The Avalanche
Forecast
The Avalanche Danger Scale uses five progressively
increasing danger levels: Low, Moderate, Considerable, High and Extreme. It
indicates the likelihood of avalanches, how they might be triggered and
recommended actions in the back country. However,
the wording is very brief and does not include a meaningful indication of risk.
Below is an explanation of each danger level, including the transitions between
levels, signs of instability at each level and the implications of slope angle,
aspect and elevation.
Low
Travel
is generally safe. The snowpack is well bonded and natural avalanches will not
be seen except for small sluffs on extremely steep slopes. Human-triggered
avalanches are unlikely except in isolated locations in extreme terrain. The
danger will usually be from wind-driven snow in gullies and chutes or deposited
across very steep open slopes near ridge lines. Ski or board one by one as
smoothly as possible without falling if you suspect the formation of wind slab.
Be aware of shaded, north to east aspects where the danger may be transitioning
to Moderate. There are few fatalities at this danger level.
Moderate
This is the most difficult danger level for back country skiers and boarders to
assess snow stability. Many of the usual indicators such as cracks, settling,
whoomphing and signs of recent avalanche are absent, especially at the lower
end of the moderate level. Key indicators are any recent snowfall, and wind
deposition. Snowpack tests may help assess stability.
Conditions are generally favourable for travel providing routes are chosen
carefully. The snowpack is only moderately bonded on some steep slopes. Areas
of danger are usually restricted to certain types of terrain such as bowls and
gullies. The altitude, aspect and type of terrain where danger can be expected
are usually detailed in the Avalanche Forecast. Remote triggering is unlikely,
so you only need to be concerned about the steepness of nearby terrain
features.
Human-triggered
avalanches are possible. Ski or board carefully, one by one, in suspect terrain
and avoid high loading of the snowpack by spreading people out on the uphill
track. Carefully evaluate the stability of very steep slopes (steeper than 35°)
and aspects identified as potentially dangerous in the avalanche forecast
Be especially careful if the higher elevation band
in the forecast, or the danger on other aspects, is Considerable. There is a
significant difference in instability between Moderate and Considerable. Do not
get sucked onto higher, steeper and more dangerous slopes. Although naturally
triggered avalanches are not expected, ice climbers should watch out for the
sun warming steep collection zones above their climbs. If deep-slab
instability due to a persistent weak layer is mentioned in the Avalanche
Forecast, you need to pay careful attention to the terrain. Avalanches from
such a layer are not only likely to be large and extensive, but they are also
completely unpredictable. Unless you have specific local knowledge, keep off
large open slopes at this danger level if the forecast warns of a persistent
weak layer.
Considerable
Conditions have become much less favourable. The snowpack is only moderately or
poorly bonded over a much larger area of the terrain. Human triggering is
possible by a single skier on steep slopes and aspects mentioned in the
Avalanche Forecast. Remote triggering of avalanches is possible, so the maximum
steepness of the slope above you should be used when deciding if you want to
continue.
Instability indicators mentioned in Moderate danger
above will likely be present. Back country touring at this danger level
requires good route-finding skills, and experience in recognising dangerous
terrain and evaluating slope stability. Keep to slopes of less than 35°,
especially slopes at the altitude and aspect indicated in the Avalanche
Forecast. Remember that remote triggering is possible. Typically the scree fans
at the bottom of gullies start out at around 30° and the slope steepens as it gets
higher. Keep off such slopes at this hazard level. The remarks about persistent
weak layers in the previous section on Moderate danger level also apply to this
danger level.
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Reports such as the above showing stripes as areas of localised
"considerable" risk to North and South within a moderate NW to SW
aspect and considerable risk NE to SE. This is the sort of thing that it's easy
to become complacent about as it’s a common feature of the Scottish winter. You
might very obviously if you have any sense, stay well clear of the NE to SE
aspects but wander into a high-risk situation on descent on the N to S aspects.
The majority of avalanche incidents in Europe occur in these moderate to
considerable forecast days as they occur most frequently in the season and folk
become complacent (the familiarity heuristic) and that's why route choice
approaching a climb and thinking about descent options prior to leaving and
during a trip as wind and weather change should become part of your thinking.
High
Conditions have become dangerous, most often as a result of significant amounts
of new snow, snowfall accompanied by wind or the snowpack becoming isothermal
and threatening wet-snow avalanches. The snowpack is poorly bonded over large
areas and human triggering is likely on steep slopes (steeper than 30°). Remote
triggering is likely and large natural avalanches are to be expected.
Stay
on slopes that are flatter than 30° for any part of the slope and be aware of
the potential for avalanches from slopes above. If you do decide to walk ski or
board on less steep slopes, be very aware of the surrounding terrain to avoid
inadvertently crossing the bottom of steeper slopes or cutting down a steep
convex rollover.
Usually
this level of hazard is only present for a few days at a time. The smart back
country traveller will stay in simple terrain until conditions improve. If you
are caught out on a multi-day trip you may have to dig in and wait for travel
conditions to improve and the avalanche danger to lessen.
These stripes in the avalanche forecast. My take is to think of them as landmine strips blown by the wind, lurking in eddies from cross loading when the wind blows across as well as down or over a slope, the colour of them is the sensitivity of the pressure plate to you the trigger. If there are enough of them the explosion will propagate setting of others, or if the surrounding slope is weak enough then it will slide with it. As you can see there are areas of High on slopes with a localised "considerable" and "considerable" risk to the South. A lethal combo of narrow safe travel options making for events that will take lives if you don't tread warily and navigate with extreme care.
Extreme
Extreme danger levels are rare in Scotland as usually this level is associated
with buildings and roads or alpine villages under threat, and usually the
result of unusually large amounts of new snow. The snowpack is weakly bonded
and unstable. Numerous large avalanches are likely. The weight of the new snow
can trigger avalanches on layers buried deep in the snowpack. Natural
avalanches can release on slopes of less than 30° Back country touring is not
recommended and often impossible. Avoid all avalanche terrain and keep well
away from avalanche path run outs.
Some Basic Snow Science
Learn some basic snowcraft. Just the simple stuff and its principles
The signs and symbols in a detailed
avalanche forecast where a snow pit and tests are carried out by a forecaster
such as a Scottish Avalanche Service Observer
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The avalanche probe is crucial to pinpoint a victims location |
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Learn how to dig effectively as time is oxygen and your shovel is the key to living or dying. Can you resuscitate your friend or provide first aid if they are injured? Avoid Groupthink In psychology group think or risky shift behaviour is well known in groups and most of us will be aware that we have given in to it or even encouraged it. I strongly believe that in avalanche incidents in Scotland this groupthink or risky shift has become the biggest education issue and maybe why we see large group incidents or group events as occurred in the Cairngorms when two separate groups were avalanched last winter. Much has been made of the quick response from folk training in the corrie who helped. And good on them. What I am about to say is not a reflection on these helper folks choices, as I am sure they stayed in safe terrain. The “however" bit though is that just by being there and numbers increase with lots of MRT's training, and groups under instruction, then a larger "Groupthink" takes place. Groups less experienced or not under instruction maybe feel safe, what McCammon labels as Social Facilitation. I would call this a “risky shift". It's often this way in the climbing and skiing honey pots such as the Northern Corries where folk gather. Aonach Mor or Stob Coire nan lochan in Glencoe are other places. Even if the waggon wheel of death shows Red on these slope aspects, they are still the places to be seen by the instructor masses who are now at the height of their annual gatherings with paying students. These are the places instructors are familiar with, and therefore where less experienced folk feel safer with an apparent safety in numbers. They maybe went there when they were on a course. Group thinking on a large scale perhaps. This kind of stuff has been getting applied to avalanche instructor
training for a while. Do current winter mountain training schemes
include enough if anything on this sort of thing? I put this as a
question, as I am certainly not in a position to know, and maybe it is
already covered. What I do know is that there is nothing that can change the
pretty piss poor odds if buried and that pretty universally all of us
involved in avalanche education are trying to jump forward and get to
"no rescue". Pre-Drop/Trip Checklist Angle Anchors Aspect Altitude Angle. Most avalanches are triggered on slopes roughly between 32 and 45 degrees. Below 32 degrees victim triggered slab avalanches are less common and above this angle slopes purge more frequently. The "Sweet Spot" where most avalanches are triggered is about 40 ish degrees with over 90% of victim triggered slides occurring in a 7-degree range bracketing that sweet spot. You can conclude from this that angle is a really important part of slope assessment and subtle changes of angle on a given slope can have major consequences, therefore route choice and awareness of slope angle is really important. Modern phone apps make judging the angle much easier. Rule of thumb for me personally is that as the avalanche forecast risk for a given altitude and aspect goes up - then the angle and altitude of what you ski comes down. More recent research has shown convexity/concavity to be less important than angle. Anchors. What is the snowpack connected to. Have you been following the weather and SAIS forecast. Are there weak layers within the snowpack. Trees and rocks can hold a slope as your friend or can be weak spots as your enemy where sun heat or hoar frost has gathered. Subtle angle changes create trigger points at these places. Trees are also natures cheese grater if you get taken into them. Also ask yourself what the slope you are on is linked into from the underlying snowpack. Unstable snowpacks can often propagate a collapse into nearby slopes and draw an avalanche into lower angled terrain. Aspect. Which compass direction does the slope you want to ski or travel
face. Like angle, subtle changes in aspect can take you from a safe slope
onto a loaded one. Carry a compass and learn about "slope aspect"
as both a navigation and safe travel tool. The SAIS forecast gives you
the necessary hazard warning for compass direction, but you need to apply it
on the ground accurately. Again some phone apps can help with this and even
give you the area forecast. Altitude. You can see by looking at the SAIS forecast that the hazard risk
is most often greater with altitude, even in Scotland. The rate of snow
deposition is higher with height, and the wind is also stronger increasing
side loading of slopes. On dodgy days stay lower as well as skiing lower
angled slopes. Complexity Commitment Consequences Complexity. As mentioned above. Be aware of subtle changes in angle and aspect and that localised instabilities are hidden and like a landmine can link one triggered mine to a chain reaction and a small slide gathering surrounding instabilities into a major avalanche event. Learn to read mapping for subtleties of terrain features and how snow may be affected and think safety by pre imagining what could go wrong. If it's a complex route, then it’s often unsafe as there are too many unknowns. Learn to know what you don't know! Commitment. Always have a plan "B" so that if conditions change or are not what you expected you have another safer option. Commitment to a slope can mean no bail out options, i.e., having nowhere to go. If you look at the pro's on YouTube, they choose their line so they can bale out onto a spine and have good runouts and that's where the next "C" comes into play - consequences. Consequences. If it’s an amber light's on in your head so you’re in a go/no go
process, then add consequence into the thought mix. Are there crags,
hollows, stream beds, trees or any other terrain features that could shred
you or trap you if there is an avalanche. Transceiver, shovel, probe and/or
airbag will not stop you getting your limbs ripped apart from tree's, your
head humped like mince, or with an inflated airbag under a few hundred tons
of snow. Airbags are good with a save rate of seven more people per hundred
victims - but only if the runout is good. More up to date North American
stats also show that many more people die from two of the triple
"H" than was thought. Hypoxia and Hypercapnia kill quickly and any
browse of excellent news sites like piste hors will tell you that even folk
dug out very quickly with advanced life support don't often survive. (Triple
"H" syndrome is Hypoxia, Hypercapnia which is re breathing your own
carbon dioxide and Hypothermia. In fact, it’s not so much the lack of oxygen
as the hypercapnia that makes survival so poor). 15 mins as often shown in
survival graphs is way too optimistic. You need to search faster and dig
faster which means practice more! |
10 Simple Rules:
The
key to avalanche safety is proactive risk management through consistent habits,
not just relying on equipment. These simple rules aim to reduce the chances of
being caught in an avalanche in the first place.
1. One at a Time: Only one person should traverse a potentially hazardous slope at a time, with others waiting in a safe zone to perform a rescue if needed. This minimizes the load on the snowpack and ensures a rescuer is available.
2. Never Cross Above Others: Avoid crossing uphill of others to prevent triggering an avalanche that could bury them.
3. Plan an Escape Route: Before entering a potentially hazardous area, identify a safe escape route. Use "slope cuts" (traversing across the slope with speed) to increase the chances of outrunning a triggered avalanche.
4. Cross High: If crossing an avalanche path, cross as high as possible to minimize the amount of snow that could bury you if a slide occurs.
5. Avoid Going First: Whenever possible, avoid being the first person to traverse a potentially hazardous slope. Let natural triggers (like cornices) or other means test the slope's stability first.
6. Start Small: Test snow stability on smaller, safer slopes before venturing onto larger, more dangerous ones. This allows you to gather data and assess the risk progressively.
7. Be Obsessed with Consequences: Constantly evaluate the potential consequences of an avalanche in a given location. Consider what's below, above, and how the slope is connected to other terrain.
8. Communicate: Maintain open and honest communication within a group. Discuss plans, observations, and concerns to avoid misunderstandings and poor decisions.
9. Pause at Critical Decision Points: Slow down and carefully consider decisions, especially at critical junctures. Avoid rushing and ensure everyone is on the same page before proceeding.
10. Carry and Know How to Use
Equipment and practice with it: Carry essential avalanche safety equipment
(beacon, shovel, probe) and be proficient in its use. This mitigates
vulnerability if caught in an avalanche.
Key take away points:
These are guidelines, not a guarantee of safety.
Consistent practice of good habits is crucial for
minimizing risk.
Focus is on prevention and proactive risk
management.
Equipment is important, but secondary to good
decision-making and good travel habits.
Digging and Recovery
Considerations
● If
possible contact mountain rescue or ski patrol as soon as possible but don’t
let it delay your search for a companion as you are the companions best chance
of survival in a full burial. The definitive locating device is the
transceiver/beacon. Carry one that's digital that has 3 antennas. And with
charged batteries. New ones like the Ortovox “Diract” Voice are
good
● The
definitive location device is a probe. Carry one that's at least 240cm,
preferably 270cm+ The Ortovox Carbon 280+ pfa is
a good one
● The
definitive initial airway opening device is a shovel. Carry one that's alu, has
a good blade and can convert to a hoe if possible. The Ortovox Pro alu III is a
good one
● RECCO
might not save your life but might save a rescuers as being searchable reduces
time on scene and rescuer exposure to secondary avalanche. Given the longest
Scottish survival is 27 hours it might also save your life. Be Searchable
● Digging
out a victim you should attempt to dig in toward the victims chest and head
from the side, not above so as not to compress any air pocket. Dig in from
below approximately the same distance down slope from the depth showing on your
probe mark. If possible have more than one probe in place to outline a victim
unless of course its needed for searching for others.
● Take
care when uncovering the mouth and nose and have an experienced avalanche
rescuer assess Airway of the ABC's. If you’re not experienced
class it as open. Clear it of debris. Expose the chest and begin CPR as soon as
is practicable. Data suggests starting CPR before complete extrication (if
possible) improves outcomes. It’s also hard work so get other climbers and
skiers on board to take turns if they offer help.
● Avalanche
Victims may have Trauma; they will also be Hypothermic. So all buried avalanche
victims should have further heat loss prevented. Trauma and Hypothermia plus
blood loss (contributing to Hypothermia) is a lethal triad.
● Other
victims in a multi burial may be very nearby, or under the first recovered
victim. If many victims are buried some may survive for a very long time due to
air spaces among other bodies. A salad of transceiver distances can be confusing.
Get as many probes in to make contacts as you can.
● Multiple
burials are resource hungry, messy, require leadership and discipline. Fail to
practice these scenarios and it’s a shitstorm. Spread limited resources too
wide and everyone might die. If limited person power get the first located
victim out first and fast before moving on. You might at least save one.
Note: Pulse and Breathing may be very hard to detect. Not finding these
vital signs does not mean that they are not present. You just may not be able
to detect them. Many cases of survival are documented where CPR had been
continuous for 5+ hours. Make it good CPR
If
you start resuscitation, regardless of how long a victim had been under, you do
not cease unless rescuers' lives are in danger or the decision is arrived at
from a consensus of experienced avalanche rescuers and a medical consensus that
it's futile.
Chest
compression's may have to be interrupted for a short time because of evacuation
and rescue procedures, although continuous unbroken CPR is the goal.
Do
not swallow the myth that most Scottish avalanche victims die from trauma. Many
undoubtedly do, but we should focus on saving those that do not have
catastrophic fatal injuries. There are no studies to prove the Scottish trauma
myth, and plenty of stats from similar maritime snowpacks where studies have
been done to support that trauma isn't the only killer and only a small
percentage. Hypoxia, Hypercapnia and
Hypothermia are the biggest killers and obviously injuries add to mortality due
to blood and heat loss. 3 three “H’s”
are why time is critical.
As
a personal opinion this trauma fallacy could cost lives by giving the
impression that being searchable and companion rescue is a waste of time for
Scottish mountaineers. Follow the ICAR
(international rescue commission) guidance and
you will not go wrong.
Prehospital
core temperature measurement in a hostile environment will be unreliable.
Unresponsive victims will often be about Swiss Staging HT3 level, and so
Severely Hypothermic. Use the Swiss
Staging Scale to describe levels of hypothermia.
Learn it.
Final rescuer thoughts. Responsive
survivors may not complain of injury as they are very cold, and unresponsive
victims who may be alive can also be assumed to have occult trauma. Careful
handling onto a vacuum matt immobilises the spine, closes the book of the
pelvis, and prevents limb fractures from moving. A vac matt also provides good
insulation. Better to use this as a standard operating procedure as it’s easy
to miss an injury in an avalanche rescue recovery.
NO AVALANCHE OR HYPOTHERMIA VICTIM IS DEAD UNTIL THEY ARE WARM AND DEAD
