Details: the drivers behind the forecast Pertisau
This page shows the main drivers of the wind system on the lake as a forecast for the next 4 days. How the forecast works
On the water the wind can differ from the values shown here. The current limits are based on the station readings.
Wind: forecast and measurement
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Wind systems at this spot
Lake Achensee has three situations that bring wind. On sunny days the thermal wind blows from the north from midday, while in the morning there is often still a light south wind. Foehn comes from the south, often already in the morning, with very strong gusts. Often, however, the foehn collapses during the day, a front approaches and the wind turns to north: then the label shows roughly from when to expect the north wind.
We recognise the situation from the forecast wind direction hour by hour.
The drivers
Thermal drive: air pressure Munich minus Innsbruck
On sunny days the Alpine valleys heat up more than the flat foreland. Air pressure falls over the mountains and air flows in from the foreland. At Lake Achensee it arrives as a thermal wind from the north, usually from midday.
The chart shows the air pressure in Munich minus the air pressure in Innsbruck. Higher pressure in Munich (up) is favourable. Higher pressure in Innsbruck (down) is unfavourable.
Foehn
Calculated and shown is the air pressure in Bolzano minus the air pressure in Innsbruck, i.e. south minus north of the main Alpine crest. If the value is positive (up), pressure is higher in the south and air pushes over the Alps from the south. On the north side it descends into the valley as a warm, dry and gusty foehn. If the value is negative (down), the higher pressure is in the north: no foehn.
In our measurements in Pertisau, from about +3 hPa (dashed line) there was south wind of 11 knots or more in around 15 % of the hours between 5 and 14 h, below that in less than 1 %.
At Lake Achensee the foehn comes from the south, often already in the morning. It frequently collapses during the day, and the wind then turns north.
Thermal drive: sunshine at the lake
No sun, no thermal wind: only the heating of the valleys builds up the pressure difference. Shown is the forecast solar radiation at the lake (area) and, dashed, the radiation possible under a clear sky. The smaller the gap, the fewer clouds. Sun all day is the best condition. If clouds build from midday, the thermal wind weakens.
Upper wind 850 hPa
Shown is the wind at about 1.5 km altitude (850 hPa) above the lake: the line shows the strength, the dots the direction (right axis).
Strong south wind at altitude usually goes with foehn. If the wind up there turns north, the foehn is over.
Wetterdaten: Open-Meteo.com (CC BY 4.0), Modelle u.a. DWD ICON – modifiziert (MOS-Windvorhersage) durch addicted-sports. · Open-Meteo.com
Statistical forecast, no warranty – not an official weather forecast and no substitute for severe-weather warnings. Water sports at your own risk; judge the conditions on site. Terms of use