Avalanche Control in ER5Posted: December 14, 2010
A snowy week and the first significant west/southwest winds of the winter at Lake Louise has given the avalanche control department even more to sink their teeth into these days. The cold weather of a few weeks ago had left its mark in the form of weak crystals in the snow close to the ground, and with the added load brough about by the new snowfall and wind, control teams were anxious to get into terrain most affected by these weather events.
With significant avalanches almost a certainty, control teams hiked up from the top of the Top of the World chair to the top of Paradise chair with packs full of explosive rounds. Their destination was ER 5, which is a huge piece of complex terrain with multiple avalanche paths and the potential to affect areas of the mountain that are already or soon to open. To access the usual shot placements, patrollers ski across the top of the Paradise Cornice and the top of the ER 5/6 shoulder, which leads down and eventually ends up at the top of Upper Kiddies’ Corner.
Starting at the very top of Upper ER5, two shots were placed, producing avalanches that ran almost down to the flats above Pika Corner, but not propagating. In other words, the avalanches picked up any snow that lay in their paths, but did not widen or cause additional areas to slide. Fracture line propagation usually happens when there are slab conditions, which form when wind-transported snow is deposited on leeward slopes. As a rule of thumb, the stronger the wind, the stiffer the slab. Slab avalanches are usually the most destructive due to the density of the snow and potential for increased propagation and large size. This was not the expected result, but with those areas cleared of snow the control teams moved down the ridge and to their next shot placements.
The next round of shots produced exactly the kind of results they expected – wide propagation and size 2-2.5 avalanches running just down to the flats. This became the story of the morning in ER5 as further explosive work produced slab avalanches that continued to remove most of the snow from the intended slopes.
Clearing snow off of slopes may sound counterproductive to some. In fact, this clearing out of widespread weak layers provided that area with the only chance it has in eventually becoming open to skiing this season. If the weak layers had been allowed to remain on the slope, the stability required for skier traffic would likely never be achieved. By starting fresh, the slope now has a chance to build properly with future snowfalls. Another benefit of the avalanches is that the debris gets deposited on the lower slopes. Avalanche debris consists of dense snow, and does a great job of filling rocky or uneven areas and providing a nice firm base for the run.
This morning, control teams are heading out along the Corridor and over to the tops of Swede’s and ER3. Their intention here is two-fold. First, they want to ensure the slope has a chance to become stable enough to open. Second, they want to make sure avalanches don’t start there and affect potentially open terrain below, as Paradise Bowl usually opens before Swede’s and ER 3.
If everything goes according to plan, control teams expect to have Paradise Bowl open today or tomorrow. There’s also a chance Lower ER5 could open as well, but more control work is required there, the results of which will determine if and when that run opens.
Meanwhile, it’s snowing in Lake Louise right now, and is expected to continue through the day. Things keep getting better!