A 10-year climatology of cold-season narrow cold-frontal rainbands in Germany

Gatzen, Christoph

doi:10.1016/j.atmosres.2010.09.018

Cited by 28 publications

(24 citation statements)

References 17 publications

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“…Severe convection has been noted elsewhere in association with mid‐level wind maxima near cold fronts (e.g. Gatzen, 2011; Gatzen et al , 2011; Simon et al , 2011). A reverse time–height plot from the Dunkeswell (Devon) wind profiler (Figure 6 (b)) provides a pseudo west–east vertical section through the wind maximum.…”

Section: Synoptic and Mesoscale Settingmentioning

confidence: 99%

Doppler radar observations of non‐occluding, cyclic vortex genesis within a long‐lived tornadic storm over southern England

Clark

2011

Quart J Royal Meteoro Soc

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Section: Synoptic and Mesoscale Settingmentioning

confidence: 99%

Doppler radar observations of non‐occluding, cyclic vortex genesis within a long‐lived tornadic storm over southern England

Clark

2011

Quart J Royal Meteoro Soc

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“…Clark, 2013), absolute differences are correspondingly small. Similarly, bulk measures of vertical wind shear cannot discriminate between tornadic and non‐tornadic NCFRs, in part because strong low‐level vertical wind shear is almost always present in NCFR environments, tornadic or otherwise (Gatzen, 2011; Clark, 2013). The consequent difficulty in forecasting tornado risk is compounded by the lack of conceptual models of synoptic or mesoscale situations favouring tornadogenesis in NCFRs.…”

Section: Introductionmentioning

confidence: 99%

Synoptic‐scale and mesoscale controls for tornadogenesis on cold fronts: A generalised measure of tornado risk and identification of synoptic types

Clark

Parker

2020

Quart J Royal Meteoro Soc

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Environments of tornadic and non-tornadic narrow cold-frontal rain bands (NCFRs) are investigated using ERA-Interim reanalyses for a sample of 114 events over the United Kingdom and Ireland (44 tornadic). The results offer a practical tool for prediction of the likelihood of tornadoes in these potentially high-impact events. Of 22 analysed parameters, a bulk measure of shear vorticity, and the front-normal wind component on the cold side of the front, yield the best discrimination between event classes, showing significantly larger values in tornadic events. A generalised measure of tornado probability, p[TN], is obtained using the distribution of points within the two-dimensional parameter space defined by these parameters. Synoptic situations commonly associated with tornadic NCFRs are identified and conceptual models describing the large-scale evolution are developed. Most events are associated with developing secondary cyclones (i.e., frontal waves) along trailing cold fronts (≥54.5%), generally within west to southwesterly large-scale flow. Another significant class of event corresponds to situations where a strong mid-to upper-level jet streak cuts across the front within an amplifying large-scale flow pattern (upstream ridge building and downstream trough extension), generally within northwesterly flow (27.3%). In frontal waves, tornadoes occurred relatively early in the wave's development and just down-front of the wave centre, where rapid increases in p[TN] occurred as the wave amplified. In northwesterly flow cases, tornadoes occurred along a well-defined NCFR bulge close to where the mid-to upper-level jet streak and an associated positive potential-vorticity anomaly intersected the front. Analysis of a high-tornadic subset of tornadic events (NCFRs producing ≥7 tornadoes) revealed an even stronger association with frontal waves (72.2% of cases), suggesting that the highest-impact events are usually associated with secondary cyclogenesis. The possible relevance of identified environmental parameters to This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…These narrow bands have variously been termed ''line convection'' (Browning and Pardoe 1973;James et al 1978;James and Browning 1979) and narrow cold frontal rainbands (NCFRs; e.g., Houze et al 1976;Houze 1993, 475-478;Jorgensen et al 2003;Gatzen 2011). The updrafts within NCFRs are associated with strong low-level convergence at the front (Browning and Harrold 1970;Browning 1990;Wakimoto and Bosart 2000;Jorgensen et al 2003).…”

Section: Introductionmentioning

confidence: 99%

On the Mesoscale Structure of Surface Wind and Pressure Fields near Tornadic and Nontornadic Cold Fronts

Clark

Parker

2014

Monthly Weather Review

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Article:Clark, MR and Parker, DJ (2014) On the mesoscale structure of surface wind and pressure fields near tornadic and nontornadic cold fronts. Monthly Weather Review, 142 (10). https://doi.org/10.1175/MWR-D-13-00395.1 eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. ABSTRACTObservations from a mesoscale network of automatic weather stations are analyzed for 15 U.K. cold fronts exhibiting narrow cold frontal rainbands (NCFRs). Seven of the NCFRs produced tornadoes. A timecompositing approach is applied to the minute-resolution data using the radar-observed motion vectors of NCFR precipitation segments. Interpolated onto a 5-km grid, the analyses resolve much of the smallmesoscale structure in surface wind, temperature, and pressure fields. Postfrontal winds varied substantially between cases. Tornadic NCFRs exhibited a near-908 wind veer and little or no reduction in wind speed on NCFR passage; these attributes were generally associated with large vertical vorticity, horizontal convergence, and vorticity stretching at the NCFR. Nontornadic NCFRs exhibited smaller wind veers and/or marked decreases in wind speed across the NCFR, and weaker vorticity, convergence, and vorticity stretching. In at least four tornadic NCFRs, increases in vorticity stretching preceded tornadogenesis. Doppler radar observations of two tornadic NCFRs revealed the development of misocyclones, some tornadic, during the latter stages of vorticity-stretching increase. The presence of cyclonic vortices only, in one case occurring at regular intervals along the NCFR, provides limited circumstantial evidence for horizontal shearing instability (HSI), though other vortex-genesis mechanisms cannot be discounted. Vorticity-stretching increases were associated with coherent mesoscale structures in the postfrontal wind field, which modified the crossfrontal convergence. Where cross-frontal convergence was large, extremely narrow, intense shear zones were observed; results suggest that tornadoes occurred when such shear zones developed in conjunction with conditional instability in the prefrontal environment.

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A 10-year climatology of cold-season narrow cold-frontal rainbands in Germany

Cited by 28 publications

References 17 publications

Doppler radar observations of non‐occluding, cyclic vortex genesis within a long‐lived tornadic storm over southern England

Doppler radar observations of non‐occluding, cyclic vortex genesis within a long‐lived tornadic storm over southern England

Synoptic‐scale and mesoscale controls for tornadogenesis on cold fronts: A generalised measure of tornado risk and identification of synoptic types

On the Mesoscale Structure of Surface Wind and Pressure Fields near Tornadic and Nontornadic Cold Fronts

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