Short-term numerical avalanche forecast used operationally at Meteo-France over the Alps and Pyrenees

Avalanche-hazard estimation for the present and the following days is one of the main tasks of the avalanche forecaster. For 4 years, some have used the results of a series of automatic numerical models in the Alpine massifs of France. Thee programs describe in real time the main meteorological conditions (SAFRAN), the evolution of the snow cover (Crocus) and the resulting avalanche risks (MEPRA) at different elevations, slopes and aspects of the massifs considered. This paper presents the latest evolution of this automatic tool. With the new version it is now possible to provide 1 day forecasts of the state of the snow cover over the massifs of both the Alps and Pyrenees, including the main characteristics of the snowpack and an assessment of the corresponding avalanche hazards. To achieve this result, the main changes were with SAFRAN. Two combined methods are used within the same package: adaptations of larger-scale meteorological forecasts and use of observations of analogous weather situations from the past. These two approaches are complementary especially for evaluating precipitation where the second solution has important fine-scale information while the first exhibits important local biases. Validation of this new application was done carefully and proved the quality of the method, now used in real-time by local forecasters. We present some validation results, concerned both with forecasted precipitation fields at the scale of the massif and forecasted avalanche risks deduced from MEPRA.