D
Duke
Well-known member
I found a good article with decent general avalanche info, very good information contained in it. Worthwhile to take the time to read. I wonder if anyone has ever made a decent in depth avalanche awareness video. Wouldn't replace an avy course but would be a good eye opener for some.
Take the time to go to an avalanche course, well worth it.
Avalanche Conditions
"Lean snow winters are often dangerous avalanche winters. That's because the thin snow cover in November and December turns to weak sugar snow. When heavier snow falls in late December and in January, that's when the problems begin. The snowpack becomes the classic house of cards, with a layer of slab snow sitting on top of the sugar snow. The slightest disturbance can bring it down," says Knox Williams, director of Colorado Avalanche Information Center (CAIC).
Williams insists the keys to fewer avalanche deaths are education and prudence, especially when people visit deep, rural regions.
Doesn't technology find and save most of those caught in an avalanche? "Yes and no," says Williams. "Yes, because avalanche beacons have saved several lives the last few years by allowing a buried victim to be found quickly; but also no, because once a person is caught in an avalanche, luck may play a larger role in survival than rescue equipment. Less than half of the people with beacons who are buried by an avalanche actually survive. That's because a beacon cannot save you if you are severely injured or buried deeply.
"Wouldn't it be better to not get buried at all?" Williams continues. "The key to survival is avoiding accidents altogether through knowledge and good decision-making in the backcountry."
Well, how serious is the threat of an avalanche anyway? How worried should you be?
Because snow avalanches are really a whole season's snow released down a mountainside at once, an avalanche may release tremendous forces and are a serious threat to the winter traveler.
If you like skiing or snow-related activity, it is very important that you learn how to avoid being in an avalanche, and increase your chances of survival if you find yourself in one.
There are literally a ton of factors that can contribute to avalanche conditions. The possible combinations of factors are endless, and the forecasting of a possible avalanche will often require the evaluation of extremely complicated situations. However, there are many practical things you'll read about here that can be helpful to you.
It's important: both experience and statistics show that fully-buried avalanche victims who are still alive when the avalanche stops moving must usually be found and dug out within 15 minutes to have any reasonable chances of survival. To tell the truth, in North America the chances of an organized professional rescue team arriving in that time frame are pretty slim unless the accident happens in an area where an avalanche safety program operates. But even in such areas, alerting a team and quickly mounting an organized rescue may well take longer than the 15-minute window of opportunity.
Therefore the efforts of those who survive or witness an accident (often called 'self rescue techniques' by those in the know) are absolutely crucial to the survival of any victims. If those on the scene fail to at least locate any buried victims, it is unlikely that the organized rescue teams will arrive in time to make a live recovery.
So the makeshift locating and possible rescue procedures should be understood and practiced by those planning a few days in a winter wonderland, in order for the event of an avalanche self rescue to truly be fast and efficient.
Every situation has some rules all its own, but these general guidelines should give you a good footing (no pun intended) when you're trying to cope with the fallout (pun here is intended) of an ugly avalanche.
Factors of Terrain
*Slope steepness - Slopes of 30-45 degrees are the ones most likely to avalanche, but anything in the neighborhood of 25-60 degrees can do so under certain conditions.
*Slope profile - Convex slopes are clearly the most dangerous; stay away from them when you can, especially during the period from late December thru January. Concave slopes are less dangerous, but they can - and sometimes do - avalanche.
*Slope aspect - North-facing slopes are the most likely to avalanche during the dreaded middle of winter. But south-facing slopes can become dangerous in the spring and during sunny days, as the sun begins to rise higher in the sky.
Also, slopes that garner snow during windy conditions are dangerous because wind-borne snow adds to their rapid accumulation; the hard, hollow-sounding wind slab may develop there. However windward slopes (those slopes sitting into the wind) generally have less snow and benefit from wind compaction.
*Ground cover - Areas with large rocks, trees and heavy brush here and there are a good help in anchoring the snow on the mountain. Smooth, grassy slopes are much more dangerous.
What about Snow?
*New Snow - You should especially suspect dangerous conditions with a foot or more of soft, new snow. However, conditions can always be hairy. Stay on your guard whenever you're around snow-covered mountain regions.
Rapid snow settlement is actually a favorable sign. Look for settlement cones around tree trunks and over rocks. Moist, dense precipitations create those sought-after settlement cones, because the snowfall settles rapidly.
Lack of settlement is a danger sign; loose, dry snows avalanche easily. During windy periods all bets are off however, as even these snows can suddenly become very dangerous.
*Old Snow - When the old snow depth is sufficient to cover natural anchors, such as rocks and brush, additional snow layers will slide more readily. Also, the nature of the old snow surface is important. Rough surfaces are of course favorable for stability; any smooth surfaces, such as sun crusts, are not.
A loose, underlying snow layer is more dangerous than a compacted one. You can check this with a ski pole, ski, or snowshoe.
Ever wonder why you see those pro skiers banging the ends of their poles into a deep snow before beginning a day of skiing? Now you know.
*Crystal Types - All snow is not created equal. You can readily observe general crystal types by letting them fall on a dark ski mitt or parka sleeve. Small crystals, such as needles and pellets, result in more dangerous conditions than the usual star-shaped crystals.
The Weather
*Wind - Sustained winds of 15 m.p.h. and over during a storm cause trouble fast. Snow plumes from ridges and peaks indicate that wayward snow is being blown onto these slopes during clear weather and that dangerous conditions may be developing, even though it is not storming.
*Temperature - Snow persists in an unstable condition longer under cold temperatures. It settles and stabilizes more rapidly during warmer weather that's near or above freezing.
But beware high and rapidly rising temperatures in the spring months. They may result in wet snow slides, particularly from south- facing slopes.
*Beware of any rapid change in temperature. Shadows creeping across a slope may change temperatures enough to create dangerous conditions.
*Snowfall Rate - Snow falling at the rate of one inch per hour or more increases avalanche danger rapidly.
General Observations
*Old Slide Paths - An avalanche path that has slid once will slide again. Look for old scars in timber and avoid steep gullies and steep, open slopes.
*Recent Avalanche Activity - Look around; if you see new avalanches you should suspect dangerous conditions.
*Sound and Cracks - If the snow sounds hollow, particularly on a slope full of wind-blown snow, conditions are probably dangerous; if the snow covers cracks that are found running in the snow, slab avalanche danger is high.
, AA
Take the time to go to an avalanche course, well worth it.
Avalanche Conditions
"Lean snow winters are often dangerous avalanche winters. That's because the thin snow cover in November and December turns to weak sugar snow. When heavier snow falls in late December and in January, that's when the problems begin. The snowpack becomes the classic house of cards, with a layer of slab snow sitting on top of the sugar snow. The slightest disturbance can bring it down," says Knox Williams, director of Colorado Avalanche Information Center (CAIC).
Williams insists the keys to fewer avalanche deaths are education and prudence, especially when people visit deep, rural regions.
Doesn't technology find and save most of those caught in an avalanche? "Yes and no," says Williams. "Yes, because avalanche beacons have saved several lives the last few years by allowing a buried victim to be found quickly; but also no, because once a person is caught in an avalanche, luck may play a larger role in survival than rescue equipment. Less than half of the people with beacons who are buried by an avalanche actually survive. That's because a beacon cannot save you if you are severely injured or buried deeply.
"Wouldn't it be better to not get buried at all?" Williams continues. "The key to survival is avoiding accidents altogether through knowledge and good decision-making in the backcountry."
Well, how serious is the threat of an avalanche anyway? How worried should you be?
Because snow avalanches are really a whole season's snow released down a mountainside at once, an avalanche may release tremendous forces and are a serious threat to the winter traveler.
If you like skiing or snow-related activity, it is very important that you learn how to avoid being in an avalanche, and increase your chances of survival if you find yourself in one.
There are literally a ton of factors that can contribute to avalanche conditions. The possible combinations of factors are endless, and the forecasting of a possible avalanche will often require the evaluation of extremely complicated situations. However, there are many practical things you'll read about here that can be helpful to you.
It's important: both experience and statistics show that fully-buried avalanche victims who are still alive when the avalanche stops moving must usually be found and dug out within 15 minutes to have any reasonable chances of survival. To tell the truth, in North America the chances of an organized professional rescue team arriving in that time frame are pretty slim unless the accident happens in an area where an avalanche safety program operates. But even in such areas, alerting a team and quickly mounting an organized rescue may well take longer than the 15-minute window of opportunity.
Therefore the efforts of those who survive or witness an accident (often called 'self rescue techniques' by those in the know) are absolutely crucial to the survival of any victims. If those on the scene fail to at least locate any buried victims, it is unlikely that the organized rescue teams will arrive in time to make a live recovery.
So the makeshift locating and possible rescue procedures should be understood and practiced by those planning a few days in a winter wonderland, in order for the event of an avalanche self rescue to truly be fast and efficient.
Every situation has some rules all its own, but these general guidelines should give you a good footing (no pun intended) when you're trying to cope with the fallout (pun here is intended) of an ugly avalanche.
Factors of Terrain
*Slope steepness - Slopes of 30-45 degrees are the ones most likely to avalanche, but anything in the neighborhood of 25-60 degrees can do so under certain conditions.
*Slope profile - Convex slopes are clearly the most dangerous; stay away from them when you can, especially during the period from late December thru January. Concave slopes are less dangerous, but they can - and sometimes do - avalanche.
*Slope aspect - North-facing slopes are the most likely to avalanche during the dreaded middle of winter. But south-facing slopes can become dangerous in the spring and during sunny days, as the sun begins to rise higher in the sky.
Also, slopes that garner snow during windy conditions are dangerous because wind-borne snow adds to their rapid accumulation; the hard, hollow-sounding wind slab may develop there. However windward slopes (those slopes sitting into the wind) generally have less snow and benefit from wind compaction.
*Ground cover - Areas with large rocks, trees and heavy brush here and there are a good help in anchoring the snow on the mountain. Smooth, grassy slopes are much more dangerous.
What about Snow?
*New Snow - You should especially suspect dangerous conditions with a foot or more of soft, new snow. However, conditions can always be hairy. Stay on your guard whenever you're around snow-covered mountain regions.
Rapid snow settlement is actually a favorable sign. Look for settlement cones around tree trunks and over rocks. Moist, dense precipitations create those sought-after settlement cones, because the snowfall settles rapidly.
Lack of settlement is a danger sign; loose, dry snows avalanche easily. During windy periods all bets are off however, as even these snows can suddenly become very dangerous.
*Old Snow - When the old snow depth is sufficient to cover natural anchors, such as rocks and brush, additional snow layers will slide more readily. Also, the nature of the old snow surface is important. Rough surfaces are of course favorable for stability; any smooth surfaces, such as sun crusts, are not.
A loose, underlying snow layer is more dangerous than a compacted one. You can check this with a ski pole, ski, or snowshoe.
Ever wonder why you see those pro skiers banging the ends of their poles into a deep snow before beginning a day of skiing? Now you know.
*Crystal Types - All snow is not created equal. You can readily observe general crystal types by letting them fall on a dark ski mitt or parka sleeve. Small crystals, such as needles and pellets, result in more dangerous conditions than the usual star-shaped crystals.
The Weather
*Wind - Sustained winds of 15 m.p.h. and over during a storm cause trouble fast. Snow plumes from ridges and peaks indicate that wayward snow is being blown onto these slopes during clear weather and that dangerous conditions may be developing, even though it is not storming.
*Temperature - Snow persists in an unstable condition longer under cold temperatures. It settles and stabilizes more rapidly during warmer weather that's near or above freezing.
But beware high and rapidly rising temperatures in the spring months. They may result in wet snow slides, particularly from south- facing slopes.
*Beware of any rapid change in temperature. Shadows creeping across a slope may change temperatures enough to create dangerous conditions.
*Snowfall Rate - Snow falling at the rate of one inch per hour or more increases avalanche danger rapidly.
General Observations
*Old Slide Paths - An avalanche path that has slid once will slide again. Look for old scars in timber and avoid steep gullies and steep, open slopes.
*Recent Avalanche Activity - Look around; if you see new avalanches you should suspect dangerous conditions.
*Sound and Cracks - If the snow sounds hollow, particularly on a slope full of wind-blown snow, conditions are probably dangerous; if the snow covers cracks that are found running in the snow, slab avalanche danger is high.
, AA
