WeatherBlog 14 2025/26 | Favorable stratospheric conditions

Weather situation and outlook

A gentle trough is approaching the Alps from the south. The precipitation, coming from the southwest, has been covering the entire southern slope of the Alps since yesterday (Tuesday), but is not very intense and will come to an end in the eastern Alps on Thursday. Some members of the ensemble are also seeing heavy snowfall, so there is a bit of suspense. Temperatures are not at all mild: on Wednesday, snowfall limits are generally below 1000 meters. You can find a more detailed assessment of the amount of fresh snow in PowderAlert 8.

Avalanche situation

We would like to remind you once again that the avalanche situation is delicate, as there is an old snow problem in large parts of the Alps (central, eastern, southern and northern Alps). The last snowfalls last weekend and Wednesday on the southern slopes of the Alps fell on a thin, transformed layer of old snow. In Trentino, there is half a meter of fresh snow on a layer of floating snow at 2,000 meters. In areas close to the crest, where wind was also involved, spontaneous dry snow slabs came off. Caution was advised, but you could also have fun. Urgent wumpf noises were usually warning enough.

Stratospheric situation

At present, the polar vortex has deformed into an ellipse whose long axis extends from North America via the North Pole to Central Eurasia. This must be seen in the context of the extremely cold temperatures in North America, which have even brought frost to Florida. This configuration will become increasingly unstable over the next few days and the polar vortex will collapse. This will create two vortices, a small one over North America and a larger one over Eurasia.

The vortex will soon disappear, so it appears that the polar vortex will swirl completely over Eurasia in the next few weeks. I dare to estimate (and hope) that this will lead to an increased northerly flow over the Alps in the coming weeks. It should be noted that the predictability of the stratosphere, like that of the oceans, is greater than that of the weather in the troposphere.

As the name implies, the stratosphere is very stably stratified and its circulation is determined by meridional temperature gradients (thermal wind). It is also disturbed and modified by waves from the troposphere (wave - mean-flow interaction). So the polar vortex is certainly breaking down and it certainly has great potential to bring winter back to the northern slopes of the Alps. The next few weeks will show it, and the WeatherBlogs and hopefully PowderAlerts will report it. The forecasts shown can be found on stratobserve.com.