Monstrous Föhnstorm over Alps
As a skier in the Alps you don’t even necessarily notice when a Föhnstorm hits the Alps, since the strong winds are up high and down at the slopes the only thing noticeable is that it’s warmer at the summits than in the valley. At the north side of the Alps it’s usually sunny with strange sigar shaped clouds covering the sky. But you will not see any paragliders in the air. The 100+ kmh winds at a right angle over the main ridge of the Alps is very threatening since at any time a wild turbulence (wind gust) can break downwards like a ladle stirring a pot of soup.
One sign that Föhn is coming is when the weather models calculate a strong pressure gradient between the south side of the Alps and the north side. These forecasts are given in the so called Föhn diagrams (see above). The under pressure up north (measured at ground level at the foot of the Alps) is a measure of the chance that the strong winds may “fall down” and make winds around lower peaks and in some valleys shoot up from a meagre 15kmh in the morning to 50-60kmh or more in the afternoon. And at those kind of wind speeds a paraglider will fly backwards, which ends in disaster if the pilot doesn’t manage somehow to stay on the upwind side of a ridge.
In the video above you see me flying backwards with a light passenger. In this case I do it on purpose because I know the terrain – at Wasserkuppe, a round middle mountain in Germany – very well and there is no danger to be flushed over a ridge. I have done it there both with trim closed and with trim open (with a child as passenger). In the latter case the landing spot was approached in backward flight and the lower winds at the ground allowed for a normal forward landing. At Wasserkuppe a calculated risk, in the Alps this would be reckless for sure. A paraglider simply doesn’t have an engine and cannot dive like an airplane to pick-up speed (some new wing designs offer this possibility but they are not used as tandems). Smaller wings allow for flying in stronger winds (both solo and tandem), but even that is not advisable in a Föhn situation.
Sometimes the Föhndiagrams show a strong pressure gradient but no real Föhn is present. This can happen when a strong low pressure area up north produces strong westerly winds and a “fake” pressure gradient. Today and tomorrow however we are seeing a classic Föhn with thunderous winds at high altitude going at a right angle over the Alps. The top speeds at 10km altitude (30.000 feet) are a 100 knots. Approaching 200kmh.
At 3km, roughly the height of the main chain of the Alps we see 55 knots, so winds speeds going over 100kmh. In the map above one can almost “feel” or at least see the jam against the south side and the “outflow” of the wind towards the flat plains up north.
The ICON-D2 model manages to even nicely calculate what happens at the lower mountains and in the (upper) valleys at around 1500m. As a tandem pilot daily checking these maps I know that the green ripples equate to “danger zones”. Traditional large scale weather models do not capture these details. The ripples are exactly what makes the true Föhn so dangerous. In rare cases this also occurs without high winds at high altitudes. In exceptional cases winds even at 5km can be low while at 3km there is a funnel where strong southerly winds are pushing through. Again stressing the need for any paraglider to be generally aware of the current synoptics (general view of the overall wider weather situation), the regional do’s and dont’s and the local “in the now” givens at the start and landing site and everything in between. A tandem pilot who is usually only 20 minutes in the air with a passenger may decide to fly in “in the now” good conditions, while for a solo pilot, who generally wants to fly much longer, it would be crazy to even take a look on the mountain.
Where are we going from here? Well the ensemble for air pressure for middle Germany clearly shows that we will be shooting up back to high pressure (anything above 1013hPa). Over 1020hPa we are usually speaking about clear skies (sinking air). Only in the mountains due to orographical effects (mountain effects – there is a lot of redundancy in “meteospeak” haha) rain or snow may occur with such pressures. Above 1035hPa even in the Alps clouds “are a thing of the past”. Well morning fog may occur of course. For skiers bad news: no fresh snow anywhere in the next 16 days. For paragliders great news: the south facing mountains sides will keep greening and more early season thermals are expected. This is great for tandem passengers too: the flights already get as long as in the summer season…. 20 minutes is easily attainable (when the passenger opts for easy gliding and no adrenaline action). The awesome 45 minute flights will only become possible from early march at the earliest. They can be very cold in that season though.
Check the immense high pressure area that is predicted to be building when the current stormy conditions are over.
Usually (but not always) a Föhnstorm brings substantial rain and snow to the south side of the Alps. In the current case both the French Alps (mostly today) and the Italian Alps (mostly tomorrow) benefit strongly albeit only above altitudes of 1500m or more. In Austria only Vorarlberg and Kärnten benefit which means that the abundance of north side ski resorts will keep getting “greener”.
After the storm the temperatures in the Alps will go down again, allowing for more snowmaking …. so the season seems to be safe till the end. Yet…. we are almost concluding that for the skiers in Europe winter 2025 is not turning into a strong powder year (an no ice for skating in The Netherlands either). That’s too bad, but it’s great that we haven’t had many avalanches either. Wishing everybody safe flights and safe runs on the slopes! VIP-paragliding
