2004-03-10 00:00:00, Tom Chalmers
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At a recent public avalanche workshop in Golden, one of the invited speakers, Grant Statham, said that the most important backcountry decisions are made before leaving the house. He was referring to more than making sure that planks are waxed and safety gear is packed and lunch is sufficiently tasty. Like most experienced backcountry shredders, Grant understands how important it is to gather current avalanche and weather information, sit down with a map, and plan a trip. Every line has a window of conditions that make it ripe and safe; a little advanced knowledge of what is happening out there is invaluable in finding the right combo of safety and sweetness. Planning ahead ensures that no precious vert will be wasted, that every turn will be worth savouring.
Bearing this in mind, the public avalanche bulletin is one of the best resources at your disposal. The Canadian Avalanche Association webpage (and its foreign counterparts) provides links to bulletins, put out by various agencies, that blanket the mountains of western Canada. Snow profiles, explosive control results, avalanche observations, weather data, and lots of backcountry travel and ski testing, are the data collected by everybody in the avalanche business, all day every day. This makes for mountains of the quality information needed to figure out what is going on out there. Public avalanche bulletins are the end result of a long chain of information gathering and experienced avalanche forecasting, analysed and condensed for you, the backcountry shredder, to help you bag the best.
So read the bulletin before heading out, and understand it.
(Click on the date links below to view the corresponding avalanche bulletin for that day in a popup window)
Glacier National Park is home to Rogers Pass, and some of the most consistently good shredding anywhere. On par with the consistent shredding is the excellent bulletin produced by the Avalanche Control Section at Rogers Pass. Conditions in the Pass became a real mixed bag through the middle of February, and a look at the bulletin though this time reflects what was and is happening.
On Valentines Day, February 14, the avalanche danger rating was at Moderate in the alpine, treeline, and below treeline, which means that, natural avalanches are unlikely, human triggered avalanches are possible. In other words, things are looking pretty good, but there may be bad spots. The bulletin notes that south facing slopes will be at Considerable danger in the afternoon; the sun gets strong by mid-February, which, on a warm day, can soften up the upper snowpack enough to make it loose enough to avalanche. The sun can also beat on big cornices and make them crack and fall. The bulletin also mentions some minor weaknesses in the upper pack that could be a problem in wind loaded areas. Under the Travel Conditions, the bulletin notes where the wind loaded areas are, and points out that the south slopes will have sun crust (and crappy skiing). So, based on reading this, the good Valentine s day lovin would be on slopes facing NE to NW that are not under big cornices and do not show signs of wind action.
On the next day (Febuary 15), the danger ratings did not change. The bulletin notes that cooler temperatures will have reduced the danger due to afternoon sun. The interesting part is the discussion about a little new snow that has covered a layer interface on sun crust and/or surface hoar. An interface is where two snow layers meet. If these layers do not bond together quickly, avalanche conditions may result, where the upper snow slab may slide on the lower layer. Surface hoar is a kind of snow crystal that grows on the snow surface when the nights are cold and calm and clear, the winter version of dew. When buried, surface hoar can form a thin weak layer of fragile crystals, sandwiched between the old snowpack and the new snowfall, that may persist for a while, creating a bad situation for avalanche surprises. A surface like sun crust can get pretty hard, as anyone who has skied is probably painfully aware. Studies have shown that avalanche release is more likely when there is an interface between snow layers that are way different in hardness. This includes new snow over sun crust , and also old snow under surface hoar under new snow. So, this bulletin indicates that, if more snow falls, the new snow slab is gonna get bigger, and may have trouble bonding to the surface created by the clear sunny weather on and before Valentines day. So watch out if it snows!
By the way, in the avalanche biz, we measure snow hardness by what you can poke into it, like a fist or one finger or a pencil. That is what the bulletin means when it is talking about 1 finger to pencil hardness suncrust.
By Febuary 16, things are starting to change for the worse in Rogers Pass. New snow is starting to build up on the sun crust/ surface hoar interface, which is starting to collapse in snowpack tests. Obviously, a weak layer collapsing under a snow slab is bad. The surface hoar was seen mostly around treeline before it got buried, so the danger rating has been bumped up to Considerable at treeline to reflect this, natural avalanches are possible, and human triggered avalanches are probable. The bulletin notes that, because there is only 15 to 20cm of soft, loose new snow on the sketchy layer, slabs have not have time to build to scary proportions. But the Considerable rating shows that it is in the mail.
On February 17, the mail has arrived. The previous loose new snow and more overnight have been shoved around by high winds from the south, creating slabs of snow that are now of dangerous size. And the sun crust/ surface hoar combo lies lurking beneath to make it easier to trigger bigger avalanches. Easier and bigger = bad. Alpine and treeline danger is now at Considerable. The bulletin describes a lack on natural activity that is surprising. Whenever the bulletin uses the word surprising to say anything other than surprisingly good skiing, you should not have a warm fuzzy feeling in your tummy when you head out the door. Backcountry skiing under surprising conditions must be undertaken with care! The bulletin backs this up when it says that, danger levels are on the rise. High danger levels could be reached within hours. Otherwise, a slower rise is eminent... Fast or slow, rising avalanche danger is rising avalanche danger, and only a punter would not heed this kind of message from a professional avalanche forecaster. On this day, reading between the lines might reveal that the safe skiing would be below treeline to avoid the surface hoar/ sun crust/ wind slab heinousness. Furthermore, north facing slopes below treeline would probably be the bestest softest turns, where the sun did not blast the surface and shed tree bombs earlier in the week.
Over the next few days, things at Rogers Pass started to shape up just as the bulletin predicted. The slabs on the surface hoar and sun crust started to produce a variety of test results, and, most importantly, skier triggered avalanches big enough to spank ya. It is worthwhile to go and read the bulletins for February 18 onward and see for yourself.
One thing becomes clear from an exercise like this, and that is how very valuable a public avalanche bulletin is to any backcountry traveler, from the newbie on snowshoes to the old bearded hippy in leather tele boots. The bulletin is chock full of good information that has been gathered and interpreted in a fashion that anyone can use, for any place in the mountains of western Canada. So read up before you go!
A final note. Reading the bulletin and planning accordingly can go a long way to reducing the risk of avalanche problems and getting good turns. But starting the day in the right spot is still only the first step. The mountains need to be respected and watched while you are out there traveling, and the bulletin cannot do that for you. Unexpected conditions or situations can always arise, and that is where you need to be able to exercise your own judgment to be safe and have fun.
Happy bulletin boarding! Man, that is my worst pun yet. Sorry.
-TC
Previous articles by Tom Chalmers
Tree Wells
Terrain Management
Testing Avalanche Beacons
Season's Greetings Biglines!
An Interview with Tom Chalmers
Backcountry Evac
Septic to Epic
Remembering a Legend: Craig Kelly
Addicted to Porn
So read the bulletin before heading out, and understand it.
 |
Diagram courtesy of The Canadian Avalanche Association |
(Click on the date links below to view the corresponding avalanche bulletin for that day in a popup window)
Glacier National Park is home to Rogers Pass, and some of the most consistently good shredding anywhere. On par with the consistent shredding is the excellent bulletin produced by the Avalanche Control Section at Rogers Pass. Conditions in the Pass became a real mixed bag through the middle of February, and a look at the bulletin though this time reflects what was and is happening.
On Valentines Day, February 14, the avalanche danger rating was at Moderate in the alpine, treeline, and below treeline, which means that, natural avalanches are unlikely, human triggered avalanches are possible. In other words, things are looking pretty good, but there may be bad spots. The bulletin notes that south facing slopes will be at Considerable danger in the afternoon; the sun gets strong by mid-February, which, on a warm day, can soften up the upper snowpack enough to make it loose enough to avalanche. The sun can also beat on big cornices and make them crack and fall. The bulletin also mentions some minor weaknesses in the upper pack that could be a problem in wind loaded areas. Under the Travel Conditions, the bulletin notes where the wind loaded areas are, and points out that the south slopes will have sun crust (and crappy skiing). So, based on reading this, the good Valentine s day lovin would be on slopes facing NE to NW that are not under big cornices and do not show signs of wind action.
On the next day (Febuary 15), the danger ratings did not change. The bulletin notes that cooler temperatures will have reduced the danger due to afternoon sun. The interesting part is the discussion about a little new snow that has covered a layer interface on sun crust and/or surface hoar. An interface is where two snow layers meet. If these layers do not bond together quickly, avalanche conditions may result, where the upper snow slab may slide on the lower layer. Surface hoar is a kind of snow crystal that grows on the snow surface when the nights are cold and calm and clear, the winter version of dew. When buried, surface hoar can form a thin weak layer of fragile crystals, sandwiched between the old snowpack and the new snowfall, that may persist for a while, creating a bad situation for avalanche surprises. A surface like sun crust can get pretty hard, as anyone who has skied is probably painfully aware. Studies have shown that avalanche release is more likely when there is an interface between snow layers that are way different in hardness. This includes new snow over sun crust , and also old snow under surface hoar under new snow. So, this bulletin indicates that, if more snow falls, the new snow slab is gonna get bigger, and may have trouble bonding to the surface created by the clear sunny weather on and before Valentines day. So watch out if it snows!
By the way, in the avalanche biz, we measure snow hardness by what you can poke into it, like a fist or one finger or a pencil. That is what the bulletin means when it is talking about 1 finger to pencil hardness suncrust.
By Febuary 16, things are starting to change for the worse in Rogers Pass. New snow is starting to build up on the sun crust/ surface hoar interface, which is starting to collapse in snowpack tests. Obviously, a weak layer collapsing under a snow slab is bad. The surface hoar was seen mostly around treeline before it got buried, so the danger rating has been bumped up to Considerable at treeline to reflect this, natural avalanches are possible, and human triggered avalanches are probable. The bulletin notes that, because there is only 15 to 20cm of soft, loose new snow on the sketchy layer, slabs have not have time to build to scary proportions. But the Considerable rating shows that it is in the mail.
On February 17, the mail has arrived. The previous loose new snow and more overnight have been shoved around by high winds from the south, creating slabs of snow that are now of dangerous size. And the sun crust/ surface hoar combo lies lurking beneath to make it easier to trigger bigger avalanches. Easier and bigger = bad. Alpine and treeline danger is now at Considerable. The bulletin describes a lack on natural activity that is surprising. Whenever the bulletin uses the word surprising to say anything other than surprisingly good skiing, you should not have a warm fuzzy feeling in your tummy when you head out the door. Backcountry skiing under surprising conditions must be undertaken with care! The bulletin backs this up when it says that, danger levels are on the rise. High danger levels could be reached within hours. Otherwise, a slower rise is eminent... Fast or slow, rising avalanche danger is rising avalanche danger, and only a punter would not heed this kind of message from a professional avalanche forecaster. On this day, reading between the lines might reveal that the safe skiing would be below treeline to avoid the surface hoar/ sun crust/ wind slab heinousness. Furthermore, north facing slopes below treeline would probably be the bestest softest turns, where the sun did not blast the surface and shed tree bombs earlier in the week.
Over the next few days, things at Rogers Pass started to shape up just as the bulletin predicted. The slabs on the surface hoar and sun crust started to produce a variety of test results, and, most importantly, skier triggered avalanches big enough to spank ya. It is worthwhile to go and read the bulletins for February 18 onward and see for yourself.
One thing becomes clear from an exercise like this, and that is how very valuable a public avalanche bulletin is to any backcountry traveler, from the newbie on snowshoes to the old bearded hippy in leather tele boots. The bulletin is chock full of good information that has been gathered and interpreted in a fashion that anyone can use, for any place in the mountains of western Canada. So read up before you go!
A final note. Reading the bulletin and planning accordingly can go a long way to reducing the risk of avalanche problems and getting good turns. But starting the day in the right spot is still only the first step. The mountains need to be respected and watched while you are out there traveling, and the bulletin cannot do that for you. Unexpected conditions or situations can always arise, and that is where you need to be able to exercise your own judgment to be safe and have fun.
Happy bulletin boarding! Man, that is my worst pun yet. Sorry.
-TC
Previous articles by Tom Chalmers
Tree Wells
Terrain Management
Testing Avalanche Beacons
Season's Greetings Biglines!
An Interview with Tom Chalmers
Backcountry Evac
Septic to Epic
Remembering a Legend: Craig Kelly
Addicted to Porn
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At a recent public avalanche workshop in Golden, one of the invited speakers, Grant Statham, said that the most important backcountry decisions are made before leaving the house. He was referring to more than making sure that planks are waxed and safety gear is packed and lunch is sufficiently tasty. Like most experienced backcountry shredders, Grant understands how important it is to gather current avalanche and weather information, sit down with a map, and plan a trip. Every line has a window of conditions that make it ripe and safe; a little advanced knowledge of what is happening out there is invaluable in finding the right combo of safety and sweetness. Planning ahead ensures that no precious vert will be wasted, that every turn will be worth savouring. <a href="../articles_readmore.php?read=1502">View Article</a>
At a recent public avalanche workshop in Golden, one of the invited speakers, Grant Statham, said that the most important backcountry decisions are made before leaving the house. He was referring to more than making sure that planks are waxed and safety gear is packed and lunch is sufficiently tasty. Like most experienced backcountry shredders, Grant understands how important it is to gather current avalanche and weather information, sit down with a map, and plan a trip. Every line has a window of conditions that make it ripe and safe; a little advanced knowledge of what is happening out there is invaluable in finding the right combo of safety and sweetness. Planning ahead ensures that no precious vert will be wasted, that every turn will be worth savouring. <a href="../articles_readmore.php?read=1502">View Article</a>
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