Recent trends of temperature and precipitation in alpine and subalpine areas in North Western Italy

Eleven stations located at different altitudes in the Italian part of the Lake Maggiore watershed (North-Western Italy) were selected to highlight trends in temperature and precipitation. The data available cover a period of about 30 years for six of the stations and 60-70 years for five sites. Data (maximum and minimum temperatures, precipitation amount, snow cover) were collected on a daily basis, and monthly, annual and seasonal values calculated. The results clearly showed increasing trends of temperature at most sites, with different significance for minimum and maximum temperatures and for the different seasons. Examination of the longest data series suggests that it is mainly in the last 30 years that this tendency towards warming has emerged. No significant trend emerged for precipitation amount, apart from a decrease recorded at one site. The analysis of data on a daily basis at four stations showed that precipitation volume has been quite constant in the last 70 years, while the number of rainy days per year has been decreasing, a particularly striking trend over the last 25-30 years. These results lead to the hypothesis that there has been an increasing occurrence of stormy precipitation events in the last decades.