Environment and Early Evolution of the 8 May 2009 Derecho-Producing Convective System

Coniglio, Michael C.; Corfidi, Stephen F.; Kain, John S.

doi:10.1175/2010mwr3413.1

Cited by 52 publications

(18 citation statements)

References 53 publications

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“…1a). This large bowing system maintained for a couple of hours until about 1800 UTC, during which a number of tornadoes of up to EF-3 intensity on the enhanced Fujita scale (Doswell et al 2009) and intense derechoes were produced Coniglio et al 2011). A warm-core MCV formed at the northern end of the bow echo, and detailed discussions on this meso-b-scale feature and its role in producing severe surface winds can be found in Weisman et al (2013) and Evans et al (2014).…”

Section: A Case Overviewmentioning

confidence: 92%

“…The mesoscale convective system of interest initially developed from scattered thunderstorms over northeastern Colorado around 0300 UTC on 8 May 2009 (2100 CST on 7 May 2009), which was accompanied by weak synopticscale forcing and limited thermodynamic instability within the environment (Coniglio et al 2011). The initial storms moved southeastward and organized into an MCS in western Kansas by 0700 UTC.…”

Section: A Case Overviewmentioning

confidence: 99%

“…Environmental conditions and the evolution of the bowing system and associated mesoscale convective vortex (MCV) were investigated by Coniglio et al (2011) andWeisman et al (2013). Based upon Doppler radar observations, Xu et al (2015, hereafter XXW15) documented the existence and general behaviors of low-level MVs in this bow echo system.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: A Case Overviewmentioning

confidence: 92%

Section: A Case Overviewmentioning

confidence: 99%

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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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“…These phenomena illustrated the surge of cold pool during the SL‐CC merger in this MFBE event was the result of local cooling from the evaporation of intensified precipitation ahead of the SL, not the mechanism that two existing cold pools of different convective systems merged and formed one deeper cold pool (French & Parker, 2014). Previous studies (e.g., Coniglio et al, 2011; James & Markowski, 2010; Richter et al, 2014) pointed out that the precipitation could potentially strengthen the downdraft and surface cold pool, therefore induced the damaging winds. Though the downdraft area at 0.15 km AGL did expand during the merger (Figures 8e–8h), this downdraft was too weak to produce damaging surface winds.…”

Section: The Surge Of Cold Pool and Redevelopment Of Rijmentioning

confidence: 99%

VDRAS and Polarimetric Radar Investigation of a Bow Echo Formation After a Squall Line Merged With a Preline Convective Cell

et al. 2020

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This paper is the first to document the development of a type of bow echo, termed merger‐formation bow echo (MFBE), in southeast China evolving from a subtropical squall line (SL) merging with a preline convective cell (CC). Although this MFBE did not produce damaging surface winds, its intense rain rate resulted in local flooding. The evolution of the kinematic, thermodynamic, and microphysical structures is investigated using the variational Doppler radar analysis system (VDRAS) analysis and polarimetric radar observations. Key factors of this MFBE event including the rear‐inflow jet (RIJ) and cold pool exhibited different characteristics from those in classical bow echoes and limited MFBE cases. As the SL propagated towards the coast, a CC was triggered along a sea breeze front. The SL did possess a RIJ, but a bow‐shaped reflectivity did not appear until the SL‐CC merger. The RIJ weakened and became elevated during the merger, while the leading edge of SL cold pool accompanied by a weak diverging outflow did not advance with the reflectivity field. The updraft was strengthened due to the merger, resulting in enhanced precipitation falling ahead of the original SL. The subcloud evaporation locally cooled the air ahead of the SL and merged with the original SL cold pool. This combined cold pool advanced forward rapidly and caught up with the bowing radar reflectivity to form this MFBE. This study illustrates the processes of a SL‐CC merger leading to the formation of a different type of MFBE that did not produce damaging surface winds.

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“…Evans et al . [] studied an intense warm‐core MCV associated with the unusually strong 8 May 2009 “Super derecho” event [ Coniglio et al ., ; Weisman et al ., ; Xu et al ., ]. Their results showed that cyclonic circulation increased in the lower troposphere owing to the local expulsion of anticyclonic vorticity within the surface‐based cold pool.…”

Section: Resultsmentioning

confidence: 99%

Mechanisms of secondary convection within a Mei‐Yu frontal mesoscale convective system in eastern China

Xue

Wang

et al. 2017

JGR Atmospheres

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The generation of secondary convection, following an earlier episode of convection, within a heavy‐rain‐producing mesoscale convective system (MCS) along a Mei‐Yu front in eastern China on 6–8 July 2013 is studied based on convection‐permitting Weather Research and Forecasting simulations. The initiation of the secondary convection is found to be directly linked to the downward development of a mesoscale convective vortex (MCV) spawn by the MCS. In the early and mature stage, the MCV center is located at the middle troposphere; it descends gradually with time as the parent MCS began to decay, with the associated convection transitioning from deep to shallow convection. The descent of the MCV occurs in response to the lowering of the maximum diabatic heating within the convective system, which increases positive potential vorticity down below. When the MCV reaches the lower troposphere, it becomes coupled with the prefrontal southwesterly low‐level jet (LLJ). The confluence of the MCV rotational flow with the LLJ notably enhances the convergence on the southern flank of the MCV, where the secondary convection is triggered and swapped through the southeastern flank of the MCV. Unlike that found in the MCV of the U.S. Central Plains, the cold pool produced by the Mei‐Yu frontal MCS is rather weak and shallow and appears to play only a minor role in promoting convection. The balanced isentropic lifting by the MCV circulation is also weak, although the MCV circulation does help localize the secondary convection.

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Environment and Early Evolution of the 8 May 2009 Derecho-Producing Convective System

Cited by 52 publications

References 53 publications

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

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

VDRAS and Polarimetric Radar Investigation of a Bow Echo Formation After a Squall Line Merged With a Preline Convective Cell

Mechanisms of secondary convection within a Mei‐Yu frontal mesoscale convective system in eastern China

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