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Cheng-Ku Yu
and
Ying-Hsun Hsieh

and Bresch 1991 ; Sun and Chern 1993 ; Leu and Lin 2004 ; Chien and Lin 2004 ; Huang 2007 ). The convective lines occurring offshore in this particular geographical location are one of the most well-known and frequent mesoscale phenomena in Taiwan ( Yu and Lin 2008 , hereafter YL08 ). Documentation of these lines can provide an excellent opportunity to improve our general understanding of physical processes leading to the formation of moist convection off a mountainous island coast. With

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A. C. Sousa
,
L. A. Candido
, and
P. Satyamurty

1. Introduction The north coast of South America is affected by mesoscale convective cloud clusters (CCCs) and their organization into squall lines (SL) parallel to the coast ( Garstang et al. 1994 ; Cohen et al. 1995 , 2009 ). These systems contribute nearly 40% of the annual precipitation of northern coastal Brazil and adjoining regions. Heavy afternoon showers caused by these systems disrupt the society in the coastal cities of Brazil ( Loureiro et al. 2014 ). Flash floods not only damage

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Matthew D. Parker

relatively little study to this point in time. Part I combined a case study and idealized numerical simulations as an introductory exposition of the basic structures of such PS systems. In Part I , convective lines with PS precipitation were found to develop in environments with a combination of deep line-parallel wind shear and low-level line-perpendicular wind shear. In such situations, lower-tropospheric storm-relative hydrometeor advection and outflow expansion toward the line’s right 1 produces

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Cheng-Ku Yu
and
Che-Yu Lin

shore ( Fig. 1 ). Such a geographical configuration represents an excellent natural laboratory to explore our knowledge of coastal convection influenced by both land–sea thermal contrasts and topographic effects. In this particular geographical location, the cloud and/or precipitation lines occurring off the eastern coast of Taiwan are one of the most well-known and frequent mesoscale phenomena. These offshore lines are typically oriented parallel to the coast. They are frequently characterized by

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Matthew D. Parker

) . Along these lines, much of the discussion about evolutionary modes of linear convective systems has centered upon the relative strength of the line-perpendicular vertical wind shear (extending back through seminal papers by Thorpe et al. 1982 ; Rotunno et al. 1988 ). However, comparatively few studies have considered the possible impacts of along-line wind shear. It is perhaps for this reason that PS MCSs appear to have received little, if any, detailed attention as a kinematically and dynamically

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Linlin Zheng
,
Jianhua Sun
,
Xiaoling Zhang
, and
Changhai Liu

convective and stratiform development and, consequently, has been increasingly used for MCS classification studies in recent years. On the basis of an 11-yr reflectivity dataset, for example, Bluestein and Jain (1985) documented four distinct formation modes of severe squall lines in Oklahoma during the spring: broken line, back building, broken areal, and embedded areal. This radar-based classification was later extended to nonsevere squall-line development by Bluestein et al. (1987) . Blanchard

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Brian F. Jewett
and
Robert B. Wilhelmson

shear of a “representative” inflow sounding still largely determine the outcome? Does long-lived forcing matter once the convection has formed, with its attendant strong updrafts, downdrafts, and cold pool? This study addresses the role of persistent forcing in the early development and structure of deep convective squall lines. Two-dimensional forcing was selected for its relative simplicity (conceptually and through numerical simulation), here taken to be a cold front, formed and evolving as an

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Matthew D. Parker

1. Introduction Squall-line maintenance and intensity have been studied for some time (e.g., Newton 1950 ), with an emerging understanding that the convective region of many squall lines occurs along the downshear edge of their outflow boundaries. Early numerical experiments (e.g., Hane 1973 ; Thorpe et al. 1982 ) helped to quantify the impacts of vertical wind shear upon such squall lines. Decades of observations and simulations were reviewed by Rotunno et al. (1988

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Megan Bickle
,
John H. Marsham
,
Stephen D. Griffiths
,
Andrew N. Ross
, and
Julia Crook

important for correctly representing the entire monsoon system including pressure gradients, winds, and the water budget ( Marsham et al. 2013 ; Birch et al. 2014 ). In this paper, we explore how aspects of this diurnal cycle support the decay or strengthening of mature squall lines. The convection parameterizations used in global models struggle to capture MCSs leading to systematic errors in both global numerical weather prediction and climate models ( Lee et al. 2007 ; Moncrieff 2013 ). Over land

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Peiyu Wang
and
Zhiyong Meng

weather cumuli or clear-air thermals. Wavelike convective bands associated with gravity waves occur mainly in a stable environment with reflectivities generally lower than 35 dB Z and below 500 hPa with the vertical velocity generally lower than 0.5 m s −1 (e.g., Du and Zhang 2019 ). Horizontal convective rolls are mainly constrained within the boundary layer, displaying as shallow cloud streets on visible satellite imagery and fine lines of <10-dB Z reflectivities on radar. Undular bore usually

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