Foehn probability diagram, the tool to forecast your snowkite sessions

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There is a tool that I have always found very practical when it comes to forecasting wind on snowkite spots in the Alps, it's the foehn probability diagram. It's an ideal tool for predicting wind in alpine valleys (Switzerland) with either a southern or northern current.

Some weather sites offer this diagram, but I've always been frustrated by the lack of precision offered, the lack of updates, and the inability to display hourly data.

So I rolled up my coder sleeves and created a modern diagram, which I find clearer, more precise, and which updates via short-term weather models every 3 hours for the next 10 days (Weather models Icon D2 and Icon Eu for now).

The graph is now integrated into the forecasts for spots where it's relevant (Forecast tab). For example, for the Simplon spot: https://letskite.ch/en/spots/49/snowkite/col-du-simplon#prevision_spot
Don't hesitate to let me know if I should add it to other spots.

How to read it?

In fact, the foehn diagram is a calculation of pressure differential between Zurich and Lugano. The greater the forecast pressure differential, the higher the probability of wind. A negative differential will give north wind, a positive one will give south foehn. So between -4 and +4, little or no wind; from 4 to 8 (-4 to -8), we're in medium wind; between 8 and 10, rather strong; and more than 12, it's more like a foehn storm.

In our example below, the blue curve indicates no wind, the red is the south foehn (with a very large peak at the end of the week at -13, which should be stormy) and the yellow part is the North foehn (or simply north wind).

So for all North-South oriented Valais snowkite spots (from Simplon to Grand St-Bernard), it's really a very good indicator. You will also need to check the classic weather forecast to know the visibility and possible subtleties.

Premium vs free

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Foehn diagram:

• Premium: 10-day forecast
• Free: Today + tomorrow