A short update today. Persistent precipitation with a high snowline caused big problems in many areas in the Northwest Alps. Higher up (>2500m), we saw a lot of snow (more than a metre locally), but below, the rain came pouring down as expected. Portes du Soleil for example, at the very edge of the Alps in the north-west, was hit extremely hard with snow cover heavily affected by the rain and a lift badly damaged by a landslide. A lift pole was taken 10 metres down with it. After clearing up, it’s almost like spring skiing with these high temperatures. Because this snow fell on a weak old snow layer, the avalanche risk was (and is) very high. Check the avalanche bulletins before heading out.
Today a cold front
A Christmas cold front approaches from the northwest during the afternoon. Some 10 to 20 centimetres of snow could fall in the stau areas. Locally, perhaps a little more. The snowline drops from around 1,800 metres to below 1,500 metres. By the end of the snowfall, cooler air has entered and it may temporarily snow up to 1000 metres.
Back to a southwesterly flow
Tomorrow, the intensity of precipitation decreases rapidly and clears from the west. On Wednesday, the south-westerly flow over the Alps recovers and the temporary cooling is basically over. Only in the southern Alps, the cold can hold out a little better. Towards the end of the week, the south-westerly flow increases in strength a bit more due to a strong low-pressure area around the British Isles. Higher up, winds will be strong again. Some more precipitation reaches the northwest Alps on Thursday evening. Here, another 10 to possibly 20 centimetres of snow will fall again. The snowline is likely to remain at around 1,500 metres. Over the weekend, temperatures will therefore rise some more, especially in the Western and Northern Alps. With temperatures around 10 degrees at 1500 metres, it is far too mild for the time of year.
Persistently mild - peak around New Year’s Eve
It also remains mild in the long term. In the GFS ensemble for Grenoble, we see the various members with a small spread, which means we can say with reasonable confidence that it remains warm. A rigorous change in the weather pattern with a decent cooling and a pack of snow is simply not shown in the weather charts yet.
My next ski holiday will be in the USA. 10 years straights of warm winters in Europe. Too much.