Tornado detection and warning by radar

Burgess, Donald W.; Donaldson, Ralph J.; Desrochers, Paul R.

doi:10.1029/gm079p0203

Cited by 39 publications

(8 citation statements)

References 22 publications

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“…More recently, a large waterspout in the outer rainbands of Hurricane Wilma (2005) was photographed near Key West (http://www.srh.noaa.gov/ key/HTML/wilma/wilma.html). A Doppler radar cannot observe a tornado or waterspout directly unless it is within several kilometers of the radar, but parent mesocyclones can be detected to identify potential tornadic activity [Burgess et al, 1993]. Statistically, only 26% of Great Plains mesocyclones produce tornadoes [Trapp et al, 2005].…”

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confidence: 99%

Supercells and mesocyclones in outer rainbands of Hurricane Katrina (2005)

Lee

Bell

Goodman

2008

Geophysical Research Letters

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[1] This study documents and describes supercells embedded within the outer rainbands of Hurricane Katrina (2005). Radar reflectivity and velocity data collected on 29 August 2005 by Weather Surveillance Radar 1988 Doppler radars were used to track the supercells. Radar analysis indicates that the supercells were characterized by heavy precipitation collocated with band-relative mesocylonic circulations containing strong vorticity and a wind speed enhancement to their northeast. Atmospheric soundings and dual-Doppler derived shear suggest that environmental conditions were comparable to those in previous hurricane-spawned supercell studies. Twenty-three storms from 0300-0900 UTC were tracked, and single-and dual-Doppler radar analyses were used to examine characteristics such as shear and rotational velocity. Remarkably, the majority of the supercells formed over the Gulf of Mexico rather than over land, which contrasts with previous studies. Furthermore, the ground-relative wind speeds of these potentially tornadic mesocyclones in the outer rainbands could have been Category 4 intensity despite sustained winds in Katrina's eyewall only reaching Category 3 at landfall.

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confidence: 99%

Supercells and mesocyclones in outer rainbands of Hurricane Katrina (2005)

Lee

Bell

Goodman

2008

Geophysical Research Letters

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“…Following standardized procedures, our analysis adjusts V d for the effects of coarse spatial sampling and inferred unobserved V gmax due to V p . V d are corrected for aspect ratio sampling error, ( 39 , 41 , 51 , 72 ) by multiplying by 1/(1−0.48(B/X d )). This adjustment is capped at 1.086, equivalent to what would be applied for B/X d > 6, to arrive at a temporary product, adjusted velocity, V da .…”

Section: Methodsmentioning

confidence: 99%

Supercell tornadoes are much stronger and wider than damage-based ratings indicate

Wurman

Kosiba

White

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Tornadoes cause damage, injury, and death when intense winds impact structures. Quantifying the strength and extent of such winds is critical to characterizing tornado hazards. Ratings of intensity and size are based nearly entirely on postevent damage surveys [R. Edwards et al., Bull. Am. Meteorol. Soc. 94, 641–653 (2013)]. It has long been suspected that these suffer low bias [C. A. Doswell, D. W. Burgess, Mon. Weather Rev. 116, 495–501 (1988)]. Here, using mapping of low-level tornado winds in 120 tornadoes, we prove that supercell tornadoes are typically much stronger and wider than damage surveys indicate. Our results permit an accurate assessment of the distribution of tornado intensities and sizes and tornado wind hazards, based on actual wind-speed observations, and meaningful comparisons of the distribution of tornado intensities and sizes with theoretical predictions. We analyze data from Doppler On Wheels (DOW) radar measurements of 120 tornadoes at the time of peak measured intensity. In striking contrast to conventional damage-based climatologies, median tornado peak wind speeds are ∼60 m⋅s−1, capable of causing significant, Enhanced Fujita Scale (EF)-2 to -3, damage, and 20% are capable of the most intense EF-4/EF-5 damage. National Weather Service (NWS) EF/wind speed ratings are 1.2 to 1.5 categories (∼20 m⋅s−1) lower than DOW observations for tornadoes documented by both the NWS and DOWs. Median tornado diameter is 250 to 500 m, with 10 to 15% >1 km. Wind engineering tornado-hazard-model predictions and building wind resistance standards may require upward adjustment due to the increased wind-damage risk documented here.

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“…A significant problem demonstrated by the emulator is the impact of velocity aliasing at X band on the potential diagnosis of the circulations. Correct dealiasing is crucial to tornado detection when the detection algorithm mainly relies on the radial velocity data (e.g., Burgess et al 1993;Liu et al 2007). Any method that can increase the effective Nyquist velocity, such as the use of staggered PRT (Gray et al 1989), would likely be helpful.…”

Section: Resultsmentioning

confidence: 99%

A Doppler Radar Emulator with an Application to the Detectability of Tornadic Signatures

May

Biggerstaff

Xue

2007

Journal of Atmospheric and Oceanic Technology

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A Doppler radar emulator was developed to simulate the expected mean returns from scanning radar, including pulse-to-pulse variability associated with changes in viewing angle and atmospheric structure. Based on the user's configuration, the emulator samples the numerical simulation output to produce simulated returned power, equivalent radar reflectivity, Doppler velocity, and Doppler spectrum width. The emulator is used to evaluate the impact of azimuthal over-and undersampling, gate spacing, velocity and range aliasing, antenna beamwidth and sidelobes, nonstandard (anomalous) pulse propagation, and wavelength-dependent Rayleigh attenuation on features of interest.As an example, the emulator is used to evaluate the detection of the circulation associated with a tornado simulated within a supercell thunderstorm by the Advanced Regional Prediction System (ARPS). Several metrics for tornado intensity are examined, including peak Doppler velocity and axisymmetric vorticity, to determine the degradation of the tornadic signature as a function of range and azimuthal sampling intervals. For the case of a 2°half-power beamwidth radar, like those deployed in the first integrated project of the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA), the detection of the cyclonic shear associated with this simulated tornado will be difficult beyond the 10-km range, if standard metrics such as azimuthal gate-to-gate shear from a single radar are used for detection.

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Tornado detection and warning by radar

Cited by 39 publications

References 22 publications

Supercells and mesocyclones in outer rainbands of Hurricane Katrina (2005)

Supercells and mesocyclones in outer rainbands of Hurricane Katrina (2005)

Supercell tornadoes are much stronger and wider than damage-based ratings indicate

A Doppler Radar Emulator with an Application to the Detectability of Tornadic Signatures

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