Neige à Noël et potentialités de production de neige de culture dans les Préalpes françaises du Nord

Abstract

Snow at Christmas in french Northern Prealps: a climatic risk problem, an operational approach example. — Winter-sports resorts below 1 500 m el. in the french Northern Prealps face a fairly high risk of insufficient snow-cover on their downhill skiing runs at Christmas holidays. It's the reason why an increasing number of them purchase snow-making equipment. Netherless, production of snow by those depends on the air temperature and the winter-sport resorts are then confronted to the variability of temperatures, instead of the snowfall's one. After describing in which way this other variability concerns the managers of the winter-sport resorts, the authors present a way to estimate it with accuracy for any site in the french Northern Prealps. This operational approach includes the computation of a long series of daily extreme temperatures on the studied site using a short series of recordings at that site and an hourly interpolation of these extremes. This allows to build up a chart, on which can be read the probability that the two months preceding Christmas contain a sufficient number of favourable hours, i.e. hours during which air temperature is sufficiently low for the operating of snow-guns.