‘Medicane’ is not just a weather buzzword. It’s a real phenomenon

By Derek Van Dam, CNN Meteorologist

Like other weather buzzwords that make the rounds in the media — bomb cyclones, polar vortex, atmospheric rivers — you can add the term “medicane” to your vocabulary to impress your friends over your next latte.

Medicanes are hurricane-like storms with dangerous, real life consequences. This week, a medicane is tearing through parts of Europe with torrential rain and flooding.

If the terminology sounds to you like a clever mixture of “Mediterranean” and “hurricane,” then you can probably piece together where they form and what they do. However, there are notable differences (and similarities) between a hurricane and a medicane — not just in where they develop, but how they behave.

Medicanes vs. hurricanes

“Medicanes are very much like hurricanes,” says Dr. Richard Seager of Lamont-Doherty Earth Observatory at Columbia University. He told CNN that because medicanes are “geographically confined over the Mediterranean Sea and are surrounded by land” they are typically smaller than a hurricane and often dissipate quicker.

We are accustomed to seeing a hurricane form over warm tropical oceans, but a medicane can evolve and even sustain itself with significantly cooler water. Hurricanes require surface water temperatures of 26°C (79°F) to form and strengthen, while medicanes have been known to form within water temperatures of only 15°C (59°F).

Another important difference is the time of the year when they develop. As the Atlantic hurricane season winds down from its peak months, we look to the Mediterranean basin for potential formation. Medicane formation usually occurs from September to December, according to CNN meteorologist Michael Guy.

Even though winds can become damaging within the core of a medicane, they rarely achieve Category 1 (119kph / 74mph) hurricane strength. Sometimes the exception occurs, such as Medicane Qendresa, which struck Malta and Sicily in 2014, causing significant damage to property. Here, sustained winds reached 111 kph, with gusts topping 150 kph. This was enough to uproot trees, topple electrical poles and demolish walls of buildings.

In September 2020, western Greece was struck by a powerful medicane named Ianos. It caused property damage and flooding to Lefkada Island.

Power was taken out from winds that reached 100 kph (62 mph) just before landfall, as seen within this wind map from 2020.

Similar to a hurricane, the clouds of a medicane swirl around a central eye-like structure, which is where the strongest part of the storm is located.

Devastating impacts from a medicane, such as flooding and mudslides, can stretch hundreds of kilometers from the center of the storm as the outer rain bands approach land.

Medicanes are rare

Medicanes are not a regular occurrence.

According to Seager, they are quite rare, with “typically one or so forming per year in the western Mediterranean basin.”

Because of this, says Seager, it’s hard to know if there are any climate-related impacts on frequency or intensity. Warmer sea surface temperatures in the Mediterranean can allow the storms to take on more tropical appearances and characteristics, increasing the wind speeds and making the storms more intense.

However, “some modeling studies have shown that climate change might make Medicanes less common but more intense when they do form, which is similar to model projections of Atlantic hurricanes.”

A 2017 study showed that medicanes are likely to become a bigger problem as the planet warms, thanks to human-caused climate change — with stronger winds and heavier rainfall.

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