Observation: Turnagain

Location: Sunburst (looking from the Magnum Ridge)

Route & General Observations

While touring up to the Magnum ridge today we noticed a fresh avalanche on the SW face of Sunburst as we gained the ridge. Photos below.

There were no apparent entry tracks or exit tracks seen with binoculars. Several hundred feet down the ridge to the East there was one party of 4 near the weather station getting ready to descend. They skied/boarded down without incident and appeared to notice the avalanche and conduct a beacon search in the debris (see photo). It seemed clear that they did not find a signal and continued with their day. Kudos to these folks!

Avalanche details:
Occurred between 12:00 and 1:00pm.
WSW facing, 3,700′
Estimated dimensions: 2′ deep, 200-300′ wide, running 1,100′ to valley bottom
Type: soft slab
Trigger: unknown – most likely to be a natural (solar loading + possibly wind loading) there is also a chance it was remotely triggered from the ridge.
Weak layer: unknown – likely facets above the January crust due to the wide propagation and the known persistent slab problem.

Weather thought to have been a contributing factor:
Though the cloud cover did not break until 3pm, ambient air temperatures were warm – up to what felt like 20F on south slopes out of the breeze. Winds bumped up during the day and were loading slopes by 4pm. Though at the time of this avalanche, neither one of these factors was in full effect which is very interesting. Nonetheless, recent warming, some sunshine and a bit of wind loading seemed to be enough to tip the balance.

Of note is at 5pm today (4 hours after the slide) a natural avalanche was witnessed in the path to the looker’s left – just as big. At this time the sun had been in full effect as well as rapid wind loading. See last photo.

Photos & Video
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