The Northern Tornadoes Project: Uncovering Canada’s True Tornado Climatology

Sills, David; Kopp, Gregory A.; Elliott, Lesley; Jaffe, Aaron L.; Sutherland, Liz; Miller, Connell S.; Kunkel, Joanne; Hong, Emilio; Stevenson, Sarah; Wang, William Yang

doi:10.1175/bams-d-20-0012.1

Cited by 18 publications

(9 citation statements)

References 33 publications

(27 reference statements)

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“…Most tornadic wind fields vary spatially and temporally, and thus tornado wind field models should be capable of capturing these variations in the wind components [35]. A series of aerial photos were acquired ten days after the tornado from the Northern Tornadoes Project [68] by a plane flying at approximately 300 m above the track. Orthomosaic images at a pixel resolution of 5 cm were produced, and the tornado centerline and damage extent were estimated as shown in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

“…The tornado centerline was estimated based on the location where the most extensive damage happened [28], while the damage extent was estimated according to the location of the furthest damaged tree on both sides (north and south) of the tornado center. A series of aerial photos were acquired ten days after the tornado from the Northern Tornadoes Project [68] by a plane flying at approximately 300 m above the track. Orthomosaic images at a pixel resolution of 5 cm were produced, and the tornado centerline and damage extent were estimated as shown in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

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Estimating Wind Damage in Forested Areas Due to Tornadoes

Mansour

Rhee

Newson

et al. 2020

Forests

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Research Highlights: Simulations of treefall patterns during tornado events have been conducted, enabling the coupled effects of tornado characteristics, tree properties and soil conditions to be assessed for the first time. Background and Objectives: Treefall patterns and forest damage assessed in post-storm surveys are dependent on the interaction between topography, biology and meteorology, which makes identification of characteristic behavior challenging. Much of our knowledge of tree damage during extreme winds is based on synoptic storms. Better characterization of tree damage will provide more knowledge of tornado impacts on forests, as well as their ecological significance. Materials and Methods: a numerical method based on a Rankine vortex model coupled with two mechanistic tree models for critical wind velocity for stem break and windthrow was used to simulate tornadic tree damage. To calibrate the models, a treefall analysis of the Alonsa tornado was used. Parametric study was conducted to assess induced tornadic tree failure patterns for uprooting on saturated and unsaturated soils and stem break with different knot factors. Results: A power law relationship between failure bending moments and diameter at breast height (DBH) for the hardwood species provided the best correlation. Observed failure distributions of stem break and windthrow along the tornado track were fitted to lognormal distributions and the mean of the critical wind speeds for windthrow were found to be higher than that for stem break. Relationships between critical wind speed and tree size were negatively correlated for windthrow and positively correlated for stem break. Higher soil moisture contents and lower knot factors reduced the critical wind speeds. The simulations show varying tree fall patterns displaying forward and backward convergence, different tornado damage widths and asymmetry of the tracks. These variations were controlled by the relative magnitudes of radial and tangential tornado velocities, the ratio between translational speed and maximum rotational wind speed and the mode of failure of the trees. Conclusions: The results show the complexity of predicting tornadic damage in forests, and it is anticipated that this type of simulation will aid risk assessments for insurance companies, emergency managers and forest authorities.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Estimating Wind Damage in Forested Areas Due to Tornadoes

Mansour

Rhee

Newson

et al. 2020

Forests

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“…The majority of populated areas in Canada are in tornado‐prone (Sills et al, 2012) and flood‐prone regions, specifically urban areas (Abebe et al, 2018; Mahmoudi et al, 2021). On 22 June 2007, Canada's most intense and the only F 5 category tornado hit Elie, Manitoba (Environment Canada, 2017).…”

Section: Introductionmentioning

confidence: 99%

Probabilistic assessment of concurrent tornado and storm‐related flash flood events

Ngui

Najafi

Souza

et al. 2023

Intl Journal of Climatology

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The concurrent occurrence of extreme events can significantly impact societies and infrastructure systems, especially when the instructions provided to the exposed communities demand conflicting responses. In this study, a probabilistic assessment of concurrent tornado and storm-related flash flood (TORFF) events is performed across southern Canada. We quantify the interdependencies between tornadoes and flash floods (extreme precipitation as proxy) using ground-based and reanalysis datasets. Windspeed values corresponding to tornado events, categorized based on the recorded Fujita rating, are derived through a resampling approach. The TORFF events are clustered and the corresponding bivariate probability distributions of the resampled windspeed and associated precipitation are characterized based on Copula framework. The individual and joint return periods of concurrent tornadoes and flash floods are then assessed under the AND (when both variables exceed predefined thresholds), OR (when either one of the two variables exceeds predefined thresholds), and conditional hazard scenarios across Canada. Results show positive strong dependencies between resampled windspeed and associated precipitation in Saskatchewan, and weaker dependencies followed by Alberta, Manitoba, Ontario, and Quebec. The Saskatchewan region shows the highest risk underestimation considering the independence scenario compared to the other regions. Higher precipitation is also expected during extreme windspeed, as observed in the conditional assessment of precipitation given windspeed. This study provides insights for more robust recurrence interval estimation for tornadoes and flash floods to aid in emergency planning of evacuation decision-making process.

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“…Over the last decade or more, Ontario's severe weather community has noted anecdotally that tornadoes now seem to occur later in the season here. In fact, all three November tornadoes on record in Ontario occurred after 2004 (F/EF1 tornadoes in 2005, 2013 and 2020), and in 2018 an EF3 tornado developed as part of a 7‐tornado outbreak in southern Ontario and neighboring Quebec in late September (Sills et al., 2020)—the first September F/EF3+ Canadian tornado in 120 years and the first tornado outbreak of such magnitude that late in the year in Canada.…”

Section: Introductionmentioning

confidence: 99%

Are Significant Tornadoes Occurring Later in the Year in Southern Ontario?

Sills

Durfy

Souza

2022

Geophysical Research Letters

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More than a dozen tornadoes occur on average every year in the Canadian province of Ontario (ECCC, 2017). While most are weak in nature (i.e., rated F/EF0-1), a number of tornadoes having far greater intensity have occurred. For example, F4 tornadoes in 1946For example, F4 tornadoes in , 1970For example, F4 tornadoes in and 1985 resulted in 31 deaths and hundreds of injuries.Though tornadoes in Ontario have been recorded March to December, the peak months are May to August. Over the last decade or more, Ontario's severe weather community has noted anecdotally that tornadoes now seem to occur later in the season here. In fact, all three November tornadoes on record in Ontario occurred after 2004 (F/EF1 tornadoes in 2005, 2013 and 2020), and in 2018 an EF3 tornado developed as part of a 7-tornado outbreak in southern Ontario and neighboring Quebec in late September (Sills et al., 2020)-the first September F/EF3+ Canadian tornado in 120 years and the first tornado outbreak of such magnitude that late in the year in Canada.For this reason, the present study investigates the long-term trend in the month of maximum tornado occurrence in Ontario. It also looks for similar long-term trends using tornado data from neighboring US states.Though no past research work investigates this aspect of tornado climatology in Canada, studies on this topic exist in the United States. Long and Stoy (2014) found that, over the past six decades in the central and southern US Great Plains, peak tornado frequency has shifted earlier by 7 days. Lu et al. (2015) investigated tornado trends in the central US and their results also suggested that the seasonal peaks for both observed tornadoes and environments conducive to tornadoes now occur earlier in the year with a trend of 3.7 days per decade.Note that the Fujita (F) scale (Fujita, 1981) was used in Canada to 2012, and was replaced by the Enhanced Fujita

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The Northern Tornadoes Project: Uncovering Canada’s True Tornado Climatology

Abstract: Capsule Western University’s Northern Tornadoes Project aims to detect and characterize every tornado that occurs in Canada – and provide open access to all data and documentation

Cited by 18 publications

References 33 publications

Estimating Wind Damage in Forested Areas Due to Tornadoes

Estimating Wind Damage in Forested Areas Due to Tornadoes

Probabilistic assessment of concurrent tornado and storm‐related flash flood events

Are Significant Tornadoes Occurring Later in the Year in Southern Ontario?

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