On Wednesday, April 23, 2025, an orange weather alert has been issued for hydraulic risk in several regions of Italy, particularly affecting the eastern Po Valley and the Adriatic coast of Emilia-Romagna. Areas such as the Ferrara coast, the Ferrara plain in Emilia-Romagna, the eastern lower plain of Lombardy, and the Po, Fissero-Tartaro-Canalbianco, and Basso Adige basins in Veneto are at heightened risk. These regions are already vulnerable due to recent soil saturation caused by heavy rains over the past few days.
The instability is attributed to an area of atmospheric disturbance hovering over Northern Italy, combined with weak winds that increase the chances of flooding and rising water levels in both major and minor waterways. Consequently, residents are advised to avoid non-essential travel in the affected areas and to stay informed through official channels such as the Civil Protection and local authorities. People are also urged to secure their properties and vehicles in flood-prone areas and to avoid standing near bridges or embankments, especially during the central and evening hours when atmospheric instability is expected to peak.
According to the latest weather alerts, storm-prone areas are likely to remain nearly stationary, posing a significant risk of heavy rainfall in localized regions. Additionally, a yellow alert is currently in effect for thunderstorms and hydrogeological risk across much of Central and Southern Italy. This includes regions such as Abruzzo, Basilicata, Calabria, Lazio, Marche, Molise, Puglia, Sicily, and Umbria, as well as extensive inland areas of Lombardy and Emilia-Romagna.
In Calabria, the alert encompasses the entire Ionian and Tyrrhenian slopes, while in Sicily, the eastern and internal mountainous areas are at risk. Hydraulic concerns have been noted for parts of the Po plain near Reggio Emilia and the eastern-central lower plain of Lombardy. Residents in these areas are advised not to linger near waterways and to steer clear of hilly or mountainous paths, as well as to avoid using cellars or basements in the event of persistent rain.
Inland regions are particularly susceptible to sudden runoff and landslides, especially on secondary roads or near embankments. Urban areas have been advised to report any blockages promptly and to refrain from discarding waste into street grates to mitigate already delicate situations. During thunderstorms, outdoor activities should be avoided, especially near isolated trees, poles, or metal structures.
As the weather deteriorates, the service PRETEMP, a working group focused on studying and forecasting severe thunderstorm phenomena in Italy, has released a new probabilistic forecast bulletin. This bulletin notes that the combined effect of a weak trough aloft and solar radiation will generate widespread instability across the country, especially in the Apennine area and the Po Valley.
In the evening, a new unstable impulse is expected to reach Northwestern Italy, bringing additional precipitation. The bulletin indicates a level 0 alert that includes the Alpine Arc, nearly all of the Po Valley and Northeast regions, the entirety of the Apennines, the Murge area, Gargano, and eastern Sicily, as well as Corsica and much of Croatia, Slovenia, and Bosnia. This alert warns of scattered thunderstorms that could produce localized heavy rain and small hail, with the possibility of local gusts of wind if storm cells can organize into a cluster or a line.
As the day progresses, CAPE values are expected to rise under the sun's rays, surpassing 1000 J/kg, particularly in the Apennine area and the Po Valley. Single-cell thunderstorms are likely to develop across the reliefs, with a convective environment that has low DLS, making it difficult for storm cells to organize effectively. However, some thunderstorms may develop directly in the Po Valley during the afternoon due to a convergence line of winds at the surface.
Wind at 700 hPa is expected to be very weak (around 20 km/h), causing the storm cells to remain in their area of origin. Nevertheless, towards the late afternoon and evening, the strengthening of southwestern winds due to the arrival of a new cyclonic impulse in the Northwest may facilitate the slow movement of these cells towards the Northeast regions.
As for the immediate forecast, after a brief lull, the weather is set to worsen starting April 23, with clouds, showers, and local thunderstorms expected. The unstable front moving in from Northern Europe will particularly affect the Po Valley, bringing scattered precipitation. On Wednesday, April 24, the weather will be characterized by a mix of clear skies and sudden downpours, making it essential for residents to be prepared with umbrellas and updated weather apps.
Despite the instability, temperatures are expected to remain mild, ranging between 21 and 23°C, with lows not dropping below 12°C. Looking ahead to Thursday, April 25, there are signs of improvement as rains may ease during the night, allowing for clearer skies in the central hours of the day. If the instability shifts eastward as forecasted, there could be opportunities for sunshine, perfect for outdoor activities.
With such unpredictable weather, residents are encouraged to plan activities both indoors and outdoors, keeping a flexible approach. Museums and exhibitions, such as the Triennale and the Museum of the 20th Century, offer great indoor options, while shopping under the porticoes of Corso Vittorio Emanuele and Via Torino can be enjoyable even in the rain. Should the sun peek through, parks like Parco delle Basiliche and Giardino della Guastalla are ideal for a picnic. Additionally, many food events and market stalls will enliven the city over the holiday weekend, so checking updates is essential to avoid surprises.
In summary, while the weather poses challenges, a little flexibility can lead to delightful surprises during the April 25 holiday weekend.
