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Jie Feng and Xuguang Wang

1. Introduction Over the past few decades, great efforts have been made to improve the accuracy of tropical cyclone (TC) forecasts. The major endeavors include the development of high-resolution cloud-resolving numerical weather prediction (NWP) models, advanced data assimilation (DA) systems, and novel observing systems for TCs. So far, the accuracy of TC analysis and prediction has been steadily and significantly improved. For example, the yearly averaged track forecast at the 5-day lead time

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David R. Ryglicki, Joshua H. Cossuth, Daniel Hodyss, and James D. Doyle

-level forcing mechanism), and this study identifies and quantifies a set of key common features for this class of TCs. The analyses in this study primarily rely on satellite observations, since these data typically provide the most complete spatial and temporal coverage over the storms, given that aircraft observations of TCs are rare in the eastern North Pacific (EPAC) and western Pacific (WPAC; Knabb et al. 2008 ). Without in situ reconnaissance data, intensity estimations and analyses are primarily

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David R. Ryglicki, James D. Doyle, Yi Jin, Daniel Hodyss, and Joshua H. Cossuth

-modulated convective asymmetry (TCA). TCAs, as diagnosed by cloud-top temperatures colder than −70°C, are cloud structures that are responsible for approximately 10 000–15 000-km 2 changes in cloud cover, that expand upshear, and, most importantly for the purposes of this study, that appear with periods between 4 and 8 h. A series of numerical simulations in this second part are analyzed to quantify further the dynamics and characteristics, including the vertical structure, of this class of TCs that undergo RI in

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David R. Ryglicki, James D. Doyle, Daniel Hodyss, Joshua H. Cossuth, Yi Jin, Kevin C. Viner, and Jerome M. Schmidt

ventilating TCs, inducing a potential vorticity–related spinup, and outright shearing of the TC, depending on the proximity of the upper-level synoptic forcing. Vertical wind shear (VWS) is generally a negative influence on TC intensification ( Merrill 1988b ; Wang and Wu 2004 ). Recent studies on wind shear’s negative effects have focused on the thermodynamic effects of VWS, such as the midlevel ventilation ( Tang and Emanuel 2010 ; Tang and Emanuel 2012 ; Ge et al. 2013 ) or the flushing of the

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Patrick Duran and John Molinari

), the coldest temperature, −86°C, was observed a few hundred meters above the highest cloud tops ( Waco 1970 ). Very near the storm center, the temperature at 16.5-km altitude increased from −86° to −77°C over a horizontal distance less than 30 km as the aircraft approached the storm center [see Fig. 2 “Run 2” in Waco (1970) ]. This strong inward temperature increase was likely associated with an intense upper-tropospheric warm core within and near Beulah’s eye. The presence of a warm core in the

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Xu Lu and Xuguang Wang

originally designed under a clear-sky assumption where the free atmosphere has little diffusion. Therefore, K m is always set to zero at the PBL top and the K m above the PBL is always following the clear-sky profiles in the HWRF PBL scheme. But this assumption is not suitable for the deep convection, such as the eyewall or spiral rainbands, where in-cloud turbulence creates large mixing above the PBL. Zhu et al. (2018) proposed a modified turbulent mixing parameterization scheme that replaces the

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Shixuan Zhang, Zhaoxia Pu, and Christopher Velden

sources for use in operational data assimilation. Unfortunately, limitations of current data assimilation methodologies prevent most satellite radiances in the TC inner core and near environmental regions from being assimilated. This occurs because of cloud and precipitation contamination, although all-sky data assimilation has become an active research area in recent years ( Zhu et al. 2016 ). Fortunately, satellite-derived products, especially atmospheric motion vectors (AMVs; Velden et al. 1997

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T. Connor Nelson, Lee Harrison, and Kristen L. Corbosiero

in the TCI dataset, as well as to examine the updrafts and downdrafts observed by the XDDs. Hock and Franklin (1999) used RD-93 dropsondes to derive vertical velocity from GPS fall speeds and a single drag force estimate presumed to be representative for all individual sondes. This method is now routine, but more recent studies use a hydrostatic pressure-derived fall speed rather than the GPS fall speed (e.g., Wang et al. 2015 ). Sonde-derived vertical velocities have been used to examine the

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Jie Feng and Xuguang Wang

1. Introduction In recent decades, research has shown that the tropical cyclone (TC) outflow layer is critically related to the TC structure evolution and intensity change rather than just a mechanism to export TC energy at the upper troposphere. The outflow layer relative to the low- and midtroposphere has weaker inertial stability and thus is more susceptible to the environmental forcing ( Holland and Merrill 1984 ; Rappin et al. 2011 ). For example, the outflow can interact with a

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