- Location: Floral Park, Berthoud Pass
- State: Colorado
- Date: 2010/03/03
- Summary Description: 2 S&R caught, carried, partially buried
- Primary Activity: Others at Work
- Primary Travel Mode: --
- Location Setting: Backcountry
- Caught: 2
- Partially Buried, Non-Critical: 2
- Partially Buried, Critical: 0
- Fully Buried: 0
- Injured: 0
- Killed: 0
- Type: SS
- Trigger: AF - Foot penetration
- Trigger (subcode): u - An unintentional release
- Size - Relative to Path: R2
- Size - Destructive Force: D2
- Sliding Surface: I - New/Old Interface
- Slope Aspect: W
- Site Elevation: 11100 ft
- Slope Angle: 32 °
- Slope Characteristic: Planar Slope
On the evening of February 28th a high precipitation rate snow storm hit the Berthoud Pass area. A little over 12" of snow fell in 3 hours at the nearby resort of winter Park from 6-9 PM. There was very little wind during this storm. In total 16" fell over a 12 hour period. At nearby Eisenhower Tunnel 9" of new snow fell, CDOT estimates of 18" at Berthoud Summit from this storm. On March 1st the storm cleared and CDOT shot numerous paths with howitzers and avalaunchers. Floral Park was shot 8-9 times times with an avalauncher. March 1-3 warmed significantly and the new snow settled rapidly. Summary from Berthoud Pass Wx station follows:
- 11AM: 22* NE 9 Gust 17 RH 66
- 12 noon: 24* NE 7 Gust 19 RH 62
- 1 PM: 25* NE 8 Gust 19 RH 63
- 2 PM: 25* NE 10 G 17 RH 63
Snow slid on multiple layers and did not go to the ground. Debris was close to 6 feet deep at the toe. People were uncomfortable with current conditions so all headed out immediately, no snowpack analysis was done.
Events Leading to the Avalanche
Two Alpine S&R members were on Berthoud Pass looking for a lost hiker. Missing since 6 pm on the 2nd. The 2 S&R members were descending out of Floral Park on descenders left side of the park through intermittent cliff bands just at treeline. Interesting...CDOT had shot the area on Monday the 1st. There were 2 or 3 craters seen by S&R team members. One of the craters was in the middle of what would become the avalanche path.
R1 & R2 were descending on the south side of Floral Park. They arrived at treeline and took snowshoes off to negotiate some cliff bands. R3 was about 100 yds north of the two descenders. R3 noted 2 other fresh slides & saw 3 craters from recent CDOT shoot. R3 got in voice contact with R1 & R2 and waited in a safe spot/denser timber. Eventually R3 could see R1 & R2 & then saw them get caught, knocked over and swept down in the avalanche. R1 & R2 rode the slide on their backs and stopped about 30 feet above the toe of the debris about mid debris pile in a prone position, feet down hill.
R1 and R2 self rescued. They were able to stand up and brush snow off, so partially buried not critical.
R1 & R2 did not read the advisory but it was read over team radios the morning of the incident.
From the advisory at 5:36 am Wednesday March 3...
The avalanche danger for the Front Range zone is CONSIDERABLE on NW-N-NE-E aspects near and above treeline. It is MODERATE elsewhere. Expect some wet slide activity in the MODERATE areas as temperatures warm today.
Snow & Avalanche Discussion
Much info below...With all of that said....We still have concerns with deep base layer facets and depth hoar...Persistant, weak, and potentially deadly.
18 rather large slides were reported to the office Tuesday (Most probably ran during the Sunday night storm) Many of these were near and below treeline, where the weakest snow was to be found prior to the storm. Still, some impressive slides were reported above treeline so all elevations had there moments. With little wind during the event, most all aspects stressed equally under the heavy snowfall. There was one human triggered slab on Mines Peak 2, a NNW aspect at about 11,500 feet from Tuesday. Fracture was fairly deep, (~6 ft?) may have been remotely triggered, no other details. Many of the reported fractures were from 200 to 600 feet wide, most involving the storm snow, but one fracture on Woods Mtn east of Ike tunnel was estimated at 8 feet deep on a N aspect.
By Tuesday afternoon the new snow had become moist to wet with the warming temperatures. This created some free water running in the snow, especially around rock out crops and cliff bands on the more solar aspects.
As temperatures warm again today the snowpack will continue to settle rapidly. Settlement is generally a good thing (As opposed to collapse), but too rapid settlement can stress the bonds between the old snow and the new snow. With the warm southwesterly flow on tap again today afternoon wet slide activity could re-enter the picture. This would first manifest itself on easterly aspects, spread around to the south then west and north aspects as the sun makes its circut around the horizon.