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Edward K. Vizy and Kerry H. Cook

, the regional model results are validated with the European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis, NASA Tropical Rainfall Measuring Mission (TRMM) rainfall estimates, and NASA AMMA dropsonde and radiosonde data; the results are presented in section 5 . Conclusions are in section 6 . 2. Background Previous research on tropical cyclone development over the past 50 years has identified some necessary environmental conditions for tropical cyclogenesis. One condition relates to

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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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John Molinari and David Vollaro

. The maximum CAPE from any level below 3 km was chosen. In all but three soundings the maximum CAPE arose from a parcel originating within the lowest kilometer. Two issues arose in the calculation of CAPE. Most sondes were released from near the 250-hPa level. Any CAPE above the release level would be missed if only the dropsonde soundings were used. This potential problem was addressed by a two-step process: (i) assigning temperature values using gridded analyses from the European Centre for

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Joël Arnault and Frank Roux

suggests that developing cases are the consequence of an interaction between AEWs and mesoscale convective systems (MCSs) that occur over West Africa during the monsoon period (we refer to the work of Laing et al. 2008 for an up-to-date description of West African MCSs during the monsoon season). Using statistics of AEWs in a 20-yr European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis dataset, Thorncroft and Hodges (2001) proposed that the cyclogenetic evolution of AEWs depends on

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

formation within the critical layer of a tropical easterly wave. Using three independent datasets—40-yr European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40) data, Tropical Rainfall Measuring Mission (TRMM) 3B42 3-hourly precipitation data, and best-track data from the NHC—the Kelvin cat’s eye within the critical layer of a tropical easterly wave was shown to be the preferred region of storm formation, located more precisely near the intersection of the wave critical latitude and

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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, ) 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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