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Open Access cult task and ffi Discussions Sciences Natural Hazards Hazards Natural and Earth System System and Earth 2,* 7418 7417 ect the Mediterranean region and they can produce , and A. Jansà ff 1 ). Some of them have features of tropical cyclones: they originate and , J. Campins 1 2003 , orts have been devoted to identify them. ff Jansà The goals of this work are to contribute to a proper description of these structures Four well-known medicane events have been described from numerical simulation This discussion paper is/has beenSystem under Sciences review (NHESS). for Please the refer journal to Natural the Hazards corresponding and final Earth paper in NHESS if available. Agencia Estatal de Meteorología, PalmaUniversitat de de Mallorca, les Spain Illes Balears, Palma de Mallorca, Spain formerly at: Agencia Estatal de Meteorología, Palma de Mallorca, Spain In the Mediterranean regiontime ( intense and small cyclonic storms develop from time to outputs of the ECMWFvalidated model. against The available observational predicted data cyclones and and numerical their analyses evolution from have literature. been 1 Introduction many e and to develop some criteria(NWP) model to outputs. identify To do medicanes that, existingand from methodologies tracking numerical for cyclones detecting, have weather characterizating been prediction adapted toFirst, small-scale a intense mesocyclone cyclonic perturbations. detectiontense and cyclones. tracking Next, algorithm the has parameters thattuned been define and modified the calculated to Hart’s to cyclone select examine phase in- their diagram thermal are structure. Tropical-like cyclones rarely a strong winds and heavy precipitations. These warm-core(MEDIterranean cyclones, hurriCANES), called are MEDICANES small size, developFor over these the sea reasons, and are the infrequent. detection and forecast of medicanes are a di Abstract Nat. Hazards Earth Syst. Sci.www.nat-hazards-earth-syst-sci-discuss.net/1/7417/2013/ Discuss., 1, 7417–7447, 2013 doi:10.5194/nhessd-1-7417-2013 © Author(s) 2013. CC Attribution 3.0 License. ena as strong windsin and maritime heavy navigation precipitations, or whichmainly when can from they cause convective make damages, processes landfall especially in and coastal air-sea areas. interaction, Heat play exchanges, a key role in the for- develop over the sea, present a warm-corea structure clear and eye surrounded in most by a ofclones the convective eye-wall have cases cloud they been pattern. have identified These quasi-tropicalcommon as cy- characteristics MEDIterranean with hurriCANES hurricanes. or They MEDICANES, are by related their to severe weather phenom- Detection and thermal description of medicanes from numerical simulation M. A. Picornell 1 2 * Received: 6 November 2013 – Accepted: 26Correspondence November to: 2013 M. – A. Published: Picornell 12 ([email protected]) December 2013 Published by Copernicus Publications on behalf of the European Geosciences Union. 5 15 10 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , ) ) er- Fita ff Tous 2013 1999 ; ( , Campins Moscatello 2006 ), although , 2011 ( Campins et al. 1987 ; , ected the Balearic Tous and Romero ff erent aspects of the ff 2001 , Lagouvardos et al. , among others). In this last ). erent points of view. In ). This event was numerically ff 2012 Tous and Romero 2005 1997 Romero and Emanuel , ( , ) but it carries a very laborious task. Picornell et al. Rasmunssen and Zick ; 2013 Emanuel Gili et al. , 7420 7419 1987 , . Initially, the diagrams have been used for fore- 2011 ( , cold-core cyclone at upper levels and with strong Chaboureau et al. ). More recently, another well-known medicane oc- ff erent numerical models and they are available at ; ff Jansà ; ) proposes a phase space where the cyclone evolution is 2003 ). A small quasi-tropical cyclone that a ( ort has been devoted to investigate di 2009 ff , ). All these papers support the idea that medicanes usually 1983 ) pointed out. The rarity of these phenomena, their maritime 2003 , ( 2000 ( 2013 , 1984 ( Hart Tous and Romero 2011 Homar et al. Davolio et al. , cult task. For this reason, studies focused to perform a medicane database ) an axisymmetric numerical model was used to do that, complemented ). An empirical genesis index, GENPDF, has been also introduced to esti- ; ). In mid January 1995, a well-studied example of medicane occurred in the ffi 2007 Mayençon 2009 2008 2013 ( ( ). Moreover, , , Ernst and Matson Pytharoulis et al. Over the last years several methodologies have been developed to follow cyclones Recently some criteria had been established by On the other hand, the atmospheric environments that favour the development and Remote sensing products in general and satellite pictures in particular are valuable In the last years, much e ment. instruments to detect thesemerical cyclones weather and prediction to observe (NWP)ready their models tracks, are and essential appropriate to nu- forecast medicanes, as al- convection activity. Surface heat and moisture fluxes play a key role in their develop- tropospheric troughs, in regionsdisequilibrium of associated small with the baroclinity trough but ( large air-sea thermodynamic mation and maintenance of medicanes. Medicanes usually develop under deep upper casting extra-tropical transition of tropical cyclones and later the diagrams have been time and inhttp://moe.met.fsu.edu/cyclonephase real time from di represented. Cyclone phase diagramscharacter inform about of symmetric/frontal the and cyclone. cold/warm The cyclone phase diagrams have been applied to past the structure (the medicane mustaround have a a clearly continuous visible cloud cyclone eye), cover sizetime and (diameter at symmetric less least shape than 6 300 h). km) In andof their life-time medicanes work, (life- have using been historical created infrared based (IR)images on Meteosat has satellite aforementioned been data, criteria. recognized lists The as usecase, a of medicanes satellite useful tool to consistently detect storms and, in this to define a medicane from the Meteosat satellite images. The criteria are based on Balearic Islands (AEMET)ent and sets some of cyclone analysis databases based were on obtained NWP systems from ( di from NWP models.clones, One including such mesocyclones, method was for developed detection in and the tracking Meteorological Mediterranean Centre cy- of the 2006 form in areas with a deep, cut-o canes a di systematically and to develophelpful. forecasts to alert of these phenomena may prove very with sensitivity analyses withprecursor a cyclonic 3-D environments model. for The medicane characteristics development of were studied precursormate in and or non- forecast the likelihood ofand medicane genesis Romero ( character and their small size make the systematic detection and forecast of medi- maintenance of medicaneset have al. been studied from di et al. work any possible tropical transitioncyclone of phase the space cyclone and istransformation. identified jet by crossing projecting is it described into the as a new key mechanism for this and Islands in September 1996 is describedsimulated in by curred on 26 September 2006et and it al. has been described in several papers ( from numerical simulations. At least threeies medicane ( events were recorded inthree the more eight- cases during2011 this period areIonian Sea. included Its in evolution recent and lists track is ( described in detail in medicanes. Some medicane events have beenorder analysed in to depth document by the several authors, appearanceand in and to evolution explore of physical these vortexes mechanisms from associated observations to their formation and maintenance 5 5 25 15 20 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | cient Walsh ffi (25 km) Miglietta Picornell ◦ ectively cap- ff Cavicchia and von ). 7422 7421 2004 , ) has been used to obtain some cyclone climatologies (10 km) in a double nested configuration. In ◦ ) focus on a subset of all Mediterranean lows, those that 2006 , 2013 ers the possibility to build a medicane database from numeri- ( ff Hart and Evans ect the region do not have quasi-tropical features, but are also re- ff ected the Mediterranean region. The predicted cyclones and their evo- ff ). In their work, several climatic mode simulations, with a high resolution Campins et al. ) several Mediterranean tropical-like cyclones are analyzed by means of ) consider that the 25 km horizontal resolution may still not capture highest ; Walsh et al. erent sets of analyses coming from NWP systems (with moderate resolutions, 2012 ( ff 2013 2013 ( 2001 ( , This paper is structured as follows. First, in Sect. 2, the aforementioned mesocy- Recently, progress has been made towards the construction of methods to detect The goals of the present work are to contribute to a proper description of the medi- 2 Methodology 2.1 Intense cyclone detection and tracking The method for detectioncyclonic and tracking perturbations, Mediterranean including cyclones designed mesocyclones, to and describe their characteristics ( and medicanes in particular. Next,to in Sect. the 3, outputs the adaptedcyclones of procedure that numerical has a been simulation applied lutions runs have to been validated detect againstses and available coming observational describe from data four literature. andconclusions Finally, numerical tropical-like in are analy- outlined. Sect. 4, the results are discussed and the main of their typology. clone detection algorithm hastense been structures. modified Furthermore in the Hart’s order cyclonetuned to phase to diagram select has correctly and been describe adapted to and the characterize in- thermal structure of small intense cyclones in general methodology. Their description through the phase diagram may allow the identification warm-core evolution ( increasingly used for structural forecasting of subtropical cyclones and cold-core to intensities of the warm-core storms and may not be high enough to e et al. scribe perturbations of less than 300 km of diameter (like the medicanes). In fact, around 50 km). Typical sizesthan of the detected typical cyclones extra-tropicalmedicanes) are cyclones, that 200–300 km but we want of clearly to radius,size larger detect smaller of and than describe the the now structures perturbations (lessresolution. than that (like Resolutions 150 can km of of be around radius). properly 25–50 The km represented are depends probably on not the enough NWP to model correctly de- from di et al. medicanes from numericaldecadal models statistics systematically. and A scenariosmeans of method a current dynamical for and downscaling possible constructing approach future had multi- medicane been activities presented by by regional atmospheric model and forbeen a performed number by of test employing cases twogrid described horizontal and in resolutions, literature, one one has “high”, “low”et with with al. 0.22 0.09 Storch numerical simulations, satellite products andautomatic lightning data, detection in algorithm order to forcyclones. achieve a discriminating future tropical-like cyclones from baroclinic cyclones that also a lated with severe weather events. These cyclones can also be described by using this resolution. This also o cal analysis or reanalysis.to Besides develop it warnings can contribute formentioned to these methodologies better infrequent forecast for phenomena. medicanes detecting, Tobeen and achieve characterizating adapted those and to goals, tracking small-scale afore- cyclones intense have cyclonic perturbations. Other small and intense have high wind speedsa and storm warm-core, detection referredmodel and to RegCM3 tracking as running at “warm-core algorithm a lows” to horizontal and grid identify spacing design them ofcanes 25 from km. and to the develop some regional objectivemodel criteria climate to outputs identify in these an structures fromdiction automatic numerical of way. This these will phenomena, favour subject the to systematic the detection and availability of pre- NWP models with su 5 5 25 20 15 10 10 25 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ≥ p Cav- ∆ at least 1 − 0.5hPa100km (hurricane-level intensity). ≥ 1 − p ∆ ), who used a radius of 200 km, ob- 2012 ( in at least six of the eight directions, which ) incorporate a variable radius, as suggested 7424 7423 1 − 2013 ( to indicate symmetry of the supposed medicane. B 3.2hPa100km Chaboureau et al. ≥ ), providing substantial insight into the cyclone structural evolution. p Miglietta et al. ∆ , the storm-motion-relative low troposphere thickness asymmetry in- at least in six of the eight principal directions around the minimum. To B 1 2003 − ( ), after considering several possible radii, obtained the best results using ), considering the extension of the warm-core anomaly at 600 hPa. In the , upper-tropospheric thermal wind, which gives the measure of the cyclone Hart , low tropospheric thermal wind, which measures the cold, neutral, or warm- L U T T 2013 V V ( 2003 ( − core structure of the cyclone in the low-middle troposphere. troposphere warm-core cyclones (e.g. tropicalcyclones cyclones) (warm-seclusions from or shallow subtropical warm-core cyclones). Parameter side the cyclone. − phase (cold vs. warm-core) for the upper troposphere and helps to distinguish full- A less demanding criterion toprevious obtain and the later full moments life-time of of an thein intense cyclone, six cyclone, including of both the eightthreshold principal is directions around the the same minimum. as This in pressure previous gradient papers. A more restrictive thresholdmedicanes), value to select intenseroughly corresponds cyclones to (including a possible wind speed of about 32ms – – In the present paper some parameters have been modified to take into account the Some aspects needed to better describe small-scale intense cyclonic perturbations In the original method, a cyclone is defined as a relative minimum in the mean 1. 2. 3. sis of their life-cycle in the phase space. small dimensions of theexploration radius cyclones of we 500 km, are proposedture, by dealing as Hart, with pointed can smooth (particularly out out by medicanes). their warm-core The struc- Three-dimensional cyclone phase spacephase diagrams, is which presented facilitate an using objective two classification of cross cyclones sections, from the the analy- fined on a circle around the cyclone centre: Each cyclone is characterised by using three fundamental magnitudes of its phase, de- the influence radius ina Cressman double filter criterion has referred been to the reduced pressure from gradient 200 is km proposed: to 50 km. Also The cyclone’s life-cycle can be analyzedposed within by the three-dimensional phase space pro- 0.5hPa100km avoid excessive noise ina some Cressman fields filter (like with vorticity,ysed an needed fields. influence for The radius the cyclone of vortexthe domain 200 description) km minimum is was pressure limited applied position. byfor to The the the smooth 700 cyclone zero-vorticity hPa the tracking. level line, anal- is searched considered around as the steeringhave been level adapted. First of all, to preserve the main features of the small structures Other criteria for medicanes will be defined in2.2 the next section. Thermal structure physical parametrization and aintense greater structures, resolution, we is have selected able theForecast to European (ECMWF) simulate Centre forecasting these for model Medium-Range small outputs, Weather with and a horizontal resolution ofsea 15 km. level pressure (MSLP) field, with a mean pressure gradient greater than ture true medicane. In order to check whether a robust operational model, with good icchia taining near-zero values of a radius of 100 km. present work, after severalcle attempts of and exploration, in the meanthree order radius to phase of use parameters. the This aLaplacian warm-core radius storm-size-dependent anomaly around is cir- is the calculated used temperatureno from to maximum temperature estimate the at maximum the line is 700 hPa located, ofa taking closest radius zero-temperature- into to of account 90 cyclonic the km centre. results is of used. If previous works, Hart 5 5 15 10 25 20 10 15 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ). Tous Reed 2001 ( Reed et al. Reed et al. ) and 1983 0. ( > U indicates left of storm motion and T V 10m. L − B < ), has been run for the selected cases. 0 and > 7426 7425 L T Ernst and Matson V − R | ) was observed over Tunisia. The storm evolved in two cult to identify its initial or final stages. This hampers the ff 925 ffi Z − 700 Z ( − ). L | ) 2013 925 , Z − indicates right of current storm motion, R 700 the upper troposphere, that is, The cyclone is thermally symmetric, with A warm-core structure of the cyclone must be present in the low-middle and in , Fig. 1). During the second phase, from 26 at 00:00 UTC onwards, the system Z ( – – The predicted cyclones and their evolution have been validated against available The ECMWF T1279L91Cy36r1 forecast model (hereafter ECT1279), which corre- In this work, the thermal structure of the selected mesocyclones is scrutinized by Moreover, two layers, 925–700 hPa and 700–400 hPa, slightly lower than those of = 3.1 January 1982 event The overview of this case is based on account that, usually, a medicane isbut in clearly most identified of when the it casesvalidation reaches it of its is di mature the stage, numerical simulationsbetween and the prevents two finding descriptions. anvalidate In our exact procedure. correspondence spite of this, these papers are a good3 reference to Results and the results are presented in the following section. observational data and numericalselected analyses cases from correspond literature. According tovortexes, to tropical-like although this, structures, the the including name four compact medicane spiral is cloud not always used. We must also take into lated to the model resolution. For each event, the best simulation has been selected Hart have been explored. Therefore: B shrank in size, takingwith the a appearance well ofsequently organized a the convective tropical-like system cloud storm made band in a spiralling IR second small into satellite loop imagery, an before eye-like accelerating centre. eastward ( Sub- the southeast of thepossessed Sicilian an coast. extensive At regionscale this of hook-shaped stage convective band the cloud is system bands.cyclonic an was The circulation. indicator relatively presence of The large of a system2001 and smaller- vortex described embedded a within small the larger loop scale south of Sicily ( On 23rd January 1982 ameanwhile storm formed at over 500 the hPa warm aphases. waters cut-o between During Sicily and the Libya, firstin 48 phase h of as it its moved development, north-westward. the It low achieved its deepened maximum nearly depth 20 when hPa it arrived to http://www.ecmwf.int/research/ifsdocs/CY36r1 For each event, four runs havestarting been performed, at with 12:00 initialization UTC times oftimes separated 24 the from h, day 06 before to the 72 h first every appearance 6 of h. the The cyclone, analysis with comes lead from the ERA-40 fields, interpo- mer and two have beenthem identified in have Central-Eastern been Mediterranean selected in winter. from Three the of aforementioned satellite-derived data base ( sponds to a horizontal resolution of 15 km (detailed documentation is available at 2.3 Numerical simulations of test cases In order to test the suitabilityand of to the discriminate aforementioned mainly criteria to betweenvious define medicanes methodology an and has intense been other cyclone applied smalltween to intense 1982 four cyclones, and well-known pre- 1996. medicane Two events of occurred them be- occurred in the Western Mediterranean in late sum- means of thecyclones two are phase imposed diagrams. to qualify The a criteria mesocyclone as proposed a by medicane: Hart to define tropical and Romero the overbar indicates the areal mean over a semicircle of exploration. where 5 5 20 25 15 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ). is lo- 1987 ff , ). The major a). Along the 3 1987 ( erentiated maxima, ff a). The warm-core is 3 ). From 25 at 00:00 UTC 2001 ( Rasmunssen and Zick ). At upper levels a cut-o is centred between Tunisia and 1 ff Rasmunssen and Zick b). The system is very symmetric and its Reed et al. b), a deep warm-core structure is present 2 3 b). On 28 at 00:00 UTC the central pressure 4 7428 7427 ). Finally it vanished after having made landfall 1 over the Western Mediterranean, centred in northern b), except at the beginning, when the cyclone is exten- ff a), although not to the observed values, while the vor- 2 2 a) and low level thermal wind reaches its maximum and positive 4 ). The cyclone is described as intense and symmetric throughout most 2001 , Fig. 1). The warm ocean and intense convection probably played a major ( b). Along this stage the cyclone is also described as symmetric and at low 2 2001 , This case is poorly forecasted by ECT1279 model. The best run, day 27 at In this simulation the system evolves in agreement with the evolution described by When this event has been simulated by the ECT1279 model, the best forecast of this On 27 September 1983 atral sub-synoptic part vortex-like of disturbance a low wasvortex of formed moved modest in in intensity, the between a Sicily cen- large andwest circle of Tunisia. After Sardinia in its and about formation, Corsica 4 the (see days Fig. and it was best developed over the sea 3.2 September 1983 event et al. is the lowest (see Fig. and agreeing withgeostrophic vorticity the increases observation (see Fig. described above, the system size shrunk and 30 September the vortex intensified. 12:00 UTC, forecasts aanalysis, moderate on cyclone 27 along at 72Sardinia h 12:00 UTC of and at simulation. an high According extensive levels to a surface the cut-o cyclone appears west of Sicily. Six hours later indicated by strong pressure fallsvorticity and in the a region. low-level On secondarywith 28, centre VIS the of image sub-synoptic showed positive the vortex relative dissolvingThe in large its cyclonic scale centre cloud activity spiral, (see wasspot, Fig. contracted 5 similar into in to themesoscale central an cloud part “eye”, vortex of was was the observed shown.by low and a On warm-core around and 29 structure. noon a Later the Septembergion cloud-free the vortex with a vortex was decreasing started sea characterized tight to surface and temperature. weaken, During when almost the it second circular moved landfall into at a Corsica re- at data from low and highAs levels, obtained described by by tracking the cloudnated elements authors, by from the a these upper deep images. air andTunisia. At cold synoptic 12:00 cut-o situation UTC on in 27 theand the region deep Meteosat IR convection. was image Three domi- exhibited hours a later, large scale the cloud formation spiral of the sub-synoptic vortex was close to its place of origin,tools as for it the is study described were in Meteosat images, from IR and visible (VIS) spectrum, and wind second stage of cyclone-lifeevolution the central described pressure in increases, literature.served disagreeing However, contraction the the in pressure scale model ofof itself the about system is 150 and km able the 26(see to radius at Fig. decreases, predict 12:00 reaching UTC, the a meanwhilelevel ob- radius the becomes warmer vorticity regarding achieves to theabout the highest 130 previous km stage value radius (see (see Fig. sive. Fig. As phase diagram II shows (see Fig. to 27 at 06:00 UTC theold mean value pressure and gradient thereby overcomes thelife-cycle, the more when cyclone restrictive cyclone is thresh- spins classified aroundits as the minimum intense. first value During loop, (see theticity the Fig. central reaches first pressure a part decreases relative of to maximum the (see Fig. throughout all life-time and theone upper in thermal each wind reaches ofmedicane two the di for two about stages 60 h. of cyclone-life. The cyclone presentsReed et characteristics al. of positions in the phase diagram I are very close among them (see Fig. of its life and withfor a much deep of simulated warm-core, path. therefore the system is identified as a medicane cated over Tunisia on 26 at 12:00 UTC, as in role in generating and maintaining this small warm-core cyclone. medicane is from run 24detected January and at the 12:00 model UTC. isabrupt Along able changes 72 to h of reproduce of direction the simulation, after a complicated the cyclone path loops is and (see to Fig. forecast the 5 5 25 15 20 10 15 20 10 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | and and ) the 1 6 5 − Lagou- b). The system 4 ) it is initially clas- a), according with 8 6 surface wind and a relative ). As it is described in detail 1 low was observed over Sicily 1 − ff ). This vortex formed behind a pre- 2000 ( ). In the phase diagram I the cyclone is classi- 7430 7429 1 Pytharoulis et al. a). Upper level thermal wind values indicate that a cold-core 4 ). 5 ) and in 1999 ( ) and from the track chart (see Fig. 7 As mentioned before, on 14 at 18:00 UTC the large cyclone splits into two smaller The analysis on 14 at 12:00 UTC, when simulation starts, shows that an extensive According to these results, we can state that both the forecast and the methodology ). On 16 January the central pressure continues rising (see Fig. reached the northern African coast, on 18 January. and deep cyclone is locatedinto in two smaller the cyclones. Ionian One Sea. ofwarm-core Six them intensifies structure. hours and later, Its becomes the symmetricFig. large evolution with cyclone a may splits deep be analysed from the phase diagrams (see and it followed abands southward around path. a The clearly Meteosatclouds defined satellite were “eye”. images spirally By distributed showed at 06:00 spiralat UTC a a cloud on radius radius 16 of of 150 January 200maximum km, km deep while of around convection lower the air clouds vortex temperature were centre. evident were A 23 reported ms by a ship. The storm dissipated when it on 15 January, a secondary low was created, it became independent of the parent low value, revealing the presence of a warm-core. In the phase diagrams (see Fig. sified as an asymmetricBut warm-core, becoming this symmetric cyclone as isduced moves not to south-eastwards. low intense troposphere. along In the this case lifecycle the and system the is warm-core classified as structure a is small re- cyclone with Along the entire simulation cyclonetowards follows the a track Libyan close coast. to the observed one, travelling cyclones. The weakest one,ponnesus an peninsula. orographic In cyclone, this is case, located in downwind the phase of diagrams the (see Pelo- Fig. fied as symmetric along its full14 life at and 18:00 an UTC structure onwards. of Warm-coreintense radius deep period varies warm-core from is up about identified to 100 from around km14 during of at the 140 12:00 km. most UTC, Minimum agreeingobserved central with pressure. pressure observed At value 12:00 strong UTC is wind on reachedmum but 15 values on January with of the the a medicane geostrophic higher is vorticity7 value very and of small, than the with the low maxi- level thermalthe wind evolution (see described Fig. in the literature,a and result the the mean cyclone pressure is gradient identified decreases. As as a medicane until 16 January, with a life-time of 24 h. a warm-core, small dimensionvardos et and al. rather long life-time, as it is explained in sented. Cyclone strength isis underestimated during not the able forecast toand period forecast therefore and not the the classified warm-core model as structure, medicane. i.e. the3.3 cyclone is not January well 1995 event simulated During the period 14–18a tropical January storm 1995 developed athis between sub-synoptic Italy vortex vortex and was Greece. with associated Satellite characteristics with imagery of a revealed that clearly defined “eye” surrounded by cloud bands, threshold value (see Fig. is present at thatat levels 18:00 during UTC the (see entire Fig. simulation, although it weakensare from able day to 28 detect and track the cyclone, although thermal features are not well repre- existing low centre, whichindependently progressed southwards towards (see the transcribed east, path while in the Fig. new vortex moved cyclone is classified as symmetricmoves eastwards cyclone and with when shallow it warm-core.suddenly tracks Later, and over the the the cyclone air island at ofthe Corsica low system levels the cools. pressure remains Since increases symmetric, 29evolves a at into 00:00 weak UTC, a low the deep pressureis level cold-core falls warm-core symmetric and cyclone, appears along increasing but all the in its system size life-time (see but Fig. the pressure gradient does not overcome the at 12:00 UTC on 14evident over January. the A sea surface west ofa low pressure Greece pressure of in 992.5 system MSLP hPa maps, (called reportednificant with by parent winds role ships. low) of Sensible in and 22 was the latent and heat deepening 29 fluxes ms of played a the sig- parent low. Twenty-four hours later, at 12:00 UTC on the previous studies, from satellite imagery a cut-o 5 5 25 15 20 10 15 20 10 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ). ). ). 1 10 1997 , Gili et al. cult to track them ffi , from 1 -shore Spanish, over the sea. ff ). During the following hours, the vortex 10 7432 7431 ), reaching a value less than 993 hPa. Strong erent authors. Medicanes are small and intense ), the ECMWF T213/L31 version (62 km horizon- ff b). 9 1997 , 2000 ( a), and begins to form a deep warm-core, but the small 9 Gili et al. ). The cyclone crossed the island of Majorca with an intense fall of pres- Pytharoulis et al. ected the Balearic Islands. From the radar images an eye of clear air sur- ff 1997 , The cyclone is classified by the procedure as a medicane during 18 h. From the As noted by In this case the best simulation started on 11 of September at 12:00 UTC, when an the observed value (see Fig. unlike the other cyclone. a shallow warm-core structure, as befits an orographic cyclone, and not as medicane, development and maintenance theconvective heat heat release flows play fromso a the in key land-sea areas role. interactionaccurately The where and and medicanes observations sometimes the develop can are make mainly unnoticed scarce, on these which phenomena, the especially can sea, in make cases di cyclone phase space that haveattempt adapted to to contribute to the the characteristicsbeen development of developed and in the complementing the medicanes, methodologies last in that yearscyclonic an have by structures di with strong pressure gradient,winds related and to a the presence thermal of structure very characterized strong by the presence of a warm-core, in which are higher than the observed ones.probably In a this higher case resolution the model cyclone would has be been needed poorly simulated; to represent it correctly. 4 Summary and discussion A method to detectmedicanes, and from NWP describe model small outputsfrom and is existing intense presented. methodologies This cyclonic method to structures, has in identify been particular developed cyclones and to study their life-cycle in the comparison of the forecast cycloneestablished track that against the the medicane track from evolution observations is it delayed can 6 h. be The forecast pressure values Six hours later thewith medicane a weakens. 100–140 Along km the radius whole (see life-time Fig. the cyclone is small, cyclone is slightlymoves asymmetric north-eastwards (see and Fig. the becomes phase symmetric diagrams, it and, isSouth-West according classified of Majorca, to as with a a their medicane. delayAt position of At this 6 18:00 h in UTC moment compared on the to 12 thevery geostrophic observed it symmetric vorticity track is and (see reaches located small Fig. its and at maximum a pronounced value, deep the warm-core medicane is is present (see Fig. sure between 12:00 UTC andin 13:00 Palma UTC (see in the Fig. pressure 8 record in from the observatory and later a rounded by a circular wall ofGili cumulonimbus et was al. observed at 04:50 UTC (see Fig. 11 in clone. The later version ofthese the structures. model represents an improvement in the3.4 description of September 1996 event On 12 of September 1996 a small quasi-tropical cyclone formed in the gulf of Valencia tal resolution), operational at 1995,the predicted east, the but translation the of forecastsmall the of for low the this centre secondary model. towards vortex Thesimulate formation version two failed, ECT1279 smaller because (15 cyclonic km it centres, horizontal was one resolution) too is of capable them to with features of quasi-tropical cy- winds were recorded on theintensity Island of and the a cyclone warm-corerived decreased. was to The identified. Sardinia cyclone At at moved 17:00 towards 21:00 UTC UTC North-East the (see and transcribed it path ar- in Fig. During the following hours,A the extensive secondary low low movesas intensifies towards North-East, an and weakening. intense six06:00 and hours UTC symmetric later, on at 12, cyclone the 00:00 but UTC minimum with on central cold-core 12, pressure structure it value at is is low detected reached levels. although At far from The system was identified as21:00 a UTC, quasi-tropical along cyclone 17 h at approximately. least between 04:00 UTC and extended low pressure centrecoast. (300 Six km hours of later a radius) secondary is centre localized is in detected front o of the Algerian 5 5 25 15 20 10 15 10 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 0 06, > + L T V − erentiated from the ff 10m, and a warm-core struc- B < 7434 7433 erent typologies of small intense cyclones, the ex- er a convenient way to describe and classify the ff ff ected. Therefore, the systematic and automatic detection , thermally symmetric, ff 1 − 3.2hPa100km 0. For the 1982 and 1995 events the detected cyclone is identified as a med- ≥ > p U T ∆ V − The three proposed criteria seem to be useful for identifying medicanes. By means We can summarize that in three of four cases an intense small cyclone is forecasted Thereby, in all three cases a medicane is simulated. The ECT1279 forecast model Although the model here used presents some limitations, the obtained results are ac- In order to adapt the method to the characteristics of medicanes and to establish Previously to test the procedure, and in order to check briefly the performance of a medicane. However, scarcity of observationsforecast over of the medicanes. sea The improvement is of asensing initials major data, conditions, drawback e.g. will in by the lead meansments of to remote can a be better achieved predictionhigh increasing resolution of convection-permitting the these models. model phenomena. Besides, resolution improve- and especiallyof by these means of criteria,cyclones. we The try phase tocyclone diagrams discriminate and, o mainly jointly with between the medicanes tracks, give and a other fairly complete small and detailed description. and an objective descriptionprocedure. of medicanes can be obtained by meansceptable. The the model automatic here usedis is adequate capable to of simulating validate intense the storms adapted and, procedure therefore, and to establish the criteria that define evolution is delayed 6 h regarding the observation. with appropriate thermal structure, thatWarm-core radii is, vary it from is about 100 symmetric140 km km. and during Cyclone with the radii most a intense range deeplows, period from warm-core. to up values to 150 km, higher around at of than the 300 time km, when corresponding medicane to is parent allows shrunk. describing medicanes, at least the larger ones, although with some limitations medicane only twelve hoursare classified after as its symmetric formation. deepgraphic cyclone warm-core. In has Besides, been the for detected the phasemedicanes and 1995 by it diagrams event using has the a the been phase weak successfully systems are diagrams. di oro- In close all to four the cases corresponding the observed simulated cyclone paths, tracks although from the 1996 medicane the event the cyclone is initially symmetric, but with cold-core structure, and becomes and icane according to the proposed criteria along much of the simulation. For the 1996 selection criteria to discriminateisting di procedures have beencriteria modified has in been two introducedhave to main been select ways: calculated small a by intense more usingtre. cyclones a restrictive In and storm-size-dependent summary, selection thermal three circle parameters criteria aroundstrength to the identify and cyclone a cen- their cyclone as thermaltense, a structure, medicane, according has with beenture their must established: be the present cyclone in the must low-middle be and in- in the upper troposphere, that is, clones. Forecast chain runs fromsmall ERA-40 analyses, cyclones, with therefore too small lowwhen resolution cyclones the to can describe ECT1279 becyclone. model properly has characterized from already H been able to simulate the deepening of the medicane events have beenone explored of and them. four Results simulationsphenomena, show have 1982 that been the and done ECT1279 1995The for forecast medicanes, each model 1983 acceptably represents event and two is approachesas of the the quasi-tropical these 1996 cyclone, worst is case. simulatedas forecasted one. a as The not medicane cyclone, enough andIn described strength the general one in the model to the pressure is bethe value literature not considered model in able simulates the very to cyclone well centre forecast the is the intensification higher and deep than variations warm-core observed, in structure. although the size of these cy- of these phenomena fromto the outputs obtain of climatology NWPphenomena models of accompanying is these the presented medicanes. phenomena as a and good to choice improvethe the operational model prediction to represent of these severe small and intense structures, four well-known in which land areas are not a 5 5 25 20 10 15 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 7421 , 2007. 7419 , 2012. 7419 , 2003. 7422 , 10.5194/nhess-7-41-2007 7418 7419 7426 7420 10.1256/qj.01.91 , 10.1007/s00382-011-1220-0 7424 7419 , 2009. , erent possibilities to better know and better ff 7423 7436 7435 , , 1983. ers di 7421 7429 ff 7420 , 7424 , 7424 7419 7419 erent scenarios of future tense as well as with non-hydrostatic 7431 ff , 10.5194/nhess-9-551-2009 The authors are grateful to J. A. García-Moya (AEMET, Madrid) who per- , 2012. 7419 7419 7419 10.1002/j.1477-8696.1983.tb04818.x 10.1002/qj.960 cient resolution climate models to study the trend of frequency and intensity of ffi Having this automatic procedure o diagnosis and forecasting, 26th ConferenceFlorida, on 3–7 Hurricanes May and 2004, Tropical Meteorology, P1–87, Miami, 2004. a small, quasi-tropicalfactors, cyclone Q. J. over Roy. Meteor. the Soc., western 129, 1469–1490, Mediterranean: doi: Dynamical vs. boundary tions and model simulations ofMet. Apps., a 6, winter 371–383, sub-synoptic 1999. vortex over the central Mediterranean, 1987. Barcelona, Spain, 28–30 November 2003, 75–85, 2003. Weather Rev., 131, 585–616, 2003. Gravity Waves, WMO PSMPMesh Report Models Series for n. the 26, WMO Mediterranean Workshop Region, on Erice, Limited Italy, Area 17–20 Fine- November 1986, 51–67, September 1996 inHazardous the Weather Balearics, in INM-WMO143–150, the International 1997. Mediterranean, Symposium Palma on de Cyclones Mallorca, and Spain, 14–17 April 1997, seven Mediterranean tropical-like stormssolving using model, Nat. an Hazards Earth axisymmetric,7419 Syst. nonhydrostatic, Sci., cloud 7, 41–56, re- doi: 2005. doi: forecast and analysis ofSci., a 9, tropical-like 551–562, cyclone doi: in the Ionian Sea, Nat. Hazards Earth Syst. Venice, Venice, 121 pp., 2013. climate model, Clim. Dynam., 39, 2273–2290, doi: tion of adoi: Mediterranean storm by jet crossing, Q. J. Roy. Meteor. Soc., 138, 596–611, ranean cyclones, Int. J. Climatol., 26, 323–343, 2006. clonic environments that lead to medicaneranean development, Storms, 11th Plinius Barcelona, Conference Spain, on 7–10 Mediter- September 2009, Plinius11–46, 2009. of severe weather events,the both verification on of the medicanemodels forecasts sea to and and forecast the these coastalsu comparison small zone. of cyclonic This capability structures. procedurethese of Besides helps phenomena numerical it in can di alsomodels of be higher used resolution. with identify forecasted medicanes. On onecontribute hand, to the obtain present ahigh methodology medicane is resolution database expected and numerical to toidentification models. study of On the some medicanes the interesting inor events other the not from forecasts hand, predict so well this rare in those procedure advance. sometimes facilitates Better go prediction the unnoticed of medicanes leads to better forecast Lagouvardos, K., Kotroni, V., Nickovic, S., Jovic, D., Kallos, G., and Tremback, C. J.: Observa- Hart, R. E. and Evans, J. L.: Real-time use ofHomar, cyclone phase V., Romero, diagrams R., to improve Stensrud, structural D. J., Ramis, C., and Alonso, S.: Numerical diagnosis of Jansà A.: Miniciclons a la Mediterrània, IX Jornades de Meteorologia Eduard Fontseré, Hart, R. E.: A cyclone phase space derived from thermal wind and thermal asymmetry, Mon. Jansà, A.: Saharian Advections in the West Mediterranean Algerian Cyclogenesis. Heavy Rain, Gili, M. A., Jansà, A., Riesco, J., and García-Moya, J. A.: Quasi-tropical cyclone on 12th Fita, L., Romero, R., Luque, A., Emanuel, K., and Ramis, C.: Analysis of the environments of Emanuel, K.: Genesis and maintenance of “Mediterranean hurricanes”, Ad.Ernst, Geo., 2, J. 217–220, A. and Matson, M.: A Mediterranean tropical storm?, Weather, 38, 332–337, Davolio, S., Miglietta, M. M., Moscatello, A., Pacifico, F., Buzzi, A., and Rotunno, R.: Numerical Chaboureau, J.-P., Pantillon, F., Lambert, D., Richard, E., and Claud, C.: Tropical transi- Cavicchia, L.: A long-term climatology ofCavicchia, medicanes, L. PhD and Thesis, von Storch, Ca’Foscari H.: University The of simulation of medicanes in a high-resolution regional Acknowledgements. formed the ECMWF simulations.(CGL200801271) This project. work has been partially supported by the MEDICANES References Campins, J., Jansà, A., and Genovés, A.: Three-dimensional structure of western Mediter- Campins, J., Genovés, A., Picornell, M. A., and Jansà, A.: A first analysis of the large-scale cy- 5 5 30 20 25 15 10 15 10 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 7424 7419 , 7421 > 7425 , , 2013. GREECE 7420 7422 ● , , Pelopon. ● ● ● σ σ ● ● σ ● ● ● σ ● ● ● 7419 ● ● 7419 ● 7421 ● ●

● σ σ Sea ● σ ● ● σ

Ionian ●●● σσσ ● σ >

● ● 7428 >

● , σ 7431 , 2013. > , , 2013. ● σ 10.1002/grl.50432 ●● 7419 7429 ,

ITALY Sicily ● 7419 7437 7438

> LIBYA 7420 , ● ● 10.1002/joc.3428 ●

7420 7419 Sardinia ● ● ● ● TUNISIA

●

7422 , > 10.1007/s00382-013-1723-y ● ● 7427 ● observed cyclone tracks transcribed from literature (dotdash lines). ● , 7420 + ● ● V Assembleia Luso-Espanhola de Geodesia e Geofísica: proceedings, ● ● σ 7426 = > 1995 1996 ● ● Balearic I. σ ARGELIA ● ●

σ

● > 1982 1983 Medicane tracks in Mediterranean Sea. In red, 1982 event, in violet, 1983 event, in Medicane track ● Goulf ● Valenc. SPAIN Clim. Dynam., 1–14, doi: ment, Int. J. Climatol., 33, 1–14, doi: rologics, Tethys, 8, 53–61, 2011. sis in the light ofsia an empirical y tropical Geofísica index, in:Sevilla, V Spain, Asamblea 30 Hispano-Portuguesa January-3 de February Geode- 2006, CD-Rom, ISBN 84-8320-373-1, 2006. uary 1995, Met. Apps, 7, 261–279, 2000. modeling of a183–202, tropical-like-cyclone 2001. in the Mediterranean Sea, Meteorol. Atmos. Phys., 7, tropical-like cyclones over the Mediterranean Seaapproach, through Geophys. a Res. combined Lett., modeling 40, and 2400–2405, satellite doi: clones from the HIRLAM(INM)21, 0.5 335–354, analyses 2001. in the Western Mediterranean, Int. J. Climatol. bance to polar lows, Tellus A, 39, 408–425, 1987. tation on Mediterranean CyclonesDecember (PSMP 1983, Rep. 145–157, 1984. Ser. No.3), Sofia, Bulgaria, 8 November–1 ricane” over south-eastern Italy, Weather, 63, 306–311, 2008. indicates medicane Walsh, K., Giorgi, F., and Coppola, E.: Mediterranean warm-core cyclones in a warmer world, Tous, M., and Romero, R.: Meteorological environments associated with medicane develop- Tous, M., and Romero, R.: Medicanes: criteris de catalogació i exploració dels ambient meteo- Fig. 1. green 1995 event and inσ orange 1996 event. Simulated cyclone tracks (solid lines) with symbol Romero, R., and Emanuel, K.: Space time probability density of Mediterranean hurricane gene- Reed, R. J., Kuo, Y. H., Albright, M. D., Gao, K., Guo, Y. R., and Huang, W.: Analysis and Pytharoulis, I., Craig, G., and Ballard, S.: The hurricane-like Mediterranean cyclone of Jan- Picornell, M. A., Jansà, A., Genovés, A., and Campins, J.: Automated database of mesocy- Miglietta, M., Laviola, S., Malvaldi, A., Conte, D., Levizzani, V., and Price, C.: Analysis of Rasmunssen, E. and Zick, C.: A subsynoptic vortex over the Mediterranean with some resem- Mayençon, R.: Warm-core cyclones in the Mediterranean, in: Report of the Informal Consul- Moscatello, A., Miglietta, M., and Rotunno, R.: Observational analysis of a Mediterranean “hur- 5 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

σ Geostrophic Vorticity Geostrophic ) 2 − 2 4 6 8 m 1 φ σ − s ● 7 12 10 8 6 4 2 0 ● ● (hPa) Medicane 10 Circulation 995 − 1000995 − 1000995 − 1000995 − 1000 ( Intense (but 1005 − 10101005 − 10101005 − 1010 1000 − 10051000 − 10051000 − 10051000 − 10051000 − 1005 not medicane) Cent. pressure 100 ● σ ● ● σ σ ● ● σ σ ● 270627062706 σ Z ● 50 ● ● A ● σ 261826182618 σ ● ● σ σ Warm Core Warm Deep Warm Core Deep Warm Shallow Warm Core Warm Shallow 260626062606 0 Mean Pressure Gradient 251825182518 + 250625062506 −50 Cold Core Mean Warm Core Radius (km) in Deep Cold Core 241824182418 −VTL [925−700hPa] Thermal wind −VTL [925−700hPa] + Start (H + 06) (A): 1982012418 End (Z): 1982012712 (H + 72) −100 0

60 40 20

300300 250250 200200 150150 100100

−20 −40 −60

Warm Core Warm Core Cold Mean Radius Radius Radius Mean Mean −VTU [700−400hPa] Thermal wind Thermal [700−400hPa] −VTU , for January 1982 event. Circle colour refers

(b) Mean Pressure Gradient (6 dir) (6 Gradient Pressure Mean ) 7440 7439 2 − 2 4 6 8 m 1 φ − σ s 7 ● ● (hPa) 2 1 5 4 3.2 3 Medicane 995−1000995−1000995−1000995−1000 10 Circulation 1005−10101005−10101005−1010 1000−10051000−10051000−10051000−10051000−1005 ( Intense (but ); for 1982 event. not medicane) Cent. pressure and II 1 − 100 s ● σ 4 (a) ● ● σ σ ● − ● σ Central Pressure (hPa) in violet σ ● σ 27062706 Z ● (a) 50 Mean Radius (km) in blue ● ● A σ ● σ ● ● σ 26182618 σ Warm Core Warm (b) Symmetric Core Warm Asymmetric Core Warm 26062606 0 25182518 −50 25062506 Cold Core ) in orange 1 − −VTL [925−700hPa] Thermal wind −VTL [925−700hPa] Symmetric Cold Core Asymmetric Cold Core 24182418 Start (H + 06) (A): 1982012418 End (Z): 1982012712 (H + 72) Geostrophic Vorticity (10 −100

Cyclone phase diagrams I Evolution over time of +

2 0 8 6 4

(Non frontal) (Non 12 10 (Frontal) −2

998

Symmetric Asymmetric

1006 1004 1002 1000 Central Pressure Pressure Central B [925−700hPa] B a) b) a) b) to central pressure value and circle size is related to geostrophic circulation value. Symbol indicates the presence of medicane. Fig. 3. orange (hPa 100 km Fig. 2.

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Geostrophic Vorticity Geostrophic ) 2 − 2 4 6 8 m 1 φ σ − s 12 10 8 6 4 2 0 ● 7 ● ● (hPa) Medicane 10 Circulation ( Intense (but 1010 − 10151010 − 10151010 − 10151010 − 10151010 − 10151010 − 10151010 − 10151010 − 10151010 − 10151010 − 10151010 − 10151010 − 10151010 − 1015 not medicane) Cent. pressure 60 300630063006 40 ● 291829182918 Warm Core Warm Deep Warm Core Deep Warm 20 Shallow Warm Core Warm Shallow ● ● 290629062906 ● ● 0 ● Mean Pressure Gradient ● ● ● ● 281828182818 + ● ● Z −20 280628062806 Cold Core −40 A ● Mean Warm Core Radius (km) in Deep Cold Core 271827182718 −VTL [925−700hPa] Thermal wind −VTL [925−700hPa] + −60 , for September 1983 event. Start (A): 1983092712 (H + 00) End (Z): 1983093012 (H + 72) 3 0

300300 250250 200200 150150 100100 50

100 −50

Mean Radius Radius Radius Mean Mean Warm Core Warm Cold Core Cold −100 −VTU [700−400hPa] Thermal wind Thermal [700−400hPa] −VTU

, as Fig. Mean Pressure Gradient (6 dir) (6 Gradient Pressure Mean ) 7442 7441 2 − (b) 2 4 6 8 m 1 φ − σ s 7 ● ● (hPa) 2 1 5 4 3.2 3 Medicane ); for 1983 event. 10 Circulation 1010−10151010−10151010−10151010−10151010−10151010−10151010−10151010−10151010−10151010−10151010−10151010−10151010−1015 ( Intense (but not medicane) 1 Cent. pressure − and II s 4 60 − Central Pressure (hPa) in violet (a) 30063006 40 ● (a) Mean Radius (km) in blue 29182918 20 Warm Core Warm ● Symmetric Core Warm (b) Asymmetric Core Warm ● ● 29062906 ● 0 ● ● ● ● ● ● 28182818 ● Z −20 28062806 Cold Core −40 A ) in orange ● 1 − −VTL [925−700hPa] Thermal wind −VTL [925−700hPa] Symmetric Cold Core Asymmetric Cold Core 27182718 −60 Geostrophic Vorticity (10 Start (A): 1983092712 (H + 00) End (Z): 1983093012 (H + 72) +

Evolution over time of Cyclone phase diagrams I

0 5

(Frontal) 15 10 frontal) (Non

Asymmetric Symmetric

1014 1012 1010 1008 1006 Central Pressure Pressure Central B [925−700hPa] B a) b) a) b) Fig. 5. (hPa 100 km Fig. 4. orange

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Geostrophic Vorticity Geostrophic ) 2 − 2 4 6 8 m 1 φ σ − s ● 7 14 12 10 8 6 4 2 0 ● ● (hPa) Medicane 10 Circulation 995 − 1000995 − 1000995 − 1000 ( Intense (but 1015 − 1020 1010 − 10151010 − 1015 1005 − 1010 1000 − 1005 not medicane) Cent. pressure ● σ 100 ● σ ● 160616061606 σ ● ● 50 ● σ A ● ● Z Warm Core Warm Deep Warm Core Deep Warm Shallow Warm Core Warm Shallow 151815181518 0 Mean Pressure Gradient + 150615061506 −50 Cold Core Mean Warm Core Radius (km) in Deep Cold Core 141814181418 −VTL [925−700hPa] Thermal wind −VTL [925−700hPa] + , for January 1995 medicane. Start (H + 06) (A): 1995011418 End (Z): 1995011612 (H + 48) −100 3 0

60 40 20

300300 250250 200200 150150 100100

−20 −40 −60

Warm Core Warm Core Cold Mean Radius Radius Radius Mean Mean −VTU [700−400hPa] Thermal wind Thermal [700−400hPa] −VTU

, as Fig. Mean Pressure Gradient (6 dir) (6 Gradient Pressure Mean ) 7444 7443 2 − (b) 2 4 6 8 m 1 φ − σ s 7 ● ● (hPa) 3.2 3 2 1 7 6 5 4 Medicane 995−1000995−1000995−1000 ); for 1995 event. 10 Circulation 1015−1020 1010−10151010−1015 1005−1010 1000−1005 ( Intense (but not medicane) Cent. pressure 1 − and II s ● σ 100 4 − Central Pressure (hPa) in violet (a) ● σ ● σ 16061606 (a) ● Mean Radius (km) in blue ● 50 ● σ A ● ● Z Warm Core Warm (b) Symmetric Core Warm Asymmetric Core Warm 15181518 0 15061506 −50 Cold Core ) in orange 1 − 14181418 −VTL [925−700hPa] Thermal wind −VTL [925−700hPa] Symmetric Cold Core Asymmetric Cold Core Geostrophic Vorticity (10 Start (H + 06) (A): 1995011418 End (Z): 1995011612 (H + 48) −100 +

Evolution over time of

Cyclone phase diagrams I

2 0 8 6 4

(Non frontal) (Non 12 10 (Frontal) −2

Symmetric Asymmetric

1015 1010 1005 1000 Central Pressure Pressure Central B [925−700hPa] B a) b) a) b) Fig. 7. orange (hPa 100 km Fig. 6.

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Geostrophic Vorticity Geostrophic ) 2 − 2 4 6 8 m 1 φ σ − s 12 10 8 6 4 2 0 ● 7 ● ● (hPa) Medicane 10 Circulation ( Intense (but 1005 − 10101005 − 10101005 − 1010 1000 − 10051000 − 1005 not medicane) Cent. pressure ● 130013001300 100 121812181218 Warm Core Warm Deep Warm Core Deep Warm ● A Shallow Warm Core Warm Shallow ● Z ● 121212121212 0 Mean Pressure Gradient 120612061206 ● + 120012001200 Cold Core −100 111811181118 Mean Warm Core Radius (km) in Deep Cold Core −VTL [925−700hPa] Thermal wind −VTL [925−700hPa] + Start 06) (A): 1995011418 (H + End (Z): 1995011518 (H + 30) , for January 1995 orographic cyclone. 3 0

300300 250250 200200 150150 100100 60 40 20

−40 −60 −20

Mean Radius Radius Radius Mean Mean Warm Core Warm Core Cold −VTU [700−400hPa] Thermal wind Thermal [700−400hPa] −VTU

, as Fig. ) dir) (6 Gradient Pressure Mean 7446 7445 2 − (b) 2 4 6 8 m 1 φ − σ s 7 ● ● (hPa) 3 2 1 6 5 4 3.2 Medicane ); for 1996 event. 10 Circulation 1005−10101005−10101005−1010 1000−10051000−1005 ( Intense (but not medicane) 1 Cent. pressure − s and II ● 4 − Central Pressure (hPa) in violet (a) 13001300 100 (a) Mean Radius (km) in blue 12181218 Warm Core Warm ● A (b) ● Z ● Symmetric Core Warm Asymmetric Core Warm 12121212 0 ● 12061206 12001200 Cold Core −100 ) in orange 1 11181118 − −VTL [925−700hPa] Thermal wind −VTL [925−700hPa] Symmetric Cold Core Asymmetric Cold Core Geostrophic Vorticity (10 Start 06) (A): 1995011418 (H + End (Z): 1995011518 (H + 30) +

Evolution over time of

Cyclone phase diagrams I

0 5

(Frontal) 10 frontal) (Non 20 15

998 996

Asymmetric Symmetric

1002 1000 Central Pressure Pressure Central B [925−700hPa] B a) b) a) b) orange (hPa 100 km Fig. 9. Fig. 8. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) 2 − 2 4 6 8 m 1 φ σ − s ● 7 ● ● (hPa) Medicane 10 Circulation ( Intense (but 1000 − 10051000 − 10051000 − 10051000 − 10051000 − 10051000 − 1005 not medicane) Cent. pressure 60 ● σ ● σ 40 Warm Core Warm Deep Warm Core Deep Warm 20 ● Z σ Shallow Warm Core Warm Shallow ● 0 ● A ● , for September 1996 event. −20 3 Cold Core −40 Deep Cold Core −VTL [925−700hPa] Thermal wind −VTL [925−700hPa] −60 , as Fig. Start 06) (A): 1996091118 (H + End (Z): 1996091300 (H + 36) 0 60 40 20

−40 −60 −20

(a, b) Warm Core Warm Core Cold −VTU [700−400hPa] Thermal wind Thermal [700−400hPa] −VTU ) 7447 2 − 2 4 6 8 m 1 φ − σ s 7 ● ● (hPa) Medicane 10 Circulation 1000−10051000−10051000−10051000−10051000−10051000−1005 ( Intense (but not medicane) Cent. pressure 60 ● σ ● σ 40 20 ● Z Warm Core Warm σ Symmetric Core Warm Asymmetric Core Warm ● 0 ● A ● −20 Cold Core −40 −VTL [925−700hPa] Thermal wind −VTL [925−700hPa] Symmetric Cold Core Asymmetric Cold Core −60 Start 06) (A): 1996091118 (H + End (Z): 1996091300 (H + 36) Cyclone phase diagrams I and II medicane

0 5

(Frontal) 10 frontal) (Non

Asymmetric Symmetric B [925−700hPa] B a) b) Fig. 10.