Right now, off the coast of Italy, a tropical storm-like weather system is developing in the Mediterranean Sea. That's not a typo: It's nearly winter, but temperatures in the Mediterranean are warm enough to support a storm more commonly found in the Caribbean.
Meteorologists call these storms "medicanes"—Mediterranean hurricanes—but there's no official forecasting center dedicated to studying or predicting them. Earlier this month, another medicane caused damage in Malta and Crete.
These storms are relatively rare in Europe, typically forming just once or so each year. This week's storm will likely take a path south of Sicily and head toward Greece by this weekend. As of Wednesday afternoon, weather models show the storm could possibly perform a small loop, briefly stalling south of Italy.
At the moment, no weather model shows this week's medicane becoming particularly strong, although heavy rains in Greece linked to the storm's moisture have already caused deadly flash floods near the capital of Athens.
Medicanes are mostly an atmospheric oddity, but have caused tremendous impacts in the past. In 1969, a particularly strong medicane hit the coast of north Africa, killing nearly 600 people in Tunisia and Algeria. In 2011, a swirling storm with an eye affected parts of France, Italy, and Spain, earning the designation 01M from the National Oceanic and Atmospheric Administration—the first official medicane.
As with hurricanes and other tropical cyclones in other parts of the world, as the planet warms, medicanes are also expected to occur with greater intensity—a worrying prospect for the densely populated coasts around the Mediterranean Sea. Right now, due to the relatively colder water of the Mediterranean, the maximum strength of medicanes is capped at winds of about 75 miles per hour. By the end of the century, in a business-as-usual scenario, stronger medicanes will become more likely, according to several recent studies.