WeatherBlog #17 2024/25 | Hoping for the Atlantic Bridge

Weather situation

The snow that we reported on in the last WeatherBlog has been put to good use in many places. There is still cold, fluffy powder on the northern slopes in particular. But anyone who has ventured onto sunny slopes has quickly noticed how powerful the March sun is already.

Even though we are still in winter from an astronomical perspective, the weather has long since felt like spring. March started with a stable bridge of high pressure over Central Europe, which is holding up well until today (Wednesday). This means plenty of sunshine during the day, mild temperatures and frosty nights - classic spring conditions.

And it's staying that way for now: An area of low pressure off the coast of Spain and France is dropping again, blocking the circulation and maintaining the influence of high pressure over the Alps. In terms of weather, there's not much action in the Alps - but at least it's great weather!

As far as ski tours are concerned, the coming days offer exciting options: If you plan cleverly, you can still catch powder in shady areas as well as firn on sunny slopes.

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Low pressure vortex over the Iberian Peninsula, high pressure over Central Europe.

ECMWF

IFS

Outlook

A low pressure system over the Iberian Peninsula will be blocked by the Central European high pressure system and will swirl and rain there all week long. Towards Sunday, the foothills of this system will reach Italy and the southern side of the Alps. There will be a lot of precipitation and certainly snow at high altitudes, but as the flow will be so southerly and rather warm, we are holding back on overly optimistic forecasts.

Interesting for next week would be a polar cold air outbreak in a trough, which is indicated in the ECMWF-IFS model and which could bring snow to the northern slopes of the Alps with cool temperatures. This is still very much up in the air, but a sudden stratospheric warming event is practically certain and could perhaps turn the whole winter upside down again.

7 days of fresh snow: light at the end of the tunnel.

PG-Wetter

ICON

Will an SSW bring back winter again?

Sudden stratospheric warming (SSW) is characterized by a rapid weakening of the circumpolar westerly winds in the stratosphere and a significant warming of the polar region. SSWs have a considerable influence on the tropospheric circulation. Following an SSW event, an equatorial shift of the tropospheric jet can occur, resulting in cold conditions over northern Europe and warm conditions over northeastern Canada and Greenland during the northern hemisphere winter (Baldwin, M. P., and T. J. Dunkerton, 1999). Since the sub-seasonal prediction skill is higher when an SSW event occurs in the initial conditions (Tripathi et al. 2015), an SSW event allows for better predictability.

The occurrence of a strong SSW event at the end of the week is virtually certain and the forecast of the European-Atlantic weather regime gives NAO or Atlantic Ridge (ATR) a good chance of occurring. ATR in particular, characterized by a blocking bridge of high pressure over the Atlantic that allows retrograde north-easterly flow over Europe, could bring us another winter comeback in the Alps. Finally, we note that this development is certainly independent of the crumbling political transatlantic bridge.