What we know about medicanes—hurricane-like storms in the Mediterranean

November 22, 2017 by Sarah Fecht, Earth Institute, Columbia University
A Mediterranean “hurricane” named Numa struck Greece last week. Credit: NASA

A rare type of storm struck Greece last week, killing at least 20 people and reportedly damaging 1,000 homes with flash floods and mudslides. Photos of the storm, named Numa, showed clouds swirling around a central eye. It's the type of storm we're accustomed to seeing in the tropical waters of the Atlantic and Pacific Oceans, perhaps leaving a trail of destruction through the Caribbean and Gulf of Mexico.

Medicanes ("Mediterranean" + "hurricanes") are not common. Meteorologists estimate that they form once or twice a year, on average.

Is a Medicane Really a Hurricane?

Medicanes have a lot in common with , with strong winds spinning around a core and torrential rainfall. In 2014, Medicane Qendresa hit Malta with sustained winds of up to 70 miles per hour and gusts of up to 95mph. Nevertheless, the waters of the Mediterranean aren't extensive or warm enough to sustain the strength needed to call these storms legitimate hurricanes. In addition, says Yochanan Kushnir, who studies climate variability at Columbia's Lamont-Doherty Earth Observatory, medicanes' physics and dynamics are different from those of hurricanes. (More on that in the section below…)

How do They Form?

Mediterranean cyclones are most likely to occur in the autumn, peaking in winter, and slowing down in the springtime.

Like conventional hurricanes, they develop over warm waters. Whereas Atlantic or Pacific cyclones require temperatures of around 80 degrees Fahrenheit to grow, medicanes have been known to evolve in waters as cool as 57 degrees. Their formation depends on cool air above.

Hurricanes form around a warm core and move from east to west, says Kushnir, whereas medicanes have a cold core and travel from west to east. They start off like regular winter storms we might experience on the East Coast of the U.S., only smaller and less intense. But sometimes the storms begin to pull heat and moisture off the Mediterranean, thermodynamically converting those ingredients into energy, just like hurricanes do. An intense low-pressure system develops, says Kushnir, "which looks very much like a with clouds circling an eye-looking feature." Steered by the westerly winds aloft, these storms move eastward.

The western part of the Mediterranean, between Spain and Sardinia, is one of two hotspots for medicane formation. The other area—in the Ionian sea, to the west of Greece—is where Numa formed.

Do Any Other Seas Have Hurricane-Like Storms?

Similar storms can form in the polar regions, including over the Labrador Sea and over the ocean just south of Greenland. "These are called polar lows and they look very much like medicanes," says Kushnir.

How Does Climate Change Affect Medicanes?

Although medicanes are expected to remain relatively rare, rising sea surface temperatures are expected to breed stronger medicanes in the future—perhaps eventually turning them into full-blown hurricanes.

Explore further: Next-generation models revealing climate change effect on hurricanes

Related Stories

Hurricanes and typhoons: cyclones by another name

August 25, 2017

No matter what they are called—cyclones, hurricanes or typhoons—the giant tropical storms that form in oceans near the Americas and Asia can be deadly, destructive and terrifyingly capricious.

What is a hurricane?

October 5, 2016

The Caribbean's worst storm in nearly a decade, Hurricane Matthew, has already killed at least nine people and was threatening the southeastern US on Wednesday.

Recommended for you

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...

Paleontologists report world's biggest Tyrannosaurus rex

March 22, 2019

University of Alberta paleontologists have just reported the world's biggest Tyrannosaurus rex and the largest dinosaur skeleton ever found in Canada. The 13-metre-long T. rex, nicknamed "Scotty," lived in prehistoric Saskatchewan ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.