News: Red Mountain, Snoqualmie Pass Washington Avalanche Incident Report

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From CAIC:

Avalanche Details
Location: Red Mountain, Snoqualmie Pass Washington
State: Washington
Date: 2011/02/01
Time: Unknown
Summary Description: 1 skier on foot caught, buried and killed
Primary Activity: Backcountry Tourer
Location Setting: Backcountry

Number
Caught: 1
Partially Buried, Non-Critical: 0
Partially Buried, Critical: 0
Fully Buried: 1
Injured: 0
Killed: 1

Avalanche
Type: C
Trigger: AF - Foot penetration
Trigger (subcode): u - An unintentional release
Size - Relative to Path: R1
Size - Destructive Force: D2
Sliding Surface: Unknown

Site
Slope Aspect: NE
Site Elevation: 5890 ft
Slope Angle: --
Slope Characteristic: Ridgeline,Cornice,Below Cornice

Avalanche Comments
The summit of Red Mountain sits atop a steep narrow northwest/southeast oriented ridge. On the east side of the ridge/summit a 600 foot, nearly vertical cliff falls to the slope below. The prevailing west to southwest storm track often builds a large over hanging cornice above the cliff on the lee (east side)of the summit ridge. The cornice impact triggered a loose snow avalanche that ran about 400 vertical feet. An impact crater from a large piece of cornice (6'x6'x8') was observed below the cliff at ~5200 feet. No crown or other evidence of a slab release was observed. The snow on similar aspects and elevations nearby was cold, dry and loose on the day of the incident.
Weather Summary

January 25 saw 1.75" of rain recorded at nearby Alpental Ski Area Study plot (3200') that reached the top of the highest peaks around Snoqualmie Pass. Three days of dry warm weahter followed. The maximum and minimum tempuratures recored at the Alpental Ski Area upper mountain weahter station (5400') for the 26th-28th where 40/30, 43/38 and 47/37. January 29th saw 1.12" of precipitation which produced 7" of new snow at 5400' and temperatures of 34/29. On January 30th an addition 8" of snow fell at 5400' with tempuratures of 37/27. Moderate WSW winds accompanied the snowfall on the 29th and 30th. The weather on January 31st was cool with clearing. February 1st was cold and clear with light west winds, temperatures at 5400' were 27/7. Although the midday sun did warm the snow surface on sun exposed terrain enough to cause a thin sun crust to form that night.
Snowpack Summary

Snowpack summary is based off of observations taken from nearby Alpental Ski Area on NE aspects from 5000' to 5400' on February 1st. The new snow from the weekend was fairly dry and unconsolidated with an average depth of 12". Hand hardness was fist with a slight density increase near the new/old snow interface. The new snow was well bonded to the old snow surface. A slight crust was observed in a few places below the new snow, otherwise the old snow consisted of moist four finger to one finger round grains. Compression tests failed to produce any failures in the top meter of the snowpack. Ski cuts produced little more than loose surface snow movement without any entrainment of additional snow. The Northwest Weather and Avalanche Center rated the avalanche danger as moderate above 5000 feet on north, east and south slopes and low below 5000 feet for both January 31st and February 1st. It should be noted that new snow accumulation below 5000' was limited by tempuratures durning precipitation. Very little snow accumulated below 4500'.

Accident Summary
The victim was reported by friends and family to have gone on a solo ski tour to Red Mountain on Tuesday February 1st. It is presumed that the victim triggered the cornice fall while walking/standing on the summit. The victim and cornice fell about 600' to the slope below. A small loose avalanche (R1D2) was triggered from the cornice fall. This slide ran about 400 vertical feet. The victim was found buried under 30cm of snow about 100' up from the debris toe.

Rescue Summary
The King Country Sherrif Department was alerted on February 2nd when a group of ski tourers found the victims' backpack, skis and other gear on the summit. The county dispatched a helicopter to do an air recon of the site. The helicopter did a transciever search of the site with no results. Two ground teams went in to the site that night. The two teams searched the site through the early morning hours. Both transiever and Recco searchers were performed. Spot probing and some organized probe lines in likely depositions areas were also performed. Several clues were found on or near the surface, however probing around these articles did not yield a find either. Poor weather including freezing rain and rain prevented the helicopter insertion of dog teams to the site on the morning of February 3rd. A number of Search and Rescue teams, as well as two dog teams attempted to reach the site by ground on February 3rd. Increasing avalanche hazard eventually forced all teams back out of the mountains late that day. Poor weather further postponed the search effort on February 4th. Early morning on February 5th a team of five searchers and two dogs skied into the site, they would eventually be joined by four friends of the victim. Several days of heavy rain and several inches of new snow hindered the search to the point that in many areas the debris field was hard to identify. After four plus hours of searching with dogs, recco and probes the victim was found by searchers disturbing the snow surface. The victim was found under 30 centimeters of snow.

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