How Weather Monitoring Can Help Ski Resorts Manage Snowmaking

"Windcrane Max system is working as we hoped. We got all the information we needed for our snowmaking system. We had very cold condition with wind and snow, but it worked very well. Also the pv panel works very well."

Michael Huber/ Manager, Axamer Lizum

The ski resort industry is highly seasonal: resorts normally operate from late November to mid April, and this period is becoming shorter due to changing climate patterns. According to the European Environment Agency, snow seasons in the northern hemisphere have become five days shorter each decade since the 1970s. A shorter snow season has a direct impact on ski resort profits, but they can compensate by making their own snow.

• Ski resorts use snowmaking systems to supplement natural snowfall, improving their snow cover and conserving adequate conditions for skiing during a longer period.
• Snowmaking demands large amounts of energy, and the process is only cost-effective under certain weather conditions.
• Ski resorts can optimise their energy costs by controlling snowmaking based on measurements from an accurate weather station. 
• Energy is saved by only using snowmaking systems under adequate weather conditions, where the process is cost-effective.

There are different types of snowmaking systems, but their basic principle is launching water and pressurised air into the air with a snow gun. This process atomizes water into fine droplets, which freeze into snow crystals more easily than large drops. This technology has also been used to create indoor skiing slopes successfully. Snowmaking systems played a critical role in the last three editions of the Winter Olympics (2014, 2018, 2022).

The European Union is aware of the economic importance of the ski resort industry, and there is a Horizon 2020 program that focuses on weather monitoring and forecasting for ski resorts.

Which Are The Ideal Weather Conditions For Snowmaking?

The two most important weather variables for snowmaking are temperature and humidity. The air can absorb less moisture as relative humidity increases, and you need lower temperatures to freeze water droplets into snow crystals. For snowmaking, the ideal combination of weather conditions is being below the freezing temperature (0°C / 32°F) and having low humidity. Water droplets are launched upward, giving them enough time to freeze before reaching the ground. When water freezes on the ground, you get an icy surface instead of powdery snow.

The wet-bulb temperature is the most important weather metric to determine if snowmaking is viable. The wet-bulb temperature can be defined as the lowest temperature to which you can cool the air with water evaporation alone, and this depends on both air temperature and humidity.

• The ideal wet-bulb temperature for snowmaking is below 20°F (-6.67°C), but the process is feasible between 20°F and 27°F (-6.67°C and -2.78°C).

• Snowmaking is also possible slightly above the freezing temperature, but you need a relative humidity below 40% and the resulting snow will be wet.
• When temperatures are close to the freezing point but relative humidity is close to 100%, snowmaking is not viable. High air humidity slows down the cooling process, and the snow gun simply showers the ground with cold water, which is a waste of energy.
• Snowmaking is viable even at 100% relative humidity if the air temperature is below 20°F (-6.67°C), since the low temperature compensates for high moisture.

Depending on temperature and humidity conditions, the resulting snow can be dry or wet. Dry snow is ideal for skiing, since it has a powdery texture and skis are less likely to get stuck. However, wet snow is useful for building up the snow cover to a suitable depth, since ski resorts only need dry snow on the surface of slopes.

Using Weather Monitoring To Optimise Snowmaking Costs

Snowmaking consumes large amounts of water and energy, which means the process is expensive and its environmental impact is significant. In many cases, snowmaking accounts for more than 50% of energy costs at ski resorts, consuming even more energy than space heating. According to SMI Snow Makers, you need over 282,000 litres of water to cover a 61 m x 61 m area with 15 cm of snow. Although this water comes from natural sources like lakes, around 80% eventually returns to the source as the snow melts

Snow guns can be controlled more effectively when you have an accurate measurement of air temperature, relative humidity and wet-bulb temperature at the ski slope. WINDCRANE can measure these variables 24/7, and it has a tough IP67 enclosure that is suitable for the harshest environments.

• WINDCRANE is dust-tight and weatherproof, and it has an operating temperature range of -40°C to 85°C (-40°F to 185°F).
• This data provides greater value than general weather forecast, since it’s measured directly at the point of interest.
• The unit can also be equipped with a solar panel to generate its own charge, becoming independent from external power sources.

Snowmaking can be planned even more efficiently when weather data from ski slopes is combined with forecasting models. An example of this is the Horizon 2020 PROSNOW project, which has the goal of forecasting snow conditions across the Alps, days and months ahead. With these forecasts, ski resorts can have an idea of their snow needs in the near future, and the associated energy and water costs. Long-term trends can also be identified, and ski resorts can plan the future expansion of their snowmaking systems.

Managing Snowmaking at Axamer Lizum with WINDCRANE

The Axamer Lizum Ski Resort is located in Austria, and it offers 32 km of slopes and 8 km of ski slopes. The winter sports area covers elevations from 1,580 to 2,340 metres, and there are 10 lifts for guest transport. The resort makes ample use of snowmaking systems to extend the ski season, and visitors can practise winter sports from late November to mid April.

Axamer Lizum requires accurate weather data to optimise its snowmaking operations, and they are currently using a WINDCRANE Max weather stations with the following sensors:

• 2x anemometers
• 1x wind vane
• 1x temperature and pressure sensor

The WINDCRANE Max unit at Axamer Lizum is equipped with a solar panel and backup battery, making it completely independent from external power sources. The unit has a dust-tight and weatherproof IP67 enclosure, and it operates reliably at temperatures as low as -40°C. WINDCRANE also provided an online dashboard where Axamer Lizum can check weather conditions in real time, along with historical charts and wind forecasts. The dashboard displays the average and maximum wind speeds measured by both anemometers, wind direction, temperature and pressure.

WINDCRANE Max system is working as we hoped. We got all the information we needed for our snowmaking system. We had very cold conditions with wind and snow, but it worked very well. Also the PV panel works very well.

Michael Huber, Manager, Axamer Lizum Ski Resort