Spring, record rains in Piedmont and Lombardy, also in Milan; but when does it stop?

It’s already the wettest Spring of the last 70 years: and it’s not over yet! If we consider the quarters of March, April and May, the volume of rain that fell in Piedmont and Lombardy (including Milan) broke all records since 1954.

The question many of you are asking us is: “but when does it stop?!“
First let’s try to understand what happened and the reason for so much rain. From March 1st to today Arpa Piemonte’s meteorological-hydrological measurement network recorded approximately double (+110%) rainfall compared to the average for the period in the thirty-year climate reference period 1991-2020, so much so that the quantities accumulated on May 21st (750 mm) are the same as those normally observed at the end of the first ten days of October. Among other things, looking at the Arpa map, you can see how the wettest area of ​​Piedmont is the band between Valsesia and Lake Maggiore where over 1100 mm of rain.

Not just Piedmont. Record rainfall also occurred in Lombardy. TO Milanwhich we can take as a reference for the central-western Po Valley, have fallen around 800/900 millimeters of rain since the beginning of the year. However, considering that January and February were relatively mild and with very few disturbed phases, the rainfall was all concentrated in Spring. It is a huge quantity in a very short period: consider that the annual average is 1000 millimetres, so it has already practically been achieved in just 5 months! In particular, up to 120 mm of rain fell in Milan on Wednesday 15 May 2024 which then caused flooding in several neighborhoods and in the eastern province. To better understand what happened, An entire month’s worth of rain fell in all of Lombardy in 15 hours.

THE ROLE OF CLIMATE CHANGE
According to a recent study which examined data on climate evolution in southern Europe, therefore also including the Mediterranean basin, it emerged that, from 1979 to today the potential energy involved has increased (CAPE) capable of triggering dangerous and sudden storms. The causes of this increase must be sought precisely in theincrease in temperatures due to global warming which, consequently, causes a greater evaporation of sea water (the hotter it is, the more evaporation increases, it is precisely a physical and measurable fact) which then translates into fuel for extreme weather events.

All this causes an increase in convective precipitation (thunderstorms) with a serious risk of large hail and storms. This is a fundamental point, Global warming does not simply mean hotter everywhere, but also a whole series of side effects such as the modification of the hydrological regime and therefore of the distribution and intensity of rainfall.
In short, here is one of the served effects of ongoing climate change. Two sides of the same coin: as the heat increases, the risk of extreme weather events increases.

WHEN IT WILL END’? UPDATED FORECASTS
At least until next weekend we will have to deal with new storm fronts descending from Northern Europe/Atlantic which will cause quite a bit of rain in a good part of Italy. The bad weather will therefore not easily let go of our country, for the handover between Spring (ultra rainy) and Summer we will have to wait untilstart of Junewhen thehigh pressure it may be able to guarantee more sunshine and generalized heat across the entire country.