Highest Precipitation in the European Alps: A Meteorological Enthusiast’s Observations from the Southern Julian Alps

The topography of the Southern Julian Alps significantly influences air movement, resulting in a pronounced local maximum of precipitation. Long-term measurements from the official meteorological network indicate that this region receives the highest precipitation in the entire European Alps, with annual totals averaging around 4000 mm at some stations (totalizers).

The distribution of precipitation near the main orographic barrier close to Vogel Mountain has been studied over the past 30 years through occasional snow water equivalent measurements. Precipitation increases as one approaches the ridge, with up to 30–40% more precipitation than at the nearest official station with regular measurements.

In 2006, a network of nine precipitation measurement sites was established for a more detailed analysis. The stations were positioned along two profiles crossing the main ridge. During the first phase (2006–2014), measurements were taken using a homemade "Hellmann totalizer," combining a collection container with the properties of the classic Hellmann rain gauge and a container for collecting precipitation throughout the dry season. This method was only suitable for liquid precipitation, and measurements were taken between May and November. At the end of the season, the collected rainwater was weighed to determine the seasonal precipitation height for each station.

In 2015, the network was upgraded with electronic rain gauges, allowing for a more detailed view of precipitation over time, better tolerance of snow conditions, and easier setup and removal in spring and autumn. These measurements show that precipitation distribution in the area is highly variable and depends on the specific weather situation. However, precipitation is consistently highest near the ridge, especially on the northern, predominantly leeward, side. This data is crucial for better understanding and forecasting avalanche hazards in the region, as well as for the verification of forecasting models.

This entire project of precipitation measurements has been carried out by a weather enthusiast, driven by a passion for meteorology, and demonstrates the dedication and commitment of individuals who contribute valuable meteorological data outside of professional or academic settings.