WeatherBlog 5 2019/20 | Foehn, foehn, foehn

To go with this, there were storms, for example on the Patscherkofel on Tuesday with gusts of around 150km/h. South of the main ridge it's snowing, but only quite high up, as explained by the oracle. Today, Wednesday, the foehn is no longer quite as strong, but it is still blowing quite a bit, especially in the foehn corridors, and it is still warm.

Current situation

A trough west of us is responsible for this, which stretches across the Iberian Peninsula to North Africa. We are located at the front of the trough in a southerly flow that directs very mild air from there to Central Europe. This won't change too much for the time being. Today, the trough no longer extends quite as far south as it did on Tuesday and a small "piece of the trough" is dripping into the Mediterranean, so the flow is less strong.

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View from the Hohe Salve to the north on Tuesday. — View from the Hohe Salve to the north on Tuesday
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LH

Outlook

By Friday, a strong low pressure system swirling off the west coast of the British Isles will move closer and we will once again be in a pronounced frontal position. The Föhn is likely to become much stronger again on Thursday or at the latest on Friday night. More accumulating precipitation will then set in again in the south, where it will generally rain or snow more or less continuously over the next few days. We suspect that the oracle will soon report back on this and we can say in advance: The snow line will be a little lower than recently, but it won't be really cold this time either.

The precipitation will probably spread to the north over the course of Friday, at least in the western Alps. There are still a few uncertainties as to how the weekend and Christmas week will develop. Although these are relatively small at the global circulation level, they could have a decisive impact on the weather character locally and regionally. Basically, it still looks like an active Atlantic and a strong westerly drift. This means that bitter cold and lowland winters are not in sight, unless there is a surprise and one or two outlier models are unexpectedly right. What seems more likely is still rather unsettled, mild westerly weather in one variation or another.

Temperature profile in Feldkirch

ZAMG

Temperature profile in Feldkirch

ZAMG

There are currently signs of a change in the direction of flow from SW to W or NW for the weekend, which will quickly turn snow-eating Föhn and double-digit temperatures in the north into cooler slushy weather, with the option of snow at least for the higher Alpine valleys. The south would then tend to be a little sunnier again, which might be quite nice after the current rain/snow phase.

In the exemplary map for next Tuesday, December 24, you can see the numerous, relatively small waves that the jet stream forms over the Atlantic and Europe. Depending on which side of the wave the Alps are currently on, there will be a southerly foehn tendency with a SW flow, or cooler NW weather. These waves are not pronounced enough to produce a blocking situation, although this can theoretically change relatively quickly if a wedge bulges up more strongly somewhere.

The current situation and further developments once again make it clear how strongly the Alps influence the weather: The effects of relatively small changes in the direction of flow would manifest themselves without the mountains as "slushy weather warm" and "slushy weather slightly less warm". Due to topography-related effects (Föhn!!), the whole thing is strongly amplified regionally and, at least in the north, we tend to oscillate between "blatantly warm" and "after all, you need a jacket again".