ER 6 Almost Ready to GoPosted: January 29, 2009
In the few weeks since the big storm that left over 60cm of new snow on the mountain, the avalanche control teams have been busy trying to get some more terrain open, proving again that they don’t necessarily need new snow to keep busy. Even in periods of low to no snowfall the teams keep busy by concentrating on yet-to-be-opened terrain. Whitehorn II B & C Gullies opened last week, and ER 6 (Fallen Angel) is getting close, too.
Having a piece of terrain like ER 6 ready to open to the public is the result of weather and the amount of time the avalanche control teams have spent in there. The forecaster must be completely confident that all avalanche hazard has been removed, and that confidence comes from many weeks and months of explosive use, ski cutting, and observation. With some more snow in the forecast, ER 6 opening day is hopefully not far off.
So – how are the conditions in ER 6? The short answer is “variable’, but that probably doesn’t paint that detailed a picture. The main open areas of the slope are nicely compacted, mainly as a result of the avalanches that have run over them in the course of control work, packing down the snow that didn’t get cleaned out. The snow is suprisingly supportive, unless you get too close to any rock features or other traditional weak spots, which are generally soft and uncompacted facets. Facets are a type of snow crystal that forms when there is a strong temperature gradient, or in other words, shallow snow and cold temperatures. Areas around protruding rocks have less snow, and are less able to deal with a large temperature difference between the air and ground (see a previous post for more temperature gradient talk).
Yesterday, we went into ER 6 with two nukes, which is our term for two regular bombs taped together, and two sticks of bamboo. Rather than lob the shots onto the slope like usual, we stuck a bamboo pole in the snow, then taped the nuke to the top end. This is an air blast, which produces a different sort of load on the snowpack than a shot in the snow would. An air blast, while not penetrating as deeply into the snowpack as a thrown shot, covers a wider area, so if you’re only concerned about the top layer(s), an air blast is the way to go.
Air blasts are useful only if you’ve already determined the stability (or not) of the snowpack with ground shots and ski cutting. In other words, you only worry about the top layers after you’ve dealt with the rest of the snowpack. We didn’t get any significant results from either of the air blasts, so our confidence increased even more. Most of the slope is in skiable shape, but there are a few narrow parts where rocks have weakened the snowpack, and likely wouldn’t survive beyond the first few skiers to ski the run. A combination of new snow and some more skier traffic (those doing the control work) should make ER 6 good to go.
The first photo below shows a control team member attaching a nuke to a stick of bamboo. Because the shot is in the air rather than in the snow, the sound of the blast is much louder, so we’ll generally retreat a little farther away to await the explosion. As shown in the second photo, the poor bamboo doesn’t fare all that well!
As our team was controlling ER 6, another was making their way down the ER 5/6 ridgeline to control Upper ER 5 and the Kiddies Corner area. This is a longer route that requires the team to make their way on foot over rough, rocky terrain and down a steep ridge. We wanted to get these areas controlled as soon as possible so that the surrounding back side terrain could open without too long a delay. For these routes, patrollers will ride Top of the World chair, then take their skis off and walk up to the top of Paradise chair and the start of the control routes. This is much faster than skiing to and riding Paradise chair.
The photo below shows a control team nearing the bottom of the steep part of the ER 5/6 ridge, just above a slope on ER 5 called the Big Kahuna (not visible in photo, but visible from Paradise chair).