Global Warming Post: Medicanes (Hurricanes in the Mediterranean Sea)
This is the first in a series of occasional posts regarding Global Warming.
What are "Medicanes"?
"Medicane" is the nickname given to a storm that develops tropical characteristics in the Mediterranean Sea. Medicanes aren’t considered full-fledged tropical systems, since the waters of the Mediterranean aren’t extensive or warm enough to sustain a true hurricane. And despite the implication embedded in the name, very few medicanes achieve sustained winds as strong as a Category 1 hurricane. However, it’s quite possible for an existing center of low pressure in the Mediterranean to briefly take on tropical characteristics, including a symmetric structure and a small core of warm air.
Our last medicane occurred October 28 – November 1, 2016, and was called 90M or Trixie. Trixie/90M peaked with sustained winds of 50 mph, and did minor damage to Malta before passing over Crete and dying. It appears the system briefly took on the symmetric warm-core features typical of a tropical storm. A powerful medicane in early November 2014 dubbed Qendresa produced wind gusts as high as 96 mph on the north coast of Malta. Winds at the Luqa, Malta, airport looked suspiciously like what one would observe with a tropical storm passing overhead--a double peak with a near-calm in between, with the pressure falling to 984 mb during the calm. In early November 2011, another noteworthy storm named Rolf took shape in the western Mediterranean. Rolf was the only medicane to be officially monitored by NOAA, whose Satellite Analysis Branch named it 01M and tracked it for two days. .
Could bona fide hurricanes develop in the Mediterranean later this century?
According to research published in 2007, an increase in ocean temperatures of 3°C (5.4°F) in the Mediterranean by the end of the century could lead to hurricanes forming there. Miguel Angel Gaertner of the University of Castilla-La Mancha in Toledo, Spain, ran 9 different climate models with resolutions of about 50 km and found that some (but not all) of the models simulated hurricanes in the Mediterranean in September by the end of the century, when sea surface temperatures there could reach 30°C (86°F). Though the Mediterranean could start seeing hurricanes by the end of the century, these storms should be rare and relatively short-lived for three reasons:
The Mediterranean is quite far north and is subject to strong wind shear from jet stream activity.
The waters are shallow, and have relatively low heat content. There is no deep warm water current like the Gulf Stream.
The Mediterranean has a number of large islands and peninsulas poking into it, increasing the chances that a tropical storm would weaken when it encountered land.
Satellite image of Rolf spinning south of the French Riviera in early November 2011. Image credit: Courtesy Dávid Hérincs.
All of the information in this post was obtained from a blog post co-written by Dr. Jeff Masters and Bob Henson from the Category 6 blog at wunderground.com