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Key Words: HazardAssessment, Stability Evaluation,Intui-
tion
ABSTRACT
There is a lot of literature written about avalanchehazard
evaluationand forecasting, butit'sseldomfromtheper-
spectiveofaskiarea avalanche worker.Because ofthe
large area ofavalanche terrain thatthey deal with,back
country, heli-ski and highway forecasters usually have to
rely on weather and snow pit data from limited areas and
interpret itforlarge areas, when making theiravalanche
hazard assessments.
Many avalanchebooks address avalanchehazardevalu-
ation from the perspective ofback country skiers,focus-
ing on the slopes an individual wants to ski.This is simi-
lar to ski areas, except ski area workers have the advantage
of using explosivesand knowing the historyofthe slide
paths, both short term and long term.Ski areas have to be
very thorough in there assessments and hazard reduction
procedures because the slopes willbe opened to numer-
ousavalanchetriggerswhohavelittleornoavalanche
knowledge.
INTRODUCTION
Backcountryandhighwayforecastersusesnowand
weather data from remote and or limited sites to formulate
theiravalanchehazardassessments.Asaresulttheir
forecasts are broad basedand general, usually giving prob-
abilities or degrees of hazard.Whenski areas open a slope
the avalanche hazard is alwaysconsidered minimal,fre-
quentlythisrequiresmitigationefforts.Atskiareas,
weather data is used mostly to determine if the avalanche
workers need to come in early or not.Then the avalanche
hazardassessment,and hazard reductionworkifneces-
sary, is performed by the individual control teams who are
out on the snow, looking at and skiing the individual slide
paths.At ski areas, avalanchehazardassessment and ava-
lanche control work are many times one and the same.
EXPERIENCE AND COMPUTERS
There is a lot of attention being given to computers these
days.In day to day avalanche work at ski areas the main
use of computers is for storing and retrieving weather and
snow data.Nearest neighbor and other types of programs
that try to predict avalanchesmay be useful for back coun-
try and other types of generalforecasts, but aren't of much
practical useatskiareas.Themostpotentialforusing
nearest neighborprograms at ski areas may be in alerting
the avalanche workers to possible old snow ordeep slab
instability.New snow hazard is relatively easy to evaluate
andamuch morereliableassessmentcanbemadeby
humans who are out on the snow.
Herbert Simon anearly artificialintelligencepractitioner
and now a Nobel Laureate at Carnegie Mellon,predicted
in 1957 that a computer would beat the world chesscham-
pion within a decade.It's now 40 years later and last Feb-
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ruary DeepBlue failed to beat world chesschampionGarry
Kasparov.Custom-built forchess by a team of IBM scien-
tists,DeepBluehas32microprocessorsthatgiveitthe
ability to look at 200million chess positions each second.
But brute computation isnot what human grand masters
use to approach the game.Studies have shown that in a
typical position a human player considers on averageonly
twomoves,thatheintuitivelyrecognizesfrompast
experience asleading tothe bestoutcome.AsIn chess,
intuition is what avalanche workers rely on when making
stability evaluations.Obviously without pastexperience,
a persons intuition won't be worth much.
Generalavalanche experience,along withexperience
ataparticulararea,areimportantaspectsofavalanche
hazard assessments.Beingable to observe individual slide
paths on a daily basis throughout the season is an advan-
tage ski areas have, because of there relatively small area.
It is very beneficial for an avalanche worker to have seen a
particular slide path the day before when making a hazard
assessment.It is difficultto determineif wind loadedsnow
is from the previous night orfrom one ortwo days ago, if
you haven't seen the path for awhile.This time difference
isveryimportant,becauseaseveryoneknowsmost
avalanches occurduring orshortlyaftera loading event.
It's also valuable to know that certain paths have slid on a
certain layer.While otherpaths have notand would be
suspect.On an even longer term it helps to know were a
particularslidepathusuallyfractures.Thisiswhy
experience ata givenareaissovaluable.Ifyou'veob-
serveda numberofslidesonaparticularpath overthe
years you get a feel for where and when it will slide.You
learn where some of those "sweet spots" are fordifferent
conditions.
Studies have shown that recognition primed response
is the primary way people make decisions during a stress-
ful situation, as in doing a control route when it's snowing
and blowing and everyone is wondering, "when'sit gonna
open".Orwhen you're skiing in the back country with a
bunch of friends who are looking to you forguidanceand
youcometoasteepslope.You'vegottodecide ifyou
should cross it orgo three miles around by a safer route.
Recognition primed decisions are when your brain rec-
ognizes thecurrentcircumstancesasbeing similar to a situ-
ation you've been in before and steers you in a direction
that worked out well in the past, or steers you away from a
response that didn't work out well in the past.A lot of this
processgoeson inthesubconsciousmindand issome-
times referred to as a sixth sense, or intuition.This intui-
tion is our brain recognizingapattern in our memory.This
pattern is a sequence of neurons firing in a certain order.
This issimilarto a computer,except ourbrains have the
abilitytorecognize similarpatterns,were as a computer
only recognizes exactly what it's been programed to iden-
tify.Also,ourbrains automatically discard data it deems
unimportant to the problem at hand.Were as a computer
can becomebogged downin endlesscalculationsif it's pro-
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