NWS Tornado Warnings with Zero or Negative Lead Times

Brotzge, Jerald A.; Erickson, S.

doi:10.1175/2008waf2007076.1

Cited by 34 publications

(14 citation statements)

References 12 publications

(12 reference statements)

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“…Over an average year in the United States, there are ~1253 tornadoes (NCEI 2016), of which ~16% can be expected to produce a TDS (Van Den Broeke and Jauernic 2014). An average of 10% of tornadoes have negative or zero lead time (Brotzge and Erickson 2009), and ~25.5% of tornadoes were unwarned before the polarimetric upgrade (Brotzge and Erickson 2010). For simplicity, it could be assumed that these rates are the same for tornadoes that produce TDSs as for those that do not.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…In a large sample of events, it was found that tornado warnings are issued on average 13 min prior to tornadogenesis, though the public would like a longer average lead time (Hoekstra et al 2011). Warnings were issued with negative or zero lead time in ~10% of events in another study, with negative lead time most common for the first tornado of the day and on days with few tornadoes (Brotzge and Erickson 2009). Storm mode has also been shown to influence tornado warning lead time.…”

Section: Introductionmentioning

confidence: 96%

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Potential Tornado Warning Improvement Resulting from Utilization of the TDS in the Warning Decision Process

Broeke¹

2017

J. Operational Meteor.

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Polarimetric tornadic debris signatures (TDSs) provide a means of confirming that a strong wind field has lofted debris to the altitude of the radar beam. They can increase confidence in an ongoing tornado, which may be noted in tornado warning text to increase the sense of urgency. They may also serve as indicators of weak tornadoes that may otherwise go unwarned. Polarimetric data have been available since 2012 on a large portion of the U.S. Weather Surveillance Radar-1988 Doppler (WSR-88D) network and since May 2013 for the entire network. It is anticipated that use of the polarimetric TDS in the tornado warning process should evolve through time. Thus, this paper presents an overview of how the TDS was used in the warning process during the 16 months when widespread polarimetric data were first becoming available (February 2012-May 2013). During this period, 22.5% of tornado warning texts for TDS-producing events mentioned the TDS. It is estimated that utilization of the TDS in the warning decision process could result in ~45 previously unwarned tornadoes being warned annually, and in ~65 tornado warnings being issued with a less negative lead time.Examples are shown that demonstrate potential operational usefulness of the TDS. ABSTRACT (Manuscript

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Potential Tornado Warning Improvement Resulting from Utilization of the TDS in the Warning Decision Process

Broeke¹

2017

J. Operational Meteor.

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“…The warning lead time of a tornado is very small compared to other disaster warnings: sometimes, it is even zero or negative (Brotzge & Erickson, 2009). In Canada, a warning can be issued with a lead time of around ten minutes if the tornado is within the coverage of a Doppler radar installation (Meteorological Service of Canada, 2003).…”

Section: Tornado Propertiesmentioning

confidence: 99%

Tornado Mitigation in the Canadian Prairie Region

Prof.¹

2014

10th Annual Conference of the International Institute for Infrastructure Renewal and Reconstruction

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Tornadoes are a destructive form of the extreme weather associated with thunderstorms. Canada gets more tornadoes than any other country with the exception of the US. This paper presents some results of a study on tornado mitigation in the Canadian Prairie region. Initially, a regression-based analysis of the Prairie tornado database was conducted, and the trend for the number of tornadoes reported in each year is discussed in this paper. The detection, warning, communication, and evacuation stages at the pretouchdown phase of a tornado were analyzed and compared with the US system to recognize the key areas that need to be improved. The factors influencing the evacuation decisions of households and drivers are also discussed based on a stated preference survey. False warning and missed event data in the Prairies were also analyzed, and suggestions to improve the warning performance are provided. Based on the overall study, this paper makes recommendations to assist stakeholders in improving the existing system to detect, warn, and communicate tornado warnings to the public as well as improving their evacuation responses.

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“…While tornado fatalities occurred in North and South Dakota, Wyoming, Colorado, New Mexico, Maryland, and New Jersey, none of these was unwarned. Brotzge andErickson (2009, 2010) suggest that the first tornado of the day and tornadoes as part of an …”

Section: Spatial Distribution Of Warnings and Fatalitiesmentioning

confidence: 99%

“…Of the unwarned fatalities that were not isolated and/or the first tornado of the day, 71.8% occurred in the 1985-95 period prior to NWS modernization in the mid-1990s. While isolated tornadoes and the first tornado of the day may have a greater likelihood of having zero or negative lead time or no warning (Brotzge andErickson 2009, 2010), they only account for about half of unwarned tornado fatalities. The remaining unwarned tornado fatalities are due to tornadoes beyond the first of the day and/or on days with seven or more tornadoes.…”

Section: Spatial Distribution Of Warnings and Fatalitiesmentioning

confidence: 99%

The Relationship between Tornadic and Nontornadic Convective Wind Fatalities and Warnings

Black

Ashley

2011

Weather, Climate, and Society

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A database of tornado fatalities, nontornadic convective wind fatalities, severe thunderstorm warnings, and tornado warnings was compiled for the period 1986-2007 to assess the spatial and temporal distribution of warned and unwarned fatalities. The time of fatality and location as reported in Storm Data was compared to tornado and severe thunderstorm warnings to determine if a warning was in effect when the fatality occurred. Overall, 23.7% of tornado fatalities were unwarned, while 53.2% of nontornadic convective wind fatalities were unwarned. Most unwarned tornado fatalities occurred prior to the mid-1990s-coinciding with modernization of the National Weather Service-while unwarned nontornadic convective wind fatalities remained at a relatively elevated frequency throughout the study period. Geographic locations with high numbers of unwarned tornado and nontornadic convective wind fatalities were associated with one high-magnitude event that was unwarned rather than a series of smaller unwarned events over the period. There are many factors that contribute to warning response by the public, and the issuance of a severe thunderstorm or tornado warning is an important initial step in the warning process. A better understanding of the characteristics of warned and unwarned fatalities is important to future reduction of unwarned fatalities.

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NWS Tornado Warnings with Zero or Negative Lead Times

Cited by 34 publications

References 12 publications

Potential Tornado Warning Improvement Resulting from Utilization of the TDS in the Warning Decision Process

Potential Tornado Warning Improvement Resulting from Utilization of the TDS in the Warning Decision Process

Tornado Mitigation in the Canadian Prairie Region

The Relationship between Tornadic and Nontornadic Convective Wind Fatalities and Warnings

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