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th 5 European Conference on Severe Storms 12 - 16 October 2009 - Landshut - GERMANY ECSS 2009 Abstracts by session ECSS 2009 - 5th European Conference on Severe Storms 12-16 October 2009 - Landshut – GERMANY List of the abstract accepted for presentation at the conference: O – Oral presentation P – Poster presentation Session 09: Severe storm case studies and field campaigns, e.g. COPS, THORPEX, VORTEX2 Page Type Abstract Title Author(s) An F3 downburst in Austria - a case study with special G. Pistotnik, A. M. Holzer, R. 265 O focus on the importance of real-time site surveys Kaltenböck, S. Tschannett J. Bech, N. Pineda, M. Aran, J. An observational analysis of a tornadic severe weather 267 O Amaro, M. Gayà, J. Arús, J. event Montanyà, O. van der Velde Case study: Extensive wind damage across Slovenia on July M. Korosec, J. Cedilnik 269 O 13th, 2008 Observed transition from an elevated mesoscale convective J. Marsham, S. Trier, T. 271 O system to a surface based squall line: 13th June, Weckwerth, J. Wilson, A. Blyth IHOP_2002 08/08/08: classification and simulation challenge of the A. Pucillo, A. Manzato 273 O FVG olympic storm H. Bluestein, D. Burgess, D. VORTEX2: The Second Verification of the Origins of Dowell, P. Markowski, E. 275 O Rotation in Tornadoes Experiment Rasmussen, Y. Richardson, L. Wicker, J. Wurman Observations of the initiation and development of severe A. Blyth, K. Browning, J. O convective storms during CSIP Marsham, P. Clark, L. Bennett The development of tornadic storms near a surface warm P. Groenemeijer, U. Corsmeier, 277 O front in central England during the Convective Storm C. Kottmeier Initiation Project (CSIP) Impact of Dryline Misocyclones on Convection Initiation on Y. Richardson, C. L. Ziegler, M. 279 O 19 June 2002 during IHOP Buban, J. Marquis, J. Wurman A. Dörnbrack, G. Craig, S. Jones, O T-NAWDEX - Basic Research allied to the future of NWP H. Wernli P Analysis of multicell storm development on 22 May 2007 N. Pavlovic Berdon 281 P The Balkan cyclone M. Stojanovic Storm-scale radar observations of supercells observed M. I. Biggerstaff, C. Ziegler, D. P during VORTEX2 Betten, T. Thompson, D. Burgess The January 2009 precipitation extremes over Calabria F. Fusto P region, Southern Italy Severe Winter Storms over the Western and Central State of A. M. Gomes, G. Held 283 P São Paulo, Brazil HARE – A new intelligent hail recorder for networks and M. Löffler-Mang 285 P field campaigns 263 Page Type Abstract Title Author(s) M. Parker, A. French, C. Mobile sounding measurements of the near storm 287 P Letkewicz, M. Morin, K. environment during VORTEX2 Rojowsky, D. Stark, G. H. Bryan Y. Richardson, P. Markowski, J. 289 P Mobile mesonet observations in VORTEX2 Wurman, K. Kosiba K. Kosiba, J. Wurman, Y. P Mesocyclone-scale mobile radar observations in VORTEX2 Richardson, P. Markowski Thunder Activity With Heavy Rain Over Egypt In Early P F. M. El Ashmawy, A. L. Essawy Spring J. Egaña, S. Gaztelumendi, D. Convective storms over Basque Country: June 2008 cases 291 P Pierna, I. R. Gelpi, K. Otxoa de study Alda Study of microphysical and thermodynamic structures K. Friedrich, R. Humphrey, J. P within supercell thunderstorms Wurman, K. Kosiba H. Y. Inoue, K. Kusunoki, W. High resolution X-band Doppler radar observation of 293 P Mashiko, S. Hayashi, H. misocyclones along the convergence line Yamauchi Very strong convection at the Baltic coast of Lithuania on 295 P I. Marcinoniene 25 November 2008 K. Kusunoki, H. Inoue, W. Mashiko, S. Hayashi, W. Kato, K. Wind gust and storm evolutions observed during the Shonai 297 P Araki, K. Bessho, S. Hoshino, M. Area Railroad Weather Project: A preliminary survey Nakazato, T. Imai, Y. Hono, T. Takemi, T. Fukuhara, T. Shibata A case study of severe convection over Central Europe with D. Plačko-Vrsnac, N. Strelec- 299 P a detailed analysis of development over Croatia on 22 nd Mahovic and 23 rd June 2007 T. Púčik, M. Francová, D. Rýva, 301 P Derecho on the 25th June 2008 M. Kolář Case study of severe windstorm over Slovakia and Hungary A. Simon, J. Kanák, A. Sokol, M. 303 P on 25 June 2008 Putsay, L. Uhrínová, K. Csirmaz N. Strelec-Mahovic, D. Plačko- P Snowstorm in southern Croatia, 18 February 2009 Vrsnac Examination of two severe thunderstorm events in southern 305 P H. Tuschy, M. Hagen, G. J. Mayr Germany Comparison of detailed model results of MCS with radar B. White, A. Blyth, J. Marsham, P observations during CSIP K. Browning 264 5h European Conference on Severe Storms 12 - 16 October 2009 - Landshut - GERMANY AN F3 DOWNBURST IN AUSTRIA – A CASE STUDY WITH SPECIAL FOCUS ON THE IMPORTANCE OF REAL-TIME SITE SURVEYS Georg Pistotnik1, Alois Martin Holzer2, Rudolf Kaltenböck3, Simon Tschannett4 1Central Institute for Meteorology and Geodynamics, Austria, [email protected] 2European Severe Storms Laboratory e.V., Germany, [email protected] 3Austrocontrol, Aeronautical Meteorological Service, Austria, [email protected] 4Weatherpark GmbH, Meteorological Research and Services, Austria, [email protected] (Dated: 15 September 2009) I. INTRODUCTION On March 1st of 2008, the powerful late winter cyclone “Emma” caused widespread damage over Central Europe. Embedded in the synoptic-scale storm field, deep convection along the cold front resulted in a significant enhancement of gusts in some places, peaking in an unusually strong downburst in a sparsely populated area near Braunau (Austria). Only a site survey revealed the extraordinary intensity of this downburst that vividly contrasted with its sparse media coverage. This study aims to elaborate how the assessment of this case would have taken a significantly different outcome without the accomplishment of this site survey. FIG. 1: MSG RGB “airmass product” image at 08:00 UTC on st II. PRESENTATION OF RESEARCH March 1 of 2008, and detected lightning within the last hour (Schipper et al., 2008). Cyclone “Emma” formed near Newfoundland and travelled eastward over the Northern Atlantic Ocean on the last days of February 2008, where it encountered an increasingly favourable environment for intensification until it reached its minimum central pressure and its maximum strength over Southern Scandinavia on March 1st. As its cold front raced south-eastward over the Netherlands and Germany in the morning hours of this day, it was overrun by a dry intrusion, a process well-known to favour the formation of a convective line along the cold front as it creates potential instability which is ready to be released by the forced ascent of cyclonic vorticity advection (CVA). Extremely dry stratospheric air is visible by the purple colour in the Meteosat “airmass product” image at 08 UTC in Fig. 1. The arrival of this dry intrusion and the superimposed forced ascent of a strong CVA maximum caused the cold front to obtain a “split front” character (Schipper et al., 2008), with a dissolving high cloud shield and incipient cooling of the upper troposphere ahead of the FIG. 2: “INCA” temperature analysis (Haiden et al., 2009) at 10:00 st surface cold front which is hence marked by an intensifying UTC, March 1 of 2008, when the cold front has just entered convective line, showing an unusual high amount of Northern Austria. Location of Braunau is denoted by the black “x”. lightning as it moved over Germany towards the Czech Republic and Austria. Evaporative cooling caused by the The circumstances enabling the formation of this falling precipitation encountering dry environmental air extraordinary local storm can be regarded as a coincidence provoked the formation of a strong cold pool immediately of supporting factors over a wide range of scales, from the behind the surface front (Fig. 2), further increasing the synoptic scale (i.e., the presence of a strong frontal zone) via temperature and pressure gradient and thus accelerating the the mesoscale (i.e., the interaction between the dry intrusion propagation of the convective line that was accompanied by and the cold front) to small scales, whose processes severe wind gusts in many places. The series of downbursts determined the final position and strength of this downburst finally culminated in the Braunau event at 09:46 UTC. event while remaining mostly concealed even to the most alert meteorologist’s eye. The authors of this study encountered a similar scale-cascade while moving their 265 5h European Conference on Severe Storms 12 - 16 October 2009 - Landshut - GERMANY attention from the confusing and widespread synoptic-scale revealed that the damage extent in the core of this downburst storm damages via mesoscale areas of even more reached T5 and locally even T6 intensity (Hubrig, 2004), pronounced downburst signs to the remote but incredible corresponding to upper F2 and locally lower F3 intensity on marks of this “king storm” near Braunau, strikingly closing the Fujita scale (Fig. 3). Thus, even the most conservative the circle between storm synthesis and storm analysis. valuation of the involved wind speed yields maximum gusts The accomplishment of the site survey was not only of at least 200 km/h, turning this event into the strongest based on meteorological ambition and supportive downburst ever documented in Austria (Fig. 4). arrangements but also on (too much of) chances and luck: if this downburst had not hit and severely damaged the III. RESULTS AND CONCLUSIONS infrastructure of a large electricity supplier, the means and Embedded in the synoptic-scale storm field of the powerful ways to perform a thorough site survey would never have late winter cyclone “Emma”, an F3 downburst occurred near unfolded, leaving this case rather buried in oblivion than Braunau (Austria) on March 1st of 2008. Only a thorough finding its way into scientific literature. site survey revealed the nature, the whole extent and extraordinary intensity of this event that received little attention in the media as it affected a sparsely populated area and was dwarfed by superficially more spectacular damage events occurring within cities, disrupting major traffic routes and / or causing injuries and even fatalities.