AVALANCHES
The Celestial Mountains Tour Company does not undertake mountaineering
or winter sports activities - so 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 travelling on the Bishkek-Osh road
during wintertime.
GENERAL RULES FOR AVOIDING AND SURVIVING SNOW AVALANCHES
AVALANCHE CONDITIONS - RULES OF THUMB
- Snow avalanches may release tremendous forces and are a serious threat
to the winter traveler. If you are involved with one and, in particular,
if you are buried, you will probably not survive. It is most important
that you learn enough about avalanches to avoid them and to increase
your chances of survival if you are caught.
- There are many factors that contribute to avalanche conditions. The
possible combinations and inter-relationships of these factors are countless
and the forecasting of avalanche danger will often require the evaluation
of a very complicated situation. However, there are many practical things
you can learn that will be helpful to you.
- 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 FACTORS
- Slope 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.
Slope profile - Convex slopes are the most dangerous. 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 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 FACTORS
- New Snow - You should always suspect dangerous conditions with a foot-of
new snow. However, conditions can be dangerous with less snow.
- Rapid snow settlement is a favorable sign. Look for settlement cones
around tree trunks and over rocks. Lack of settlement is a danger sign.
- Loose, dry snows avalanche easily. Moist, dense snows tend to settle
rapidly, but during windy periods 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.
- 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 FACTORS
- 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.
- 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.
- Beware of a rapid rise or fall of temperature. 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 authoritues.
Route Selection and Precaution - Rules of Thumb
Route Selection
- The safest routes are on ridge tops and slightly on the windward side
away from cornices.
- Windward slopes are almost 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.
Avalanche Involvement - Rules of Thumb
Precaution
- Only one person at a time on a suspect slope: all others 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, carry a sectional probe.
If 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 "whumping"
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.
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