What is medicane?
A medicane is a Mediterranean tropical-like cyclone that forms over warm Mediterranean Sea waters during autumn. Medicane's names usually end with the "-ane" suffix, just like hurricanes that develop in the Atlantic Ocean and Pacific Ocean. The genesis region of medicanes varies from the Ionian Sea to the Western Mediterranean including the Gulf of Lion. They occur in late summer and mostly in autumn, but in some cases also in early winter. Due to their characteristics and the time of their occurrence, medicanes have also been called Mediterranean hurricanes or Mediterranean cyclones.
Tropical cyclones generally do not form over the Mediterranean due to unfavorable environmental conditions, such as relatively cool sea-surface temperatures and the existence of strong vertical wind shear. However, under appropriate atmospheric conditions, small-scale tropical-like cyclones form over the Mediterranean acquiring some of the attributes of large-scale tropical systems: warm cores, symmetric and organized deep convection, and maximum sustained winds of tropical storm intensity (at least 39 mph or 63 km/h) near their centers.
The main characteristics of medicanes include:
- Small size: Medicane diameters (defined by the distance of their gale force winds, force 8 Beaufort) are typically less than 186 mi (300 km).
- High-density winds: Medicane low-level winds are comparable in intensity to tropical storm-strength winds.
- Strong vertical wind shear: Medicane-like circulations are embedded within a larger-scale cyclonic circulation with high vertical wind shear.
- Cold air intrusions: Medicane development frequently includes interactions with upper-tropospheric cold air intrusions.
- Symmetric and organized convection: Medicane cloud structures generally exhibit curved banding features and the presence of concentric deep convective eyewalls.
- Warm core structures: Medicane-scale vortices develop warmer internal temperatures than the environments in which they reside, especially in the upper troposphere and lower stratosphere. Medicane warm cores are similar to tropical cyclones or subtropical cyclones.
Medicane occurrences are infrequent. Based on historical records, over the last century 1–2 systems with tropical-like characteristics appear over the Mediterranean per year, with only about half of these vortices achieving tropical storm intensity. Their rarity results from the fact that the Mediterranean Sea exhibits conditions only marginally favorable to tropical cyclogenesis.