Investigating the development conditions for cyclones with tropical features in the Mediterranean Basin.

In recent years, the impact of cyclones with tropical characteristics in areas of the Mediterranean
Sea, also called Medicanes (MEDIterranean hurriCANES; Emanuel, 2005), has caused extensive
damage, particularly in coastal areas of Greece, Italy and North Africa. These cyclones have a
relatively low frequency in Mediterranean areas, although they are associated with extreme
weather phenomena (heavy rainfall, strong winds, and landslides). Therefore, the main goal of this
work is to create an index of meteorological conditions that can determine favourable
environment for the development of cyclones with tropical characteristics in the Mediterranean
basin. For this purpose, we have selected some of the most intense Medicanes occurring during
the last years. Using ERA5 data we study variables such as Convective available potential energy
(CAPE), coupling index (CI; Bosart & Lackmann, 1995), Wind shear, Geopotential in 500 hPa and
Sea surface temperature (SST).The findings of this study reveal that the development of cyclones
with tropical characteristics in the Mediterranean is strongly linked to the formation of an intense
trough, which is exposed to strong convective processes (high CAPE and CI values), low wind shear
at high levels and a Mediterranean Sea temperature above 15oC. The combination of all these
conditions at the same time is quite uncommon, so this could explain the infrequent and extreme
nature of this type of cyclones.