Avalanches
We, in the Celestial Mountains Tour Company, do not undertake mountaineering or winter sports activities – so our clients are unlikely to be involved in avalanches. However, avalanches can, and do, occur at times and places where you may be exposed to risk – such as traveling on the Bishkek-Osh road during wintertime.
The weather in recent years has not been typical. In 2003, for example, there was a lot of rain and unseasonably late snow – even a “White Easter” in Bishkek. More importantly, this led to a number of landslides and avalanches (referred to locally as “snow dragons”). The most serious was a landslide at Karatarik, a village of between 200 and 300 people in the Uzgen District, about 100 km east of Osh. Thirty eight people died including seventeen children. Avalanches fell on the main Bishkek-Osh road blocking the road and causing delays. Also a couple of large avalanches (one of 1,250,000 cubic meters of snow) closed the main road between Bishkek and Naryn near the Dolon Pass in late of April.
In subsequent years there have been more such cases. In 2004, the Bishkek-Naryn road was blocked for ten days. Other villages have also been isolated from time to time.
GENERAL RULES FOR AVOIDING AND SURVIVING SNOW AVALANCHES
AVALANCHE CONDITIONS
Avalanches of snow may release tremendous forces and they can be a serious threat to the winter traveller. Many people who are involved with one and, in particular, those who are buried in one, do not survive. It is most important to know enough about avalanches in order to avoid them and to increase the chances of survival if caught in one.
- There are many factors that contribute to avalanche conditions with numerous possible combinations and inter-relationships which make the forecasting of avalanches difficult.
- The following general guidelines must not be accepted as absolute rules. They are only an organized list that a thinking observer can use to develop an opinion about the presence and degree of danger.
TERRAIN:
- Steepness – Slopes of 30-45 degrees (60-100%) are most likely to avalanche, but anything from 25-60 degrees (46-170%), or even more or less, can do so under certain conditions.
- Profile – Convex slopes are the most dangerous. Concave slopes are less dangerous, but they can, and sometimes do, experience avalanches.
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Aspect
- North-facing slopes are the most likely to avalanche during the middle of winter. South-facing slopes become dangerous in the spring and during sunny days as the sun begins to rise higher in the sky.
- Leeward slopes are dangerous because wind borne snow adds to rapid accumulation of depth; also, the hard, hollow- sounding wind slab may develop there. Windward slopes generally have less snow and benefit from wind compaction.
- Ground cover – Areas with large rocks, trees and heavy brush help to anchor the snow on the mountain. Smooth, grassy slopes are much more dangerous.
SNOW:
- New Snow – even thirty centimeters of new snow lying on appropriate terrain can create dangerous conditions.
- Settlement – Rapid snow “settlement” is a favorable sign. Look for settlement cones around tree trunks and over rocks. Lack of settlement is a danger sign.
- Type of snow: Loose, dry snows avalanche easily. Moist, dense snows tend to settle rapidly, (but during windy periods these can also be 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 being favorable for stability and smooth surfaces such as sun crusts being unfavorable.
- Layering – A loose, underlying snow layer is more dangerous than a compacted one. You can check this with a ski pole, ski, or snowshoe.
- Crystal Types – 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.
WEATHER:
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Wind – Sustained winds of 15 m.p.h. and over during a storm cause danger to increase rapidly.
- Snow plumes from ridges and peaks indicate that snow is being moved onto leeward slopes during clear weather and that dangerous conditions may be developing, even though it is not storming.
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Temperature
- Snow persists in an unstable condition longer under cold temperatures. It settles and stabilizes more rapidly during warmer weather, near or above freezing.
- High and rapidly rising temperatures in the spring months may result in wet snow slides, particularly from south- facing slopes.
- Rapid changes in temperature (either rising or falling), can create dangerous conditions – even shadows creeping across a slope may change temperatures enough to create dangerous conditions.
- Rate of Snowfall – 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.
- Sluffing – Sluffing indicates that stabilization is taking place.
- 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 leeward slope, conditions are probably dangerous; if the snow cover cracks and the cracks run in the snow, slab avalanche danger is high.
INFORMATION:
- Check weather forecasts. Contact the local authorities.
SELECTING A SAFE ROUTE
- The safest routes are on ridge tops and slightly on the windward side away from cornices.
- Windward slopes are al:most always safer than leeward slopes.
- If you cannot travel on ridges, the next safest route is out in the valley away from the bottom part of slopes.
- Stay high and near the top if you must cross dangerous slopes or avalanche paths; if you can see old or new avalanche fracture lines, be sure to avoid them and other similar areas.
- Go straight up or down if you must ascend or descend a dangerous slope; do not make traverses back and forth across it.
- Take advantage of areas of dense timber, ridges or rocky outcrops as islands of safety. Use them for lunch and rest stops and spend the least time possible out on the open slopes.
- Snowmobiles must not travel across the lower part of slopes; especially long, open slopes or known avalanche paths.
- Look for, and obey, all signs or other warnings of avalanche danger.
PRECAUTIONS TO TAKE
- Only one person at a time on should be a suspect slope: all others should watch the person that may be in danger.
- Remove ski pole straps, ski safety straps, loosen all equipment, put on mitts, cap, and fasten clothing before being exposed to avalanche danger.
- Carry and use an avalanche cord and carry a sectional probe.
IF YOU ARE CAUGHT IN AN AVALANCHE
- Discard all equipment.
- Get away from your snowmobile.
- Make swimming motions, try to stay on top and work your way to the side of the avalanche.
- Do not cry out or open your mouth after you are in the avalanche.
- Get your hands in front of your face and try to make an air space as you are coming to a stop.
IF YOU ARE THE SURVIVOR
- Mark the place where you last saw the victim.
- Search for him in the fall line and directly below the last seen point.
- Search the area of greatest deposition first.
- You are his best hope for survival. Do not desert him and go for help unless help is only a few minutes away.
- Remember, you must consider not only the time for you to get to help, but the time required for help to return, and the victim has only a 50% chance of surviving for an hour.
- If you go for help, mark the route so a rescue party can follow it back.
Avalanche quick checks
- What have the weather conditions been over the past few days? Recent heavy snows?
- Can you observe any wind loading on the slopes?
- Do you have a good sense of the snowpack? Have you performed any snowpit or shear tests?
- Have you noticed many fracture lines, heard “humping” or cracking sounds, or hollow noises in the snowpack?
- Are you keeping an eye on the orientation and steepness of the slopes as you cross them?
- Are you lingering in gullies, bowls, or valleys?
- Noticed any recent avalanche activity on other slopes similar to the one you are on?
- If a slope looks suspect, are there alternative routes?
Extra precautions to take
- If there is no alternative to crossing a suspect slope, do so one person at a time to minimize risk.
- When descending or ascending a slope, try to stay as far to the sides of a potential avalanche chute as possible to decrease your chances of being caught if an avalanche runs.
- Be aware of the condition of those in your party. If someone is tired, hungry, or cold they may not be using their best judgement.
- Remain constantly aware of changing weather or temperature conditions, particularly if your trip will last more than a few hours.
- Consider avalanche rescue equipment, such as beacons, ski-pole probes, and collapsible shovels, as a necessary part of your gear.
Bishkek