Please comment (can be done anonymously) with any suggestions to improve these entries. It would be great to get some discussion going on an unofficial medicane record.
Since there is no official monitoring of the tropical storm like cyclones in the Mediterranean, here is an unofficial record with some amateur comments. Names are chosen randomly and alphabetically. The medicane season would probably start in September and end in January. Once again I emphasize I am an amateur, and there is nothing official about these thoughts below.
The designations I will use are
Invest: Disturbance with the potential to develop into a tropical system
Medistorm: Maximum sustained wind-sp0eeds below 39mph (equivalent to tropical depression)
Medicane: Maximun sustained wind-speeds between 39mph and 74mph (equivalent to tropical storm)
Major Medicane: Maximun sustained wind-speeds above 74mph (equivalent to cat1 hurricane)
Invests will be documented as they occur, but will not form part of this summary. I can make no promises that these storms are tropical-like, as I have limited means to do so. In the tropics the weakest tropical cyclone (tropical depression) simply needs to show closed circulation and deepening. For the Mediterranean this is inadequate because there is no guaranteed a cyclone is tropical-like, further baroclinically fueled storms are every bit as capable of producing strong winds (if not more so) than tropical-like systems. The difficult part is separating the mid-latitude storms from the tropical like systems. The following criteria will be taken into account:
1) Whether or not the cyclone has a warm core: cyclone phase diagrams from the following source are especially useful: moe.met.fsu.edu/cyclonephase/
2) Evidence of frontal systems. Cloud patterns associated with cold, warm and occluded fronts strongly oppose a tropical like nature. However occluded fronts may sometimes, unfortunately, mimic tropical like cloud patterns
3) Characteristic features, especially eye-wall and eye.
4) Absence of significant lightning, lightning implies strong vertical motion; in cyclones we would expect more horizontal motion. This might be a useful way to distinguish organised thunderstorms from cyclones.
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Medistorm Christopher
Duration: 21st November - 22nd November
Maximum sustained wind-speed (estimated): 35mph
Minimum surface pressure: 990mb
Above: track of tropical-like system in 3 hour intervals from 8pm UTC
Cold air, originally from the arctic, flooded south on the 21st behind a cold front which stretched across central and southern parts of Europe. At this time of year cold air, particularly at upper levels can be a catalyst for tropical-like development. In this case, cold air in the upper atmosphere but relatively mild air at the surface interacted in the wake of the cold front allowing the formation of a short lived system. One interesting property of this system was how rapidly it developed, with an approximate 20mb deepening in only a few hours, given its very close proximity to land one can theorize that if the system had a less enclosed environment it could potentially have developed into a major medicane; indeed at its peak intensity it arguably obtained sustained winds of 40mph (meriting full medicane status).
The system moved due SE impacting Italy after only 5 hours, however due to its small size the disruption caused by this storm was extremely limited. The remnants of Christopher moved quickly over Italian mainland, with some regeneration actually happening in the Adriatic. However this was short lived and the system once again dissipated on becoming flush with the land to the east.
Above: 1) Reformation of Christopher in the Adriatic (visible image), 2) Christopher at peak intensity, note the eye wall encircles most of the centre with the exception of the SE quadrant despite being so close to land. Note also the cold front lying to the south east that introduced upper level cold air that catalysed the formation of Christofer. Images courtesy of sat24.com
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Diary entry: http://quantumoverlord.blogspot.co.uk/2015/10/invest02.html
Medistorm Bessie
Duration: 22nd October
Maximun sustained wind-speed (estimated): 30mph
Minimum surface pressure: 998mb
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Above: track of tropical-like system in 6 hour intervals
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Unusually moist air moving out of Tunisia interacted with the Mediteranian sea on the 21st of October. Thunderstorms were particularly widespread and a frontal based system aided the development of storms on both sides of the Adriatic. Cold air at the 500mb level also provided a good environment for tropical-like development, however it was not until 10am on the 22nd of October that evidence of said development had occurred. Convective clouds started to rotate around a centre of circulation in the south Adriatic sea and deepening of the cyclone occurred (presumably due to non-baroclinic means). An eye marking the centre of the cyclone was visible at about 12pm, although very quickly diminished after the system moved close to the Albanian coastline. The system did, however, return westward and moved towards Italy making landfall at around 5pm UTC. During this journey the system became disorganized and dissipated completely after making landfall. The biggest hazard associated with this system was the 'feeder' storms on its periphery which were tempestuous (a tornado was even spotted close to Athens). Overall this system was fairly underwhelming and could only be marginally considered a medistorm for a period of 7 hours.
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| Medistorm Bessie at 11:55 at her peak strength (courtesy of sat24.com) |
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Medicane Alison
Duration: (September 30 - October 2)
Maximum sustained wind-speed (estimated): 45mph
(left: track of alison at 6hr intervals, right: alison at peak intensity from sat24.com)
An invest moving north out of Africa on the 30th quickly developed tropical characteristics later that morning, with a very strong convection affecting the Spanish balearic islands. During the afternoon of the 30th Alison became far less organised, and seemingly affected by strong wind sheer with the majority of convection limited to the northern flank. Overnight the system became slow moving and intensified with banding features not untypical of a dvorak T3.5 system, however the system was asymmetrical with most of the thunderstorm activity well to the north and west. During the early hours of the 1st October Alison encountered an upper trough, and wind sheer fell substantially allowing significant intensification from medistorm to medicane status at approximately 3am. Sustained windspeeds of up to 45, possibly 50mph may have occurred early on the 1st when Alison reached peak intensity. Just after noon on the 1st Alison hit Sardinia. Heavy rain and flooding was associated with this system particularly on the western side of the island. As Alison made landfall she weakened significantly and opened out into a trough like system more typical of a mid-latitude depression. Nevertheless corsica saw rainfall totals exceeding 100mm. During the 2nd Alison lost most of her tropical characteristics, becoming highly asymmetrical and orientated from NW to SE. However shortly after noon and after having left Corsica, Alison briefly regained tropical characteristics and medistorm status once again, however this brief burst of new convection did not last and within hours alison had completely dissipated. The remnants of Alison encountering the relief of the alps caused further heavy rain on the mainland including severe flooding in Cannes. 17 people unfortunately lost their lives due to to floods in the south of France.
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