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What is exactly “Retour d’Est”?

Live from Val d’Isère! We are currently seeing a continuous succession of heavy snowfalls, more commonly known as a “RETOUR D’EST”, an easterly weather front.  For powder skiing enthusiasts this weather front is a genuine gift from the Gods. For those working in the mountains it requires a great deal of vigilance: securing the ski area with controlled avalanche triggering, securing the village and roads thus the people in resort.

❄❄❄Huge quantities of snow❄❄❄

 

This eastern weather front occurs several times a season in Val d’isère and the resulting snow or rainfalls are quite considerable. Here is a more technical explanation of this phenomenon by Thomas Blanchard who manages www.meteoalpes.fr

The easterly weather front is an area of low pressure located in the Mediterranean generating masses of warm humid air which travel up from the south.

As they encounter the initial Piedmont Italian mountain range via the Pô plains, this air rises, condenses and becomes even more humid (orographic effect). This creates very heavy rain/snow falls over the southern Italian Grand Paradis mountain range which “overflow” from east to west (due to the east to south-east meteorological current) via the sources of the Arc and Isere rivers which are the zones most commonly concerned.

The quantity of snow which may fall during an episode may reach three metres in two days. These snowfalls may reach Val d’Isère when the weather situation is very active (which is what is actually happening at the moment).

Once the air mass passes over the high summits of the Grande-Casse to the Mont-Pourri, it dries out very rapidly and warms up (this is known as the Foehn effect) as it moves down the valley towards Bourg St Maurice and the Tarentaise region.

This weather phenomenon is greatly influenced by both the French and Italian mountainous areas. This explains the important variation of snowfalls between Bourg St Maurice and Val d’Isère/Tignes.

It has often occurred that 0cm of snow falls in Bourg St Maurice and up to Sainte-Foy-Tarentaise, heavy snow may begin to fall in Tignes and gigantic amounts on the Pissaillas glacier.