snow which will likely begin failing naturally. Even deeper avalanches are well within the realm of possibility.
Avoid all avalanche terrain.The likelihood of deep persistent slab avalanches will increase with each day of warm weather.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1.5 - 2.5

Loose Wet

An icon showing 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.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 18th, 2019 2:00PM

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