This study investigates the atmospheric conditions associated with major tornado outbreaks (at le... more This study investigates the atmospheric conditions associated with major tornado outbreaks (at least seven tornadoes of magnitude EF2 or higher) in the United States during May using maximum covariance analysis (MCA). We focus on identifying the leading modes of covariability between 500-hPa geopotential height anomalies and the WMAXSHEAR parameter, a bivariate proxy of atmospheric buoyancy and vertical wind shear. By analyzing 91 significant tornado outbreaks from 1950 to 2019, we identify three primary multivariate patterns, each exhibiting distinct anomaly locations and intensities for both variables. These patterns account for 97 % of the covariability between the two fields, with the leading pattern (MCA1) explaining 71 %, the second (MCA2) 20 %, and the third (MCA3) 6 %. The application of MCA to tornado outbreak analysis is a novel approach, providing a nuanced understanding of the complex multi-scale atmospheric conditions leading to these events. We find that tornado outbreaks associated with the first two leading covariability patterns last longer ad can occur at any time of day and night, whereas those associated with the third pattern tend to be shorter and begin in the late morning or early evening. The identified patterns are significantly different from those observed on null-event days, suggesting that these patterns are useful for future research aimed at simulating and comparing tornado outbreak characteristics under scenarios of a warming climate. This research enhances our understanding of the complex interplay between mesoscale and synoptic-scale atmospheric conditions and provides valuable insights for improving tornado outbreak predictions and preparedness in a changing climate.
This study supports efforts directed toward research on large-scale atmospheric patterns and on t... more This study supports efforts directed toward research on large-scale atmospheric patterns and on the variability of tornado outbreaks. Specifically, we applied rotated principal component analysis to identify synoptic-scale patterns of 500-hPa geopotential height associated with tornado outbreaks in the United States. We created a database of historic tornado outbreaks using kernel density estimation on events composed of at least seven tornadoes of magnitude (E)F2 or higher (major tornado outbreaks) that occurred in May from 1950 to 2019 (91 events). Results of the analysis show that the first three principal components explained the majority, that is, 74% of the total variation. Based on the analysis of congruence coefficients, the Promax oblique transformation was chosen as the most representative rotation in portraying physically meaningful modes and resulted in three main atmospheric patterns. Two of these, to the best of our knowledge, have not been yet identified as the most representative of tornado outbreaks in any previous studies. Additionally, results suggest that although synoptic patterns associated with major May tornado outbreaks remain the same over time, partial variability in their geographic location exhibits some cyclical behaviour, especially on decadal and multidecadal scales. Identifying these patterns can serve as a first step in determining how they may change under anthropogenic climate change in the future. K E Y W O R D S 500-hPa geopotential height, climate change, climatology, large-scale atmospheric patterns, principal component analysis, tornado outbreaks, United States
Role of backwash in sedimentation from tsunami on confined coastal plain on western Greenland - insights from textural properties of 2000 AD landslide-generated tsunami deposits
Identification of mid-tropospheric patterns associated with tornado outbreaks in the United States
The identification of large-scale atmospheric patterns associated with tornado outbreaks poses a ... more The identification of large-scale atmospheric patterns associated with tornado outbreaks poses a great challenge. It involves analysis of physical processes occurring at different time and space scales that, in the right configuration, result in environmental conditions favoring tornado outbreak formation. Over the years, there have been numerous studies that utilize the notion of ‘tornado outbreaks.’ The term has been used to define severe weather events where the occurrence of multiple tornados has been determined. The exact meaning of ‘tornado outbreak,’ however, has been repeatedly redefined and has evolved throughout the years. Depending on the availability of scientific data, technological advancements, and the purpose of these definitions, different authors offered diverse approaches to shape the perception and applications of ‘tornado outbreak.’ This work provides an extensive review of the evolving nature of the ‘tornado outbreak’ definition. Each decade contains multiple e...
Climatology of <scp>500‐hPa</scp> geopotential height anomalies associated with May tornado outbreaks in the United States
International Journal of Climatology, Sep 18, 2022
This study supports efforts directed toward research on large‐scale atmospheric patterns and on t... more This study supports efforts directed toward research on large‐scale atmospheric patterns and on the variability of tornado outbreaks. Specifically, we applied rotated principal component analysis to identify synoptic‐scale patterns of 500‐hPa geopotential height associated with tornado outbreaks in the United States. We created a database of historic tornado outbreaks using kernel density estimation on events composed of at least seven tornadoes of magnitude (E)F2 or higher (major tornado outbreaks) that occurred in May from 1950 to 2019 (91 events). Results of the analysis show that the first three principal components explained the majority, that is, 74% of the total variation. Based on the analysis of congruence coefficients, the Promax oblique transformation was chosen as the most representative rotation in portraying physically meaningful modes and resulted in three main atmospheric patterns. Two of these, to the best of our knowledge, have not been yet identified as the most representative of tornado outbreaks in any previous studies. Additionally, results suggest that although synoptic patterns associated with major May tornado outbreaks remain the same over time, partial variability in their geographic location exhibits some cyclical behaviour, especially on decadal and multidecadal scales. Identifying these patterns can serve as a first step in determining how they may change under anthropogenic climate change in the future.
US tornado outbreaks in May: characteristics of atmospheric patterns identified by maximum covariance analysis
Under a warming climate, it is unclear how environments associated with US tornado outbreaks are ... more Under a warming climate, it is unclear how environments associated with US tornado outbreaks are changing. This work narrows this gap by using maximum covariance analysis (MCA) to find multivariate relationships between 500-hPa geopotential height anomalies and a severe thunderstorm proxy – WMAXSHEAR (a product of convective available potential energy and 0–6 km vertical wind shear) associated with past (1950-2019) May major tornado outbreaks. Results highlight three main patterns that explain the majority of covariance between tornado outbreaks and the large-scale atmospheric environment. Tornado outbreaks occurring under the dominant pattern (MCA1) initiate at different hours of the day and tend to last for many hours. Tornado outbreaks associated with the second (MCA2) and third (MCA3) patterns are shorter in duration and tend to initiate during the warmest daytime hours. Moreover, an increase in the magnitude and the spatial extent of the patterns conducive to tornado outbreaks ...
Climatology of 500‐hPa geopotential height anomalies associated with May tornado outbreaks in the United States
International Journal of Climatology
This study supports efforts directed toward research on large‐scale atmospheric patterns and on t... more This study supports efforts directed toward research on large‐scale atmospheric patterns and on the variability of tornado outbreaks. Specifically, we applied rotated principal component analysis to identify synoptic‐scale patterns of 500‐hPa geopotential height associated with tornado outbreaks in the United States. We created a database of historic tornado outbreaks using kernel density estimation on events composed of at least seven tornadoes of magnitude (E)F2 or higher (major tornado outbreaks) that occurred in May from 1950 to 2019 (91 events). Results of the analysis show that the first three principal components explained the majority, that is, 74% of the total variation. Based on the analysis of congruence coefficients, the Promax oblique transformation was chosen as the most representative rotation in portraying physically meaningful modes and resulted in three main atmospheric patterns. Two of these, to the best of our knowledge, have not been yet identified as the most r...
Bulletin of the American Meteorological Society, 2021
Heavy precipitation events and their associated flooding can have major impacts on communities an... more Heavy precipitation events and their associated flooding can have major impacts on communities and stakeholders. There is a lack of knowledge, however, about how stakeholders make decisions at the subseasonal-to-seasonal (S2S) time scales (i.e., 2 weeks to 3 months). To understand how decisions are made and S2S predictions are or can be used, the project team for “Prediction of Rainfall Extremes at Subseasonal to Seasonal Periods” (PRES2iP) conducted a 2-day workshop in Norman, Oklahoma, during July 2018. The workshop engaged 21 professionals from environmental management and public safety communities across the contiguous United States in activities to understand their needs for S2S predictions of potential extended heavy precipitation events. Discussions and role-playing activities aimed to identify how workshop participants manage uncertainty and define extreme precipitation, the time scales over which they make key decisions, and the types of products they use currently. This co...
New insights in tsunami hazard assessment in polar regions from studies of the 2000 AD tsunami in Vaigat Strait, west Greenland
To date, the effects of tsunami have been mainly reported from tropical and temperate regions. Ts... more To date, the effects of tsunami have been mainly reported from tropical and temperate regions. Tsunami in polar regions have been mainly recorded in fjords, which are particularly prone to hazards associated with landslide-generated tsunamis. The rapid climate warming being observed in the high latitudes effects in an increase of human activities in coastal zone. Thus problem of hazard assessment is of increasing importance. Here we report the geological and environmental effects of a landslide-triggered tsunami that occurred on 21st November 2000 in Vaigat Strait, northern Disko Bugt in west Greenland. We have investigated sedimentary and geomorphological effects of the tsunami along eighteen coast-perpendicular transects in a range of depositional settings: cliff coasts, narrow to moderate width coastal plains and a coastal lake. At each setting we completed a detailed map using a laser scanner and DGPS survey. The tsunami deposits were described from closely spaced trenches and, ...
Bulletin of the American Meteorological Society, 2021
The term “tornado outbreak” appeared in the meteorological literature in the 1950s and was used t... more The term “tornado outbreak” appeared in the meteorological literature in the 1950s and was used to highlight severe weather events with multiple tornadoes. The exact meaning of “tornado outbreak,” however, evolved over the years. Depending on the availability of scientific data, technological advancements, and the intended purpose of these definitions, authors offered a diverse set of approaches to shape the perception and applications of the term “tornado outbreak.” This paper reviews over 200 peer-reviewed publications—by decade—to outline the evolving nature of the “tornado outbreak” definition and to examine the changes in the “tornado outbreak” definition or its perception. A final discussion highlights the importance, limitations, and potential future evolution of what defines a “tornado outbreak.”
This study supports efforts directed toward research on large-scale atmospheric patterns and on t... more This study supports efforts directed toward research on large-scale atmospheric patterns and on the variability of tornado outbreaks. Specifically, we applied rotated principal component analysis to identify synoptic-scale patterns of 500-hPa geopotential height associated with tornado outbreaks in the United States. We created a database of historic tornado outbreaks using kernel density estimation on events composed of at least seven tornadoes of magnitude (E)F2 or higher (major tornado outbreaks) that occurred in May from 1950 to 2019 (91 events). Results of the analysis show that the first three principal components explained the majority, that is, 74% of the total variation. Based on the analysis of congruence coefficients, the Promax oblique transformation was chosen as the most representative rotation in portraying physically meaningful modes and resulted in three main atmospheric patterns. Two of these, to the best of our knowledge, have not been yet identified as the most representative of tornado outbreaks in any previous studies. Additionally, results suggest that although synoptic patterns associated with major May tornado outbreaks remain the same over time, partial variability in their geographic location exhibits some cyclical behavior, especially on decadal and multidecadal scales. Identifying these patterns can serve as a first step in determining how they may change under anthropogenic climate change in the future.
Bulletin of the American Meteorological Society, 102(4), pp.E817-E835., 2021
The term "tornado outbreak" appeared in the meteorological literature in the 1950s and was used t... more The term "tornado outbreak" appeared in the meteorological literature in the 1950s and was used to highlight severe weather events with multiple tornadoes. The exact meaning of "tornado outbreak," however, evolved over the years. Depending on the availability of scientific data, technological advancements, and the intended purpose of these definitions, authors offered a diverse set of approaches to shape the perception and applications of the term "tornado outbreak." This paper reviews over 200 peer-reviewed publications-by decade-to outline the evolving nature of the "tornado outbreak" definition and to examine the changes in the "tornado outbreak" definition or its perception. A final discussion highlights the importance, limitations, and potential future evolution of what defines a "tornado outbreak."
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