Backcountry Advisory 

As of Wednesday, May 2

Once again a series of winter-like storms gave us some great conditions in the mountains. Bikes got put away for a few days and the diehards braved the weather in search of what could be the last real powder turns of the season. We received approximately 40 cm. of new snow during the storm cycle. The snowfall was associated with moderate to strong winds from the SE through to the SW. On April 30, the peak of Whistler Mountain recorded several hours of gusts over 100 km/h.

Explosive and ski testing carried out on Whistler produced some slab activity. In general though, the new snow settled rapidly each day, assisted by brief glimpses of brightness that rapidly changed the snow quality. New cornice growth was very much in evidence and some natural fall was noted.

As was mentioned in last week’s article, the spell of warm, cloudy days that ended on April 28 turned the snowpack to mush and triggered a cycle of natural avalanches that ran down to the November facet layer. On Whistler Mountain a moderately compacted moraine also performed on this layer. The writing is on the wall for anyone planning spring trips in the Coast Mountains. You can expect to see significant avalanche activity when the weather conditions destroy the crusts that are holding the snowpack together and bridging over the weak facetted layer. Cornice fall could also promote deeper failures.

For now, the immediate hazard is the storm snow that has yet to go through a melt/freeze cycle. Once it becomes moist, the snowballing and sluffing will begin. Underlying crusts may provide a nice smooth sliding surface. There is the potential for a considerable amount of snow to become entrained in a sluff – don’t get in the way of it!

The forecast is calling for a few sunny, warm days to end off the week. By the weekend though we are expected to be back into the precipitation. For any trivia buffs, the new snow for the month of April on Whistler Mountain totaled 130 cm. It was the snowiest April since 1988.

As of May 2, the backcountry avalanche danger is rated as MODERATE. This may increase during the day with warming and direct sunshine. Conditions will change rapidly, so check for the most current information before you head out.

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