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Oreste Reale, William K. Lau, Kyu-Myong Kim, and Eugenia Brin

European Centre for Medium Range Weather Forecasts (ECMWF) so-called nature run (a 13-month-long simulation in free running mode performed with the then-operational ECMWF model at the horizontal resolution of T511, corresponding to approximately 40 km) and verified that the simulation contained quasi-realistic AEW activity and a realistic number of Atlantic tropical cyclones. Strictly speaking, the resolutions adopted by the previously referenced studies cannot yet be considered adequate to resolve the

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Zhaoxia Pu, Xuanli Li, and Juanzhen Sun

importance for effectively warning the public and reducing economic damage and deaths. Over the last two decades, the hurricane-track forecast has been improved significantly. However, the intensity forecast remains a great challenge in operational and research communities. According to Rogers et al. (2006) , the official 48-h hurricane-track forecast error has reduced by 45% in the past 15 years, whereas the intensity forecast error has decreased by only 17%. They suggest that the major reasons for the

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Edward K. Vizy and Kerry H. Cook

. Recker , 1977 : The structure and properties of African disturbances as observed during phase III of GATE. Mon. Wea. Rev. , 105 , 317 – 333 . Reed , R. J. , A. Hollingsworth , W. A. Heckley , and F. Delsol , 1988a : An evaluation of the ECMWF operational system in analyzing and forecasting easterly wave disturbances over Africa and the tropical Atlantic. Mon. Wea. Rev. , 116 , 824 – 865 . Reed , R. J. , E. Klinker , and A. Hollingsworth , 1988b : The structure and

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Syed Ismail, Richard A. Ferrare, Edward V. Browell, Gao Chen, Bruce Anderson, Susan A. Kooi, Anthony Notari, Carolyn F. Butler, Sharon Burton, Marta Fenn, Jason P. Dunion, Gerry Heymsfield, T. N. Krishnamurti, and Mrinal K. Biswas

mesoscale prediction experiments are designed to explore the sensitivity of AEW 4 ( Fig. 9b ) forecasts to these data inputs. The 26 August case, where the AEW weakened during very dry conditions brought about by dry air intrusions, is of special interest. Preliminary analysis shows that the modeled AEW was too wet, based on operational first-guess analysis. This control forecast resulted in a developing storm. However, when that experiment was repeated using the LASE humidity profiles, we noted that

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Zhuo Wang, M. T. Montgomery, and T. J. Dunkerton

during August–September 1998–2001, and 53 storms were shown to develop near the center of the wave’s pouch as analyzed in ERA-40 data in accord with the hypotheses. 1 Using global model operational data, Wang et al. (2009) developed real-time forecast products based on the findings of DMW09 and showed that the tropical cyclogenesis location can be predicted up to three days in advance with an error less than 200 km. DMW09 proposed an overarching framework that provides a useful roadmap for

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Jonathan Zawislak and Edward J. Zipser

– 172 . Chen , T. C. , 2006 : Characteristics of African easterly waves depicted by ECMWF reanalyses for 1991–2000. Mon. Wea. Rev. , 134 , 3539 – 3566 . Derber , J. C. , D. F. Parrish , and S. J. Lord , 1991 : The new global operational analysis system at the National Meteorological Center. Wea. Forecasting , 6 , 538 – 547 . Diedhiou , A. , S. Janicot , F. Viltard , P. de Felice , and H. Laurent , 1999 : Easterly wave regimes and associated convection over West

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Robert Cifelli, Timothy Lang, Steven A. Rutledge, Nick Guy, Edward J. Zipser, Jon Zawislak, and Robert Holzworth

locations. European Centre for Medium-Range Weather Forecasts operational analyses (0.5° resolution, four times daily; available from the AMMA data user Web site, http://database.amma-international.org/ ) were used to define the spatial extent of wave 5 and to determine the timing of the ridge and trough at each radar location. To define the extent of wave 5, the ECMWF 700-mb meridional wind was examined for the time period of interest (30 August–4 September 2006) across West Africa and the eastern

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Stephen R. Guimond, Gerald M. Heymsfield, and F. Joseph Turk

Oceanic and Atmospheric Administration (NOAA) WP-3D (P-3) aircraft have been providing a wealth of details on TCs that has revolutionized the understanding and operational forecasting of these systems (e.g., Jorgensen 1984 ; Marks and Houze 1987 ; Aberson et al. 2006 ; Reasor et al. 2009 ). In addition to the P-3 TA radar, the more advanced Electra Doppler Radar (ELDORA) operated by the National Center for Atmospheric Research (NCAR) has flown recent missions into TCs revealing convective

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Robert Rogers

1. Introduction One of the most challenging problems in tropical cyclone (TC) forecasting is predicting TC intensity change. While track forecasts have improved markedly in the past 20 years, progress in intensity forecasting has lagged significantly behind ( Rogers et al. 2006 ; DeMaria et al. 2005 ). Intensity forecasting is challenging because the processes important in intensity change occur within and between scales of many orders of magnitude, including environmental, vortex, convective

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Chanh Q. Kieu and Da-Lin Zhang

1. Introduction The life cycle of tropical cyclones (TCs) is typically divided into the following four phases: pregenesis with little closed circulation, tropical depression (TD), tropical storm (TS), and hurricane. Of the four, the pregenesis and its subsequent growth to TD and TS stages, the so-called tropical cyclogenesis (TCG), are the most difficult phases to predict by numerical TC models and operational forecasters. Despite the many processes involved during TCG, the recent successes of

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