Medic-5150
November 17th, 2009, 10:03 AM
I started this because I just read Brody's comment on the LHC run about "something doesn't feel right". That was something they stressed last night. REI had a clinic lsat night Colorado Mountain school and Boulder Rock Club. They provided very basic information on determining where an avalanche is most likely and how to spot and avoid these areas. Being new to the area, especially snow, it was just about all new information to me.
Here's some of the things they mentioned. Over 50% of avalanches happen on slopes between 30 and 45 degrees....Get yourself an inclinometer. Within that range, over half of them occurred between 35 and 40 degrees. To put that into perspective, that's black diamond and double black diamond. Anything steeper or shallower than that tended not to slide.
When hiking, cross country skiing etc look for signs of an avalanche within the last 48 hours, as this is obviously signs that the snowpack is unstable. Avoid going out if the snow rate is over 1 inch per hour or there has been 24" within the past 24 hours. Another big thing they stressed on was wind loading. The wind can move snow much quicker than an storm could ever drop it. While you're hiking check the wind, see where it's blowing and see where it's loading snow. They had technical terms for this...I don't remember them...
Signs of areas where an avalanche is like would be areas where trees only have limbs on one side, skiing/hiking/snowmobiling above cliffs. Rocks and such that could create a shallower snowpack which would create weaker bonds and increase the likelihood of a slide. That all too famous fissure in the snow. That's a sign that an avalanche has occurred, but was not steep enough to slide. Or that Whumping sound we've all heard as we ski over an area. Or a hollow sound. These last two indicate an avalanche but in an area where it is not steep enough to slide. The whumping is caused by a thin layer between the snowpack and the top portion breaking/crushing. Big sign of unstable snow, don't get on anything steeper! As spring approaches, the snowpack becomes more stable due to the thawing and freezing overnight, it makes it more uniform. However, during the day when it is thawing, it can be very unstable until it begins to freeze again
For safety measures, keep an eye out on what you may be forced into if you are cot in a slide. i.e. a forest, over a cliff, rock garden, deep valley, etc. For those that may spend a lot of time in avalanche country http://www.rockymountainxtreme.com/rmx_main.htm It's like a parachute. You pull a string and those bags inflate keeping you on top of the avalanche instead of being buried. Advisable to go with someone, as SAR teams probably won't get to you in time if you are caught. After 15 minutes, survival rates plummet. Beacons, probes, and shovels are very beneficial as well!
I'm by no means an expert on this and don't claim to be. Just passing on some stuff I learned last night. Colorado Mountain School offers several classes on the subject if anyone's interested further!
Here's some of the things they mentioned. Over 50% of avalanches happen on slopes between 30 and 45 degrees....Get yourself an inclinometer. Within that range, over half of them occurred between 35 and 40 degrees. To put that into perspective, that's black diamond and double black diamond. Anything steeper or shallower than that tended not to slide.
When hiking, cross country skiing etc look for signs of an avalanche within the last 48 hours, as this is obviously signs that the snowpack is unstable. Avoid going out if the snow rate is over 1 inch per hour or there has been 24" within the past 24 hours. Another big thing they stressed on was wind loading. The wind can move snow much quicker than an storm could ever drop it. While you're hiking check the wind, see where it's blowing and see where it's loading snow. They had technical terms for this...I don't remember them...
Signs of areas where an avalanche is like would be areas where trees only have limbs on one side, skiing/hiking/snowmobiling above cliffs. Rocks and such that could create a shallower snowpack which would create weaker bonds and increase the likelihood of a slide. That all too famous fissure in the snow. That's a sign that an avalanche has occurred, but was not steep enough to slide. Or that Whumping sound we've all heard as we ski over an area. Or a hollow sound. These last two indicate an avalanche but in an area where it is not steep enough to slide. The whumping is caused by a thin layer between the snowpack and the top portion breaking/crushing. Big sign of unstable snow, don't get on anything steeper! As spring approaches, the snowpack becomes more stable due to the thawing and freezing overnight, it makes it more uniform. However, during the day when it is thawing, it can be very unstable until it begins to freeze again
For safety measures, keep an eye out on what you may be forced into if you are cot in a slide. i.e. a forest, over a cliff, rock garden, deep valley, etc. For those that may spend a lot of time in avalanche country http://www.rockymountainxtreme.com/rmx_main.htm It's like a parachute. You pull a string and those bags inflate keeping you on top of the avalanche instead of being buried. Advisable to go with someone, as SAR teams probably won't get to you in time if you are caught. After 15 minutes, survival rates plummet. Beacons, probes, and shovels are very beneficial as well!
I'm by no means an expert on this and don't claim to be. Just passing on some stuff I learned last night. Colorado Mountain School offers several classes on the subject if anyone's interested further!