Some wind and instability parameters associated with strong and violent tornadoes: 1. Wind shear and helicity

Davies, Jonathan M.; Johns, Robert H.

doi:10.1029/gm079p0573

Cited by 74 publications

(75 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The 0-6-km vertical shear and the storm-relative environmental helicity (SREH) are useful for distinguishing between environments supporting tornadic and nonsevere thunderstorms (Davies and Johns 1993;Rasmussen and Blanchard 1998;Craven et al 2002). The SREH depends on both the vertical shear and the estimated storm motion vector (SMV; computed following Bunkers et al 2000).…”

Section: The Effect Of Amplifying the Sp On Vertical Shear Parametersmentioning

confidence: 99%

Potential Vorticity Diagnosis of the Severe Convective Regime. Part III: The Hesston Tornado Outbreak

Gold

Nielsen‐Gammon

2008

Monthly Weather Review

View full text Add to dashboard Cite

Nonlinear balance potential vorticity (PV) inversion is used to diagnose the sensitivity of the severe convective parameter space to the amplitude of a subsynoptic-scale PV anomaly on 13 March 1990, a day on which a significant tornado outbreak impacted the Great Plains. PV surgery is used to both amplify and remove the PV anomaly, and the contemporaneous impact on various convective parameters is subsequently quantified by using piecewise PV inversion to compute the changes in those parameters attributable to each PV alteration. It is found that amplifying the anomaly increases the CAPE by amounts typically ranging from 20% to 30% within the atmospheric columns experiencing the maximum PV increase. Ascent is increased slightly downshear of the PV anomaly, consistent with extant conceptual models governing synoptic-scale forcing for vertical motion. Amplifying the PV anomaly increases deep-layer shear over the southern half of the outbreak region and reduces storm-relative helicity over the northern half, primarily through changes in the estimated storm motion vector. Removing the anomaly produces complementary changes of the opposite sign. Thresholds of several commonly used convective parameters are chosen on the basis of prior empirical studies, and the horizontal displacement of these threshold contours produced by the PV alterations reveals that relatively modest subsynoptic-scale PV changes would not likely change the predominant convective mode during the Hesston outbreak.

show abstract

Section: The Effect Of Amplifying the Sp On Vertical Shear Parametersmentioning

confidence: 99%

Potential Vorticity Diagnosis of the Severe Convective Regime. Part III: The Hesston Tornado Outbreak

Gold

Nielsen‐Gammon

2008

Monthly Weather Review

View full text Add to dashboard Cite

show abstract

“…Much more significant impacts on these two parameters were simulated by RSR02: BRNSHR and SREH reductions on the order of 20 m 2 s Ϫ2 and 95 m 2 s Ϫ2 , respectively, were found in the modeled environments. It is important to note that RSR02 used the storm-motion computation methodology of Davies and Johns (1993) while we use Bunkers et al (2000), possibly accounting for some of the difference in magnitude between their shear parameter reductions and those produced by the balanced diagnostics. Nonetheless, the current approach correctly diagnoses the sign of the change.…”

Section: Comparing the Diagnosed And Simulated Resultsmentioning

confidence: 99%

Potential Vorticity Diagnosis of the Severe Convective Regime. Part IV: Comparison with Modeling Simulations of the Moore Tornado Outbreak

Gold

Nielsen‐Gammon

2008

Monthly Weather Review

View full text Add to dashboard Cite

A potential vorticity (PV) diagnostic framework is used to explore the sensitivity of the 3 May 1999 Oklahoma City tornado outbreak to the strength of a particular PV anomaly proximate to the geographical region experiencing the tornado outbreak. The results derived from the balanced PV diagnosis agree broadly with those obtained previously in a numerical simulation of the same event, while offering additional insight into the nature of the sensitivity. Similar to the findings of other cases, the balanced diagnosis demonstrates that intensifying (removing) the PV anomaly of interest increases (decreases) the balanced CAPE over the southwestern portion of the outbreak region, reduces (increases) the storm-relative helicity, and increases (reduces) ascent. The latter finding, coupled with the results of the modeling study, demonstrates that intensifying a PV anomaly proximate to an outbreak environment can increase the likelihood that more widespread and possibly less tornadic convection will ensue. The overall results of the balanced diagnosis complement those of other case studies, leading to the formulation of a conceptual model that broadly anticipates how the convective regime will respond to changes in intensity of upper-tropospheric weather features.

show abstract

“…극단적인 값은 600 m 2 s (1) 여기서, h'는 자유 대류 고도 혹은 약 3 km 고도이며, 수평 속도 벡터(Horizontal Velocity Vector) V H 와 스톰 모션 벡터(Storm Motion Vector) V C 는 적분에 사용된 다. 수많은 연구에서 저층 SRH가 토네이도의 잠재성 을 나타내는 좋은 도구이며, 위험기상의 예측을 위한 중요한 예후 변수(Prognostic Variable)로서 활용 가능 함(e.g., Leftwich, 1990;Davies and Johns, 1993;Colquhoun and Riley, 1996;Kerr and Darkow, 1996;Rasmussen and Blanchard, 1998;Thompson et al, 2003Thompson et al, , 2007 …”

Section: )unclassified

Three-dimensional Analysis of Heavy Rainfall Using KLAPS Re-analysis Data

Jang¹,

You²,

Jee³

et al. 2016

Atmosphere

View full text Add to dashboard Cite

Some wind and instability parameters associated with strong and violent tornadoes: 1. Wind shear and helicity

Cited by 74 publications

References 10 publications

Potential Vorticity Diagnosis of the Severe Convective Regime. Part III: The Hesston Tornado Outbreak

Potential Vorticity Diagnosis of the Severe Convective Regime. Part III: The Hesston Tornado Outbreak

Potential Vorticity Diagnosis of the Severe Convective Regime. Part IV: Comparison with Modeling Simulations of the Moore Tornado Outbreak

Three-dimensional Analysis of Heavy Rainfall Using KLAPS Re-analysis Data

Contact Info

Product

Resources

About