Relationship of Tornado Deaths to Severe Weather Watch Areas

Galway, Joseph G.

doi:10.1175/1520-0493(1975)103<0737:rotdts>2.0.co;2

Cited by 44 publications

(21 citation statements)

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“…This 24-h criterion was employed because tornado outbreak days imply organization and influence by synoptic-scale atmospheric conditions that can in turn be influenced by larger, more global-scale atmospheric components. This outbreak criterion was alluded to and utilized in previous studies of tornado outbreaks (Pautz 1969;Galway 1975Galway , 1977Brooks et al 2003;Schneider et al 2004;Doswell et al 2006). January to March periods of tornado day activity were an initial focus of the study, although April tornado days were included to examine several damaging, historic outbreaks (e.g., 11 April 1965 Palm Sunday outbreak; 3 April 1974 Super Outbreak) while also assessing continued teleconnections between El Niño-La Niña and atmospheric patterns in the United States beyond boreal winter.…”

Section: A Physical Tornado Climatologymentioning

confidence: 99%

The Impact of El Niño–Southern Oscillation (ENSO) on Winter and Early Spring U.S. Tornado Outbreaks

Cook

Leslie

Parsons

et al. 2017

Journal of Applied Meteorology and Climatology

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In recent years, the potential of seasonal outlooks for tornadoes has attracted the attention of researchers. Previous studies on this topic have focused mainly on the influence of global circulation patterns [e.g., El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation, or Pacific decadal oscillation] on spring tornadoes. However, these studies have yielded conflicting results of the roles of these climate drivers on tornado intensity and frequency. The present study seeks to establish linkages between ENSO and tornado outbreaks over the United States during winter and early spring. These linkages are established in two ways: 1) statistically, by relating raw counts of tornadoes in outbreaks (defined as six or more tornadoes in a 24-h period in the United States east of the Rocky Mountains), and their destructive potential, to sea surface temperature anomalies observed in the Niño-3.4 region, and 2) qualitatively, by relating ENSO to shifts in synoptic-scale atmospheric phenomena that contribute to tornado outbreaks. The latter approach is critical for interpreting the statistical relationships, thereby avoiding the deficiencies in a few of the previous studies that did not provide physical explanations relating ENSO to shifts in tornado activity. The results suggest that shifts in tornado occurrence are clearly related to ENSO. In particular, La Niña conditions consistently foster more frequent and intense tornado activity in comparison with El Niño, particularly at higher latitudes. Furthermore, it is found that tornado activity changes are tied not only to the location and intensity of the subtropical jet during individual outbreaks but also to the positions of surface cyclones, low-level jet streams, and instability axes.

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Section: A Physical Tornado Climatologymentioning

confidence: 99%

The Impact of El Niño–Southern Oscillation (ENSO) on Winter and Early Spring U.S. Tornado Outbreaks

Cook

Leslie

Parsons

et al. 2017

Journal of Applied Meteorology and Climatology

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“…Early studies of individual outbreak types (Carr 1952;Pautz 1969;Galway 1975Galway , 1977Grazulis 1993, among others) provide a baseline for the work in D06, which, in turn, serves as a point of departure for the current study. D06 provides a ranking of TOs and NTOs using severe weather report occurrence data from the Storm Prediction Center [see Schaefer and Edwards (1999) for a review of that database], based on multiple weighted parameters associated with each outbreak type.…”

Section: Introductionmentioning

confidence: 99%

Synoptic Composites of Tornadic and Nontornadic Outbreaks

Mercer¹,

Shafer²,

Doswell³

et al. 2011

Mon. Wea. Rev.

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Tornadic and nontornadic outbreaks occur within the United States and elsewhere around the world each year with devastating effect. However, few studies have considered the physical differences between these two outbreak types. To address this issue, synoptic-scale pattern composites of tornadic and nontornadic outbreaks are formulated over North America using a rotated principal component analysis (RPCA). A cluster analysis of the RPC loadings group similar outbreak events, and the resulting map types represent an idealized composite of the constituent cases in each cluster. These composites are used to initialize a Weather Research and Forecasting Model (WRF) simulation of each hypothetical composite outbreak type in an effort to determine the WRF's capability to distinguish the outbreak type each composite represents.Synoptic-scale pattern analyses of the composites reveal strikingly different characteristics within each outbreak type, particularly in the wind fields. The tornado outbreak composites reveal a strong low-and midlevel cyclone over the eastern Rockies, which is likely responsible for the observed surface low pressure system in the plains. Composite soundings from the hypothetical outbreak centroids reveal significantly greater bulk shear and storm-relative environmental helicity values in the tornado outbreak environment, whereas instability fields are similar between the two outbreak types. The WRF simulations of the map types confirm results observed in the composite soundings.

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“…Most efforts to define tornado outbreaks focus on the numbers of tornadoes, but these numbers often vary from study to study (e.g., Pautz 1969;Galway 1975Galway , 1977Grazulis 1993). Recently, D06 proposed a new methodology that, instead of defining tornado outbreaks formally, ranked these events in terms of meteorological significance and societal impact.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of WRF Forecasts of Tornadic and Nontornadic Outbreaks When Initialized with Synoptic-Scale Input

Shafer

Mercer

Doswell

et al. 2009

Monthly Weather Review

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Uncertainty exists concerning the links between synoptic-scale processes and tornado outbreaks. With continuously improving computer technology, a large number of high-resolution model simulations can be conducted to study these outbreaks to the storm scale, to determine the degree to which synoptic-scale processes appear to influence the occurrence of tornado outbreaks, and to determine how far in advance these processes are important. To this end, 50 tornado outbreak simulations are compared with 50 primarily nontornadic outbreak simulations initialized with synoptic-scale input using the Weather Research and Forecasting (WRF) mesoscale model to determine if the model is able to distinguish the outbreak type 1, 2, and 3 days in advance of the event. The model simulations cannot resolve tornadoes explicitly; thus, the use of meteorological covariates (in the form of numerous severe-weather parameters) is necessary to determine whether or not the model is predicting a tornado outbreak. Results indicate that, using the covariates, the WRF model can discriminate outbreak type consistently at least up to 3 days in advance. The severe-weather parameters that are most helpful in discriminating between outbreak types include low-level and deep-layer shear variables and the lifting condensation level. An analysis of the spatial structures and temporal evolution, as well as the magnitudes, of the severe-weather parameters is critical to diagnose the outbreak type correctly. Thermodynamic instability parameters are not helpful in distinguishing the outbreak type, primarily because of a strong seasonal dependence and convective modification in the simulations.

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Relationship of Tornado Deaths to Severe Weather Watch Areas

Cited by 44 publications

References 0 publications

The Impact of El Niño–Southern Oscillation (ENSO) on Winter and Early Spring U.S. Tornado Outbreaks

The Impact of El Niño–Southern Oscillation (ENSO) on Winter and Early Spring U.S. Tornado Outbreaks

Synoptic Composites of Tornadic and Nontornadic Outbreaks

Evaluation of WRF Forecasts of Tornadic and Nontornadic Outbreaks When Initialized with Synoptic-Scale Input

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