Avalanche on Fireplug aka The Diamond

Updated info on this avalanche gathered on Apr 4 after visiting the site and receiving an email from the triggering party.

"I just wanted to provide you some info on the avalanche witnessed yesterday on Fireplug.  I believe I remotely triggered the slide as I dropped into the top of the Diamond.  My plan was to carefully ski the far skiers right of the face, staying out of the middle as I could tell the snow on the face was pretty saturated and it was late in the day (about 12:30pm).  As I traversed to the right, I took a couple turns downward before continuing my traverse and at that time I saw the slide trigger some 40-50 ft below me.  It looked as though it was sliding on the interface of the new snow from Monday (3/28) and old snow surface.  After the slide, I skied down the far right before traversing over onto the slide path and examining the bed surface it slid on.  The crown looked to be around 10-12 inches." - Reporting Party

From TNF/SAC forecaster (B. Schwartz) after visiting the sight of the avalanche on Apr 4: Wet slab avalanche on open E aspect (100 deg). Slope angle along the crown line ranged from 38 to 40 degrees. Pit profile was collected along the climber's left flank at 9:45 am, approx 21 hrs after the avalanche occurred. At 9:45 am on Apr 4, the full height of the snowpack (70 to 100 cm) in this area was melt forms with no signs of remnant storm snow. A weak snow surface refreeze had occurred overnight. Conditions on the bed surface became marginally boot supportable at 10:30 am.

Crown height was mostly in the 15 to 25 cm range with a few small sections to 30 cm. Debris were mostly 30 cm deep with pockets to 90 cm deep.

Wet slab avalanches are poorly understood and a subject of ongoing research within the professional avalanche community. Most occur naturally. Triggering with explosives is usually difficult and ineffective. The skier on the slope could have caused a remote trigger, or just have happened to be on the upper portion of the slope when a natural avalanche occurred.

Snowpit tests performed on the flank on Apr 4 may not be representative of conditions at the time of the avalanche on Apr 3 due to some weak refreeze of the slab overnight and the presence of non-persistent, melt form snow crystal type at the slab/bed surface interface.

Photo 1: Apr 3 photo submitted by Mt. Rose Ski Patrol, taken from the ski area across the highway.

Photo 2: Apr 4 as seen from Tamarack Pk parking area.

Photo 3: Apr 4 as seen from toe of debris.

Photo 4: Apr 4 photo of highest portion of crown.

Photo 5: Apr 4 photo of debris 1 to 3' deep.

Photo 6: Apr 4 photo of debris/runout zone.

Photo 7: Apr 4 photo of crown and track of skier who was on the slope at the time that the avalanche occurred.

Original info posted Apr 3 based on initial report received that evening. -------------------------------------------------------------------------------------------------------------------------

Reported by Mt. Rose Ski Patrol as viewed from the ski area across the highway. Additional details will be collected on Apr 4 by TNF/SAC forecaster and will be updated here after visiting the site.

Initial Apr 3 report subject to revision after scheduled site visit on Apr 4:

Possible natural wet slab avalanche size D2 R3 occurred around 1400 on Apr 3. Crown possibly 1 foot deep. Lots of old tracks on the slope going into the avalanche site. No new tracks from today visible from afar.