Using vertical sounding data to forecast Zonda wind in the Andes region

The Zonda wind is a downslope windstorm that occurs on the leeward eastern slopes of the Central Andes in Argentina. This feature is much like the Foehn wind in the northern Alps, in which the wind produces extremely warm and dry conditions. These severe weather anomalies can cause substantial socioeconomic impacts in the region's agricultural communities.

Because of the major disruptions brought on by the Zonda wind, meteorologists want to better forecast the phenomenon. The Central Andes features significant elevation changes, making conventional observations more difficult. However, vertical atmospheric profiles via radiosonde on both sides of the mountain barrier may be the answer.

Argentinian atmospheric scientists Federico Otero and Diego C. Araneo from Instituto Argentino de Nivología recently published a study in Advances in Atmospheric Sciences showing the vertical conditions of the atmosphere surrounding the Central Andes Mountains. Applying principal component analysis to raw radiosonde data, they found that soundings can find key wind flows throughout the atmosphere that signal an oncoming Zonda wind. Along with temperature, humidity, and stability data, this method allows reliable Zonda wind forecasts with up to 24 hours of lead time.

“Our next step is applying an operational forecasting tool using this technique.” said Dr. Otero. “We also intend to investigate implementing this tool to obtain a longer-term forecast.

Prof. Otero also emphasized that this methodology is applicable to any part of the world that has this type of wind, such as in the Alps, or in many leeward regions within the mountain rain shadow.