Genesis of the Goshen County, Wyoming, Tornado on 5 June 2009 during VORTEX2

Kosiba, Karen; Wurman, Joshua; Richardson, Yvette; Markowski, Paul; Robinson, P.; Marquis, James

doi:10.1175/mwr-d-12-00056.1

Cited by 99 publications

(74 citation statements)

References 58 publications

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“…4 and 5) emanating from intense downdrafts. The leading edges of these horizontal momentum surges are often referred to as secondary rear-flank gust fronts (SRFGF), which are known to accompany the intensification of nearground vertical vorticity also in observed storms (Marquis et al 2008;Kosiba et al 2013). Adlerman et al (1999) also identified outflow trajectories in their Del City simulation (in addition to trajectories originating east of the rear-flank gust front, which were considered error prone; see also Dahl et al 2012).…”

Section: Discussionmentioning

confidence: 99%

“…The development of rotation at ground level, 1 on the other hand, cannot be achieved by mere upward tilting of initially horizontal vortex lines, but a downdraft is required, as discussed by Davies-Jones (1982), DaviesJones and Brooks (1993), Walko (1993), Markowski and Richardson (2010), and Davies-Jones and Markowski (2013). The reason is that an initially horizontal nearground vortex line is lifted away from the surface as it is reoriented into the vertical at the updraft edge.…”

Section: Introductionmentioning

confidence: 99%

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Imported and Storm-Generated Near-Ground Vertical Vorticity in a Simulated Supercell*

Dahl

Parker

Wicker

2014

Journal of the Atmospheric Sciences

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The authors use a high-resolution supercell simulation to investigate the source of near-ground vertical vorticity by decomposing the vorticity vector into barotropic and nonbarotropic parts. This way, the roles of ambient and storm-generated vorticity can be isolated. A new Lagrangian technique is employed in which material fluid volume elements are tracked to analyze the rearrangement of ambient vortex-line segments. This contribution is interpreted as barotropic vorticity. The storm-generated vorticity is treated as the residual between the known total vorticity and the barotropic vorticity.In the simulation the development of near-ground vertical vorticity is an outflow phenomenon. There are distinct ''rivers'' of cyclonic shear vorticity originating from the base of downdrafts that feed into the developing near-ground vortex. The origin of these rivers of vertical vorticity is primarily horizontal baroclinic production, which is maximized in the lowest few hundred meters AGL. Subsequently, this horizontal vorticity is tilted upward while the parcels are still descending. The barotropic vorticity remains mostly streamwise along the analyzed trajectories and does not acquire a large vertical component as the parcels reach the ground. Thus, the ambient vorticity that is imported into the storm contributes only a small fraction of the total near-ground vertical vorticity.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Imported and Storm-Generated Near-Ground Vertical Vorticity in a Simulated Supercell*

Dahl

Parker

Wicker

2014

Journal of the Atmospheric Sciences

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“…Enhancement of convergence by rearflank downdrafts or internal cold-pool air surges within tornadic supercells has been documented by radar observational studies (e.g., Lemon and Doswell 1979;Marquis et al 2008;Lee et al 2012). Tornadogenesis and tornado maintenance have also been found in close relationship with intensifying downdrafts (Marquis et al 2012;Kosiba et al 2013).…”

Section: Downdrafts and MV Developmentmentioning

confidence: 94%

The Genesis of Mesovortices within a Real-Data Simulation of a Bow Echo System

Xue

Wang

2015

Journal of the Atmospheric Sciences

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The genesis of two mesovortices (MVs) within a real-data, convection-resolving simulation of the 8 May 2009 central U.S. bow echo system is studied. Both MVs form near the bow apex but differ distinctively in intensity, lifetime, and damage potential. The stronger and longer-lived mesovortex, MVa, stays near the bow apex where the system-scale rear-inflow jet (RIJ) is present. The descending RIJ produces strong downdrafts and surface convergence, which in turn induce strong vertical stretching and intensification of MVa into an intense mesovortex. In contrast, the weaker and shorter-lived mesovortex, MVb, gradually moves away from the bow apex, accompanied by localized convective-scale downdrafts.Lagrangian circulation and vorticity budget analyses reveal that the vertical vorticity of MVs in general originate from the tilting of near-surface horizontal vorticity, which is mainly created via surface friction. The circulation of the material circuit that ends up to be a horizontal circuit at the foot of the MVs increases as the frictionally generated horizontal vortex tubes pass through the tilted material circuit (tilted following backward trajectories defining the material circuit) surface, especially in the final few minutes prior to mesovortex genesis. The tilted material circuit becomes horizontal at the MV foot, turning associated horizontal vorticity into vertical. The results show at least qualitatively that, in addition to baroclinicity, surface friction can also have significant contributions to the generation of low-level MVs, which was not considered in previous MV studies.

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“…In the other two cases, an EF2 tornado on 5 June 2009 in Goshen County, Wyoming (e.g., Wakimoto et al 2011Wakimoto et al , 2012Markowski et al 2012a,b;Atkins et al 2012;Wurman et al 2013;Kosiba et al 2013;French et al 2013French et al , 2014, and an EF1 tornado on 19 May 2010 near FIG. 10.…”

Section: February 2015mentioning

confidence: 97%

Bulk Hook Echo Raindrop Sizes Retrieved Using Mobile, Polarimetric Doppler Radar Observations

French

Burgess

Mansell

et al. 2015

Journal of Applied Meteorology and Climatology

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Polarimetric radar observations obtained by the NOAA/National Severe Storms Laboratory mobile, X-band, dual-polarization radar (NOXP) are used to investigate ''hook echo'' precipitation properties in several tornadic and nontornadic supercells. Hook echo drop size distributions (DSDs) were estimated using NOXP data obtained from 2009 to 2012, including during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2). Differences between tornadic and nontornadic hook echo DSDs are explored, and comparisons are made with previous observations of estimated hook echo DSDs made from stationary S-and C-band Doppler radars. Tornadic hook echoes consistently contain radar gates that are characterized by small raindrops; nontornadic hook echoes are mixed between those that have some smalldrop gates and those that have almost no small-drop gates. In addition, the spatial distribution of DSDs was estimated using the high-spatial-resolution data afforded by NOXP. A unique polarimetric signature, an area of relatively low values of differential radar reflectivity factor Z DR south and east of the tornado, is observed in many of the tornadic cases. Also, because most data were obtained using 2-min volumetric updates, the evolution of approximated hook echo precipitation properties was studied during parts of the life cycles of three tornadoes. In one case, there is a large decrease in the percentage of large-raindrop gates and an increase in the percentage of small-raindrop gates in the minutes leading up to tornado formation. The percentage of large-drop gates generally increases prior to and during tornado dissipation. Near-storm environmental data are used to put forth possible relationships between bulk hook echo DSDs and tornado production and life cycle.

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Genesis of the Goshen County, Wyoming, Tornado on 5 June 2009 during VORTEX2

Cited by 99 publications

References 58 publications

Imported and Storm-Generated Near-Ground Vertical Vorticity in a Simulated Supercell*

Imported and Storm-Generated Near-Ground Vertical Vorticity in a Simulated Supercell*

The Genesis of Mesovortices within a Real-Data Simulation of a Bow Echo System

Bulk Hook Echo Raindrop Sizes Retrieved Using Mobile, Polarimetric Doppler Radar Observations

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