FORTE DEI MARMI. In the early afternoon of Wednesday, September 9, a sudden and intense hailstorm hit the area of Forte dei Marmi and several locations in Versilia. The hailstones, of exceptional size, surprised residents and tourists: many collected the pieces of ice, as large as golf balls, and photographed them, posting the images on social media, where they went viral within minutes.
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The supercell
The thunderstorm cell that crossed the Versilian coast generated hailstones of unusual size, some comparable to tennis balls. A brief but very intense phenomenon, typical of thunderstorms with strong vertical development that are currently affecting Tuscany. Flooding in several locations was also reported, reaching the province of Massa-Carrara.
How hail forms: the science inside the “ice bullets”
Hail is a solid precipitation that forms inside cumulonimbus clouds, the large thunderclouds that can exceed 10 kilometers in height. The hailstones form when water droplets are pushed toward the colder layers of the cloud, where they freeze and begin to grow in multiple stages.
The role of updrafts
Updrafts (updraft) are fundamental: they push supercooled water droplets upward, which remain liquid despite temperatures below zero. In supercell thunderstorms, the most organized thunderstorm structures, these currents can keep the hailstones suspended for a long time, allowing them to grow to exceptional sizes.
The layered structure
Hail is a kind of “atmospheric archive”: each hailstone has an onion-like structure, with concentric layers that tell the different growth phases. Some layers are transparent (wet growth), others opaque (dry growth), depending on the temperature and humidity encountered during its journey inside the cloud.
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Why some hailstones become huge
The largest hailstones form when:
- the atmosphere is very unstable,
- there is a lot of humidity in the lower layers,
- updrafts exceed 100 km/h,
- the cloud has a complex structure with well-defined ascending and descending zones.
Under these conditions, the hailstone can undergo multiple cycles of ascent and descent, accumulating layers of ice until reaching sizes of several centimeters.
A preview of the severe weather wave expected in Tuscany
The hailstorm in Versilia is only the prelude to the violent weather wave forecast between the night of Wednesday, September 9 and Thursday, September 10. The regional Civil Protection has issued an orange alert for all of Tuscany, signaling the possibility of:
- very intense thunderstorms,
- wind gusts exceeding 70–90 km/h,
- new hailstorms, including large ones,
- possible flash flooding in the most exposed areas.
The atmospheric conditions that generated the hailstorm in Versilia — strong instability, warm and humid air at the surface, cold currents aloft — are the same that will fuel the thunderstorms expected in the coming hours.
Versilia under observation
The area hit today could again be affected by the most intense phenomena during the night. Authorities urge maximum caution, especially when traveling and in areas prone to water stagnation.
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