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Jeff Willison, Walter A. Robinson, and Gary M. Lackmann

address the synoptic- and climate-scale importance of latent heat release from condensation, which occurs in mesoscale features that GCMs resolve poorly. Hoskins et al. (1985) described the interaction of upper- and lower-tropospheric disturbances in a developing cyclone within a potential vorticity (PV) framework. Baroclinic instability can be envisioned as the mutual reinforcement between upper-level PV (UPV) associated with the high-PV polar stratosphere and lower-level PV (LPV) associated with a

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Katrina S. Virts and Robert A. Houze Jr.

1. Introduction The Madden–Julian oscillation (MJO; Madden and Julian 1971 , 1972 ; Zhang 2005 ) modulates tropical atmospheric variability at intraseasonal (30–80 day) time scales, and its primary effects are observed over the region extending from the central Indian Ocean eastward to the western Pacific Ocean. In a typical MJO episode, a region of enhanced deep convection and mesoscale cloudiness and precipitation is preceded by low-level moisture convergence in association with

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D. Alex Burrows, Craig R. Ferguson, and Lance F. Bosart

et al. 1997 ; Yang et al. 2007 ; Weaver et al. 2009 ; Hodges and Pu 2018 , 2019 ; Weaver et al. 2012 ), particularly through their support of mesoscale convective system initiation and maintenance (e.g., Maddox 1983 ; Squitieri and Gallus 2016a , b ; Song et al. 2019 ), and thus constitute a key weather and climate forecast target. Important to the prediction and understanding of GPLLJ events, including positioning of their entrance, axis, and exit (convergence) regions, is a recognition

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Riwal Plougonven, Valérian Jewtoukoff, Alvaro de la Cámara, François Lott, and Albert Hertzog

) indicates the height at which most of the analyses are carried out. Note that the color bars are adapted to each panel. Fig . 3. Winds averaged from Sep to Dec 2010, from the analyses of the ECMWF. See Fig. 2 caption for panel details. Note that the color bars are adapted to each panel. The numerical dataset is derived from mesoscale simulations carried out with the Weather Research and Forecasting (WRF; Skamarock et al. 2008 ) Model, with a domain encompassing Antarctica and the Southern Ocean and

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Stefan N. Tulich and George N. Kiladis

-resolution satellite data to examine some of the mesoscale aspects of convection–wave coupling in the tropics. Results in sections 2 and 3 show that much of the coherent variability of tropical convection on the meso-alpha scale (200–2000 km) can be attributed to equatorially trapped inertia–gravity waves with implied equivalent depths in the range 15–40 m (i.e., pure gravity wave speeds in the range 12–20 m s −1 ). This variability includes 2-day waves over the tropical western Pacific, as well as squall

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Jon M. Schrage, Andreas H. Fink, Volker Ermert, and Epiphane D. Ahlonsou

zone is reviewed by Fink et al. (2006) . While a wide variety of mesoscale convective systems (MCSs) are important in the sub-Sahelian wet zone, highly organized squall line systems are perhaps the most extensively studied MCS type. The Global Atmospheric Research Program (GARP) Atlantic Tropical Experiment (GATE) brought about a considerable advancement in our understanding of the mesoscale structure of squall line systems that moved across the West African coast and passed over the GATE ship

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G. J. Shutts

concern here was with the excessive energy dissipation rate in the model’s free atmosphere and within frontal zones. It was also motivated by the possibility that upscale energy cascades associated with deep convection and mesoscale convective systems are underrepresented by the combined effects of convective parameterization and explicit, near-gridscale dynamics. Similarly, it was argued that mountain drag formulations address deficiencies in the momentum budget but act as an unrealistic energy sink

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Wallace A. Hogsett and Stacy R. Stewart

, the buoyant updrafts are superimposed on mesoscale ascent ( Eastin et al. 2005 ). 5. Discussion and forecasting implications In this study, we have shown that a highly idealized TC vortex in a quiescent synoptic environment, without regard for the TC secondary circulation, may support left-moving cyclonically rotating convective updrafts, or “left movers.” Similar to midlatitude cyclonic supercells, they propagate to the right of the local shear vector, which coincidentally is to the left of the

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Robert F. Rogers, Michael L. Black, Shuyi S. Chen, and Robert A. Black

distribution of latent heat release is quite challenging, however, and improving our understanding and forecasting of intensity and rainfall remains an elusive goal for the operational and research communities. For example, the forecast skill for intensity is only about one-half (one-third) of that for track at 36 h (72 h) forecast time ( DeMaria and Gross 2003 ), while standardized techniques for evaluating tropical cyclone rainfall are only now being developed ( Marchok et al. 2007 ). Continuing

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Jason A. Sippel, Scott A. Braun, and Chung-Lin Shie

, M. , J. A. Knaff , and B. H. Connell , 2001 : A tropical cyclone genesis parameter for the tropical Atlantic . Wea. Forecasting , 16 , 219 – 233 . Doswell , C. A. , III , and E. N. Rasmussen , 1994 : The effect of neglecting the virtual temperature correction on CAPE calculations . Wea. Forecasting , 9 , 625 – 629 . Dudhia , J. , 1989 : Numerical study of convection observed during the winter monsoon experiment using a mesoscale two-dimensional model . J. Atmos. Sci

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