Avalanche Forecast

Issued: Mar 17th, 2019 3:48PM

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.

ghelgeson, Avalanche Canada

South Coast.

The heat is on and the game is changing. The strong spring sun and steadily warming 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 going to have a pretty significant impact on our snowpack.SUNDAY NIGHT: Light east/southeast wind, freezing level holding 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 holding around 3000 m, no precipitation, no overnight re-freeze.WEDNESDAY: Clear skies, light southeast wind, freezing level around 2500 m, no precipitation, no overnight re-freeze.

Avalanche Summary

No new avalanche activity has been reported recently.

Snowpack Summary

The heat wave 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 very concerned about the upper 20 to 30 cm of snow that sits on crust on steep south slopes and possibly weak surface hoar crystals on sheltered and shaded slopes.The even bigger questions are deeper in the snowpack. A layer of weak and sugary faceted grains sits on a melt-freeze crust about 50 to 120 cm deep. This layer is most prominent in the North Shore Mountains on north aspects. 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. 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

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

Expected Size

1.5 - 2.5

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 - Very Likely

Expected Size

1 - 2

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