South America tornado outbreak of 11–12 June 2018

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Detection of a tornado damage path north of Pontao, RS. The GFW algorithm detected forest areas of forest loss in pink; reflectivity shows the full tornado path below. Pontao, RS tornado track imagery.jpg
Detection of a tornado damage path north of Pontão, RS. The GFW algorithm detected forest areas of forest loss in pink; reflectivity shows the full tornado path below.

Damage surveys were necessary in order to establish a cause for the damage, as the nocturnal nature of the outbreak resulted in a lack of visual confirmation of tornadoes. However, surveying the damage proved a challenge due to limited resources and the remote areas which were affected. Nonetheless, surveyors from the Federal University of Santa Maria (UFSM) and Brazil Civil Defense jointly surveyed the damage. Most attention was given to the long-tracked Coxilha tornado, as it was more difficult to survey shorter and weaker tornadoes due to the aforementioned difficulties. The choice to survey damage using the original Fujita Scale rather than the newer Enhanced Fujita Scale was made because of the lack of adaptations to the latter based on Brazilian building codes. Due to limitations with ground surveying, aerial surveying and analysis of satellite imagery were useful in assessing damage and path size. Deforestation detection programs were also helpful in this regard. [1] : 6–10 

Researchers from the UFSM assessed the intensity of the Coxilha at F3 strength, although they warned that their damage analysis may have underestimated the actual intensity of the tornadoes. [1] : 18  Meanwhile, a separate damage analysis conducted by MetSul Meteorologia found evidence of F4 intensity. [4] [b]

Research

Learning algorithms were used to assess forest damage and identify 10 different tornado tracks across Argentina and Brazil (one tornado's path was not detectable due to its brevity and low intensity; it was identified only by video evidence). [1] : 8–10  Many tornadoes were observed on Doppler weather radar, allowing for the observation of phenomena such as tornado debris signatures. Furthermore, this was the first ever cyclic supercell and first ever case of multiple simultaneous supercell tornadoes in South America on record. [1] : 2 

See also

Notes

  1. 1 2 All dates are based on the local time zone where the tornado touched down; however, all times are in Coordinated Universal Time for consistency.
  2. 1 2 Due to the disclaimer by UFSM researchers regarding potential underestimation of tornado intensity in their analysis, the higher intensity given by MetSul is prioritized in this article.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Murilo Machado Lopes; Maurício Ilha de Oliveira; Vitor Goede; Vanessa Ferreira; Ernani de Lima Nascimento (1 July 2025). "Damage Survey and Multisensor Analysis of a Cold Season Tornado Outbreak in Southern Brazil" . Journal of Applied Meteorology and Climatology. 64 (7). American Meteorological Society: 831–855. doi:10.1175/JAMC-D-24-0146.1 . Retrieved 13 July 2025.
  2. 1 2 Yan Castro Lisboa; Gleiciane Fernanda de Carvalho Blanc; Márcia da Silva Jorge (26 July 2019). "Passagens de tornados nas áreas rurais dos municípios de Água Santa e Coxilha-RS" [Tornado passages in the rural areas of Água Santa and Coxilha-RS]. Geopauta (in Brazilian Portuguese). 3 (1): 61–74. doi: 10.22481/rg.v3i1.5079 . Retrieved 17 July 2025.
  3. 1 2 3 Ribeiro, Bruno (11 June 2023). Revisiting the tornadoes of June 11-12, 2018. PREVOTS (Report).
  4. 1 2 3 4 5 "Violento tornado entre Coxilha e Tapejara". MetSul Meteorologia (in Brazilian Portuguese). 12 June 2018. Retrieved 16 July 2025.
  5. ↑ "Tornados causam duas mortes e destruição". Jornal do Comércio (in Brazilian Portuguese). 13 June 2018. Retrieved 16 July 2025.
  6. ↑ Ernesto Azarkevich. "Misiones: un tornado dejó un muerto y serios daños". Clarín (in Spanish).
  7. ↑ Fábio Schaffner (13 June 2018). "Uma visita ao epicentro da destruição causada pela tempestade em Coxilha". Zero Hora (in Brazilian Portuguese).
  8. ↑ Anderson Aires; Débora Ely (13 June 2018). "Imagens aéreas reforçam hipótese de tornados em série no norte do RS". Zero Hora (in Brazilian Portuguese).
  9. 1 2 3 Nagel, Luciano (12 June 2018). "Tornado passa pelo RS, deixa 2 mortos e causa destruição em dezenas de municípios". UOL (in Brazilian Portuguese).
  10. 1 2 "União reconhece situação de emergência de seis cidades do RS atingidas por temporais". Zero Hora (in Brazilian Portuguese). 6 July 2018. Retrieved 16 July 2025.
South America tornado outbreak of 11–12 June 2018
12 Jun 2018 Mos D HD 0400 SA satellite imagery cropped.jpg
The storm system responsible for the outbreak over the region in the early morning of 12 June, shortly before the Coxilha tornado dissipated.
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