WSR-88D Tornado Intensity Estimates. Part II: Real-Time Applications to Tornado Warning Timescales

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  • 1 NOAA/NWS/NCEP/Storm Prediction Center, Norman, OK
  • 2 NOAA/NWS/NCEP/Storm Prediction Center, Norman, OK
  • 3 NOAA/NWS/Weather Forecast Office, Norman, OK
  • 4 NOAA/NWS/NCEP/Storm Prediction Center, Norman, OK
  • 5 NOAA/NWS/NCEP/Storm Prediction Center, Norman, OK
  • 6 Cooperative Institute for Mesoscale Meteorological Studies/University of Oklahoma, Norman, OK
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Abstract

A sample of damage-surveyed tornadoes in the contiguous United States (2009–2017), containing specific wind-speed estimates from damage indicators (DIs) within the Damage Assessment Toolkit dataset, were linked to radar-observed circulations using the nearest WSR-88D data in Part I of this work. The maximum wind speed associated with the highest-rated DI for each radar scan, corresponding 0.5° tilt angle rotational velocity (Vrot), significant tornado parameter (STP), and National Weather Service (NWS) convective impact-based warning (IBW) type, are analyzed herein for the sample of cases in Part I and an independent case sample from parts of 2019–2020.

As Vrot, and STP both increase, peak DI-estimated wind speeds and IBW warning type also tend to increase. Different combinations of Vrot, STP, and population density —related to ranges of peak DI wind speed— exhibited a strong ability to discriminate across the tornado damage intensity spectrum. Furthermore, longer duration of high Vrot (i.e., ≥ 70 kt) in significant tornado environments (i.e., STP ≥ 6) corresponds to increasing chances that DIs will reveal the occurrence of an intense tornado (i.e., EF3+). These findings were corroborated via the independent sample from parts of 2019–2020, and can be applied in a real-time operational setting to assist in determining a potential range of wind speeds. This work provides evidence-based support for creating an objective and consistent, real-time framework for assessing and differentiating tornadoes across the tornado intensity spectrum.

Corresponding Author: Bryan T. Smith, Email: bryan.smith@noaa.gov, Phone: 405-325-2040, Address: 120 David L. Boren Blvd., Suite 2300, Norman, OK 73072

Abstract

A sample of damage-surveyed tornadoes in the contiguous United States (2009–2017), containing specific wind-speed estimates from damage indicators (DIs) within the Damage Assessment Toolkit dataset, were linked to radar-observed circulations using the nearest WSR-88D data in Part I of this work. The maximum wind speed associated with the highest-rated DI for each radar scan, corresponding 0.5° tilt angle rotational velocity (Vrot), significant tornado parameter (STP), and National Weather Service (NWS) convective impact-based warning (IBW) type, are analyzed herein for the sample of cases in Part I and an independent case sample from parts of 2019–2020.

As Vrot, and STP both increase, peak DI-estimated wind speeds and IBW warning type also tend to increase. Different combinations of Vrot, STP, and population density —related to ranges of peak DI wind speed— exhibited a strong ability to discriminate across the tornado damage intensity spectrum. Furthermore, longer duration of high Vrot (i.e., ≥ 70 kt) in significant tornado environments (i.e., STP ≥ 6) corresponds to increasing chances that DIs will reveal the occurrence of an intense tornado (i.e., EF3+). These findings were corroborated via the independent sample from parts of 2019–2020, and can be applied in a real-time operational setting to assist in determining a potential range of wind speeds. This work provides evidence-based support for creating an objective and consistent, real-time framework for assessing and differentiating tornadoes across the tornado intensity spectrum.

Corresponding Author: Bryan T. Smith, Email: bryan.smith@noaa.gov, Phone: 405-325-2040, Address: 120 David L. Boren Blvd., Suite 2300, Norman, OK 73072
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