Hardly any snow reserves plus high-pressure weather

Between May 5 and 15, unstable weather conditions south of the Alps led to some precipitation, as Lisa Moser from the Federal Office of Meteorology and Climatology (MeteoSwiss) in Locarno-Monti explained at the request of the Keystone-SDA news agency.

However, the total amount of around 100 to 125 millimetres of precipitation would not have been enough to compensate for the water deficit in the southern canton. So far, the month of May south of the Alps has been drier than in the reference period from 1991 to 2020. The forecasts for the coming week also point to stable and dry weather, Moser continued. This is likely to further increase the water deficit.

Even for the week after next, no large amounts of rain are in sight. Since midnight on Thursday, MeteoSwiss has issued a drought warning level 2 (moderate risk) for central and northern Ticino and other regions of Switzerland.

Hardly any snow reserves in Ticino

The reservoir levels in Ticino are also below the multi-year average, namely by 4.3 percent, as explained by Pietro Jolli, spokesman for the Ticino electricity provider AET, on request. Reservoir levels in the rest of Switzerland are also lower than in other years: According to the latest figures from the Swiss Federal Office of Energy, they are currently 12.8 percent full. This means that the levels are 11 percentage points lower than the average at the same time in the last 20 years.

The deficit in snow reserves in Ticino this spring is even more pronounced than in the reservoirs, Laurent Filippini, Head of the Cantonal Office for Waters, stated at the request of Keystone-SDA. Accordingly, the so-called snow water equivalent at the beginning of May was around 35 percent of the average value at the beginning of the month.

This situation is the result of a winter with low snowfall and could affect water availability in the coming months, explained Filippini. However, progress will depend on how the weather develops.

Scarce water reserves in Lombardy

Available water reserves are also decreasing in nearby northern Italy, as reported by the Italian news agency Ansa. Above-average temperatures in April had accelerated the melting of snow in the Alps, while there had been little rainfall.

Compared to the beginning of the month, the state of the water reserves has improved somewhat. However, it was still 27.8 percent below the historical average in Lombardy as of May 20, according to the Italian news agency Adnkronos. There had been some snowfall, which had not made up for the deficit, but had halted the decline in water reserves.

Thanks in particular to the precipitation of recent weeks and particularly careful management of discharges, valuable reserves could have been stored in the large lakes, Adnkronos quoted Massimo Sertori, water resources officer for the Lombardy region.

Discharges too low

According to the current drought bulletin published on Thursday evening, the runoff volumes in large parts of Switzerland are generally low to very low for the time of year. Only in western Switzerland is the situation less tense. The runoff deficit is particularly high in parts of Valais, the Bernese Oberland, Ticino and Graubünden.

At this time of year, the rivers have to carry more water due to the melting snow, according to the national drought platform. However, there is currently significantly less snow than usual in the mountains. The snow water equivalent corresponds to values that would normally only be reached one month later in the year.