A methodology to conduct wind damage field surveys for high-impact weather events of convective origin

Abstract

Abstract. Post-event damage assessments are of paramount importance to document the effects of high-impact weather-related events such as floods or strong wind events. Moreover, evaluating the damage and characterizing its extent and intensity can be essential for further analysis such as completing a diagnostic meteorological case study. This paper presents a methodology to perform field surveys of damage caused by strong winds of convective origin (i.e. tornado, downburst and straight-line winds). It is based on previous studies and also on 136 field studies performed by the authors in Spain between 2004 and 2018. The methodology includes the collection of pictures and records of damage to human-made structures and on vegetation during the in situ visit to the affected area, as well as of available automatic weather station data, witness reports and images of the phenomenon, such as funnel cloud pictures, taken by casual observers. To synthesize the gathered data, three final deliverables are proposed: (i) a standardized text report of the analysed event, (ii) a table consisting of detailed geolocated information about each damage point and other relevant data and (iii) a map or a KML (Keyhole Markup Language) file containing the previous information ready for graphical display and further analysis. This methodology has been applied by the authors in the past, sometimes only a few hours after the event occurrence and, on many occasions, when the type of convective phenomenon was uncertain. In those uncertain cases, the information resulting from this methodology contributed effectively to discern the phenomenon type thanks to the damage pattern analysis, particularly if no witness reports were available. The application of methodologies such as the one presented here is necessary in order to build homogeneous and robust databases of severe weather cases and high-impact weather events.

Tornadic environments in the Iberian Peninsula and the Balearic Islands based on ERA5 reanalysis

“…The moister and relatively warm marine boundary layer of that area increases low‐tropospheric instability and makes environmental conditions more favourable to deep convection (Miglietta et al ., 2017), which is also consistent with the spatial and temporal distribution of lightning events (Taszarek et al ., 2019). This has been highlighted by the exhaustive monitoring of tornadoes and waterspouts in Catalonia and the Balearic Islands during the last three decades by several studies (Gayà et al ., 2001; Gayà, 2011; Arús, 2018; Rodríguez et al ., 2020). This may explain the higher detection of non‐damaging or weakly‐damaging events such as waterspouts and (E)F0 tornadoes in this subarea, in contrast to the rest of the Iberian Peninsula where the ratio of these types of events is much lower.…”

C-Band Dual-Doppler Retrievals in Complex Terrain: Improving the Knowledge of Severe Storm Dynamics in Catalonia

“…For instance, the authors in [35] found that the yearly average economical losses produced only by hail events in the western area of Catalonia were EUR 15M for the period 2000-2009. In the case of straight-line winds or tornadoes, the frequency of occurrence is lower, although most of the events affect densely populated areas and therefore, the economic impact may be even higher [36,37].…”

“…This can be seen in Figure 4, which shows the track of the convective cell that produced the tornado, overlaid on top of the topography. Due to the resolution and the scanning strategies, it has never been possible to observe the tornado itself with the XRAD (smaller than 1 km wide), and thus, as in analyzed cases from the past, the tornado information was obtained with "on the ground" post-event debris analysis [37]. Additionally, in this case, the storm propagated up the valley (valley floor height of 250 m ASL), and the closest radar, CDV, was located 42 km away at 825 m ASL.…”

Satellite-Based Study and Numerical Forecasting of Two Tornado Outbreaks in the Ural Region in June 2017

“…Most of the tornadoes passed outside of settlements and were found only with the use of satellite images of forest damage tracks. Ideally, forest damage survey or high-resolution aerial imagery of damaged forest is needed to correctly estimate the intensity of such tornadoes [13,15,65,66]. Due to their lack, we used high-resolution (with~0.5 m pixel size) satellite images from Google Earth to assess tornado intensity.…”