The first big warm up of the season really begins to flex on Sunday. 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.SATURDAY NIGHT: Freezing level rising to 2000 m, light west/northwest wind, no significant precipitation, no overnight re-freeze.SUNDAY: Clear skies, light variable wind, freezing level skyrocketing to 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 lowering to 2500 m, no precipitation, no overnight re-freeze.
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 warms considerably. A size 2 natural wind slab avalanche was reported from a north facing feature at 1900 m. A size 1 remote triggered storm slab avalanche was also reported from a north facing feature between 2200 and 2000 m.Small loose wet avalanches were reported on Tuesday on south-facing slopes. There was also a size 1.5 remote-triggered avalanche reported at 1400 m.During the previous storm, there was an avalanche cycle to size 2.5. Operators noted some avalanches showed wide propagations.
Another 15-20 cm new snow added to previous amounts to give storm totals in the range of 30-50 cm. Towards the end of the storm, winds shifted to the north, potentially creating some unusual wind slabs on south-facing slopes. Beneath the 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 Sunday, we're most concerned about the upper 30 to 50 cm of snow.The bigger questions are deeper in the snowpack. After Saturday night, we're not expecting an overnight re-freeze for at least a few nights. That's going to allow the snowpack to warm and start freeing up a lot of water which acts like lubrication. 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.