AST 1 Flashcards
We are always hoping for them to change into … these are as a bunch of tennis balls in a tupperware bin with lots of surface area to make strong bonds to one another.
rounds. We can think of rounds
The good news or sometimes good news is our snowpack is always changing. Depending on …4 our snow crystals change form
weather, load, temperature & vapour movement
When we head out into popular backcountry areas sometimes the weak layers can get broken up from all of the snowboarder / skier traffic, we call this …
compaction “Tracks never mean that a slope is safe.”
We can identify a loose avalanche by:
The avalanche starting from a single point
Fanning out, creating a triangle shape
Loose snow avalanches do not need a …. It is the surface snow that slides and can sometimes step down to a slab if there is a buried weak layer below.
weak layer
… avalanches are the monsters that we hear about in the news. They tend to be larger than loose avalanches & release suddenly & all at once quickly turning a fun day into a potentially deadly one.
Slab
What we need for a slab avalanche to occur:
4
Weak layer
Slab
Trigger
Terrain steep enough to slide
T: This is the smooth wall that forms where the fracture line is at the top of the avalanche.
crown face
Our … snow avalanches happen mid winter when the snow is cold and the riding is good.
dry
..avalanches happen when the weather warms up, typically in the spring or if we have a mid winter warm u
.Wet
Some common signs that the snow is starting to become wet are; … (little balls of snow rolling down the surface) and snow falling out of trees.
pin wheeling
Avalanche sizing is …., each size is 10 times bigger than the previous size
exponential
It is challenging to estimate size & mass in the field so the easiest way to size an avalanche is by …
destructive potential
a size 1 can be deadly depending on what terrain we are in
t
What were the 3 things we needed for a slab avalanche ….
Weak layer
Slab
Trigger
terrain
T: A relatively thick cohesive layer of snow that slides during a slab avalanche
slab
what happens to weak layer when slab av
Collapses
what role does bed surface play in slab av
sliding surface
loose avalanches do not need a weak layer
t
Characteristics of a start zone: 2
Steeper slope angle
We usually observe the crown in the start zone of an avalanche path
T: The area covered by an avalanche in motion.
track
T: This is where it all comes to a stop.
run out zone
T: the sliding surface
bed surface
Remember we need a …3 for a slab avalanche to occur
slab, weak layer & trigger
6 natural triggers
Cornice fall New snow Sun Rain Wind loading Animals
5 human triggers
Snowmobiles Snowboarding & Skiing Snowshoeing Other machines – helicopters, groomers ect Explosives
Crusts create the perfect sliding surface.
t
when stability is the question … is the answer.
terrain
How can we mitigate our risk in the backcountry? Terrain choice!
matching our avalanche terrain to the avalanche conditions.
We like to call our cut blocks …
surface hoar farms. It is the perfect place for surface hoar to grow & is generally well protected from the wind by the trees left surrounding it
pros and cons of uniform slope
While uniform slopes can increase the consequence of a large propagating avalanche when the right conditions are present, the less convoluted a slope is, the more evenly distributed the snow will be, resulting in fewer common trigger points
… is the direction a slope faces
Aspect
how to find out aspect in the backcountry
When we are in the backcountry we can figure out the slope aspect by turning our back to the slope & holding a compass in front of us. Whatever that compass reads is the slope aspect.
Why is aspect important?
wind exposure, sun exposure & snow metamorphism.
3 ways sun influences
More likely to have a sun crust & / or temperature crust
Typically has a shallower snowpack then North aspects
Can undergo rapid warming, especially in the spring time
shaded 3?
Generally face North or East
Can preserve weak layers (such as surface hoar) longer then south aspects
More likely to have surface hoar or facets
S or N sun facing?
South facing: direct sun, wind scouring
North facing: Wing loading, shade
Our wet slab avalanches will either fail on a weak layer or when our snowpack becomes .. (the entire snowpack is 0 degrees) we will see these monsters side right to ground.
.isothermal
Signs that things are heating up:
pinwheeling
no snow on trees
Long term sun affect can result in a …
sun crust.
This means our typical or prevailing winds are …
westerly or south westerly winds.
T: is the aspect that faces the wind.
windward side
id we had westerly winds the … aspect would be the windward side
west
The opposite aspect of the wind direction is called ..
.leeward
Why are thin spots dangerous
. We may have a problem that is 2 meters down & difficult for us to trigger until we hit a thin spot where our problem might only be 30 cm down creating an easy trigger point that can result in a monstrous avalanche.
… occurs when the wind is blowing snow over ridges onto the leeward side.
Ridge top loading
.. occurs when the wind is transporting snow across the slope.
.Cross loading
So how do we know when something is wind loaded?
Does it look fat & pillowy?
Better than anything else around?
Very good chance it is wind loaded!
T: hey are essentially a large overhanging chunk of snow and when you are standing on them you are typically standing over air… not on a mountain.
cornices.
When do cornices collapse?
random
We do see an increase in cornice collapses at the start of the season when they are just forming & are still weak as well as at the end of the season when the sun is out and warming those bad boys up.
How do we know if we are on a cornice?
probe for earth
We have 3 main elevation bands we talk about when we are trip planning & looking at our avalanche bulletin.
alpine
treelike
below treeline
characteristics of alpine
Open slopes
No trees
Not all mountains have alpine
Contains the terrain that is usually the most exposed to sun, wind, cold, and precipitation
Start zones of large avalanche paths
characteristics of treelike
Enjoyable tree skiing
Nicely spaced trees
Exposure to sun, wind, cold, and precipitation is generally less here than in the alpine but greater than below treeline
Start zones of large avalanche paths or tracks of very avalanche paths can run through here
Can expect to find well preserved surface hoar
characteristics below treelike
Tight trees
The heinous part of the tour that you just need to get through
Covered by forest
Usually sees less sun, wind, cold & precip
Variable snowpack
Can see more crusts throughout the winter being lower elevation
Runout zones may clear out areas below treeline
… are a terrain feature we want to try to avoid in the backcountry. They are an unsupported roll under tension making for an extremely easy trigger point.
Convexities or convex rolls
.. are the opposite. The are a gradual mellowing out of the slope and give it lots of support.
.Concavities
Below are some examples of anchors
trees
rocks
when do trees hurt
If we only have one or two trees on the slope then they are a potential weak point. We can see Facets form around them and want to make it a habit to avoid the single tree on the slope.
when are rocks good vs bad
. If they are large enough to break up a weak layer and isolate it then they can help us out. But if we only have one rock or they create a shallow rocky spot then they turn into an easy trigger point.
Common trigger points:
Between anchors
Thin spots (potentially brings us that much closer to the weak layer)
Rocky outcrops
Convexities
The top of a steep slope
Locations where the snowpack has reached critical loading through wind loading or new precipitation;
Places where the snowpack is perforated by rocks or trees.
why thin spots dangerous
Lets say we have a deep persistent avalanche problem that is 2 meters down, tricky for us to trigger… until we hit a thin spot, lets say the wind has been blowing creating a thin spot. Now our deep persistent problem is only 50cm down
… refers to the changes we see within the snowpack as we move through terrain
Spatial variability
Factors that effect spatial variability:
elevation aspect ground cover slope shape terrain features
The trees along the edge of an avalanche path are called …
trim lines the trees get older the further away you get
Some common terrain traps we want to be able to identify & avoid when traveling in the backcountry are:
Gullies
Cliffs/rock bands
Thick trees
Creeks
Lakes
Roads
Sharp transitions
Boulder fields
Crevasses
If we can find a … to keep us higher & out of terrain traps that is our best option.
ridge or rib feature, high points
When riding down something we want our escape route to be a ..degree angle and ideally towards a high point or out of the avalanche path to a safe spot
45
… is when trees only have branches on one side. This is a vegetation clue we find in avalanche paths and run out zones.
Flagging
Natural avalanches possible, human triggered avalanches likely what rating
considerable = most callenging rating
moderate. Do not let your guard down as we can still see avalanches up to ..
size 2!
Loose wet management techniques
Avoid start zones & paths when the snow is moist
Wind slabs management techniques
Recognize and avoid areas where wind slabs have formed
In BC our weather comes from the west coast typically resulting in West or South West winds. When we have a cold snap we can expect to have … winds.
northerly
how can you recognize wind slabs
Can recognized by: appearance of snow surface, changes in snow surface hardness, hollow drum like sounds, shooting cracks
Persistent slabs managment techniques
Conservative terrain choices
Allow extra time to stabilize
Cautious approach to new terrain
Increase caution after storms or during warming periods
deep persistent slabs management techniques
Conservative terrain choices
Allow extra time to stabilize
Cautious approach to new terrain
Increase caution after storms or during warming periods
cornices management techniques
Approach ridges cautiously
Avoid travel on or near overhanging cornices
Limit exposure time on slopes with cornices above
Storm slabs
Conservative terrain choices during & after storms
wet slabs
Avoid start zones & paths when the snow is moist
loose dry
Avoid Terrain Traps
Avoid large steep slopes
Sluff management
glide cracks
avoid if you see one. A glide crack will fail at the ground, this is the easiest way to identify a glide crack. Not all glide avalanches start as a glide crack but it can be a good indicator. Our glide avalanches typically happen on wet smooth surfaces such as grass or smooth rock. We do not frequently see glide avalanches but when they do happen they tend to be very destructive since they take the entire snowpack with them.
what does SPAW stand for
special public avalanche warning
when are SPAW warnings issued
There is a particular avalanche hazard or persistent weak layer public is not picking up on
Blue bird conditions after storm periods and pent up powder stoke
Mountain Information Network (MIN)what is ti
Avalanche Canada created the MIN network as an information sharing tool for recreational users.
dif types of MIN reports
quick report, avalanche report,
incident report, snowpack report
The Avalanche Terrain Exposure Scale (ATES) was created by Avalanche Canada & Parks Canada as a tool for our pre trip planning. They went to popular areas throughout our province and rated the terrain into three categories; …3
simple, challenging & complex.
We always start our trip planning by looking at the Avalanche Bulletin & weather. From that information we pair it with the…
terrain that is appropriate for the conditions that day.
… is primarily low angle slopes, with limited exposure to avalanche paths & has lots of opportunities for us to reduce our risk.
Simple terrain
The biggest indicating factor that we are in Complex terrain is exposure to ….
multiple overlapping avalanche paths.
red and yellow in the trip planner?
The red lines are the main avalanche paths in that zone (not all).
Yellow line is the trail in.
signs of instability from the snow
Whumpfing
Shooting cracks
Recent avalanches
Pinwheeling
Weather factors that influence avalanche danger:
Precipitation
wind speed and direction
temperature
solar radiation
what time of precipitation is dangerous
Anything that comes in hard & fast is going to cause avalanche danger to spike immediately.
With smaller accumulation over time we could expect our avalanche danger to slowly rise.
what kind of temp dangerous
rapid change
If we have a rapid drop in temperature we could expect to start seeing …
Facets forming after a couple of days creating a weak layer for future snowfalls to sit on. We could see loose dry avalanches as our snow starts to facet out as well.
Our avalanche forecast is only as good as our …
weather forecast.
weather: Next I am going to use …. and type in the closest town. You can move the red spot around and place it on your exact location for the day.
.spotwx.com
T: scroll along with mouse to get temps, total snow amounts and cloud cover percentage. Further down the page you will find wind speed & direction.
GEM- LAM
Look at the top for elevation & make sure it is at the appropriate elevation band for your trip.
why look at RH
Relative humidity (we need a high RH for surface hoar to form)
..: How much snow has fallen in 12 hours. Measured in centimetres. Cleared in the morning and afternoon by ski patrol.
.HN board
…: Storm snow board. They will leave this board until the storm ends so we can have a total amount of snow accumulated from the storm as well as settlement rates.
HST board
…: Height of snow. Total amount of snow from the ground.
HS
…: A running total of the calculated hourly new snow.
Run tot calc hr new
…: This is our average wind speed in kilometres per hour
…: Wind direction. The number correlates to our compass.
….: the max gust in the past hour in kilometres per hour.
2 min avg WS KPH
Spot WD
Max gust KPH
What if our points are too high?
change terrain
safe travel habits
Safe spot to safe spot Reduce exposure to one on slope at a time Watch your buddies! Regroup and reassess. Be ready to act. Don’t tether gear to your body. Avoid terrain traps and cornices Escape route. void traveling above & below people.
Human behaviours differences?
familiarity acceptance commitment expert halo tracks social proof risk tolerance
positive human behaviours
communication
;leadership
patience
discipline
Personal performance check in:
sleep lifestyle injuries mental health confidence in skill set
When we talk about our avalanche risk we are talking about: 2 things
Avalanche Hazard + Vulnerability = Avalanche Risk
If we have a high level of uncertainty then we have low …
confidence.
The best example of uncertainty is when our danger rating is …
considerable.
They may go out & make tons of pour decisions but have luck on their side & don’t suffer from any sort of consequence :T
non event feedback
what does the third antenna do
The third antenna in the three antenna units has a very short range and assists with the fine search phase of the search.
The effectiveness of an avalanche transceiver is related to: 4
How it is worn.
How it is functioning.
The ability of the person operating it (PRACTICE, PRACTICE, PRACTICE!!)
Your companions
ONLY USE ..BATTERIES.
.ALKALINE
With our standard 3 antenna transceivers we will emit a signal as shown in the photo below.
We call these
flux lines (curve into them not straight)
The older transceivers do still work but they suffer from …2which can both be deadly in a rescue
signal overlap & interference
Some of our favourite features are:
on a transiver
group check
multiple burial indicator
marking function
Revert to send
The … symbol indicates that signals are received from additional buried subjects that cannot be isolated and entered in the list of buried subjects ye
+
When our transceivers are in send they need to be at least… cm away from any device that can interfere.
20
When our transceivers are in search they needs to be at least .. cm away from any device that can interfere.
50
how often do a transfer check
everyday
There are two ways we can complete a transceiver check.
group check
We also need to re do our transceiver check if we switch our transceivers between search / send weather it is for a practice scenario or real life rescue situation.
t
how to check without group check
The checker will turn their transceiver into search & stand far enough away that they do not pick up everyones transceiver signals all at once (5o meters).
The rest of the group will put their transceivers into send & keep them in send for the rest of the day.
The last person always checks the checker. They can switch into search mode & ensure the checker’s transceiver is properly sending. Then everyone stays in send for the remainder of the day.
Each person in the group will walk up to the checker 1 at a time.
When purchasing a probe make sure it is … meters!
3
The skiing / snowboarding air bags have the trigger on the left side of the bag so you would reach across with your …
right hand
What to do if caught in an avalanche
yell avalanche escape route Airbag or Avalung ditch gear swimming Grab trees or rocks Make an airspace & extend hand up Try to relax
a backstroke motion will help keep you afloat. If possible get your feet pointed downhill to help protect your head from trauma.
t
A couple of key points that regularly get missed:
choose a leader turn all trans to search asses for safety surface clues call for outside help
Looking at the chart above we can see our chances of survival drop drastically at the … minute mark.
15
have 10 min to save someone
The first phase of our transceiver search is called our …
signal search.
In this search phase our transceiver DOES NOT have a signal.
If you have multiple searchers & a large debris field spread out .. meters from each other & walk straight down
40
stages of search
signal search
course search
10 m check (slow)
fine search (knee height , no arrow)
course search is how far away
from 40 – 70 meters away.
fine search in what range
3 m
If our lowest number is 0.5 then they are roughly …deep.
50cm
steps
stop asses safety (future hazards) head count choose leader switch to search mode call for help (location, nature, name, phone number) determine where to search search for signal and visual cues yell for others when signal gotten call for probe and shovel follow signal to burial area shovel fast and effectively
how to probe
We want 2 hands on the probe & to keep our probe perpendicular to the ground.
Our spacing is 25cm from each probe hole (about a boot length).
We want to probe all the way down to the ground (or as deep as we can) so we get a clear indication when we get a strike.
probe perpendicular to slope
If the lowest reading on my transceiver is 4 meters, I know that I need to …
dig down a platform until my lowest reading is within 3 meters (my probe length).
Once we get a strike
When we get a strike we want to ..
.leave the probe in until we have that person out!
when do you hit mark
As soon as you get a probe strike you can hit the mark button (if you have it) on your transceiver. You do not want to hit it before the probe strike in case it is a false positive.
is the hardest part of the rescue & takes the longest (prepare to find this out first hand on the field day!). :T
shovelling
We shovel in a …, lining up a shovel length away from one another.
conveyor style
We are going to start at the probe unless it is a deep burial or we do not have the optimal number of shovelers, then we want to ..
.start back from the probe & shovel a ramp in towards them.
Always shovel on the … side of the probe.
downhill
We want to dig a … into the person so we can easily get them out of there. If we dig directly to them, we will end up with a hole straight down & will be unable to get them out.
ramp
We want to rotate every …minutes. It is best to get the second person to call the rotation.
2 – 3
If you have more than … people shovelling it can start to get crowded
4
rescue without transceiver
visual sweep
spot probing
probe line
Probe lines are time consuming & have never had a live recovery.
t
5 search phases
Visual sweep – clues, spot probing
Signal search
Coarse search
Fine search
Pinpoint search – probing
…2 are great tools to have in the backcountry. They allow you to send & receive messages as well as hit an SOS button
inReaches or SPOTS
Emergency communication devices
inReaches or SPOTS
radios ( VHF)
some essentials we need to carry with us when heading into the backcountry:
Transceiver
Probe
Shovel
Extra batteries
Airbag – if possible, is a great addition
Helmet
Emergency communication – SPOT or inReach
Radio
Repair kit – having a solid repair kit for your equipment is key. You do not want to call Search & Rescue for a broken binding.
Navigation – I use gaia & fat maps on my phone. If you are going to rely on phone apps be sure to pack a battery pack with you as well.
Bivy
Warm clothing
Food
Water
Fire Starter
First Aid Kit – have a bomber first aid kit. Buy one & then add what you need to it. We highly recommend taking some wilderness first aid training!
Avaluator
Solid group that communicates well, makes group decisions & has rescue skills dialled
decision making supports we can use
Avalanche Forecast ATES Ratings Avaluator Trip Planner: Weather Forecast: Avalanche Canada’s mountain weather forecast, environment Canada, Spot WX & weather stations to name a few! Information from locals the internet
… are what we are going to do to achieve that goal.
Objectives
Plan your Trip: We are going to start with our at home … chart to see what terrain is appropriate for the current conditions. From there we can use Avalanche Canada’s Trip Planner, guide books, blog posts & information from locals to decide where we want to go.
Avaluator
Evaluate slopes: before traveling up or down anything pull out your … & have a group discussion.
avaluator
levels of competency?
Unaware – No Training
Beginner – AST 1
Intermediate – AST 2
Advanced – Professional
Expert – Very experienced professional
