Finescale Radar Observations of Tornado and Mesocyclone Structures

Wurman, Joshua; Kosiba, Karen

doi:10.1175/waf-d-12-00127.1

Cited by 74 publications

(34 citation statements)

References 52 publications

(20 reference statements)

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“…The calculated best fit parameters were V 0 = 22 m s −1 , R 0 = 40 m, and α = 0.6 in the forward sector, and V 0 = 20 m s −1 , R 0 = 20 m, and α = 0.4 in the rearward sector (Table ). The magnitude of V 0 marginally satisfied a proposed definition of tornado strength, i.e., velocity difference across the vortex 2 V 0 > 40 m s −1 [ Wurman and Kosiba , ], and was similar to the strength of a tornado reported by Kosiba et al . [].…”

Section: Near‐surface Structure Of a Tornadic Vortex Observed By Lawpssupporting

confidence: 82%

Analysis of the horizontal two‐dimensional near‐surface structure of a winter tornadic vortex using high‐resolution in situ wind and pressure measurements

Kato

Kusunoki²,

Satô³

et al. 2015

JGR Atmospheres

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The horizontal two-dimensional near-surface structure of a tornadic vortex within a winter storm was analyzed. The tornadic vortex was observed on 10 December 2012 by the high-resolution in situ observational linear array of wind and pressure sensors (LAWPS) system in conjunction with a high-resolution Doppler radar. The 0.1 s maximum wind speed and pressure deficit near the ground were recorded as 35.3 m s À1 and À3.8 hPa, respectively. The horizontal two-dimensional distributions of the tornadic vortex wind and pressure were retrieved by the LAWPS data, which provided unprecedented observational detail on the following important features of the near-surface structure of the tornadic vortex. Asymmetric convergent inflow toward the vortex center existed. Total wind speed was strong to the right and rear side of the translational direction of the vortex and weak in the forward part of the vortex possibly because of the strong convergent inflow in that region. The tangential wind speed profile of the vortex was better approximated using a modified Rankine vortex rather than the Rankine vortex both at 5 m above ground level (agl) and 100 m agl, and other vortex models (Burgers-Rott vortex and Wood-White vortex) were also compared. The cyclostrophic wind balance was violated in the core radius R 0 and outside the core radius in the forward sector; however, it was held with a relatively high accuracy of approximately 14% outside the core of the vortex in the rearward sector (from 2 R 0 to 5 R 0 ) near the ground.

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Section: Near‐surface Structure Of a Tornadic Vortex Observed By Lawpssupporting

confidence: 82%

Analysis of the horizontal two‐dimensional near‐surface structure of a winter tornadic vortex using high‐resolution in situ wind and pressure measurements

Kato

Kusunoki²,

Satô³

et al. 2015

JGR Atmospheres

View full text Add to dashboard Cite

show abstract

“…reported in previous studies (e.g., Bluestein et al 2007;Tanamachi et al 2012;Wurman and Kosiba 2013), and contain several of the prominent features reported in those studies, including the weak-echo notch, and a region of relatively low reflectivity within the tornadic circulation itself.…”

Section: B Structure Of Intense Tornadoes In the Modelsupporting

confidence: 66%

“…7a), and local maxima in the updraft, vertical vorticity, and horizontal wind fields (Figs. 7b-d)-similar satellite vortices (in terms of relative positioning and scale) have been observed via radar in prior observational studies (e.g., Wurman and Kosiba 2013).…”

Section: B Structure Of Intense Tornadoes In the Modelsupporting

confidence: 58%

Tornado-Resolving Ensemble and Probabilistic Predictions of the 20 May 2013 Newcastle–Moore EF5 Tornado

Snook

Xue

Jung

2019

Monthly Weather Review

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An ensemble of 10 forecasts is produced for the 20 May 2013 Newcastle–Moore EF5 tornado and its parent supercell using a horizontal grid spacing of 50 m, nested within ensemble forecasts with 500-m horizontal grid spacing initialized via ensemble Kalman filter data assimilation of surface and radar observations. Tornadic circulations are predicted in all members, though the intensity, track, and longevity of the predicted tornado vary substantially among members. Overall, tornadoes in the ensemble forecasts persisted longer and moved to the northeast faster than the observed tornado. In total, 8 of the 10 ensemble members produce tornadoes with winds corresponding to EF2 intensity or greater, with maximum instantaneous near-surface horizontal wind speeds of up to 130 m s−1 and pressure drops of up to 120 hPa; values similar to those reported in observational studies of intense tornadoes. The predicted intense tornadoes all acquire well-defined two-cell vortex structure, and exhibit features common in observed tornadic storms, including a weak-echo notch and low reflectivity within the mesocyclone. Ensemble-based probabilistic tornado forecasts based upon near-surface wind and/or vorticity fields at 10 m above the surface produce skillful forecasts of the tornado in terms of area under the relative operating characteristic curve, with probability swaths extending along and to the northeast of the observed tornado path. When probabilistic swaths of 0–3- and 2–5-km updraft helicity are compared to the swath of wind at 10 m above the surface exceeding 29 m s−1, a slight northwestward bias is present, although the pathlength, orientation, and the placement of minima and maxima show very strong agreement.

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“…Because surface wind damage is frequently caused by microbursts and tornadoes, whose wind speeds attain maximum values at around 200 m AGL and decrease with altitude (Wilson et al 1984;Wurman and Kosiba 2013), it is important to monitor the wind field at altitudes that are as low as possible. Therefore, the error factors of WS PPI-VAR and WS CAPPI-VAR at the lowest level (500 m AGL) are discussed in detail.…”

Section: Resultsmentioning

confidence: 99%

Impact of Observation Operators on Low-Level Wind Speed Retrieved by Variational Multiple-Doppler Analysis

Shimose

Shimizu

Maesaka

et al. 2016

SOLA

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This study investigated the impact of observation operators on low-level wind speed analysis. An evaluation of wind speeds retrieved by variational multiple-Doppler analyses using radial velocities (V r ) based on the formats of both a Plan Position Indicator (PPI) (hereafter, PPI-VAR) and a Constant Altitude Plan Position Indicator (CAPPI) (hereafter, CAPPI-VAR) was performed for comparison with wind speeds observed by a wind profiler during the warm season of three consecutive years. The statistical analysis showed that PPI-VAR was more accurate than CAPPI-VAR at 500 m above ground level (AGL). The error of CAPPI-VAR at 500 m AGL was caused by a representative error of CAPPI-formatted V r derived from a certain radar whose beam height was far from the analysis level, and this error became more obvious the greater the vertical difference in wind speed across the analysis level. CAPPI-VAR uses CAPPI-formatted V r from each radar equally; thus, the representative error might cause performance degradation of CAPPI-VAR at 500 m AGL. Conversely, PPI-VAR uses PPI-formatted V r from each radar with appropriate weighting based on the beam height distance from the analysis level. PPI-VAR showed better results at 500 m AGL because the observation grid points were dense around 500 m AGL.

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Finescale Radar Observations of Tornado and Mesocyclone Structures

Cited by 74 publications

References 52 publications

Analysis of the horizontal two‐dimensional near‐surface structure of a winter tornadic vortex using high‐resolution in situ wind and pressure measurements

Analysis of the horizontal two‐dimensional near‐surface structure of a winter tornadic vortex using high‐resolution in situ wind and pressure measurements

Tornado-Resolving Ensemble and Probabilistic Predictions of the 20 May 2013 Newcastle–Moore EF5 Tornado

Impact of Observation Operators on Low-Level Wind Speed Retrieved by Variational Multiple-Doppler Analysis

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