INTEGRATION OF THE SNOWDRIFT MODELING INTO THE FRENCH OPERATIONAL CHAIN FOR AVALANCHE HAZARD FORECASTING.

ABSTRACT: Over the last years, the Snow Study Centre of Météo-France (CEN) has developed several versions of a model called Sytron for the assessment of the snowdrift events and their consequences on the snow pack stability and the avalanche hazard estimation. These models are based on in-situ measurements and observations: • Sytron1 simulates the erosion and accumulation of two modelled snow profiles on the opposite slopes of a virtual crest undergoing wind effects. This model takes into account the modifications of snow morphology, the amount of snow moved by the wind, the densification of the accumulated snow, … • Sytron2/3 (based on the previous one) has been designed to simulate the snow distribution on a limited domain by taken into account an estimated wind field. The both versions of Sytron have been validated by using the data of an experimental site. In order to improve the operational forecasting for avalanche hazard, a new version of Safran-Crocus-Mepra (SCM) including Sytron1 was developed and first tested over 3 years on the Vanoise Massif. Then, this new version of SCM has been evaluated over 3 massifs of the Isere department during the last winter season with the collaboration of the local forecaster team. We will show the principle of the integration of snowdrift modelling into the operational chain. We will also show preliminary results of the comparison with the current chain by using the Mepra snow pack stability analysis and the evaluation of avalanche hazard made by the forecaster, so as 2D simulations on limited areas