Sandwich IR108 n HRVIS  2020_09_17_09_00UTC

Mediterranean cyclones

18 February 2007-2 November 2021

Sandwich IR108 n HRVIS  2020_09_17_09_00UTC
Sandwich IR108 n HRVIS  2020_09_17_09_00UTC

This case study combines a number of examples of medicanes, as seen in satellite imagery.

Last Updated

25 May 2023

Published on

17 February 2007

Mediterranean tropical-like cyclones, often referred to as medicanes (a portmanteau of Mediterranean hurricanes) are meteorological phenomena occasionally observed over the Mediterranean Sea between September and January. They bring gusty winds and heavy rain.

According to Wikipedia, Mediterranean tropical cyclones are rare weather phenomena. These systems are the subject of some debate within meteorological circles, whether they closely fit the definition of tropical cyclones, or subtropical cyclones. Their origins are typically non-tropical, and develop over open waters under strong, initially cold-core cyclones (cut-off lows), similar to (sub)tropical cyclones in the Atlantic Basin.

Cold air aloft appears to be the main trigger for instability in the development of these systems. If a hurricane season were ever to be defined for the Mediterranean region, it would extend from June to May the following year, based upon occurrences so far. Thus, the formation of Mediterranean (sub)tropical cyclones are possible, during anytime of the year, but with a maximum frequency in autumn (September-December) when both cut-off lows and warm surface water occur at the same time.

According to Robert Hart (Florida State University), tropical and extratropical cyclones have, historically, been viewed as two discrete, mutual exclusive cyclone groups. However, warm SSTs, increased surface fluxes, enhanced convection and enhanced latent heat release can blur that once-perceived fine line between tropical and extratropical cyclones.

While it is well known that symmetric, non-frontal warm-core tropical cyclones can become asymmetric, frontal, cold-core extratropical cyclones, it is less well known that, in contrast, cold-core, extratropical cyclones can convert to warm-core, tropical cyclones. This often occurs when a cold-core, cut-off low remains stationary for several days over an area with relatively high SSTs (but not necessarily 26°C).

This case study is a collection of exmaples showing how medicanes are seen in satellite imagery.



23 Oct-2 Nov, Italy, Tunisia, Algeria, Libya, Turkey
By Federico Fierli, Jochen Kerkmann, Vesa Nietosvaara, HansPeter Roesli, Ivan Smiljanic and Phil Watts

Between 23 October and 2 November 2021, a series of upper-level lows caused disturbances (including a Medicane), in the western Mediterranean/northern Africa area, bringing torrential rainfall to the adjacent countries, in particular Algeria, Tunisia and southern Italy.

Southern Italy was the most severely affected by catastrophic rain, in particular Sicily, which was hit three times in one week — 24, 26 and 28-29 October (after experiencing record temperatures of 50°C this summer). The Sicilian meteorological agency, Servizio Informativo Agrometeorologico Siciliano, reported 312.2mm of rain fell in 24 hours to 25 October at a weather station at Linguaglossa, while the station at Lentini recorded 279.8mm during the same period.

Figure 1 shows the upper-level low that caused the flash floods in Sicily on 24 October. The highest, coldest clouds can be seen over north-eastern Sicily and southern Calabria (indicated by the more white colours in this Airmass RGB).

Meteosat-11 Airmass with H300 overlaid
Figure 1: Meteosat-11 Airmass RGB plus ECMWF geopotential 300 hPa, 24 October 2021 18:00 UTC. Source: EUMeTrain.

Figure 2 shows the 12-hour animation of this RGB product, together with the near-real time H03B (H SAF) precipitation product. As this product is based on infrared data calibrated by precipitation measurements from polar microwave satellite sensors, the strongest precipitation rates (red to magenta colour, corresponding to 25 to 35mm/hr, see colour scale) are observed over the coldest clouds in north-eastern Sicily and southern Calabria.

Figure 2: Meteosat-11 Airmass RGB and H SAF precipitation rate product, 24 October 2021 12:00-24:00 UTC.

In Algeria the Algerian Civil Defence department reported heavy rain and stormy weather across the country from early 23 October. The worst affected provinces include Algiers, Boumerdes, Chlef and Tizi Ouzou. Civil protection teams rescued dozens of people and helped clear flood water from more 138 homes, six of which partially collapsed. Some areas of Algiers city recorded more than 140mm in 24 hours to 24 October.

Floods also affected several regions of neighbouring Tunisia overnight from 23 to 24 October. Two people died in Thala, Kasserine Governorate, after a car was washed away. A third victim died in similar circumstances in Borj Chakir, a locality near the city of Tunis. Severe flooding was also reported in Bizerte Governorate. Tunisia’s National Institute of Meteorology (INM) reported 166mm of rain in Ras Jebel, Bizerte Governorate, and 136mm in Sidi Thabet, Ariana Governorate.

Figure 3 shows a six-day satellite animation of the Airmass RGB over the Mediterranean area. As discussed above, the strongest precipitation can be expected under the highest, coldest clouds (strong white colour). Most of the intense precipitation occurred over the sea (for example the convective clouds south-east of Sicily on 25 October), but on 26 October and 28-29 October Sicily was again hit by large convective cells.

Figure 3: Meteosat-11 Airmass RGB, 23 October 2021 12:00 UTC to 29 October 12:00 UTC (15-min intervals).

Interestingly, at the beginning of the loop (first 24 hours) a red-pink plume can be seen moving quickly from Sicily across Greece towards Turkey (see this snapshot). The colour is typical for SO2 plumes from volcanic eruptions. Also the form, an elongated triangular plume, suggests it is a volcanic plume from Mount Etna, as confirmed by reports of an early morning Etna paroxysm on 23 October.

Medicane Apollo

On 25 October, with the convection in the centre of the upper-level low becoming more organised, a Low Level Circulation Centre (LLCC) started to form in the Ionian Sea south of Sicily.

This LLCC is best observed in fast animations of the HRV channel of Meteosat-8/10 and 11, see Figures 4, 5 & 11. Note that the Airmass RGB (Figure 3) is not suited to observe the LLCC, as low-level clouds do not have a good contrast in this RGB.

Meteosat-11 HRV, 26 Oct 07:00-13:00 UTC
Figure 4: Meteosat-11 HRV images, 26 October 2021 07:00-13:00 UTC (forward/backward animation).
Meteosat-11 HRV, 28 Oct 07:00-13:30UTC
Figure 5: Meteosat-11 HRV images, 28 October 2021 07:00-13:30 UTC (forward/backward animation).

Around 27-28 October, the LLCC over the Ionian Sea intensified and the low became deeper, prompting forecast offices in Europe to call it a Medicane (or Subtropical Low) and to name it. The most commonly used name for the cyclone is Apollo, which was used by the Free University of Berlin and the Italian NMS. On the same day, the National Observatory of Athens in Greece named it Nearchus, after the voyager of the same name.

Meteosat-11 Airmass RGB, 29 Oct 18:00UTC
Figure 6: Meteosat-11 Airmass RGB and GFS surface pressure analysis, 29 October 2021 18:00 UTC.

The track of Apollo can be seen in a series of Terra MODIS True Color RGB images and in the long Meteosat-11 animations (Figure 7 and 12).

Figure 7: Meteosat-11 Tropical Airmass RGB, 27 October 2021 06:00 UTC-31 October 08:00 UTC (15-min intervals).

While the LLCC initially tracked eastward, on 28 October it turned around and approached Sicily, without making landfall. It reached its closest position to Sicily in the evening of 29 October (Figure 6), with a central pressure of just below 1000hPa.

Meteosat-10 rapid scan (5-minute) HRV imagery on 29 October reveals some details about the convection, when Apollo was at is mature stage (Figure 8).

Figure 8: Meteosat-10 HRV images, 29 October 2021 05:30-15:50 UTC (5-min intervals).

As can be see, the area of Catania, and the region south of it, was strongly affected by Apollo, with an additional 100-200mm of rain in 48 hours. Other areas of Sicily also received substantial amounts of rainfall. On the mainland Calabria, in southwest Italy, was also hit. During 29 October, there was a phase of barrage clouds developing along the Calabrian mountain ridges. This cloud bank stands out very well as a stationary feature in the first hours of the HRV movie.

From the afternoon of 29 October the low headed south-eastward and appeared to make a landfall east of Benghazi, Libya on 31 October (Figure 9).

Meteosat-11 HRV Clouds RGB overlaid with ECMWF geopotential field at 950 hPa (blue isolines) and 300 hPa (red isolines)
Figure 9: Medicane touching the African continent on 31 October 2021 09:00 UTC. Meteosat-11 HRV Clouds RGB overlaid with ECMWF geopotential field at 950hPa (blue isolines) and 300hPa (red isolines).

However, instead of landfall, the cyclone did a ‘land-bounce’, only skirting the African continent and continuing rotation across the eastern Mediterranean (Figures 10 and 11), making landfall in the south of Turkey, east of Antalya, in the early hours of 2 November. Apollo’s low pressure disturbance was at this point very much constrained to low levels, which is apparent when comparing geopotential fields at low (950hPa) and high (300hPa) levels, and also from the cloud rotation that appeared in the lower cloud field.

Meteosat-11 HRV Clouds RGB overlaid with ECMWF geopotential field at 950 hPa (blue isolines) and 300 hPa (red isolines)
Figure 10: Medicane crossing the eastern Mediterranean on 1 November 2021 09:00 UTC. Meteosat-11 HRV Clouds RGB overlaid with ECMWF geopotential field at 950hPa (blue isolines) and 300hPa (red isolines).
Figure 11: Medicane crossing the eastern Mediterranean during the day on 1 November 2021 05:00-14:00 UTC. Meteosat-8 HRV channel.

The complete journey of Apollo, together with the lifecycle of the cyclone that preceded it (that was responsible for floods e.g. over Sicily on 24 October) is captured in the 10-day Airmass RGB loop in Figure 12.

Figure 12: Low pressure disturbances over Mediterranean in the 10-day window, 23 October 2021 06:00 UTC to 2 November 06:00 UTC. Meteosat-11 Airmass RGB product.

Cloud analysis of Apollo

The Optimal Cloud Analysis (OCA), a SEVIRI instrument cloud product capable of differentiating and visualising different cloud layers, gives a different perspective on the medicane. In the Meteosat Day Natural Colour RGB image slice taken across the medicane Apollo centre 28 October 11:45 UTC (Figure 13, top), the eye-like feature is clearly seen. In the OCA cross section (bottom of the image) the centre of the medicane is quite cloud-free, surrounded by a thick wall of clouds, extending up to 12-13km in the troposphere. The liquid phase clouds are shown in green colours in the cross section, while ice phase clouds are shown in blue-orange colours.

Note: the cloud top height and optical thickness are directly estimated from SEVIRI measurements – the geometric thickness and thus the cloud base is inferred from a statistical relationship to these two values. The in-cloud cloud intensity shown is directly proportional to the optical thickness.

Optimal Cloud Analysis
Figure 13: Meteosat-11 Natural Colour RGB image slice (top) with  OCA analysis (bottom), 28 October 2021 11:45 UTC.

Other image sources

Meteosat-11 Dust RGB animation of Apollo, 27-28 October (Source: CIRA)
Terra MODIS True Color RGB image of Apollo, 29 October (Source: NASA)
SNPP VIIRS DNB image of Apollo, 29 October (Source: NASA)

Media reports

Flash flooding in Italian city turns roads into rivers (CNN)
Catania: Two dead as rare storm floods streets of Sicilian city (BBC News)
Maltempo a Catania, morto un uomo a Gravina. Allagato il centro storico, a decine messi in salvo dalla furia dell’acqua (Corriere, in Italian)
Subtropischer Sturm im Mittelmeer: Medicane trifft Sizilien (wetter online/YouTube, in German)



16-18 Sept, Greece, Italy
By Aida Alvera Azcarate (University of Liège), Vesa Nietosvaara, Natasa Strelec Mahovic and Ildiko Szenyan (OMSZ)

A medicane, named 'Ianos' by the Hellenic National Meteorological Service, started to develop over the Mediterranean Sea on 14 September, just off North African shores.

The general synoptic environment was characterised by an upper level low over the Mediterranean, where additional synoptic forcing was ensured by the 300hPa jet-stream bringing dry air (black in water vapour image) with high vorticity values from the upper levels to the system (see Figure 14).

 Left: Meteosat-11 IR10.8, 14 September 09:00 UTC, with 500 hPa absolute topography (blue) and Mean Sea Level Pressure (black) overlaid. Right: Meteosat-11 WV6.2, 14 September 18:00 UTC, with 300 hPa wind barbs overlaid
Figure 14: Left: Meteosat-11 IR10.8, 14 September 2020 09:00 UTC, with 500hPa absolute topography (blue) and Mean Sea Level Pressure (black) overlaid. Right: Meteosat-11 WV6.2, 14 September 18:00 UTC, with 300hPa wind barbs overlaid

By 16 September the cyclone had intensified and strong winds developed surrounding its centre. Figure 15 shows the winds measured by the ASCAT (scatterometer) instrument on the Metop satellites, indicating wind speeds over 90km/h (25m/s) around the cyclone.

 Metop ASCAT winds: a) Metop-A on 15 September, 19:25 UTC, b) Metop-C on 16 September, 08:13 UTC, c) Metop-B on 16 September, 20:19 UTC, d) Metop-C on 17 September, 19:11 UTC. Source: NESDIS
Figure 15: Metop ASCAT winds: a) Metop-A on 15 September 2020 19:25 UTC, b) Metop-C on 16 September, 08:13 UTC, c) Metop-B on 16 September, 20:19 UTC, d) Metop-C on 17 September, 19:11 UTC. Source: NESDIS

By early 17 September the cyclone had moved closer to the Italian coast over the Ionian Sea, with advancement of strong quasi-stationary rain bands reaching the southern shores of the Calabria region, and causing locally high precipitation amounts (Figure 16).

Figure 16: Meteosat-11 IR 10.8 Enhanced image, 16 September 2020 00:00 UTC–18 September, 11:00 UTC.

The cyclone's centre had an eye-like structure in the morning of 17 September. The Metop-B image on 17 September at 08:40 UTC (Figure 17) shows a well defined vortex centre with surrounding rain bands in the north. The rain band over Calabria is clearly visible.

 Metop-B AVHRR Cloud RGB image (0.63 µm, 0.865 µm and 10.8 µm), 17 September 08:40 UTC
Figure 17: Metop-B AVHRR Cloud RGB (0.63 µm, 0.865 µm and 10.8 µm), 17 September 2020 08:40 UTC

Later that day the cyclone's centre moved slowly towards the east, approaching west coast of Greece. The Greek Meteorological Service issued red warnings for parts of Greece for 17 and 18 September, in particular for high precipitation and lightning, and orange warnings for the wind (Figure 18).

 Meteoalarm warnings issued by the Hellenic National Meteorological Service for 18 September
Figure 18: Meteoalarm warnings issued by the Hellenic National Meteorological Service for 18 September 2020

The whole episode took five to six days. The sequence of various development stages is shown in the Sandwich product (High Resolution Visible imagery overlaid by IR10.8 cloud top temperature information) (Figure 19). The development started within an unstable air mass, with several individual convective clusters between Sicily and the North African coast, during 13 and 14 September. On 15 September the vortex started to develop, and on 16 September it rapidly intensified, developing a clear tropical-like cyclone appearance. Finally the mature Medicane moved over the Ionian Sea to the Greek coast during 17 and 18 September.

Figure 19: Meteosat-11 Sandwich product (High Resolution Visible overlaid with IR10.8 temperature), 13-18 September 2020. Source: Hungarian Meteorological Service.

During the evening of 17 September Medicane Ianos made landfall on the Greek islands and the west coasts of Greece. The Ionian Sea islands of Zakynthos, Kefalonia and Ithaca were all badly hit. Wind speeds of up to 100 km/h were reported.

On 18 September the storm travelled across mainland of Greece. Heavy precipitation and flash flooding, caused by convective storms developing within the Medicane, occurred in many places. Intensive precipitation occurred on the islands in the night and early morning.

The near-real time precipitation product H03B, generated by IR images from the SEVIRI instrument 'calibrated' by precipitation measurements from microwave satellite sensors on polar-orbiting satellites, is shown in Figure 20.

Figure 20: Near-real time precipitation product H03B (IR + MW measurements) loop, 18 September 2020 00:00–21:00 UTC.

Later in the day a convective storm embedded into the medicane cloud-band, causing persistent heavy precipitation over central and eastern parts of Greece. In the towns of Lamia and Karpenissi the flooding led to people being trapped by their houses and vehicles. Due to damage to the railway line, the train connection between Athens and Thessaloniki was disrupted. Hundreds of people had to be rescued from flooded buildings, especially in the region north of Athens. At least three people were reported to have been killed by the storm.

Tropical storms, including medicanes, rely on warm underlying water to release heat into the upper atmosphere and create rotating winds. Warmer water supplies more energy, which can result in increased intensity of the storm. Therefore, it can be assumed that a major contributing factor in the development process and the intensification of medicane Ianos, was the warm surface of the sea near where it initiated.

Figure 21 shows the Sea Surface Temperature on 12 September, before the formation of the storm and on 18 September, after the storm has passed over the sea. The L3 multi-sensor product (on the left of Figure 21) is built from bias-corrected L3 mono-sensor products at the resolution 0.02 degrees, with the following hierarchy of the datasets used: Metop-B AVHRR, SEVIRI, SLSTR, SNPP VIIRS, AVHRRL-19, AVHRRL-18, AQUA MODIS-A, TERRA MODIS, AMSR2. Missing data was reconstructed using DINEOF resulting in the right-hand image. With the storm developing and moving over the Ionian Sea, the sea surface was getting cooler. After the medicane left, the sea surface was almost 5 deg cooler than before the storm.

 Multi-sensor sea surface temperature (left) and SST reconstructed using DINEOF (right) for 12 September 2020 (top panel) and 18 September 2020 (bottom panel). Credit: University of Liège.
Figure 21: Multi-sensor sea surface temperature (left) and SST reconstructed using DINEOF (right) for 12 September 2020 (top panel) and 18 September 2020 (bottom panel). Source: University of Liège.

The photographs in Figure 22 show the ground-to-ground and cloud-to-cloud lightning caused by the medicane in the early hours of 17 September.

 Lightning strikes off the Calabrian coast in the early hours of 17 September. Credit: Caterina Mazzuca
Figure 22: Lightning strikes off the Calabrian coast in the early hours of 17 September. Credit: Caterina Mazzuca

Media reports

'Medicane,' a rare, hurricane-like storm in the Mediterranean, makes landfall in Greece (CNN)
Medicane Ianos Lashes Kefalonia, Ithaca, and Zakynthos, Causing Floods, Blackouts, Fallen Trees (Greek Reporter)
Warning of storm Ianos in several regions - Greece (Global Monitoring
Storm Ianos: Three dead as rare ‘medicane’ batters Greece (Al Jazeera)



15-19 Nov, Greece, UK

By Djordje Gencic and HansPeter Roesli

On 13 November a deep Genoa low started to pushed polar air in the direction of southern Italy. From 15 November onwards the depression widened and moved to the central Mediterranean. In particular, over the still warm Ionian Sea (between southern Italy and Greece) the cold and now very humid airmass destabilised under weak vertical wind shear.

 Suomi-NPP VIIRS Natural Color RGB, IR10.763, Cloud Type RGB, Cloud Phase RGB, 18 Nov, 12:14 UTC
Figure 23: Suomi-NPP VIIRS Natural Color RGB (top left), IR10.763 (top right), Cloud Type RGB (bottom left), Cloud Phase RGB (bottom right), 18 November 2017 12:14 UTC

These were the necessary ingredients for the formation of a Medicane, a MEDIterranean hurriCANE, or Tropical-Like Cyclone (TLC).

Taking on the name Numa, on 18 November it appeared as a whirl of convective cloud and a distinct quasi cloud-free eye. The structure was short-lived — by the evening of 18 November the Medicane had dissipated due to a trough and increased wind shear.

The evolution of Numa can be followed in the sequence of Meteosat-10 Airmass RGBs from 15–19 November. The TLC-phase on 18 November is shown in a sequence of HRV images overlaid in semi-transparency by the false-coloured IR10.8 band, both from the rapid-scanning Meteosat-9 between 06:00 UTC and 15:00 UTC.

Figure 23 is four images from SNPP VIIRS on 18 Nov at 12:14 UTC (like Figure 24) which show in clockwise order the Natural Colour RGB (NCOL), the false-colour temperature map from band IR10.763 (M15), the Cloud Type RGB (CTYP) and the Cloud Phase RGB (CPHA). Note that in particular in the NCOL frame there isolated strangely-coloured pixels due to specular reflection of the sunlight.

 SNPP, 18 Nov, 12:14 UTC
Figure 24: SNPP VIIRS True Color RGB, 18 November 2017 12:14 UTC
 Met-9, 18 Nov, 12:00 UTC
Figure 25: Meteosat-9 HRV with MSLP charts & GFS analysis overlaid, 18 November 2017 12:00 UTC

A True Color RGB of the VIIRS imager on Suomi-NPP shows some more details of the cloud structures shortly after 12:14 UTC (Figure 24).

Another typical feature of a hurricane is its warm core. As shown by the composite of the HRV band with the charts of MSLP and equipotential temperatures from the Global Forecast System (GFS) analysis (Figure 25) Numa at 12:00 UTC on 18 November had its eye collocated with the MSLP centre and a warm 700hPa area.

Other image source

Cyclone Numa in the Mediterranean Sea (CIMSS Blog)



26-31 Oct, Greece
By Scott Bachmeier (CIMSS Blog), Djordje Gencic and Jochen Kerkmann

Between 28–31 October, a compact medicane moved across the Mediterranean.

 Meteosat-10 Airmass RGB, 31 Oct 05:00 UTC
Figure 26: Meteosat-10 Airmass RGB, 31 October 2016 05:00 UTC

Initially, on 26–27 October a cut-off low moved from northern to southern Italy, triggering deep convective storms along the Italian west coast. On 28 October, a new PV anomaly arrived from Hungary. This new PV anomaly crossed the Adriatic Sea on 28 October at O4:00 UTC and then quickly moved to Sicily and further to Tunisia and Algeria.

At the same time, the Medicane started to develop in the area south of Sicily (just east of Malta) in the area of the old PV anomaly. These various weather developments could be seen in the Meteosat-9 Airmass imagery, Figure 26 (above right) and the Meteosat-9 animation from 26 October 21:00 UTC to 31 October 06:00 UTC

On 29 October, the Medicane got stronger staying east of Malta. Finally, on 30 October it moved eastward towards Greece.

The eye structure of the Medicane could be best seen at 04:00 UTC on 30 October.

The Meteosat-10 infrared imagery (Figure 27 and animation) showed the system as it developed over the Ionian Sea between Italy and Greece, moved southwestward, then turned to the east, eventually passing near Crete on 31 October. It was reported to have producing a wind gust to 96km/h at Chania’s Souda Airport and caused some wind and water damage.

 Met-10, 30 October, 12:00 UTC
Figure 27: Meteosat-10 Infrared, 30 October, 12:00 UTC. Download animation, 28 October 2016 05:15 UTC–31 October 06:30 UTC
 Met-10, 30 October, 12:00 UTC
Figure 28: Meteosat-10 Visible, 30 October, 12:00 UTC. Download animation, 28 October 06:00 UTC–31 October 15:00 UTC

The Meteosat-10 Visible imagery (Figure 28 and animation) provides a more detailed look at the structure of the storm during the daylight hours of those four days.

 Met-10, 30 October, 12:00 UTC
Figure 29: Meteosat-10 Natural Colour RGB with MSLP overlaid, 30 October 2016 12:00 UTC. (Credit: EUMeTrain)
 Terra, 30 October, 09:30 UTC
Figure 30: Terra MODIS Natural Color RGB, 30 October 2019 09:30 UTC. (Credit: NASA).

The Meteosat-10 Natural Colour RGB with the analysis overlaid (Figure 29) and the MODIS Natural Color RGB (Figure 30) show the circulation of the system, as a tight spiral in the centre. On Figure 29 the Medicane can be clearly seen surrounded by more benign weather conditions.

 ASCAT 25 km wind product, 30 October.
Figure 31: ASCAT 25km wind product, 28-30 October.

The winds speeds of the system can be seen on the ASCAT 25km wind products from 28–30 October (Figure 31). The surface wind circulation of the medicane reached around 50kts (the black markers signify the higher winds).

Scott's full analysis of the medicane (CIMSS Blog)

Media report

Last weekend’s bad weather now classified as a tropical storm (The Malta Independent)



2-3 Dec, Italy
By Vesa Nietosvaara and Jose Prieto

A swirling area of low pressure over Lazio on 3 December showed a clear eye - indicating a medicane.

The infrared Dust RGB animation (Figure 32) shows convective systems generating in the north-western Mediterranean (Tyrrhenian Sea). These evolved into an almost circular small sized cyclone, known as a medicane.

Figure 32: Meteosat-10 Dust RGB, 2 December 2014 00:00 UTC-3 December 14:00 UTC

The storm hit Italy a few kilometres west of Rome, bringing heavy rain to the country.

Metop-B Natural Colour RGB, 3 December 08:35 UTC
Figure 33: Metop-B Natural Colour RGB, 3 December 08:35 UTC

On the Metop-B Natural Colour RGB, from 3 November 08:36 UTC (Figure 34), and the composite Meteosat-8 HRV/RGB image, from 3 November 08:00 UTC (Figure 35), a distinct eye can be seen to the west of Rome.

Metop-B, 03 December 2014, 08:36 UTC
Figure 34: Metop-B Natural Colour RGB, 3 December 2014 08:36 UTC
Meteosat-8, 03 December 2014 08:30 UTC
Figure 35: Meteosat-8 HRV (70%) mixed with RGB 234 (30%), 3 December 2014 08:30 UTC


7-8 Nov, Malta, Italy
By Mark Higgins, Jochen Kerkmann, Sancha Lancaster, Hans-Peter Roesli, Dr Michael Sachweh and Eleftheria Tsiniari (Hellenic National Meteorological Service)

On 7 November the storm first hit Lampedusa on the island of Linosa, then Malta (at around 16.30 UTC) and then the eastern coast of Sicily before it disappeared to the east.

 S-NPP, VIIRS Day-Night Band and I5, 08 November 01:43 UTC
Figure 36: SNPP VIIRS Day-Night Band and I5, 8 November 01:43 UTC

Gusts of 135km/h were recorded at Lampedusa in Linosa and up to 154km/h in Malta. Airport and ferry operations were suspended and many areas were left without power, as the storm caused damage across the three countries.

The system can be clearly seen on the a Day-Night-Band image (750m resolution) in black and white with yellow hues of IR11.45 (band I5 at 375m resolution) from cold-white to warm-yellow — high cloud appears white, lower cloud and artificial light is yellow (Figure 36). The scene is well lit by the full Moon.

The Airmass RGB animation (Figure 37), shows the birth of the medicane out of cut-off low and its progress across the Mediterranean. It also shows the deceleration of the rotation after the TLC hit the Catania coast.

Figure 37: Meteosat-10 Airmass RGB, 7 November 03:00 UTC–8 November 12:00 UTC

Earlier in the week the heavy rains from the deep trough, at the origin of the cut-off, had caused Lago Maggiore in the Alps to overflow.

A branch of a polar jet stream over south western Europe headed sharply towards the south, starting to meander over Tunisia. In the Water Vapour (WV 6.2µm) images from 6 November 18:00 UTC–8 November 00:00 UTC (Figures 3–8) the location of the jet stream is identified as a strong gradient from high to low humidity (dark stripes).

Met-10 Water Vapour, 6 Nov 18:00 UTC
Figure 38: Meteosat-10 Water Vapour, 6 November 18:00 UTC
Met-10 Water Vapour, 7 Nov 00:00 UTC
Figure 39: Meteosat-10 Water Vapour, 7 November 00:00 UTC
Met-10 Water Vapour, 7 Nov 06:00 UTC
Figure 40: Meteosat-10 Water Vapour, 7 November 06:00 UTC
Met-10 Water Vapour, 7 Nov 12:00 UTC
Figure 41: Meteosat-10 Water Vapour, 7 November 12:00 UTC
Met-10 Water Vapour, 7 Nov 18:00 UTC
Figure 42: Meteosat-10 Water Vapour, 7 November 18:00 UTC
Met-10 Water Vapour, 8 Nov 00:00 UTC
Figure 43: Meteosat-10 Water Vapour, 8 November 00:00 UTC

Water vapour imagery clearly shows the stratospheric air extruded well downwards into the troposphere indicative of strong cyclogenesis. The sequence of WV images also reveal the main stages of this development. Noteworthy features can be seen, such as baroclinic leaf, a comma head and the cloud hook (Figures 38 and 39).

 Met-10 Airmass RGB, 7 Nov 12:00 UTC
Figure 44: Meteosat-10 Airmass RGB, 7 November 12:00 UTC

After 12:00 UTC, the characteristic dry swirl pattern is evident (Figures 41–43), indicating that the cyclone was entering the occluded phase of its life cycle.

A scalloped pattern is clearly visible along the dark WV stripe, indicating a maximum of cyclonic shear vorticity (Figures 39 and 40 – yellow arrow).

The position of the jetstream can also be seen in the Airmass RGB image, 7 November 12:00 UTC (Figure 44) where there is a colour difference (red changes to purple – black arrows).

Figure 45 shows the storm seen from Metop-B on 7 November at 08:25 UTC. The images are the 0.6 micron channel from AVHRR and the winds are taken from ASCAT 12.5km coastal wind product. The winds are approximately hour mean winds, showing the gross speed and direction — gusts will have been much stronger. Areas with wind greater than 74km/h (40kts) are shown in brown and red.

Metop image comparison

Metop-B AVHRR with 12.5 km ASCAT winds overlay compare1

Figure 45: Comparison of Metop-B AVHRR images of the medicane, with and without ASCAT winds, 7 November 2014, 08:25 UTC

The animated gif of Meteosat-10 HRV imagery, from 07:00–11.45 UTC (Figure 46), shows the storm over Lampedusa.

 Met-10 HRV imagery, 7 Nov 07:00–11:45 UTC
Figure 46: Meteosat-10 HRV imagery, 7 Nov 07:00–11:45 UTC

Development of marine conditions using ASCAT observations

The region to the south of the low pressure centre is a region of strong pressure gradient, with resulting strong winds. The wind field near the surface can be captured by the Advanced Scatterometer (ASCAT) instruments on board the Metop satellites (Figure 47).

 Metop-B ASCAT winds, 07 Nov, 08:37 UTC
Figure 47: Metop-B ASCAT winds, 7 November 08:37 UTC
 Metop-A ASCAT winds, 07 Nov, 09:25 UTC
Figure 48: Metop-A ASCAT winds, 7 November 09:25 UTC

A close examination of the wind direction retrieved from ASCAT Metop-B (Figure 47) showed a defined vortex with maximum speed of more 50kt (92km/h).

 Metop-B ASCAT winds, 07 Nov, 19:56 UTC
Figure 49: Metop-B ASCAT winds, 7 November 19:56 UTC

According to Figure 27 the centre of the system was located east of the coasts of Tunisia at about 08:37 UTC. The winds exceeded 50kt locally to the south and southwest of the low where the wind flow converged.

We have similar vector winds observations from ASCAT on Metop-A at 09:25 UTC (Figure 48).

At about 18:00 (19:56 UTC), as the low pressure system had moved eastwards, west northwest winds of 40–45kt maxima value were observed in the area of interest (Figure 49).

The tropical-like cyclone of 7 November 2014 seems to have been a notably severe one, with gradient wind strengths up to 75kt over the island of Lampendusa (ICAO index LICD). This value of wind speed coincides with the data retrieved from ASCAT at the same time.

Strong winds produced high waves of about 3m or more. The highest waves were located right of the track of the cyclone, at the 'danger semicircle' as was expected.

Observations of both wave and swell height show that a wave height of 6ft (about 3m of total wave height) in the area between Sicily and Malta at 02:00 UTC, seem in good agreement with the model forecast.

According to the Extreme Forecast Index (EFI) values, the marine situation seems to have been unusual and dangerous, and could have been expected to generate strong swells.

Taking into account the fact that the model wave height fields showed a wave maximum area exceeding the threshold values warnings, it would be expected that warnings would be issued. Indeed, Greece, who is responsible for the provision of marine bulletins for the eastern Mediterranean Sea and Black Sea, issued a strong gale warning for Boot, Sidra Melita and Gabes.

The intensity of the wind field was quite well forecast: the cyclone lost its strength after landfall (Figure 50) at about 02:00 UTC on 8 November, and began to weaken rapidly, as seen from the Metop-B ASCAT winds on 8 November at 08:16 UTC (Figure 51).

 SNPP Day-Night Band (DNB), 08 Nov, 01:43 UTC
Figure 50: SNPP Day-Night Band (DNB), 8 November 01:43 UTC
 Metop-A ASCAT winds, 08 Nov, 08:16 UTC
Figure 51: Metop-A ASCAT winds, 8 November 08:16 UTC

The models did well in forecasting the location of the storm centre, the drop and timing of mean sea level pressure and the significant wave height.

The strong winds near the centre of the storm, were not well described in the models because of the rapid deepening of the cyclone.

Satellites as weather observing tools seem to offer a new dimension in the field of marine meteorology improving markedly forecasting ability.

Addendum by Dr Michael Sachweh

MSG — Rapid Scans

Meteosat-9 RGB, 7 November 12:00 UTC (source: RGB images created by MeteoGroup)
Figure 52: Meteosat-9 RGB, 7 November 12:00 UTC (source: RGB images created by MeteoGroup)
Download animation, 7 November 06:45 UTC–8 November 08:13 UTC
Watch the animation on YouTube

The RGB animation shows the development of Medicane Qendresa as seen by Meteosat-9 5-minute rapid scans, from the birth in the area of Pantelleria to its dissipation in the area east of Sicily.

The standard RGB using the HRV and the IR10.8 channels is shown (ie RGB HRV-HRV-IR10.8).

In the night the images look blue as the HRV images (which are put on the red and green beams) are not available at night. From 17:15 UTC to 05:00 UTC the images are only available at 15-min frequency, thus the imagery judders slightly during the night hours.

Dissipation of the storm

The land contact of Qendresa over eastern Sicily (overnight 7–8 November) caused a reduction of the energy, moisture and fluxes from the warm sea surface, and also led to an unbalance of the system both of which probably contributed to the quick dissipation on 8 November. Storms of this kind are very sensitive to rotational asymmetries.

Strong winds in Catania

It is interesting to note that, during the passage of Qendresa, Catania recorded very strong N to NE winds. This could be a barrier effect, from Mount Etna, which enhanced the winds on the left side of the vortex (a funnelling effect).

This northerly funnel might be the reason why the system, after hitting Sicily, moved back to the south. It would be interesting to simulate this case with high-resolution NWP models.


As previously stated, Qendresa caused heavy precipitation in Malta and Sicily.

On 8 November, more than 100 mm in 24 hours were recorded in the Catania and Ragusa Provinces.

The animated GIF of the radar (Figure 53) nicely shows the eye as the storm passed along the east coast of Sicily, revealing the tropical storm nature of Qendresa.

Rainfall radar, 8 November 02:00–06:00 UTC
Figure 53: Rainfall radar, 8 November 02:00–06:00 UTC. Source: Protezione Civile, Italy
Ground observations

Because of its track hitting several synop stations, Qendresa offered perfect ground truth observations of a Medicane (e.g. the pressure funnel recorded on the Island of Linosa , Italy).

Pressure funnel recording at Bugibba, Malta
Figure 54: Pressure funnel recording at Bugibba, Malta

The recording at Bugibba, in the north-west of Malta, perfectly shows the structure of a tropical storm:

  1. The eye-wall with average winds of 111km/h and gusts up to 154km/h.
  2. 15 minutes later, the eye of the storm (see pressure funnel) with totally calm conditions (no wind) with a remarkable pressure of 978.6hPa.
  3. The second eye wall with about 50km/h winds.

Topografic effects may have increased the wind (first eye wall) or reduced the wind (second eye wall), as the wind recording is not symmetric, unlike the pressure recording.

This photograph shows the damage north of Catania (Giardini-Naxos) from Cosimo Manitta.

Further analysis from Dr Michael Sachweh (in German)

Media reports

Rare Medicane Hits Malta and Sicily With Tropical Storm-Like Conditions (Weather Underground)
Rare Medicane Hits Malta and Sicily With hurricane Conditions (Live Leak)
A tropical cyclone and torrential rain hit Sicily (Reuters video)
Maltempo, ciclone tropicale a Malta - 7 novembre 2014 (MeteoWeb/YouTube)
Update 3: Airport operations resume, several areas without power, cars damaged as fierce storm lashes Malta (Times of Malta)



8 Nov, Italy, Spain, France
By Scott Bachmeier (CIMSS) and Jochen Kerkmann

The tropical storm of November 2011 started over the period 4–6 November 2011, when an extratropical system slowly transformed into a subtropical low over the warm waters of the Mediterranean Sea (Figure 55). The storm was then given the identification Invest 99L, by the United States Naval Research Laboratory (NRL).

Figure 55: Meteosat-9 Airmass RGB, 3 November 01:00 UTC–7 November 08:00 UTC

As the storm slowly moved westwards, it caused flooding in Spain and the Balearic Islands (Figure 56). As the storm further continued its westward movement, it slowly became organised, and convection began to increase.

Figure 56: Meteosat-9 HRV, 6 November 07:15–16:00 UTC

On 7 November 2011, NOAA began watching the subtropical area of low pressure, now located in the Gulf of Lions and which NOAA had earlier identified as INVEST 99L, as the storm organised itself into a subtropical disturbance. Later that day, the subtropical disturbance transformed and strengthened, into a tropical depression off the coast of France. The storm was then given the identification 01M/99L by NOAA. Late on November 7, the storm was upgraded to tropical storm status as it strengthened significantly. At that time, the Satellite Services Division and NESDIS both classified the storm as Tropical Storm 01M.

On 8 November 2011, the storm continued to strengthen as it came closer to France. At peak intensity, the storm had a minimum low pressure of 991hPa. Wind speeds were estimated to have reached 45kts according to various satellite analysis techniques (Figure 57). On 9 November, however, the storm made landfall in south-eastern France, near Hyères, where it dissipated completely shortly thereafter.

Tropical storm develops in the Mediterranean Sea
Figure 57: Meteosat-9 HRV with Metop-A ASCAT winds overlaid, 8 November 10:00 UTC

Overall, the tropical storm caused severe flooding, in parts of Spain, Italy and France. From 6 to 8 November 2011, the storm produced a total of 600mm of rain in about 72 hours over southwestern Europe. Eleven people died from the storm, six Italians and five French.

The animations below show several sequences of Meteosat-8 HRV images at five-minute intervals (rapid scans). The development of the tropical storm over the western Mediterranean Sea during the period 6–9 November can be easily followed. The rapid scan HRV images have also been used to derive an approximate storm track, based on the low level circulation centres that are sometimes visible when there are enough gaps in the high level clouds.

Tropical storm develops in the Mediterranean Seaa
Figure 58: Meteosat-8 HRV, 8 November 2011, 10:00 UTC

Additional content

Meteosat-8 HRV Animation 1 (6 November, 07:15–16:00 UTC)
Meteosat-8 HRV Animation 2 (7 November, 07:15–16:00 UTC)
Meteosat-8 HRV Animation 3 (8 November, 07:15–16:00 UTC)
Meteosat-8 HRV Animation 4 (9 November, 07:15–16:00 UTC)
Meteosat-8 HRV Animation 5 (6 November 06:30–9 November 16:30 UTC)

14–17 January 1995 (Mediterranean Sea)
9–10 October 2005 (Hurricane Vince, Madeira) (animated source: Meteo Portugal)
29 Nov–9 Dec 2005 (Hurricane Epsilon)
15 December 2005 (MODIS image) (source: NASA)
26 September 2006 (Puglia, Italy)
18 October 2007 (Mediterranean Sea, Libya) (source: Hungarian Meteorological Service)
>1–3 June 2009 (Tropical Storm, Azores)
30 Sep–1 Oct 2009 (Tropical Storm Grace, Azores)

02 February 2010 (Tropical Storm, Canaries and Madeira)
1–2 February 2010 (Tropical Storm, Canaries and Madeira)



17 Feb, Europe
By Jochen Kerkmann

In February 2007, during the stand-by period of MSG-2 (Meteosat-9), a 168-hour period of rapid scans was performed with this satellite. The images and animations below show the situation on 18 February 2007 when Central Europe was under the influence of a high pressure system whilst the Mediterranean area was affected by cut-off cyclones (one over the Western Mediterranean and a smaller one over Israel and the Middle East).

As one can see in the animations, the high repeat cycle leads to very smooth movements/transitions of the cloud systems (i.e. no jumps as regards position and movement of clouds) when compared to the 15-minutes repeat cycle (see Animation, 07:59–13:59 UTC).

Moreover, the high repeat cycle is essential for monitoring rapid changes of cloud properties like cloud phase and cloud particle size. Examples of this can be seen over Northern Africa (see animation of ascending cloud band, 06:44–13:59 UTC) and over the Middle East (see animation of convective clouds, 11:04–13:04 UTC).

Met-9, 18 February 2007, 12:04 UTC
Figure 59: Meteosat-9 RGB Composite VIS0.8, IR3.9r, IR10.8, 18 February 2007, 12:04 UTC.
Animation (07:59–13:59 UTC). Animation (Zoom) (06:44–13:59 UTC)
Met-9, 18 February 2007, 12:04 UTC
Figure 60: Meteosat-9 RGB Composite VIS0.8, IR3.9r, IR10.8, 18 February 2007, 12:04 UTC
Animation (05:04–13:59 UTC)
Met-9, 18 February 2007, 12:04 UTC
Figure 61: Meteosat-9 RGB Composite WV6.2–WV7.3, IR9.7–IR10.8, WV6.2, 18 February 2007, 12:04 UTC. Animation (07:59–13:59 UTC)
Met-9, 18 February 2007, 12:04 UTC
Figure 62: Meteosat-9 Channel 12 (HRV), 18 February 2007, 12:04 UTC. Animation (07:19–13:54 UTC)

Additional content

Animation (Western Mediterranean) (Met-9, HRV Channel, 08:09–13:59 UTC)
Animation (Central Europe) (Met-9, HRV Channel, 09:49–13:49 UTC)
Animation (Northern Europe) (Met-9, HRV Channel, 08:29–13:19 UTC)
Animation (Western Europe) (Met-9, RGB VIS0.8, IR3.9r, IR10.8, 07:19–13:59 UTC)
MSG rapid scans with 3 minutes repeat cycle (15 December 2003)