Avalanche Forecast

Issued: Mar 26th, 2018 4:01PM

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

Avalanche Canada jmcbride, Avalanche Canada

Heavy precipitation, wind, and rising freezing levels are expect Monday night and Tuesday. High alpine areas will receive snow while at lower elevations a mix of heavy snow and rain are expected. Avalanche activity will increase with the storm.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

There is uncertainty with freezing levels and how much precipitation will fall as rain/snow up to treeline. Alpine areas will likely see heavy snowfall.TONIGHT: Snow and rain. Precipitation 25-35 mm. Ridge wind moderate to strong, southwest. Temperature at treeline near 0. Freezing level 1200 m.TUESDAY: Snow and rain. Precipitation 5-15 mm. Ridge wind moderate, west. Temperature at treeline near 0. Freezing level rising to 1700 m.WEDNESDAY: Mix of sun and cloud. Ridge wind light, northwest. Temperature at treeline near -3. Freezing level 1000 m.THURSDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind light west. Temperature at treeline near -1. Freezing level 1200 m.

Avalanche Summary

Ski cutting on the North Shore mountains on Monday morning produced widespread size 1 storm slab releases on all aspects within the recent storm snow.Reports from the northern part of the region around Squamish over the weekend indicate that a natural avalanche cycle occurred in steep and convex alpine terrain with last week's storm.Expect natural activity to continue with the new storm load, rain,  and rising freezing levels on Tuesday.

Snowpack Summary

The North Shore mountains received 25-30 cm overnight on Sunday and another 10-15 cm throughout the day on Monday, bringing storm snow totals to around 60-80 cm since last Thursday which is generally bonded well to the old surface up to treeline elevations.Alpine areas around Squamish have likely received about 60-100 cm of storm snow and more wind. In these areas the storm snow is likely sitting on a mixture of weak grains including a crust on solar aspects and potentially facets/surface hoar on polar aspects. Below the storm snow the snowpack is generally well settled and strong.

Problems

Storm Slabs

An icon showing Storm Slabs
Significant snow and southwest winds have formed reactive storm slabs. These may be surprisingly deep and touchy in wind loaded areas near treeline and in the alpine. Rising freezing levels and rain will increase natural avalanche activity.
Avoid avalanche terrain during periods of heavy loading from new snow, wind, or rain.Watch for whumpfing, shooting cracks and recent avalanches which indicate unstable storm slabs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Valid until: Mar 27th, 2018 2:00PM