User:Atomic7732/Mediterranean tropical cyclone

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A Mediterranean hurricane on January 16, 1995.

Mediterranean tropical cyclones, sometimes referred to as Mediterranean hurricanes or medicanes, are rare meteorological phenomena observed in the Mediterranean Sea. Due to the dry nature of the Mediterranean region, formation of tropical cyclones is infrequent, with only 112 recorded tropical-like storms between 1948 and 2016. No agency, however, is officially responsible for monitoring the formation and development of medicanes. Tropical cyclogenesis typically occurs within two separate regions of the sea. The first region, encompassing areas of the western Mediterranean, is more conducive for development than the other, the Ionian Sea to the east. On very rare occasions though, a tropical or subtropical cyclone may develop within the Black Sea. The rough mountainous geography of the region raises additional difficulties despite being favorable for the development of severe weather and convective activity in general, and only with abnormal meteorological circumstances can medicanes form. Numerous studies have been conducted on the impact of global warming on Mediterranean tropical cyclone formation, generally concluding that fewer yet more intense storms would form.

The development of tropical cyclones in the Mediterranean Sea can usually only occur under somewhat unusual circumstances. Low wind shear and atmospheric instability induced by incursions of cold air are often required. A majority of medicanes are also accompanied by upper-level troughs, providing energy required for intensifying atmospheric convection—thunderstorms—and heavy precipitation. The baroclinic properties of the Mediterranean region, with high temperature gradients, also provides necessary instability for the formation of tropical cyclones. Another factor, rising cool air, provides necessary moisture as well. Warm sea surface temperatures (SSTs) are mostly unnecessary, however, as most medicanes' energy is derived from warmer air temperatures. When these favorable circumstances coincide, the genesis of warm-core Mediterranean tropical cyclones, often from within existing cut-off cold-core lows, is possible in a conducive environment for formation.

Several notable and damaging medicanes are known to have occurred. In September 1969, a north African Mediterranean tropical cyclone produced flooding that killed nearly 600 individuals, left 250,000 homeless, and crippled local economies. A medicane in September 1996 that developed in the Balearic Islands region spawned six tornadoes and inundated parts of the islands. Several medicanes have also been subject to extensive study, such as those of January 1982, January 1995, September 2006, and November 2011. The January 1995 storm is one of the best-studied Mediterranean tropical cyclones, with its close resemblance to tropical cyclones elsewhere and availability of observations. The medicane of September 2006, meanwhile, is well-studied due to availability of existing observations and data. In November 2011, the NOAA's Satellite Analysis Branch monitored a possible medicane, named Rolf by the Free University of Berlin (FU Berlin), though it ceased doing so the following month. No agency is officially responsible for monitoring the basin. If a "hurricane season" were ever to be demarcated in the Mediterranean, it would extend from June to May during the next year, based upon occurrences so far. Thus, the formation of Medicanes is possible during any time of the year.

Climatology[edit]

Visible satellite imagery of a medicane above the Balearic Islands on October 7, 1996

Mediterranean tropical cyclones are not considered to be formally classified tropical cyclones and their region of formation is officially monitored by any agency,[1] and though the Satellite Analysis Branch released information related to a medicane in November 2011 while it was active, it ceased doing so on December 16, 2011.[2] The Mediterranean Sea, however, lies within the Greek area of responsibility,[3] while France's Météo-France National serves as a "preparation service" for the areas as well.[4] A majority of Mediterranean tropical cyclones form over two separate regions. The first, more conducive for development than the other, encompasses an area of the western Mediterranean bordered by the Balearic Islands, southern France, and the shorelines of the islands of Corsica and Sardinia. The second identified region of development, in the Ionian Sea between Sicily and Greece and stretching south to Libya, is less favorable for tropical cyclogenesis. An additional two regions, in the Aegean and Adriatic seas, produce fewer Medicanes, while activity is minimal in the Levantine region. The geographical distribution of Mediterranean tropical cyclones is markedly different from that of other cyclones, with the formation of regular cyclones centering on the Pyrenees and Atlas mountain ranges, the Gulf of Genoa, and the island of Cyprus in the Ionian Sea.[5] Although meteorological factors are most advantageous in the Adriatic and Aegean seas, the closed nature of the region's geography, bordered by land, allows little time for further evolution.[6]

The geography of mountain ranges bordering the Mediterranean are conducive for severe weather and thunderstorms, with the sloped nature of mountainous regions permitting the development of convective activity.[7] Although the geography of the Mediterranean region, as well as its dry air, typically prevent the formation of tropical cyclones, when certain meteorological circumstances arise, difficulties influenced by the region's geography are overcome.[8] The occurrence of tropical cyclones in the Mediterranean Sea is generally extremely rare, with an average of 1.57 forming annually and merely 99 recorded occurrences of tropical-like storms discovered between 1948 and 2011 in a modern study, with no definitive trend in activity in that period.[9] Few medicanes form during the summer season, though activity typically rises in autumn, peaks in January, and gradually decreases from February to May.[5] In the western Mediterranean region of development, approximately 0.75 such systems form each year, compared to 0.32 in the Ionian Sea region.[10]

Studies have evaluated that global warming can result in higher observed intensities of tropical cyclones as a result of deviations in the surface energy flux and atmospheric composition, which both heavily influence the development of medicanes as well. In tropical and subtropical areas, sea surface temperatures (SSTs) rose 0.2 °C (32.4 °F) within a 50-year period, and in the North Atlantic and Western Pacific tropical cyclone basins, the potential destructiveness and energy of storms nearly doubled within the same duration, evidencing a clear correlation between global warming and tropical cyclone intensities.[11] Within a similarly recent 20-year period,[12] SSTs in the Mediterranean Sea increased by 0.6 to 1 °C (33.1 to 33.8 °F),[11] though no observable increase in medicane activity has been noted, as of August 2013.[9] In 2006, a computer-driven atmospheric model evaluated the future frequency of Mediterranean cyclones between 2071 and 2100, projecting a decrease in autumn, winter, and spring cyclonic activity coinciding with a dramatic increase in formation near Cyprus, with both scenarios attributed to elevated temperatures as a result of global warming.[13] Other studies, however, have been inconclusive, forecasting both increases and decreases in duration, number, and intensity.[14] A third study, conducted in 2013, evaluated that while Medicane activity would likely decline between 10 and 40 percent by 2100, a higher percentage of those that formed would be of greater strength.[15]

Development and characteristics[edit]

A Mediterranean tropical cyclone south of Italy on October 27, 2005
Satellite image of a December Medicane from 2005

Factors required for the formation of Medicanes are somewhat different from those normally expected of tropical cyclones; known to emerge over regions with sea surface temperatures (SSTs) below 26 °C (79 °F), Mediterranean tropical cyclones often require incursions of colder air to induce atmospheric instability.[5] A majority of medicanes develop above regions of the Mediterranean with SSTs of 15 to 26 °C (59 to 79 °F), with the upper bound only found in the southernmost reaches of the sea. Despite the low sea surface temperatures, the instability incited by cold atmospheric air within a baroclinic zone—regions with high differences in temperature and pressure—permits the formation of medicanes, in contrast to tropical areas lacking high baroclinity, where raised SSTs are needed.[16] While significant deviations in air temperature have been noted around the time of Mediterranean tropical cyclones' formation, few anomalies in sea surface temperature coincide with their development, indicating that the formation of medicanes is primarily controlled by higher air temperatures, not by anomalous SSTs.[17] Similar to tropical cyclones, minimal wind shear—difference in wind speed and direction over a region—as well as abundant moisture and vorticity encourages the genesis of tropical cyclone-like systems in the Mediterranean Sea.[18]

Due to the confined character of the Mediterranean and the limited capability of heat fluxes—in the case of medicanes, air—sea heat transfer—tropical cyclones with a diameter larger than 300 km (190 mi) cannot exist within the Mediterranean.[19] Despite being a relatively baroclinic area with high temperature gradients, the primary energy source utilized by Mediterranean tropical cyclones is derived from underlying heat sources generated by the presence of convection—thunderstorm activity—in a humid environment, similar to tropical cyclones elsewhere outside the Mediterranean Sea.[20] In comparison to other tropical cyclone basins, the Mediterranean Sea is generally presents a difficult environment for development; although the potential energy necessary for development is not abnormally large, its atmosphere is characterized by its lack of moisture, impeding potential formation. The full development of a medicane often necessitates the formation of a large-scale baroclinic disturbance transitioning late in its life cycle into a tropical cyclone-like system, nearly always under the influence of a deep, cut-off, cold-core low within the middle-to-upper troposphere, frequently resulting from abnormalities in a wide-spreading Rossby wave—massive meanders of upper-atmospheric winds.[21]

A weak and disorganized Mediterranean tropical cyclone on January 28, 2010

The development of medicanes often results from the vertical shift of air in the troposphere as well, resulting in a decrease in its temperature coinciding with an increase in relative humidity, creating an environment more conducive for tropical cyclone formation. This, in turn, leads to in an increase in potential energy, producing heat-induced air-sea instability. Moist air prevents the occurrence of convective downdrafts—the vertically downward movement of air—which often hinder the inception of tropical cyclones,[21] and in such a scenario, wind shear remains minimal; overall, cold-core cut-off lows serve well for the later formation of compact surface flux-influenced warm-core lows such as medicanes. The regular genesis of cold-core upper-level lows and the infrequency of Mediterranean tropical cyclones, however, indicate that additional unusual circumstances are involved the emergence of the latter. Elevated sea surface temperatures, contrasting with cold atmospheric air, encourage atmospheric instability, especially within the troposphere.[16]

In general, most medicanes maintain a radius of 70 to 200 km (40 to 120 mi), last between 12 hours and 5 days, travel between 700 to 3,000 km (430 to 1,860 mi), develop an eye for less than 72 hours, and feature wind speeds of up to 144 km/h (89 mph);[22] in addition, a majority are characterized on satellite imagery as asymmetric systems with a distinct round eye encircled by atmospheric convection.[19] Weak rotation, similar to that in most tropical cyclones, is usually noted in a medicane's early stages, increasing with intensity;[23] medicanes, however, often have less time to intensify, remaining weaker than most North Atlantic hurricanes and only persisting for the duration of a few days.[24] The maximum achievable intensity of medicanes is equivalent to the lowest classification on the Saffir–Simpson hurricane wind scale, Category 1. While the entire lifetime of a cyclone may encompass several days, most will only retain tropical characteristics for less than 24 hours.[25] Circumstances sometimes permit the formation of smaller-scale medicanes, although the required conditions differ even from those needed by other medicanes. The development of abnormally small tropical cyclones in the Mediterranean usually requires upper-level atmospheric cyclones inducing cyclogenesis in the lower atmosphere, leading to the formation of warm-core lows, encouraged by favorable moisture, heat, and other environmental circumstances.[26]

Mediterranean cyclones have been compared to polar lows—cyclonic storms which typically develop in the far regions of the Northern and Southern Hemispheres—for their similarly small size and heat-related instability; however, while medicanes nearly always feature warm-core lows, polar lows are primarily cold-core. The prolonged life of medicanes and similarity to polar lows is caused primarily by origins as synoptic-scale surface lows and heat-related instability.[7] Heavy precipitation and convection within a developing Mediterranean tropical cyclone are usually incited by the approach of an upper-level trough—an elongated area of low air pressures—bringing downstream cold air, encircling an existing low-pressure system. After this occurs, however, a considerable reduction in rainfall rates occurs despite further organization,[27] coinciding with a decrease in previously high lightning activity as well.[28] Although troughs will often accompany medicanes along their track, separation eventually occurs, usually in the later part of a Mediterranean tropical cyclone's life cycle.[27] At the same time, moist air, saturated and cooled while rising into the atmosphere, then encounters the medicane and permits further development and evolution into a tropical cyclone. Many of these characteristics are also evident in polar lows.[29]

Known/Documented Occurrences[edit]

The September 1983 storm, on September 30.
The December 1984 storm.

Numerous other Mediterranean cyclones have occurred, but few as better-documented as those in 1969, 1982, 1995, 1996, 2006, and 2011. On 27 September 1983, a medicane was observed at sea between Tunisia and Sicily, looping around Sardinia and Corsica, coming ashore twice on the islands, before making landfall at Tunis early on 2 October and dissipating. The development of the system was not encouraged by baroclinic instability; rather, convection was incited by abnormally high sea surface temperatures (SSTs) at the time of its formation. It also featured a definitive eye, tall cumulonimbus clouds, intense sustained winds, and a warm core. For most of its duration, it maintained a diameter of 200 to 300 km (120 to 190 mi), though it shrank just before landfall on Ajaccio to a diameter of 100 km (62 mi). Four other notable cyclones occurred in the late twentieth century, on 26 March 1983, 29–30 December 1984, 30–31 October 1997, and 5–8 December 1997, all exhibiting characteristics closely resembling tropical cyclones elsewhere.[30]

Meteorological literature documents a total of 112 "Mediterranean Hurricanes" (or "Medicanes"), that have occurred between 1948 and 2016. These systems have occured in: September 1947, September 1969, September 1973, August 1976, January 1982, September 1983, December 1984, December 1985, January 1991, October 1994, January 1995, September 1996, twice in October 1996, September 1997, March 1999, twice in September 2003, October 2003, August 2005, September 2005, twice in October 2005, December 2005, August 2006, twice in September 2006, March 2007, twice in October 2007, June 2008, August 2008, September 2008, December 2008, January 2009, May 2009[31], twice in September 2009, October 2009, October 2010, November 2010, November 2011, twice in February 2012, once in March 2012, April 2012, October 2012, November 2012, November 2013, November 2014, December 2014, and in October 2016. However, 2 storms formed over the Black Sea: once in 2005, and on January 2012.[32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45]

A study performed in 2013 revealed several additional storms and additional information on medicanes that formed on April 7, 1984, December 14, 1985, December 5, 1991, January 15, 1995, December 10, 1996, January 26, 1998, March 19, 1999, and May 27, 2003.[46] A second study, conducted in 2007, revealed that additional storms formed on October 18, 2003, October 27, 2005, and December 15, 2005.[47] A third study revealed several more tropical cyclones, of which developed on September 13, 1999, September 10, 2000, October 9, 2000, September 19, 2004, November 3, 2004, October 26 and 17, 2007, December 4, 2008, and April 13, 2012.[25]

1960s[edit]

September 23–30, 1969[edit]

ESSA-8 visible satellite imagery of the September 1969 tropical cyclone

An unusually severe Mediterranean tropical cyclone developed on 23 September 1969 southeast of Malta, producing severe flooding.[30] Steep pressure and temperature gradients above the Atlas mountain range were evident on 19 September, a result of cool sea air attempting to penetrate inland; south of the mountains, a lee depression—a low-pressure area in a mountainous region—developed. Under the influence of mountainous terrain, the low initially meandered northeastward. Following the entry of cool sea air, however, it recurved to the southeast before transitioning into a Saharan depression associated with a distinct cold front by 22 September. Along the front's path, desert air moved northward while cold air drifted in the opposite direction, and in northern Libya, warm arid air clashed with the cooler levant of the Mediterranean. The organization of the disturbance improved slightly further before emerging into the Mediterranean Sea on 23 September, upon which the system experienced immediate cyclogenesis,[48] rapidly intensifying while southeast of Malta as a cold-core cut-off low,[49] and acquiring tropical characteristics.[30] In western Africa, meanwhile, several disturbances converged toward Mauritania and Algeria, while the medicane recurved southwestward back toward the coast, losing its closed circulation and later dissipating.[49]

The cyclone produced severe flooding throughout regions of northern Africa. Malta received upward of 123 mm (4.8 in) of rainfall on 23 September, Sfax measured 45 mm (1.8 in) on 24 September, Tizi Ouzou collected 55 mm (2.2 in) on 25 September, Gafsa received 79 mm (3.1 in) and Istanbul measured 46 mm (1.8 in) on 26 September, Cap Bengut collected 43 mm (1.7 in) on 27 September, and Biskra received 122 mm (4.8 in) on 28 September.[50] In Malta, a 20000-ton tanker struck a reef and split in two, while in Gafsa, Tunisia, the cyclone flooded phosphate mines, leaving over 25,000 miners unemployed and costing the government over £2 million per week. Thousands of camels and snakes, drowned by flood waters, were swept out to sea, and massive Roman bridges, which withstood all floods since the fall of the Roman Empire, collapsed. In all, the floods in Tunisia and Algeria killed almost 600 individuals, left 250,000 homeless, and severely damaged regional economies.[51] Due to communication problems, however, flood relief funds and television appeals were not set up until nearly a month later.[50]

1980s[edit]

January 23–27, 1982[edit]

NOAA-7 visible satellite imagery of the Mediterranean tropical storm at 1236 UTC on January 26, 1982

The unusual Mediterranean tropical storm of January 1982 was first detected in waters north of Libya.[30] The storm likely reached the Atlas mountain range as a low-pressure area by 23 January 1982, reinforced by an elongated, slowly-drifting trough above the Iberian Peninsula. Eventually, a closed circulation center developed by 1310 UTC,[52] over parts of the Mediterranean with sea surface temperatures (SSTs) of approximately 12 °C (54 °F).[53] A hook-shaped cloud developed within the system shortly thereafter, rotating as it elongated into a 150 km (93 mi)-long comma-shaped apparatus. After looping around Sicily, it drifted eastward between the island and Peloponnese, recurving on its track again,[54] exhibiting clearly curved spiral banding before shrinking slightly.[55] The cyclone reached its peak intensity at 1800 UTC on the following day, maintaining an atmospheric pressure of 992 mbar (29.30 inHg), and was succeeded by a period of gradual weakening, with the system's pressure eventually rising to 1009 mbar (29.80 inHg). The system slightly reintensified, however, for a six-hour period on 26 January. Ship reports indicated winds of 93 km/h (58 mph) were present in the cyclone at the time, tropical storm-force winds on the Saffir–Simpson hurricane wind scale,[52] likely near the eyewall of the cyclone, which features the highest winds in a tropical cyclone.[53]

The Global Weather Center's Cyclone Weather Center of the United States Air Force (USAF) initiated "Mediterranean Cyclone Advisories" on the cyclone at six-hour intervals starting at 1800 UTC on 27 January until 0600 UTC the following day.[56] Convection was most intense in the eastern sector of the cyclone as it drifted east-northeastward. On infrared satellite imagery, the eye itself was 58.5 km (36.4 mi) in diameter,[53] contracting to just 28 kilometres (17 mi) one day prior to making landfall.[56] The cyclone passed by Malta, Italy, and Greece before dissipating several days later in the extreme eastern Mediterranean. Observations related to the cyclone, however, were inadequate, and although the system maintained numerous tropical characteristics, it is possible it was merely a compact but powerful extratropical cyclone exhibiting a clear eye, spiral banding, towering cumulonimbi, and high surface winds along the eyewall.[30]

1990s[edit]

January 13–18, 1995[edit]

Mediterranean Cyclone 16 jan 1995 1004Z.jpg

Among numerous documented medicanes, the cyclone of January 1995 is generally considered to be the best-documented instance. Emerging off of the Libyan coast into the central Mediterranean Sea toward the Ionian shoreline of Greece on 13 January as a compact low-pressure area, the precursor low maintained winds reaching up to 108 km/h (67 mph) as it traversed the Ionian Sea,[57] while the German research ship Meteor noted winds of 135 km/h (84 mph).[58] Upon the low's approach near Greece, it began to envelop an area of atmospheric convection; meanwhile, in the middle troposphere, a trough extended from Russia to the Mediterranean, bringing with it extremely cold temperatures.[59] Two low-pressure areas were present along the path of the trough, with one situated above Ukraine and the other above the central Mediterranean, likely associated with a low-level cyclone over western Greece. Upon weakening and dissipation on 14 January, a second low, the system which would evolve into the Mediterranean tropical cyclone, developed in its place on 15 January.[58]

At the time of formation, high clouds indicated the presence of intense convection,[58] and the cyclone featured an axisymmetric cloud structure, with a distinct, cloud-free eye and rainbands spiraling around the disturbance as a whole.[60] Soon thereafter, the parent low separated from the medicane entirely and continued eastward,[59] meandering toward the Aegean Sea and Turkey.[57] Initially remaining stationary between Greece and Sicily with a minimum atmospheric pressure of 1002 mbar (29.59 inHg), the newly formed system began to drift southwest-to-south in the following days, influenced by northeasterly flow incited by the initial low, now far to the east, and a high-pressure area above central and eastern Europe.[59] The system's atmospheric pressure increased throughout 15 January due to the fact it was embedded within a large-scale environment, with its rising pressure due to the general prevalence of higher air pressures throughout the region, and was not a sign of deintensification.[60]

Initial wind speeds within the young medicane were generally low, with sustained winds of merely 28 to 46 km/h (17 to 29 mph), with the highest recorded value associated with the disturbance being 63 km/h (39 mph) at 0000 UTC on 16 January, slightly below the threshold for tropical storm on the Saffir–Simpson hurricane wind scale. Its structure now consisted of a distinct eye encircled by counterclockwise-rotating cumulonimbi with cloud top temperatures below −50 °C (−58 °F), evidencing deep convection and a regular feature observed in most tropical cyclones.[61] Intense convection continued to follow the entire path of the system as it traversed the Mediterranean, and the cyclone made landfall in northern Libya at approximately 1800 UTC on 17 January, rapidly weakening after coming ashore.[59] As it moved inland, a minimum atmospheric pressure of 1012 mbar (29.89 inHg) was recorded, accompanied by wind speeds of 93 km/h (58 mph) as it slowed down after passing through the Gulf of Sidra.[62] Although the system retained its strong convection for several more hours, the cyclone's cloud tops began to warm, evidencing lower clouds, before losing tropical characteristics entirely on 17 January.[63] Offshore ship reports recorded that the medicane produced intense winds, copious rainfall, and abnormally warm temperatures.[64] The system dissipated the next day.[32]

September 12–13, 1996[edit]

Mediterranean tropical cyclone 1996.JPG

This storm was a typical Mediterranean tropical cyclone that developed in the Balearic Islands region.[65] At the time of the cyclone's formation, a powerful Atlantic cold front and a warm front associated with a large-scale low, producing northeasterly winds over the Iberian peninsula, extended eastward into the Mediterranean, while abundant moisture gathered in the lower troposphere over the Balearic channel.[66] On the morning of 12 September, a disturbance developed off of Valencia, Spain, dropping heavy rainfall on the coast even without coming ashore. An eye developed shortly thereafter as the system rapidly traversed across Majorca and Sardinia in its eastward trek. It made landfall upon the coast of southern Italy on the evening of 13 September with a minimum atmospheric pressure of 990 mbar (29.24 inHg), dissipating shortly after coming ashore,[67] with a diameter of about 150 km (93 mi).[26]

At Valencia and other regions of eastern Spain, the storm generated heavy precipitation, while six tornadoes touched down over the Balearic Islands. While approaching the coast of the Balearic Islands, the warm-core low induced a pressure drop of 11 mbar (0.32 inHg) at Palma, Majorca in advance of the tropical cyclone's landfall. Medicanes as small as the one that formed in September 1996 are atypical, and often require circumstances different even from those required for regular Mediterranean tropical cyclone formation.[26] Warm low-level advection–transfer of heat through air or sea–caused by a large-scale low over the western Mediterranean was a primary factor in the rise of strong convection.[7] The presence of a mid- to upper-level cut-off cold-core low, a method of formation typical to medicanes, was also key to the development of intense thunderstorms within the cyclone. In addition, interaction between a northeastward-drifting trough, the medicane, and the large-scale also permitted the formation of tornadoes within thunderstorms generated by the cyclone after making landfall.[68]

October 4–9, 1996[edit]

The last major Mediterranean tropical cyclone of 1996 while west of Italy on October 7.
The system on October 4.

The second of the three recorded Mediterranean tropical cyclones in 1996 formed between Sicily and Tunisia on 4 October, making landfall on both Sicily and southern Italy. The medicane generated major flooding in Sicily; meanwhile, in Calabria, wind gusts of up to 108 km/h (67 mph) were reported in addition to severe inundation.[30] The third major Mediterranean tropical cyclone of that year formed north of Algeria and strengthened while sweeping between the Balearic Islands and Sardinia, with an eye-like feature prominent on satellite. The eye was distorted and disappeared after transiting over southern Sardinia throughout the evening of 8 October, with the system weakening as a whole. On the morning of October 9, a smaller eye emerged as the system passed over the Tyrrhenian Sea, gradually strengthening, with reports 100 km (62 mi) from the storm's center reporting winds of 90 km/h (56 mph). Extreme damage was reported in the Aeolian Islands after the tropical cyclone passed north of Sicily, though the system dissipated while turning southward over Calabria. Overall, the lowest estimated atmospheric pressure in the third medicane was 998 mbar (29.47 inHg).[69] Both October systems featured distinctive spiral bands, intense convection, high sustained winds, and abundant precipitation.[30]

October 6–11, 1996[edit]

Mediterranean hurricane 1996.jpg

As the previous system was at its peak, a frontal wave extended through the western Mediterranean. It developed into a frontal low on the 6th, and strengthened and became better organized as it moved eastward over warm waters. With little upper level shear, a warm core, an organized vertical structure, and an eyewall, the system was possibly a hurricane, late on the October 7, just before hitting Sardinia. Over land, the storm lost its eye structure, but quickly reorganized and acquired a new eye, early on the 8th, after crossing Sardinia. The storm reached hurricane strength again, during the same day in the Tyrrhenian Sea. On the 9th, serious damage from winds up to 145 km/h (78 knots) was reported over the Eolian Islands. Four people were reported dead. The storm retained its organization for a day, before hitting northern Sicily on the 10th and weakening. The storm dissipated on October 11, just south of Crete. Floods occurred on the Balearic Islands, Sardinia, and south Italy. The development of a hurricane in the central Mediterranean Sea was well-predicted by computer models in the days prior to the storm's genesis.[70]

March 27–28, 1999[edit]

Mediterranean subtropical storm 1999.jpg

A deep cyclone cutoff in the Gulf of Lyons on March 26. Winds at Portbou, Spain increased to 150 km/h, 41.6 m/s (81 knots, 93 mph) by the evening of March 26. The pressure of the cyclone fell to 990 hPa by midnight. By the morning of March 27, it was no longer connected to its occluded front and satellite imagery briefly revealed an eye feature, though convection around it was shallow. Water temperatures around 15°C, lower than the values typically observed during Mediterranean tropical vortices (higher than 20°C), justify the low values of the heating fluxes. Moreover, while the 10 meters wind speed showed an apparent increase mostly in the area south of the sea level pressure minimum till March 27, 1999 at 12 UTC, after which it is almost constant for 6-8 hours, which explains the increase in the sensible and latent heat fluxes, an almost windless area appears at low levels at the low centre. Such feature propagates at higher levels till about 400 hPa, producing a virtually windless air column above the cyclone “eye”, surrounded by higher wind speeds with a strong horizontal gradient. It is accompanied by a warm core from the surface up to about 600 hPa. Soon afterwards, the system weakened as it approached northern Italy. This system was probably a subtropical cyclone.

2000s[edit]

September 16–19, 2003[edit]

Mediterranean tropical cyclone 2003.jpg

On September 16, over warm waters of Tunis coast (+27,5°C), a low pressure system developed tropical characteristics. A day later, the storm turned east and it reached tropical storm intensity (35 - 40 knots) between Sicily and Tunis. It dissipated over Ionian sea on September 19. The storm caused deaths and floods over Sicily and Tunis (514mm /46h over Siracusa - 380mm /24h; on Pantelleria island 333mm/24h). Over Tunis (190mm/24h) the social and economic impact of this storm were severe, causing damage to infrastructure and many deaths.

September 28–29, 2003[edit]

Mediterranean tropical storm 2003.jpg

This storm formed from a well-organized thunderstorm complex on the warm waters of the Gulf of Gabes (+27°C) on September 28. It rapidly intensified into Mediterranean tropical storm with 45 knots wind (83 km/h) that morning (QuikSCAT), just 150 km south of Sicily. This mediterranean tropical storm never threatened any land area. It dissipated near the islands of Greece, during the next morning on September 29.

October 17–19, 2003[edit]

Forming from an active convective system emerging from the Iberian peninsula moving slowly east, it converged with a small cyclonic vortex from the south, becoming a "medicane" on October 17, over Mallorca Island. While over Mallorca island, it exacuted a cyclonic loop lasting a few hours. The storm then moved east for the rest of its life, while decreasing in radii. The storm dissipated on October 19. It was a weak system, with peak winds of only 20 knots per hour.

October 26–28, 2005[edit]

Mediterranean Tropical storm.JPG

On 26 October, a convective complex of thunderstorm spawned a low pressure system that took on tropical characteristics over warm water of Libyan coast. A day later, the storm turned north east and it reached tropical storm intensity (35 knots) just 50 km east of Sicily. It dissipated over the Ionian sea, on October 28.

December 5–12, 2005[edit]

This storm was a heavy convective system, which formed off the coast of Tunisia. It stalled for about 24 hours, before moving west, and dissipated in the extreme eastern Mediterranean. Despite being very convective and looking alot like a hurricane, it only had winds of 25 knots, only being a "tropical depression."

Tropical Storm Querida (September 25–27, 2006)[edit]

The tropical cyclone on September 26, 2006.

A short-lived medicane developed near the end of September 2006, along the coast of Italy. The origins of the medicane can be traced to the alpine Atlas mountain range on the evening of 25 September,[65] likely forming as a normal lee cyclone.[71] At 0600 UTC on 26 September, European Centre for Medium-Range Weather Forecasts (ECMWF) model analyses indicated the existence of two low-pressure areas along the shoreline of Italy, one on the west coast, sweeping eastward across the Tyrrhenian Sea, while the other, slightly more intense, low was located over the Ionian Sea.[72] The more intense low was named Querida by the Free University of Berlin. As the latter low approached the Strait of Sicily, it met an eastward-moving convection-producing cold front, resulting in significant intensification, while the system simultaneously reduced in size.[71] It then achieved a minimum atmospheric pressure of approximately 986 mbar (29.12 inHg) after transiting north-northeastward across the 40 km (25 mi)-wide Salentine peninsula in the course of roughly 30 minutes at 0915 UTC the same day.[72]

Wind gusts surpassing 144 km/h (89 mph) were recorded as it passed over Salento due to a steep pressure gradient associated with it, confirmed by regional radar observations denoting the presence of a clear eye.[72] The high winds inflicted moderate damages throughout the peninsula, though specific damage is unknown.[65] Around 1000 UTC,[72] both radar and satellite recorded the system's entry into the Adriatic Sea and its gradual northwestward curve back toward the Italian coast. By 1700 UTC, the cyclone made landfall in northern Apulia while maintaining its intensity, with a minimum atmospheric pressure at 988 mbar (29.18 inHg). The cyclone weakened and eventually dissipated while drifting further inland over the Italian mainland, eventually dissipating as it curved west-southwestward. A later study in 2008 evaluated that the cyclone possessed numerous characteristics seen in tropical cyclones elsewhere, with a spiral appearance, eye-like apparatus, rapid atmospheric pressure decreases in advance of landfall, and intense sustained winds, concentrated near the storm's eyewall;[73] the apparent eye-like structure in the cyclone, however, was ill-defined.[64] Since then, the medicane has been the subject of significant study as a result of the availability of scientific observations and reports related to the cyclone.[72]

January 27–29, 2009[edit]

The storm on January 28, 2009, near peak intensity.

On January 27, a low pressure system over the Tyrrhenian sea developed subtropical characteristics. On January 28, near northeastern Sicily, a QuikSCAT satellite pass over the storm found surface winds of 45 to 55 mph (72 to 88 km/h). Although over cold waters, estimated at 59 °F (15 °C), the storm was found to have developed a warm core and tropical characteristics. Despite this, the National Hurricane Center did not monitor the storm, as such it was not named. The storm dissipated over the Ionian sea, on January 29.[74]

2010s[edit]

Tropical Storm Rolf/01M (November 1–9, 2011)[edit]

Tropical Storm 01M (Invest 99L) at peak intensity, on November 8.
Map plotting the track and intensity of the storm according to the Saffir–Simpson scale

On November 1, an extratropical disturbance developed within the Western Mediterranean Sea. During the next couple of days, the system stalled off the coast of Liguria, and began to strengthen. On November 3, rainfall from the storm began to cause flooding in Liguria. On November 4, 2011, the extratropical system slowly transitioned into a subtropical low over the warm waters of the Mediterranean Sea. It was then named Rolf by the Free University of Berlin, which names all low pressure systems affecting Europe. The storm was then given the identification Invest 99L, by the United States Naval Research Laboratory (the NRL). As the storm slowly moved westwards, it caused flooding in the Balearic Islands. As the storm continued its westward movement, it slowly organized, and convection began to increase. Over the next few days, the storm looped to the east, as it continued to organize. On November 7, the NOAA began watching the subtropical area of low pressure, which was now located in the Gulf of Lions, which NOAA identified as INVEST 99L, as the storm organized into a subtropical disturbance. Later that day, the subtropical disturbance transitoned and strengthened, into a tropical depression, off the coast of France. The storm was then given the identification 01M/99L by NOAA.[2] Late on November 7, the storm was upgraded to tropical storm status as it strengthed significantly. At that time, the Satellite Services Division and NESDIS both classified the storm as Tropical Storm 01M. The storm then began to impact and bring heavy rainfall, to other nearby countries, including Northern Italy and Eastern Spain. On November 8, the storm continued to strengthen (45 kt), as it came closer to France. At peak intensity, the storm had a minimun low pressure of 991 mb (29.3 inHg), and the storm had peak winds of 45 mph (72 km/h). On November 9, however, the storm made landfall on the island of Île du Levant, France, and soon afterwards on Southeastern France, near Hyères. Tropical Storm Rolf (01M) dissipated completely soon after the second landfall.[75]

The storm caused severe flooding, in parts of Italy, Switzerland, and France. From November 6–8, the storm dropped a total of 23.62 in (60.0 cm) of rain in about 72 hours over southwestern Europe. About 12 people total died from the storm; with 6 people being Italian, and 5 people being French; 1 person still remains missing. However, the damage caused by the storm is still unknown, as of November 2011.

Tropical Storm Qendresa (November 5–11, 2014)[edit]

Qendresa I on November 7, 2014

On November 5, 2014, a low-pressure system formed near northern Italy. Shortly afterwards, the system split, with the storm in the south, located just west of northern Italy, receiving the designation Qendresa I from the University of Berlin.[76] On November 7, Qendresa I briefly lost its cold front and acquired a closed low-level circulation, while located over the western Mediterranean, developing into a Medicane. The tropical cyclone moved across the island of Malta, producing sustained winds of 69 mph (110 km/h), gusts up to 96 mph (154 km/h), and a minimum barometric pressure of 979 mb (hPa; 28.91 inHg).[77] Farther west, the island of Lampedusa was reported as devastated, with dozens of ships capsized.[78] On November 8, as the system continued to move eastward, the storm regained it's cold front, while maintaining it's intensity.[79] On November 9, Qendresa I re-acquired tropical characteristics in the southern Mediterranean, but by then, the storm was weakening.[80] On November 10, the system continued to decay, while moving over the island of Crete.[81] On November 11, Qendresa I dissipated.[82]

Tropical Storm Xandra (November 24–December 12, 2014)[edit]

Tropical Storm Xandra on December 3, 2014

On November 24, an extratropical disturbance developed over Eastern Canada.[83] On November 26, the storm system emerged into the North Atlantic Ocean, while slowly gathering strength.[84] On November 27, the storm system was named Xandra by the Free University of Berlin, as the system strengthened to the southeast of southern Greenland.[85] During the next couple of days, Xandra accelerated to the southeast, until it reached the coast of Portugal, on November 29.[86] On November 30, Xandra weakened slightly, as it crossed over Portugal and Spain and entered the western Mediterranean Sea.[87] On December 1, Xandra gradually began to reintensify, as the system slowly moved eastward.[88] Late on December 2, Xandra briefly lost its cold front and became a tropical storm, as it reached its peak intensity of 995 millibars (29.4 inHg).[89] Later on December 3, Xandra redeveloped its cold front and began to weaken, as its low level circulation center developed three central vorticies.[90] On December 4, Xandra drifted northward, while becoming even more disorganized.[91] On December 5, Xandra lost its cold front again, but remained disorganized.[92] On December 6, Xandra began to approach northern Italy, and slightly reorganized.[93] On December 7, Xandra began to move ashore Italy as a tropical depression, even as the system weakened again.[94] This triggered thunderstorms and flooding across the region. On December 8, Xandra redeveloped into an extratropical cyclone, even as it shifted to the south of Italy.[95] On December 9, Xandra intensified as it began to sweep eastward across the Mediterranean.[96] On December 10, Xandra weakened to a 1015 mbar storm, as it moved into the Black Sea.[97] On December 11, Xandra moved over Crimea and stalled, while continuing to weaken.[98] On December 12, Xandra finally dissipated over Crimea.[99]

Tropical Storm 90M (October 27–November 3, 2016)[edit]

Tropical Storm 90M intensifying to the south of Italy, on October 30

On October 27, 2016, an extratropical storm formed over Corsica, in the Mediterranean Sea.[100] During the next 2 days, the storm moved southeastward, while slowly strengthening.[101] On October 29, while located east of Malta, the storm turned to the southwest, and weakened below gale-force intensity. On October 30, the storm turned to the northeast and re-organized, with the system's convection clustering around its center of circulation, and transitioned into a subtropical storm. The storm was assigned the identifier Invest 90M at this time.[102][103] The storm continued to intensify as it moved eastward, before fully transitioning into a tropical storm later on the same day, developing a distinctive, spiral cloud structure and an eye. Early on October 31, Tropical Storm 90M reached its peak intensity, with peak sustained winds of 62.1 mph (99.9 km/h) and a minimum central pressure of around 1,005 mb (29.7 inHg). Around this time, Tropical Storm 90M lashed Crete and Greece with gale-force winds and heavy rain.[104][105] However, later on the same day, the storm began to be sheared by the jet stream, and it also began to merge with a cold front near Greece, causing 90M to transition back into an extratropical storm. On November 1, 90M merged into the cold front, while located over Cyprus.[106][107] The storm continued moving eastward while continuing to merge into the larger frontal system, before fully being absorbed on November 3.[108]

Study[edit]

  • Genesis and maintenance of 'Mediterranean Hurricanes - 1982
  • The development of a Hurricane in the central Mediterranean Sea - 1996
  • Observational analysis of a Mediterranean Hurricane over south-eastern Italy - 2006
  • Mediterranean Sea Hurricane of 1995
  • Warm waters may trigger Mediterranean hurricane - 2008
  • Numerical Analysis of a Mediterranean Hurricane over Southeastern Italy
  • Tropical cyclones may develop over Mediterranean Sea - 2008
  • Analysis of the risk of tropical cyclone development over the Mediterranean Sea
  • A Quasi - Tropical Cyclone Over The Western Mediterranean - 1996
  • Tropical-like Mediterranean Storms: an analysis from satellite - 2005
  • Analysis of the environments of seven Mediterranean tropical-like storms
  • Tropical Cyclone in the Extratropics (Mediterranean): Observational Evidence and Synoptic Analysis - 1996

Notes[edit]

See also[edit]

References[edit]

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  18. ^ Cavicchia et al. 2013, p. 15
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  79. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141108.gif
  80. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141109.gif
  81. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141110.gif
  82. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141111.gif
  83. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141124.gif
  84. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141126.gif
  85. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141127.gif
  86. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141129.gif
  87. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141130.gif
  88. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141201.gif
  89. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141202.gif
  90. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141203.gif
  91. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141204.gif
  92. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141204.gif
  93. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141206.gif
  94. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141207.gif
  95. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141208.gif
  96. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141209.gif
  97. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141210.gif
  98. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141211.gif
  99. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20141212.gif
  100. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20161027.gif
  101. ^ [http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20161029.gif
  102. ^ [Halloween Surprise: Rare Tropical Storm Forms in Mediterranean Sea
  103. ^ Cyclonic Storm in the Mediterranean
  104. ^ Rare tropical storm forms in the Mediterranean Sea
  105. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20161030.gif/
  106. ^ A Tropical Cyclone in the Mediterranean Sea
  107. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20161101.gif
  108. ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20161102.gif

External links[edit]