Distance of maximum avalanche runout is calculated by four topographical factors. An empirical equation found by regression analysis of 206 avalanches is used to predict the maximum runout distance in terms of average gradient of the avalanche path (angle α). The correlation coefficient R = 0.92, and the standard deviation of the residuals SD = 2.3°.The avalanche paths are further classified into different categories depending on confinement of the path, average inclination of the track 6, curvature of the path y", vertical displacement Y, and inclination of rupture zone Q. The degree of confinement is found to have no significant effect on the runout distance expressed by a. Best prediction of runout distance is found by a classification based on 5 and Y. For avalanches with β <30° and Y > 900 m, R = 0.90 and SD = 1.02°.The population of avalanches is applied to a numerical/dynamical model presented by Perla and others (1980). Different values for the friction constantsvand M/DY are computed, based on the observed extent of the avalanches. The computations are supplied by velocity measurements v from a test avalanche where Y = 1 000 m, and vmax= 60 m s−1. The best fitted values are μ = 0.25 and M/DY = 0.5, which gives R = 0.83 and SD = 3.5°.

Distance of maximum avalanche runout is calculated by four topographical factors. An empirical equation found by regression analysis of 206 avalanches is used to predict the maximum runout distance in terms of average gradient of the avalanche path

A near continuous record of avalanche deaths in Norway is compiled for 130 years from 1855, and shows a distinct downward trend, but large variations from winter to winter, with a periodicity of 12-13 years. Twelve major avalanche winters are selected, and their synoptic climatology examined using Grosswetterlagen, an index of atmospheric circulation over southern Norway, and monthly sea level pressure anomaly maps. More than one climatological pattern is needed to explain these winters. Major avalanche winters tend to be cold in December and/or January, and have more meridional and less mixed weather types compared with minor avalanche winters. Some have enhanced north or east circulations associated with large anomalies in the semi-permanent pressure systems. Others display intense anticyclonic blocking near Britain that maintains sustained west to north-west airflows onto Norway. A switch in circulation pattern from these to a more southerly regime is also important. These aspects of synoptic climatology are related to the mechanisms for producing big avalanches.

The Norwegian Geotechnical Institute, NGI, has recently developed and tested a new automatic precipitation gauge for rain and snow which can measure accumulated precipitation with a resolution better than 0.1 mm. The gauge, which is a direct weighing device, is based on the use of vibrating-wire strain gauges. NGI's prototype instrument has a capacity of up to 300 mm precipitation before the gauge must be emptied. A new improved version designed by Geonor has a capacity of 600 mm precipitation. A diagram showing the relationship between the automatic observations and the manual measurements is included. In the NGI prototype the precipitation container is suspended from three small steel wires, each of which is in effect the sensing element in a vibrating-wire type strain gauge. When these gauge wires are set into vibration by an electromagnetic exciter, their resonant frequency of vibration is proportional to the square of the tension in the wire. Thus change in the frequency signals is a measure of the change in tension in the wires and correspondingly a measure of the accumulative weight of precipiation in the container. The distance between the precipitaion gauge and the monitoring station can be up to one kilometre without any loss in performance.