Heavy Rainfall in Southern Europe in Autumn 2012

Deutscher Wetterdienst, Offenbach

Numerous episodes of heavy rainfall in southern Europe in autumn 2012

Authors: P. Bissolli, H. Nitsche and A. Becker Last update: 17 December 2012

Several heavy precipitation events occurred in Europe in autumn 2012, particularly in the south. Seasonal totals exceeded 600 mm (200 mm/month) especially north and east of the Adriatic Sea, but also locally in Portugal, Spain, France and Turkey. Some places in Slovenia and Croatia received even more than 900 mm. While such seasonal amounts are close to normal within Europe only in Norway and Scotland (Figure 2, top right), they were much higher than normal (more than 125% of the 1951-2000 average) north of the Adriatic Sea, where the absolute anomalies exceeded 200 mm (Figure 2, bottom left). Compared to those of the Adriatic Sea, percentage anomalies were even higher in southern Spain and also in other areas, e.g. in north-eastern Europe (Figure 2, bottom right), though the total amounts were lower there (Figure 2, top left). According to the gridded monthly data products of the Global Precipitation Climatology Centre (GPCC) operated at the Deutscher Wetterdienst it was the 5th highest seasonal total in this region since 1951 and the highest in the present century (Figure 1). This particular region was affected in all three autumn months, most of the others in southern Europe particularly in the second half of the season (end of October and November 2012, see table below). Low pressure activity in Europe was higher than normal in autumn 2012, resulting in a lower-than- normal surface pressure over the whole continent. Upper-air troughs extended several times far to the south, leading to quasi-stationary cut-off lows particularly over the western and central Mediterranean region. The cyclones did not only cause much rain, but also thunderstorms with local gusts up to hurricane level. Water vapour content in the atmosphere was considerably higher than normal in the Mediterranean region especially in November (Figure 3), also driven by a considerable positive anomaly of the Mediterranean sea surface temperatures (SSTs, Figure 5). Consequently the threshold SST for the development of so-called ‘Medicanes’ (24°C) where exceeded widespread and even the Hurricane threshold (27°C) was trespassed in southern and eastern parts (Figure 4). Some example reports of outstanding rainfall events in autumn 2012, taken from websites:  19 September: Violent storms and up to more than 100 mm of rain, especially in areas in central/northern regions of Tuscany (Italy) causing damage and inconvenience due to landslides and flooding. http://www.meteoweb.eu/2012/09/forte-maltempo-in-toscana-picchi- di-oltre-100mm-nel-livornese-danni-e-disagi/153546  Heavy rains and storms have affected much of the evening of 30 September in Tuscany. The major disruptions occurred in Livorno and Florence. At Calenzano, due to flooding, fire- fighters helped many people to leave the subways which were no more accessible. Torrential rains also in Pisa and Pistoia. The accumulations were up to more than 150 mm, many places received more than 50 mm. http://www.meteoweb.eu/2012/09/maltempo-toscana- colpita-e-affondata-bombe-dacqua-tra-livorno-e-firenze-citta-in-tilt-picchi-di-150mm-foto-e- video/155220  Starting on 10 October, heavy rainstorms affected Italy and the countries of the Balkan Peninsula. Autumn was conducive to violent storms; they were even stronger than after a hot summer. The temperature of the surface water of the Mediterranean was abnormally high (2- 3°C above average, Figure 5). Against this background, the virulence of a depression was enhanced especially as it was supplied with cold air coming from Germany while the hot air rose from Libya to Greece and Hungary. All this combined increased the violence of rains

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Deutscher Wetterdienst, Offenbach

and thunderstorms in this part of Europe. Mainly the coastal regions of the western Balkan Peninsula were the most vulnerable to violent storms. From 10 to 13 October, between 50 and 200 mm were reported, causing river floods. http://actualite.lachainemeteo.com/actualite-meteo/2012-10-13-06h00/violents-orages-en- croatie-depuis-mercredi-18471.php

 Heavy rains in southwest France on the weekend of 20 October had put much of the famous pilgrimage town of Lourdes under water. The Gave de Pau River flowing through the city caused flooding of accommodation of pilgrims and also the Sanctuary itself. http://derstandard.at/1350258946715/Schwere-Ueberschwemmungen-in-franzoesischem- Wallfahrtsort-Lourdes  Cyclone Ladislav developed over northern Italy and northern Adriatic Sea, causing floods along Adriatic Sea coastlines on November 1, 2012. Combination of full moon, low air pressure along with strong winds blowing from the sea toward the coast, increased Adriatic Sea levels and submerged streets of almost every city along coastline. http://soundofheart.org/galacticfreepress/content/cyclone-ladislav-raised-adriatic-sea-levels- submerged-streets-along-croatian-coastline-citie  In Carinthia (Austria) there were numerous floods even along major rivers like Drava and Gail on 5 November. The reason was not just the heavy rain the few days before, but the many heavy rainfall events over the last two weeks. At the station on Loiblpass for example nearly 400 mm of rain had accumulated in the last 14 days, around 150 mm just in 24 hours. These are huge amounts considering that in autumn on Loiblpass the average rainfall for an entire month is around 230 mm. Furthermore, the snow melt after end of the previous cold spell at the end of October caused additional water masses. The town Lavamünd was particularly affected because it was flooded by two rivers: http://diepresse.com/home/panorama/oesterreich/1308893/Hochwasser-in- Lavamuend_Aufraeumarbeiten-gestartet The following link contains a table of daily precipitation totals of 5 November as well as 14- day totals. http://www.zamg.ac.at/cms/de/wetter/news/hochwasser-in-teilen-suedoesterreichs This event also caused extremely severe flooding in Slovenia: http://www.wettergefahren-fruehwarnung.de/Ereignis/20121106_e.html (more data see www.dwd.de/rcc-cm - Products - Significant Weather Events – Monthly calendar) Furthermore, there were also catastrophic landslides after extreme precipitation in Madeira. Madeira: Temporal no norte da Madeira (5 e 6 Nov. 2012)  A low-pressure system stalled over northern and central Italy in early November 2012. At least 13 mm of rain fell daily for five consecutive days, and often more. Some of the heaviest rainfall — more than 320 mm from November 6 to 13 — was concentrated southeast of Florence. The long-term average for rainfall in November in Italy is 80 mm. However, November precipitation totals have surpassed 100 mm seven times since 1999. November is typically the rainiest month for Florence. Rivers in Tuscany burst their banks as residents awaited rescue from their rooftops. In the area of Carrara alone, about 50 people had to leave their homes. 4 fatalities in Tuscany were reported. The head of Tuscany’s regional government asked for intervention from the army to assist with rescue and cleanup efforts. http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=79716

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Deutscher Wetterdienst, Offenbach

Numerous daily totals exceeded 100 mm of rain between Veneto and Friuli Venezia Giulia (Italy) on 11 November 2012. In Veneto, 70% of the territory of Venice was flooded. Water level in Venice was the 6th highest since 1872 and the highest since 2008. http://www.inmeteo.net/blog/2012/11/11/maltempo-veneto-e-friuli-alluvione-e-piogge-record- 11-novembre-2012 Further damage occurred in Rome due to flooding. The Ponte Milvio Bridge was closed. Near Orvieto, residents were rescued from roofs of their homes.  Carrara, Tuscany (Italy): On 27 November in the late evening a terrible storm hit Carrara again and created flash flood. About 200 mm of precipitation fell of which 170 mm in just 3 hours. Large areas were completely submerged in Carrara and dozens of people had to leave their homes. There was a lot of disruption to traffic, both for cars and trains due to flooding, but with landslide risk. http://www.meteogiornale.it/notizia/25457-1-toscana- alluvione-200-mm-carrara

Acknowledgement: We thank our colleagues K. Friedrich, A. Obregón, M. Körber and J. Bollenbach for providing the following figures and table and/or proofreading the text, and M. Rocek for layout assistance.

Mean monthly precipitation for autumn (September-November) 1951-2012 Gridded data from GPCC for box 45° - 47°N and 14° - 16°E 200

180

160

140

120

100

precipitation (mm/month) precipitation 60

0 1951 1961 1971 1981 1991 2001 2011

Figure 1: Mean monthly precipitation for autumn (September-November) 2012 from 1951-2012 for a sub-section 45°-47°N and 14°-16° E also by red boxes in Figure 2 based on GPCC’s analyses.

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Deutscher Wetterdienst, Offenbach

Figure 2: Autumn (September-November) 2012 precipitation in WMO-RA-VI in terms of total amount (top left), climatic normal (top right), absolute anomaly (bottom left) all in mm/month and percentage anomaly (bottom right). Source: GPCC First Guess Product, doi:10.5676/DWD GPCC/FG M 100, Deutscher Wetterdienst.

Table 1: Precipitation totals in the Mediterranean for the period 01 Sep 2012 to 30 Nov 2012 (SYNOP stations, maximum of each country in red)

WMO-ID Station name Country Altitude Latitude Longitude RR (1)* RR (2)* RR(1+2)* in m in mm in mm in mm 08027 San Sebastian Spain 251 43.30 N 002.30 E 275 331 606 08482 Malaga Spain 16 36.67 N 004.48 E 65 170 235 08495 Gibraltar Spain 5 36.15 N 005.35 E 131 269 400 08451 Jerez Spain 27 36.75 N 006.07 E 143 180 323 08175 Reus Spain 71 41.15 N 001.17 E 110 104 214 08021 Santander Spain 6 43.43 N 003.82 E 203 135 338 08410 Cordoba Spain 90 37.85 N 004.85 E 81 232 313 08419 Granada Spain 567 37.81 N 003.78 E 75 242 317

08506 Horta Portugal 60 38.52 N 028.63 W 283 363 646 08521 Funchal Portugal 58 32.68 N 016.77 W 72 473 545 08561 Beja Portugal 194 38.07 N 007.92 W 58 267 325 08501 Flores Portugal 28 39.45 N 031.13 W 165 307 472

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Deutscher Wetterdienst, Offenbach

08512 Ponta Delgade Portugal 71 37.73 N 025.70 W 228 119 347

14008 Kredarica Slovenia 2514 46.38 N 013.85 E 398 573 971 14021 Slovenj Gradec Slovenia 452 46.48 N 015.12 E 234 278 512 14105 Portoroz Slovenia 2 45.48 N 013.62 E 122 203 325 14014 Ljubljana Slovenia 384 46.22 N 014.48 E 223 357 580

13611 Durres Albania 15 41.30 N 019.45 E 76 200 276 13624 Qyteti Stalin Albania 32 40.80 N 019.90 E 96 169 265 13600 Shkodra Albania 43 42.10 N 019.53 E 166 159 325 13623 Sazan Island Albania 340 40.30 N 019.17 E 244 168 412

13462 Podgorica Montenegro 33 42.37 N 019.25 E 276 324 600 13461 Bar Montenegro 4 42.10 N 019.10 E 226 191 417

16641 Kerkya Greece 2 39.62 N 019.92 E 170 199 369

17042 Hopa Turkey 33 41.40 N 041.43 E 367 386 753 17034 Giresun Turkey 37 40.92 N 038.38 E 95 297 392

11231 Klagenfurt Austria 448 46.65 N 014.33 E 214 186 400 11212 Villacheralpe Austria 2140 46.60 N 013.67 E 162 350 512 11213 Villach Austria 494 46.62 N 013.88 E 229 255 484 11136 Krimml Austria 1009 47.23 N 012.18 E 164 105 269 11142 St.Johann Austria 634 47.32 N 013.18 E 241 101 342 11240 Graz Austria 340 47.00 N 015.43 E 177 102 279 11345 St.Veit Austria 750 47.33 N 013.15 E 219 87 306

14314 Mali Losinj Croatia 53 44.53 N 014.48 E 321 249 570 14219 Parg Croatia 863 45.60 N 014.63 E 425 527 952 14307 Pula Croatia 63 44.90 N 013.92 E 43 255 298 14428 Zadar/Puntamika Croatia 5 44.13 N 015.22 E 340 154 494 14330 Gospic Croatia 564 44.55 N 015.37 E 323 355 678 14216 Rijeka Croatia 120 45.33 N 014.45 E 564 439 1003 14308 Pazin Croatia 291 45.32 N 013.93 E 183 327 510 14321 Rab Croatia 24 44.75 N 014.77 E 209 346 555 14324 Zavizan Croatia 1594 44.82 N 014.98 E 401 508 909

07560 Monte Aigoual France 1567 44.12 N 003.58 E 300 427 727 07684 Cannes France 3 43.53 N 006.95 E 119 383 502 07761 Ajaccio France 5 41.92 N 008.80 E 142 253 395 07790 Bastia France 10 42.55 N 009.48 E 159 97 256 07690 Nice France 4 43.65 N 007.20 E 188 270 458 07660 Toulon France 24 43.10 N 005.93 E 69 204 273 07610 Pau France 183 43.38 N 000.42 W 174 136 310 07481 Lyon France 234 45.73 N 005.08 E 168 161 329 07577 Montelimar France 73 44.58 N 004.73 E 175 223 398

16344 Monte Scuro Italy 1669 39.33 N 016.40 E 110 180 290

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Deutscher Wetterdienst, Offenbach

16332 Lecce Italy 48 40.29 N 018.13 E 107 165 272 16172 Arezzo Italy 248 43.47 N 011.85 E 115 311 426 16114 Mondovi Italy 559 44.38 N 007.82 E 110 151 261 16040 Tarvisio Italy 777 46.50 N 013.58 E 268 339 607 16110 Trieste Italy 8 45.65 N 013.75 E 168 185 353 16134 Monte Cimone Italy 2165 44.20 N 015.70 E 214 189 403 16429 Trapani Italy 7 37.55 N 012.30 E 84 129 213 16120 Genova Italy 2 44.25 N 008.51 E 173 372 545 *Periods: 01 Sep - 20 Oct 2012 RR (1) 21 Oct – 30 Nov 2012 RR (2)

Figure 3: Anomalies of TPW (total precipitable water) from SATEM reports November 2012, 1980-2005 reference. Source: DWD

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Deutscher Wetterdienst, Offenbach

Figure 4: Sea Surface temperature derived from the DWD model GME. Source: DWD

Figure 5: Anomalies of sea surface temperature in autumn 2012 (September-November, 1971-2000 reference) Source: IRI: http://iridl.ldeo.columbia.edu/SOURCES/.NOAA/.NCEP/.EMC/.CMB/.GLOBAL/.Reyn_SmithOIv2/.monthly/.ssta

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