The heat is on and the game is changing. Direct sun and increasingly warm 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.
Summary
Confidence
Low -
Weather Forecast
Hot days & warm nights look to be with us through at least Thursday. Were not expecting any kind of substantive re-freeze for the foreseeable future.SUNDAY NIGHT: Light east/southeast wind, freezing level 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, light to moderate southeast wind, freezing level holding around 3000 m, no precipitation, no overnight re-freeze.WEDNESDAY: Clear skies, light southeast wind, freezing level around 2600 m, no precipitation, no overnight re-freeze.
Avalanche Summary
A natural avalanche cycle to size 1.5 was reported from the Whistler area with a few size 2 avalanches visible in the Spearhead on Sunday.Reported avalanche activity on Saturday was limited to loose wet avalanches on solar aspects.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 continues to warm.
Snowpack Summary
About 30 cm of snow has fallen in the last week. Towards the end of the last storm winds shifted to the north forming some unusual wind slabs on south-facing slopes. Beneath this more 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 Monday, we're most concerned about the upper 30 to 50 cm of snow.There may be bigger questions deeper in the snowpack. We're not expecting an overnight re-freeze for the forseeable 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. 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.
ghelgeson,
Avalanche Canada
