3 x 3 avalanche hazard scale by Werner Munter

3 x 3 Avalanche Assessment Process
Created by Werner Munter
3x3 Table and Reduction Method are to be used together to obtain acceptable avalanche risk
Note: This system is not designed nor intended for use in the United States. It is presented as an example of the excellant work being done in Europe on avalanche hazard analysis. For further information on this method get the book.

Factors | Reduction Method | Reference Tables | Example | Home

3Factors/3Filters	Snowpack/Weather	Terrain	Human Factor
Regional TourPlanning	Avalanche Report, Weather forcast, Info. from locals, etc.	Use 1:25,000 Map, Guide books, Photos, Own knowledge	Who's coming with? Skill level? Equipment? Who's responsible?	Researchable information
Local Visible area and route selection	General snow conditions, Wind direction and loading, New snow amounts, Oddities, Visibility, Temperature	Check info you've previously received, I.e. Relief, slope angle, steepness, ski tracks, etc.., Are there existing ski tracks-how many and when made?	Who's in my group? Equipment and Transceivers with? Time plan for tour? Itinerary left with someone?	Observations before setting out
Zonal Exact location of questionable slope	Check new snow amounts, Visibility, Solar radiation, Assess possible slab potential, What's keeping the snow together?	What's above and below me?, Steepest part of slope, Near the ridge? Any wind pockets?	Tiredness, Discipline, Technique, Distance between each other, how wide of a track? Think!	Go or not to Go

Reduction Method

Acceptable Risk =	Danger Potential	<=1
	Red. Factor x Red. Factor

Avalanche Report	Danger Potential
1	2
2	4
3	8
4	16
5	32

Reduction Factors:

First Class	Steepest Slope Angle 35-39 Degrees	RF2
First Class	Steepest Slope Angle 30-34 Degrees	RF4
Second Class	Northern Sector Slope (NW-N-NE)	RF2
	Northern half Sector Slope (WNW-N-ESE)	RF3
	Avoiding Named Avalanche slope sectors	RF4
Third Class	Constantly skied slope	RF2
	Large groups with distance between each	RF2
	Small group (2-4 persons)	RF2
	Small group with distance between each	RF3

Do not use this system without more knowledge of avalanches

Example:
You're skiing with one other person in a new area with no visible tracks

Avalanche Report is 4	Danger Potential = 16
Steepest Slope angle is 38 degrees	RF 2
Slope is in Northern Section	RF 2
Small group (2-4 persons)	RF 2

Reduction Method example computed

Acceptable Risk =	16	= 2
	2 x 2 x 2=8

The result is greater than one so No Go!

Ideally the Acceptable Risk Factor will be less than 1.
Equal to 1 is questionable!