Blown Away
Posted: January 31, 2009 Filed under: Winter 2011-12 | Tags: Lake Louise, wind 11 Comments »January came in with a big snow storm and went out with an ever bigger wind storm as high to extreme winds have pounded the mountain for the last two days (Fri & Sat). The winds started after lunch yesterday, and as everything started to blow away it was almost time for the patrol to do their end-of-day sweep of the mountain, leaving little time to batten down the hatches.
We arrived this morning to find out the wind had reached gusts of 140 km/h, and then there had been 2cm of new snow with moderate winds. The avalanche forecaster, after finishing the stability evaluation and planning the morning’s control work, instructed everyone to expect both typical and atypical wind loading in avalanche terrain. The winds were still gusting 80-100 km/h at the top of Top of the World chair, so we loaded Glacier chair shortly after 8:00am wondering if any of the upper lifts would be able to run in that wind (and knowing they probably couldn’t).
Sure enough, no upper mountain lifts were able to run, but it was important that the patrol and control teams were able to get up high to begin the work of cleaning up and getting the complicated control work done. We enlisted a cat to take ten of us from the bottom of Top of the World chair to the top. When we arrived, the winds were howling, and we got our first glimpse of the destruction, shown in the video below:
A large aluminum recycling and garbage container was found at the bottom of ER7, and a heavy wooden bench ended up a hundred metres from the top of the lift. Fences were scattered all over, and countless bamboo and signs were broken or missing. A member of the trail crew was carrying a large roll of plastic fence and was blown backward uphill. Pebbles and small pieces of shale were everywhere, just like pine cones, needles, and branches (and even trees) littered all of the lower mountain runs.
Hitching a ride from a snow cat.
Fences blew all over the place (and there's a panel missing on the big sign).
Control teams discuss plan of attack at the top of Paradise chair.
2cm of Snow and 140km Winds
Posted: January 31, 2009 Filed under: Winter 2011-12 Leave a comment »Anyone skiing the Lake yesterday got a good taste of what extreme winds will do to the ski area. Shortly after lunch, the barometer dropped and the winds picked up to the 90-100km range, with maximum gusts exceeding 105km. The whole upper mountain and Larch areas were closed mainly because chairlifts can’t operate in those kinds of winds, but also because much of our fencing and signage blew away, and those sustained winds can cause rapid wind-loading of leeward slopes and cause the avalanche hazard to increase sharply. And while the Summit Platter is less susceptible to winds because it’s a surface lift, 100km winds are too strong even for it.
So, this morning we arrived to have a look at the overnight weather data, and saw that while overall the winds diminished from extreme to high, there were still gusts exceeding 140km. Along with 2cm of new snow in the last 24 hours, we’re likely going to find some variable conditions – from scraped-clean places on the front side to blown-in places on the back side. As you likely already know, 2cm can end up being a lot more on wind-loaded slopes. Exactly how much remains to be seen.
We have a busy morning ahead of us as we venture onto the upper mountain this morning. Places like Home Run and Sunset Terrace use a lot of fence, and we expect that much of it blew away during the night. During yesterday’s excitement, for example, some fence on ridge top just down from the top of Paradise chair ended up down at the bottom of ER 6 & 7.
The avalanche control teams will also likely find some interesting conditions. Where the snow ends up on a slope depends on the strength of the wind, so with two distinct wind events with different mean wind speeds, the avalanche forecaster is mounting a two-pronged attack to deal with the results – namely, the new snow that was accompanied by moderate to high winds, and previously fallen snow that was blown around by the high to extreme winds we had yesterday, which means that snow is likely to have been deposited farther down the slope.
Wind speed classifications as outlined in the Canadian Avalanche Association’s Weather Observation Guidelines are as follows:
- Calm = 0 km/h, no air motion, smoke rises vertically.
- Light = 1-25 km/h, light to gentle breeze, flags and twigs in motion.
- Moderate = 26-40 km/h, fresh breeze, small trees sway, flags stretched, snow begins to drift.
- Strong = 41-60 km/h, Strong breeze, whole trees in motion and snow drifting.
- Extreme = >60 km/h, gale force or higher, difficulty in walking and slight to considerable structural damage occurs.
ER 6 Almost Ready to Go
Posted: January 29, 2009 Filed under: Avalanche Control | Tags: ER 6, Lake Louise 1 Comment »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!
Setting up an air blast in ER 6.
Bamboo - after.
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).
ER 5/6 Ridge.
Melt/Freeze
Posted: January 25, 2009 Filed under: Winter 2011-12 2 Comments »A few days ago I was asked a question about how the recent warm weather affected the snowpack at Lake Louise.
Warm days (+0C) and cold nights cause a melt/freeze cycle which forms a crust at the top of the snowpack. How strong and thick the crust is depends on daily maximum and minimum temperatures and the uninterrupted amount of time the air temperature stays below 0C. The longer and colder it is, the stronger the crust becomes. If it stays above freezing for too long, the snowpack becomes isothermal, which means it holds the same temperature from top to bottom and becomes completely unsupportive. There have been times when only the runs that have been groomed often (and the snow has therefore been packed and packed) will support the weight of a skier, even in flat areas. If one was to venture even a metre off the groomed trail, they’d find themselves sinking right through to the ground.
During avalanche control in long spells of warm weather, gently lobbing a snowball onto the top of a slope can be enough to get the whole thing to slide, which tends to happen in places that spend all day baking in the sun, like the Ptarmigan Chutes or above the Wounded Knee cat track on Saddleback. The photo below, from May 10, 2007 shows the latter, with lots of natural snowballing and even a small point release avalanche towards the right. The shaded area is the slope that usually avalanches in the spring.
Controlling Wounded Knee is actually a somewhat complicated affair, since it is usally performed with explosives sometime in the afternoon, when the day is at its hottest , and skiers are all over and can come from any direction. A snow cat is also on scene to clear the cat track of avalanche debris, and we can’t have a cat operating in an open area. To prepare, the gate into Saddleback is closed and manned, patrollers are stationed around the area to stop skiers approaching from other directions, and the control team does its stuff.
Snowballing above Wounded Knee cat track.
The short video below shows the use of ANFO at Wounded Knee a few years ago. As you can see, no skier could stand a chance getting hit by that avalanche of heavy wet snow. The sign we forgot to move stayed buried in snow until long after we closed for the season:
Melt/freeze cycles happen mostly in spring, but we had one last week when there were a few days in a row when the maximum temperature went above freezing for most of the day. As we get into April and May, they’re quite common. The temperature usually stays cold enough for a crust to bridge the weak snow underneath. That also explains the spring avalanche closures you’ll start seeing when it gets warm – runs will close before the end of the day if the crust is no longer supportive. The most obvious spring avalanche closure is the Grizzly Gully area, when an uninterrupted fence will run from the top of Paradise chair and down the front side, all the way along Home Run and down the right side of Wrong Turn, well below the top of the old Olympic chair. This closure protects areas like Flight Chutes, Mirkwood, Grizzly Gully, and Kernahan’s Folly.
Since a crust is a poor bonding surface, new snow above is more likely to avalanche, especially if the the crust is smooth and undisturbed. A rougher crust, like in moguls, will do a better job of anchoring the snow. New snow on top of crust doesn’t necessarily make for good skiing, since it has to be enough to keep you off the crust below. At the Lake, we can sometimes count on the wind to blow new snow around and pack on top of the crust, making a firmer base and improving skiing conditions.
So, since the sun can cause so much warming in the snowpack, it stands to reason that those slopes that spend most of their time in shade stay cooler, and can offer winter-like conditions when the south-facing aspects are melting down. Places like Whitehorn II and ER 7 are classic examples of great winter skiing well into spring.
Paradise Pocket Revisited
Posted: January 19, 2009 Filed under: Uncategorized Leave a comment »In a recent post, I speculated about the naming of the Paradise Pocket above Pine Cone Way. I wasn`t even close, but a reader came to the rescue and supplied the following information::
The Paradise Pocket name goes back to the Sixties.
When Whitehorn Lodge was built, the road that we now call Pine Cone Way, was used in the winter as a way to join the Temple Ski Out, and was called Paradise.
There was no Whiskey Jack Lodge, so skiers used the Gondola to access Whitehorn and then use the Eagle Poma, so Paradise was the way out at the day’s end.
Where the Paradise run met the Temple road and ski out, there was a telephone on a tree that we used to call in that the Whitehorn area and Temple area were “clear” on Sweep.
We then took the ski out down, then up and over the big hill to the Gondola Base, and skied over to the Post Hotel.
Thank you Peter!
ANFO in Whitehorn II
Posted: January 17, 2009 Filed under: Avalanche Control 4 Comments »Another beautiful sunny day at Lake Louise today, and the avalanche control team made use of the good visibility to try and get some results in E, F, & G Gullies of Whitehorn II. Previous attempts to get results with our regular 1kg and 2kg shots were unsuccessful, so we decided to pull out the big guns – ANFO, that is.
ANFO stands for ammonium nitrate and fuel oil, and comes in large bags. It looks like lawn fertilizer, and can be used to make custom size shots to fit the needs of the control team. In this case, three 7kg bombs were made by placing the ANFO in separate bags, then inserting a 1kg shot with fuse and igniter.
We loaded the lift around 8:30 and arrived at mid-station just as the sun was beginning to peek over the mountaintops. By the time we got to the top of Summit, Whitehorn II and the rest of the backside was bathed in a beautiful early-morning light. I travelled around to Shoulder Roll on Boomerang so I could get some photos of the action (if there was going to be any). The first two shots were used in E and F Gullies, and both produced very minor results – just a little surface snow around the shot placement.
The shot in G Gully was a different story. As shown in the photos below, as soon as the bomb went off, fracture lines appeared along almost the entire vertical length of the run, and the slope avalanched down to the bottom and up the other side of the terrain slump that runs along most of the bottom of Whitehorn II. This was a size three avalanche, enough to bury or destroy a car. One patroller was asked why Whitehorn II hadn’t been open yet, and the reply was, “Go ski Boomerang, then look up to your right and you’ll get your answer”.
The yellow cloud of ANFO, and fracture lines appear at lowerl left.
Fracture lines continue downslope as snow begins to move.
Snow is on the move.
Avalanche widens lower on the slope.
Snow comes to a stop.
A Taste of Spring
Posted: January 15, 2009 Filed under: Winter 2011-12 3 Comments »For those arriving at Lake Louise today for a day of skiing, you wouldn’t be blamed for wondering how good the day was going to be based on the socked-in clouds that hugged the mountain.
Until you rode the lift, that is. A thick valley cloud cut off any hint of what conditions awaited skiers – a beautiful, warm sunny day. In fact, some solar aspects even started getting a little slushy towards the end of the day, a fact difficult to fathom when the terrifyingly cold temperatures of December are probably still fresh in everyone’s mind!
If you’ve been to the Lake since last week’s storm, you’ll notice that the wind has once again drastically alterd the landscape by scraping every last flake from some spots and placing them in others. Places like the Headwall and Windy Gap, which is the narrow part en route to Boomerang, suffered visibly, as rocks that had been buried for weeks were back happily sunning themselves today. Other places, like Whitehorn I and other leeward slopes, had many of their features filled in, and new lines have appeared for those who like to hunt for them.
The wind also filled in many of the slopes that had avalanched last week, either naturally or by control work. If you were here last Thursday, you could easily see the results of that morning’s heli-bombing all around the resort, most obviously from the Saddle looking over towards Richardson’s Ridge. A few days later, and one must look hard to find any sign that avalanches happened at all.
Some photos from today…
Whitehorn I shines in the sunlight.
Ridge Run on Whitehorn I, with Mt. Hector in the background.
Skiers at the top of ER3.
Top of the World.
Grizzly Gully.
Juniper.
Avalanche Areas Below Tree Line
Posted: January 14, 2009 Filed under: Avalanche Control | Tags: Avalanche Control, comer's, Lake Louise 7 Comments »In the wake of the storm that left over 60cm of new snow on the mountain, the avalanche forecaster was forced to consider parts of the mountain that normally aren’t a problem with regards to avalanche hazard. While many of the places are in the alpine, there are also a few that are tucked away in hard-to-find pockets hidden in the woods. While hard to find, they’re still in open terrain, so must be considered when planning the day’s avalanche control. Four of these areas are located on the front side of the mountain - Midstation Pocket to the skier’s right of Men’s Downhill, Ladies’ Pocket to the skier’s right of Ladies’ Downhill, Comer’s below Eagle Meadows cat track, and Paradise Pocket just above Pine Cone Way. These pitches aren’t big enough to attract those looking for untouched powder, but they are big and steep enough to avalanche and do get traffic nonetheless.
Comer's
On Saturday, two of us headed towards Comer’s and Paradise Pocket, since both can be controlled on the same lap. Dropping into Comer’s, there was lots of snow, and it was also apparent that there had been traffic throughout the storm, stabilizing the snow. Ski cuts here did not produce any results. Moving down to Paradise Pocket* the signs of traffic became less and less, and when we arrived at the top of the slope, we were pretty sure we’d get results.
Since the pocket looms directly over Pine Cone Way, we called a patroller to do a spot closure at the top of the run. A spot closure is just a temporary and usually brief closure of a run with a patroller standing guard rather than setting up closure fences and signage. Once the run was secured, we began by putting a ski cut across the top of the slope, which produced an immediate result as most of the feature avalanched the full length of the pitch. The skier’s left 1/3 of the slope did not slide, so I ski cut the top and got all of that to go as well. The debris ran to within a metre or two of Pine Cone Way, so not only were we glad to have closed the run, but also to have controlled the slope and removed any avalanche hazard.
The next photos are of Paradise Pocket before and after the avalanche, and you can see in the first how close the pitch is to Pine Cone Way. And, a short video (0:10) shows the first ski cut getting a good result.
Paradise Pocket - before.
Paradise Pocket - after.
It’s always good to go to places that are seldom visited in the course of a work day – there’s always something to be learned.
*It may seem strange that a pocket on the front side is named after a chair on the back side, but Paradise Pocket was named long before the chair of the same name existed. Perhaps it was named after Paradise Valley by Mt. Temple?
Avalanche in West Bowl
Posted: January 10, 2009 Filed under: Winter 2011-12 | Tags: avalanche, Lake Louise, west bowl 6 Comments »Despite all the recent news of avalanche fatalities in North America and despite no shortage of warnings of high to extreme avalanche hazard in the backcountry of Banff National Park, two riders found the lure of untracked powder too powerful to resist today just outside the area boundary of the Lake Louise Ski Area.
West Bowl is located immediately west and outside of the Outer Limits boundary fence, and is probably the most travelled area outside the boundary due to ease of access. It can be reached from the top of Outer Limits or through the Window, which accesses the very top of the bowl as you head towards Boomerang.
Below is a diagram that’s posted at the Outer Limits access point to West Bowl:
Parks Canada diagram of West Bowl - © Parks Canada
About mid-afternoon today (which, by the way, was Avalanche Awareness Day at Lake Louise), a patroller working in the Summit area was skiing down Outer Limits, and stopped to look into West Bowl. She saw a startling sight – West Bowl had avalanched, and there was a boarder above the slide climbing back to the top of the ridge, and another in the debris pile trying to dig himself out. The avalanche was reported to our Avalanche Forecaster, who immediately instructed patrol dispatch to contact the Parks Canada warden service to prepare for and assist with a possible rescue, then started to head that way with other members of the avalanche control team.
As I mentioned in a recent post, Lake Louise Ski Patrol will respond to an out-of-bounds rescue, but the avalanche forecaster is the only person who can authorize any staff member to leave the area boundary, and except in very low-hazard conditions, only those patrollers with their Canadian Avalanche Association Level 2 avalanche course certification will be involved in the rescue. The public safety wardens called for a helicopter to assist in the rescue, but once it was confirmed that the two people we observed were the only ones involved in the avalanche and no rescue was required, it was called off. The wardens also stood down and let us do our thing.
A staff member was sent to the Window to intercept the person climbing back to ridge-top, and after ensuring their own safety, two patrollers skied in towards the rider who had by now dug himself out of the debris and was waiting for assistance. It’s possible to ski West Bowl most of the way down and still get back to the bottom of the Summit lift, but the avalanche had carried this one person well below that point, so he and the patrollers skied down the one prominent gully below called Deep Throat and down to the Monkey Trail (aka Star Wars), which is the long forest traverse that returns people to the resort via Juniper Jungle. Once in the avalanche forecaster’s office, they were able to tell their story…
The two were both snowboarders from Calgary in their 20′s, and, deciding to take advantage of the untouched powder, entered West Bowl through the Window. Even in good snow years, you need to pick your way through a few rocks to get down to the actual bowl since the top ridge gets scoured clean by the wind. Once they did so, the first rider decided to do a quick traverse across the top of the slope, but as he did so, he hit a rock that forced him to turn down into the slope. He then decided that since he was on the slope he might as well keep riding. He only managed a few turns when he realised the slope was starting to slide around him. As this realisation sunk in, and before he had a chance to react, the slide suddenly increased in width so that it covered almost two-thirds the width of the bowl – about 250m.
The avalanche slid to ground, and while the snow depth was only about 40cm or so, the depth and width combined to make a large avalanche – a size 2.5, which is enough to bury or kill a person, and typically has a mass of 100 tonnes. The rider was swept up and carried down the slope, and he described being tossed around, alternatively ending up on top of the debris and being completely buried, over and over again. He “fought like crazy” and tried to swim to stay on top, but the avalanche was just too powerful. When it came to a rest about 250m below where it started, the rider was upright and buried up to his chest. He looked up slope to see that his friend had not been caught in the slide, and noticing that there was still snow that had not avalanched, yelled for him to climb back up to the top rather than try to get to him and possibly start another avalanche. He had managed to free himself from the debris by the time patrollers arrived.
As he recounted his story, an hour or more had passed since the incident, and as the adrenaline faded, he broke into tears realizing how lucky he was to be alive. Had he been completely buried, the lack of oxygen would mean he only had about fifteen minutes before brain damage was likely, and his chances of survival would have plummeted. It was lucky that a patroller observed what was going on just after it happened and was able to report it, but even then, getting to the victim in fifteen minutes or less would have been unrealistically optimistic.
Both of these riders had taken avalanche awareness courses in the past, but the message appears not to have sunk in (although there’s no doubt in my mind it has now). Also, as the victim and patrollers arrived at the start of the Monkey Trail, there was a group of eight snowboarders who had just come down Maintenance, another out-of-bounds run near but not quite as big as West Bowl. Not one of them had avalanche rescue gear, and one of them, upon seeing the rider with the patrollers, remarked “Riding alone? What an idiot”. If only he knew…
The two boarders were asked to come to the avalanche office to tell their stories, because there are always lessons to be learned from an incident like this for both those involved and others as well. No doubt they’ll tell their families and friends about this. They were not punished, since they did nothing wrong from a policy point of view. Our boundary is open, and these two crossed it in a way that contravened no laws or resort regulations. What they did contravene are the protocols for safe travel in avalanche terrain – among others, know the hazard, have and know how to use a beacon, shovel, and probe, tell people where you’re going, and have a plan.
The two left here today with a new attitude about avalanches, and we hope they’ll spread that experience to as many people as they can. Others haven’t been so lucky.
Another Epic Day at the Lake
Posted: January 8, 2009 Filed under: Avalanche Control | Tags: Lake Louise, Powder 2 Comments »While the snow may have let up a bit today, the smiles did not as skiers and boarders enjoyed another day of powder turns at Lake Louise. This recent storm, nearing a total of 50cm over the last few days, has added a third to a half of our total snowpack, and with forecasts calling varying amounts over the next three or four days, it doesn’t look like it’s about to stop.
The wind that was absent during the bulk of this storm finally arrived early this morning, and we started to see some of this new snow get moved around. If the wind keeps up, avalanche control teams will have a lot of work ahead of them since wind-deposited snow tends to make the hairiest avalanche conditions with the biggest consequences. By consequences, I mean destructive power. Over the last few days, we’ve been able to get some small loose snow avalanches started in steeper terrain, but these slides didn’t pick up much mass or run all that far. The snow remained loose, so even the avalanche debris made for good skiing.
When wind-blown snow is deposited on leeward slopes, it forms a slab, and this is due to a few things. First, as the wind moves the flakes over the ground, the delicate crystals break into smaller pieces, meaning they can be packed more densely. Also, the wind acts as a packer, pushing the pieces of crystals even closer together. The resulting slab becoms one big piece of snow, meaning that if one section of the slope wants to slide, the rest of the slope is more likely to go with it. The dense chunks of slab have the potential to cause much more damage than a loose snow avalanche, which can flow around objects more easily. Of course, if there’s enough volume, a loose snow avalanche can be very destructive.
Powder, powder, everywhere...8:30am, Summit.
With all of this new snow and the huge load it has now placed on the underlying snow layers, we will be heli-bombing for about half-an-hour tomorrow morning. I’ll be there, camera and all, and will post all about it in the next day or two (or three).
