****Before the slide*** _______________________________________________________________***After
the slide***
Safety:
If you do not already consider one of your primary life goals safety
it had better become important when you venture into backcountry skiing
and avalanche terrain. The two are virtually synonymous. Avalanches
have a tendency to clear out the forest and fill in with snow and
do it again. And the alpine is the starting zone often below the wind
drifted ridge. Bruce Tremper boils it down quite well when he equates
that 95% percent of the time the snow on avalanche terrain is stable,
if you ski 100 days in avalanche terrain and mind not the random stability
you will get slid, launched, swept away into the cheese grater river
of snow five times. If you have never been in this river swimming
you can only imagine the power, more like concrete slurry in the end.
Imagine swimming down a steep, mountain slope in a current of cold
concrete and you get the idea.
So that is what we are trying to avoid when talking avalanches: starting
a slide on a slope we can safely ski otherwise or avoid entirely.
Avalanche slopes have an angle that is conducive to skiing. Every
time you turn on a slope it shocks the snowpack which may cause a
slide to start. The slope angle professionals tell us that the mean
of the bell curve for avalanche accidents is 38 degrees: wear that
inclinometer around your neck and measure your slope angles, it may
save your life…seriously. Below 35 degrees avalanches become
less frequent as they do above 45 degrees. Below 30 degrees they are
quite rare as starting zones but will slide from a release above very
readily.
So if you pay micro attention to the slope angles that you ski, you
will reduce the risk of stepping on a trigger and going down the hill
in an avalanche. Triggers can be slow to find in some cases. Hence
there is a set of golden rules to skling avalanche terrain. First
has got to be wearing a beacon, avalung and helmet for your self protection,
and carrying a shovel and probe in your pack. Secondly in avalanche
terrain spread out the group. Obviously more weight is more likely
to trigger slides. Spread out the group on both uptrack and while
skiing. This makes groups of 2-4 ideal. With good safety coverage
and not too many to induce bunching, three to four in a group can
cycle through breaking trail chores and trade off skiing runs first
or last with the best efficiency and safety.
Secondly expose only one person at a time to avalanche terrain or
if that is totallyt impractical due to the length or size of the feature
being crossed or skied spread out as much as possible, this might
mean ten minutes on the uptrack and giving each other three or more
full minutes on the descent. Use your watch to measure time as we
are all excited to hit the powder. A third rule is to operate from
a position of safety. Before dropping into the avalanche zone, and
while waiting for your partner to ski, it is imperative that you are
in a safe location preferably, but secondarily with a view of the
skiers on the run. Likewise when you finish skiing through avalanche
terrain move away to the sides, onto a hillock, or into the trees
so that you are no longer exposed to a slide from above. Keep your
skis pointed in the direction of further safety in case you need to
move quickly. Only through constant diligence towards recognizing
exposure to avalanche threats can we reduce the chances of being slid,
buried, and not having a partner capable of rescue. Be aware when
you are breaking the rules and make others in your party aware as
well. Remember this is your and your partners' lives at stake and
there should be no powder frenzy like at the ski area. Other rules
while skiing into avalanche terrain include being aware of escape
routes, stack tracks or figure eight if possible, and ski the fallline.
Try to avoid falling especially during more considerable avalanche
hazard when you know the snowpack is touchy and reactive. Ski with
at least one partner whenever possible; take considerably less risk
when alone. There is always the option of avoiding avalance terrain
altogether.
Trigger points are an important part of realizing safety in avalanche
terrain. Steep rollovers, convex slopes, rock islands, and steep headwall
entries, and wind loading areas are all potential trigger spots. Be
constantly on the lookout for them. Pay close attention to crossloaded
spots that build up isolated heavy bulges that are not anchored well
below or on the sides. Know when you step from safe terrain to hazardous
terrain as it is always a matter of just a few feet. Trigger points
are very important as we well know the cases where many skiers have
hit a run before it releases. Use this knowledge to judge your line,
they are all a bit different. Be careful during wind events as slopes
can quickly become a considerable hazard that were moderate before
the wind.
Trees can afford a good margin of safety if they are on a slope between
25-35 degrees. Above 35 do not expect the trees to do much to inhibit
a slide if the snow is unstable. Furthermore trees are very dangerous
when you are caught in a slide. They will break you up and kill you
quicker than all else save cliffs and gully features. When skiing
avalanche terrain it is very important not only to assess the slope's
steepness and hazard at that time but what is the survivability of
being caught in a slide. If the run is a big, concave run with a long
low angled runout with no trees and rocks or cliff bands then if you
are slid you have a much higher probability of escaping death or serious
trauma then if the slope has trees, rocks, cliffs or an abrupt gully
or flat ending. Think about all these things before commiting to avalanche
terrain.
Warning signs that the snowpack is unsafe or of marginal safety include
whumpfing of the snow on any steepness. This is the upper snowpack
collapsing a weak layer(s) and settling. This often happens in early
season but can be experienced at any time of season. Shooting cracks
from your skis is another obvious sign of instability. Natural avalanches
show that snow stabilty is quite bad. Knowing there is buried surface
hoar is another sure indicator of instability. This fact makes touring
before the next storm and getting an idea of local surface hoar production
a very good idea. Surface hoar grows as plate-like and feather-like
crystals on the surface of the snowpack during clear nights. It is
obvious to see when advanced and less so during the first day of production.
Assuming there is some on sheltered terrain if you have had clear
nights is reasonable. Wind and sun are good surface hoar busters.
If your latest storm came in with little wind preceeding it, then
assume that you have some surface hoar underneath especially on shaded
aspects. When breaking fresh trail observe the way the snow breaks
up between your skis and when making switchbacks. If it is blocky
and cracks when turning then you know that stability is not great.
Don't let any clues go unnoticed. When snow is settling and falling
from trees this is a good sign that the snow is settling, not that
it is safe. Steeper slopes may have evidence of regular sloughing.
This is a good thing as it means the snow is regularly equalizing
and sliding to reach stasis. This regular sloughing encourages settling
and stabilizing.
Snowpits: ******Movie*****
Movie
Digging into the snowpack to determine stability has become a necessity
for the backcountry traveler. If you want to play and do it safely
digging pits right next to your line will give you the best look at
the stability there. Of course the pit digger needs to know what to
look for in the snow profile 6 feet deep. What causes most avalanches
is a bed surface failure, otherwise known as a collapse of the weakest
layer affected by your skis and weight. The layer loses all its bonds
in a brief few moments, and then the slab on top is free to slide
if the stauchwall at the bottom allows the slab to pop out of the
snow and start ripping down the mountain with an ever increasing velocity
depending on the slope length. Long avalanche paths aka great ski
runs can produce large avalanche, small slopes can produce smaller
but equally dangerous slides to the skier.
Use test slopes to get a feel for stability. Small steep sections
along the trail and during the day can tell you a bit about the stability
of larger more deadly slopes. Never use just one isolated stability
test to determine your go or no go decision for a slope on a tour.
Spend the time to gather evidence the whole day to your objective
and remember that saying no will save your life.
Snow
pit evaluation tests:
Shovel Shear test- identifies shear layers in the pit
Compression test-identifies how much compression is necessary to
create failure at various layers. Stuffblock and Shovel Tap
Rutschblock Test- similar to the compression test with a full size
column isoltae and a skier used as the compression force.
Tilt test-
A test to isolate weaknesses in the upper 18 inches of snow.
Generally avalanches start to slide on open and open treed slopes.
If you can ski downhill through the glade it is open enough to slide,
look for branches missing to determine slide history. So your lane
is open enough to ski and steep enough to be exciting; voila avalanche
country. No wonder the number of deaths has been steadily increasing
amongst skiers, boarders and snow mobiles, it is really fun to play
where the avalanche dragon lies. There are really good books about
avalanche awareness and learning more detail about avoiding them.
Golden rules to reduce risk in avalanche terrain:
-Spread out the party on the uptrack
-Ski one at a time while in avalanche terrain with 3 minute rule.
-Wear a tested beacon and have experience using it. Wear a helmet
and avalung.
-Carry a shovel, and a probe, in a pack with emergency gear
-Wait in safety zones and communicate effectively with your partners
-Do not ski avalanche terrain when danger rating is considerable or
higher
-Dig a series of snow profile pits throughout the season to learn
about snow
stability.
Safety is a constant group and personal dialogue where we must continually
monitor ourselves as much as the conditions. Pay attention to your
instincts. While you are inexperienced it is good if you usually feel
nervous in avalanche terrain. Only through years of studying regularly
avalanche danger signs will you truly begin feeling somewhat comfortable
in avalanche terrain; otherwise you will be best served by being scared
and cautious.
The most rewarding aspect to a tour is having spent a safe and exciting
day in the mountains and heading home or to the tent to a good meal
and sleeping comfortably with those you love safe around. Skiing avalanche
terrain is often very scary at first and dealing with this fear factor
as well as the excitement factor is every bit as challenging as analyzing
the snowpack for signs of instability. Dealing with your ego is every
bit as important as determining a sense of snow stability.
If avalanche terrain is safe for travel 95% of the time, what are
the conditions that produce slides. As may be obvious heavy snowfall
and winddrifting of snow are the most obvious factors in producing
instability. Beware of snowstorms and high winds at ridge tops and
across snowfields.
The other major factor increasing snow instability is rapid warming.
This most frequently occurs through two factors solar gain and rain.
Heavy rain may be the most dangerous sign of impending doom, fortunately
it is not a desirable time to ski as well.
But while the storm rolls in and blankets your favorite lines with
a fresh icing and the cold powder sits there waiting for your tracks
it is also adjusting to itself and the snow it landed upon. These
conditions can be the best deep powder days of your life, like never
truly known at the ski area . With snow blowing up around your chest
and neck and frosting your nose and view, deep powder is a unique
substance to ski. After a day or three new snow will be more settled
compared to fresh snow, making multiple day snowstorms a must for
the fat skis on moderate angled terrain.
In snow science the professionals have identified a number of lemons
that seem to recur in the avalanches that get people and that the
pros monitor.
These lemons include:
-a weak layers in the top meter of snow,
-a thin weak layer, more than a single step in hardness difference
between
adjacent layers,
- the prescence of near surface recrystalized snow (facets).
So now we have the basics of knowing avalanche terrain, knowing avalanche
weather, and how to avoid being avalanched. Experience is the key
and instead of writing anymore on it, get some more experience, and
read some of the great books available with a click of the mouse.
In Montana check Chapter One Bookstore in Hamilton they will order
for you. In a few days only you will have the book.
Staying Alive In Avalanche Terrain Bruce Tremper
Avalanche Safety for Climbers and Skiers Tony Daffern
The ABCs of Avalanche Safety Dick LaChapelle
Further Online Resources:
Gallatin
Nat'l Forest Tutorials Links
Gallatin Nat'l Forest
Videos
Utah
Avalanche Center Tutorial
Utah
Center You Tube Channel
Surviving
an Avalanche Strategies
*******************************************************************************************************
Backcountry skiing and travel in the wild mountains is a potentially
dangerous sport. Hazards range from trees, rocks, ice, avalanches,
stream crossings, lake crossings, wind, blizzards, sunshine, cold,
to snowmachines, ego, over exertion, hunters, mountain lions, bears,
wolverines, wolves, and other skiers. The publisher and editor encourage
all backcountry users to have sufficient skills, knowledge, and judgement
in their use of the infomation in this website. Using the information
herein is solely at the discretion of and is the responsibility of
the user/reader and we expect all to understand the inherent risks
in following any of the tour descriptions found on these pages. Different
snow years will produce differing conditions, and of course different
times of year and day will alter conditions as well. Most of the tours
in this website are subject to skier triggered avalanches. Beware
of these conditions. There may be errors in the descriptions and you
may have trouble finding the exact locations described. Use good judgement
and communication. Rely on yourself and your party for this judgement
and also for self rescue. Know when to turn back; leave the ego for
book reading and time spent with family. -eds
