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The region often enjoys optimal weather conditions for paragliding, especially during shoulder seasons like spring and fall. Regular thermals and favorable winds offer good flying opportunities. Just talking with local tandem pilots, instructors and locals can give extensive insight for thermic activity, shifting valley winds, understanding phenomenon like Foehn winds, etc.Â
Strong Winds: The foehn creates strong and turbulent winds on the leeward side of mountains, which can make paragliding very dangerous.
Turbulence: The turbulence generated by the foehn can cause wing collapses and make controlling the paraglider difficult.
Avoid Flying in Foehn Conditions**: If foehn conditions are forecasted or observed, it is generally safer not to fly. Strong winds and turbulence can be extremely dangerous.
The foehn, föhn, or foehn (pronounced /føn/) phenomenon is a type of wind that occurs when a mass of moist air is forced to rise over a mountain range, such as the Alps, and then descends on the other side. The ascent of the air leads to cooling, which causes precipitation on the windward side. Once the air has crossed the ridge, it descends on the other side, warms up, and dries out. This can create a warm, dry wind on the leeward side of the mountain.
Ascent and Cooling: When moist air encounters a mountain range, it is forced to rise. As it rises, the air cools, and its capacity to hold moisture decreases, leading to the condensation of water vapor and the formation of clouds. These clouds can produce precipitation.
Descent and Warming: Once the air has crossed the mountain peak, it descends on the opposite side. As it descends, the air warms up due to increasing atmospheric pressure, which causes the air to compress. This warming is often associated with the loss of any remaining moisture, making the wind warmer and drier.
Grand Foehn: This term often refers to a foehn phenomenon associated with a larger atmospheric depression, such as one located south of France, in the Bay of Biscay, or the Gulf of Genoa. The grand foehn is generally linked to large-scale weather systems affecting a broad region. Moist air is drawn toward the depression, forced to rise, and then descends on the other side, producing the foehn effect.
Bise Foehn: This phenomenon is more localized and often associated with specific weather conditions, such as a local depression and high pressure. For example, in the Alps, a bise foehn can occur following a disturbance. In this case, a depression on the windward side (towards Mont Blanc) and high pressure on the leeward side (towards Chamonix) can enhance this localized wind. This configuration can create favorable conditions for the development of the foehn.
For more details, it might be useful to consult specialized meteorological resources or speak directly with meteorologists. Here are a few sources to deepen your knowledge:
Météo-France: A site providing information on meteorological phenomena in France.
MeteoSwiss: For specific information about the Swiss Alps and foehn phenomena.
