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Zhaoxia Pu, Xuanli Li, and Juanzhen Sun

1. Introduction Hurricanes are one of the nature’s most intense phenomena and one of the coastal resident’s greatest fears. They threaten the maritime industry, devastate coastal regions, and cause floods and erosion inland through torrential rainfall, high winds, and severe storm surges. As suggested by Landsea (1993) , hurricane damage increases exponentially with the low-level wind speed. Therefore, accurate forecasting of hurricane intensity changes near their landfall is of great

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

methodology. Finally, it should be stressed that the DAS for this experiment is configured without any bogus vortex or vortex relocation technique. As a consequence, tropical development, if any, is spontaneously produced by the model. One 35-day global data assimilation, starting at 0000 UTC 13 August 2006, is performed with the GEOS-5 DAS to cover the entire period of the SOP-3 phase of the NAMMA campaign. From the analyses, two sets of thirty-one 5-day forecasts, at two different horizontal resolutions

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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

were studied during NAMMA, three of which intensified to form Tropical Storms Debby and Ernesto and Hurricane Helene ( Zipser et al. 2009 ). An examination of the SAL in the NAMMA domain indicated that the SAL was a quasi-steady-state feature, with significant modulations of aerosol content and a periodicity of ∼5 days from 15 August to 15 September 2006. There were only three minor (1–2 day) breaks when the SAL was not overspreading the NAMMA study region. However, satellite imagery and forecasts

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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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Jonathan Zawislak and Edward J. Zipser

GDAS uses a T254 Gaussian grid, equivalent to a 1° × 1° latitude/longitude grid spacing with global coverage. The GDAS archive provides fields four times daily (0000, 0600, 1200, and 1800 UTC) for the following variables at 64 vertical pressure levels: temperature, height, absolute vorticity, vertical velocity, relative humidity, and u and υ wind. The analyses are produced by using the current analysis to initialize the Global Forecast System (GFS), which then produces 3-, 6-, and 9-h forecasts

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Edward K. Vizy and Kerry H. Cook

the National Center for Atmospheric Research–National Oceanic and Atmospheric Administration (NCAR–NOAA) Advanced Research Weather Research and Forecasting model (ARW-WRF) and National Aeronautics and Space Administration observations taken in support of the African Monsoon Multidisciplinary Analyses (AMMA) field campaign. Background on the conditions necessary for tropical cyclogenesis is reviewed in section 2 . Section 3 describes the regional model and the modeling approach. In section 4

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

observations, providing improvement in the forecasting of TC evolution ( Kepert et al. 2006 ). For example, the use of passive microwave instruments mounted on a variety of satellites has assisted in the monitoring of eyewall replacement cycles, one important aspect of the intensification process ( Willoughby et al. 1982 ; Hawkins et al. 2006 ; Jones et al. 2006 ). In addition, the Advanced Microwave Sounding Unit (AMSU) series of satellites has assisted researchers and forecasters alike through the

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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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Scott A. Braun, Michael T. Montgomery, Kevin J. Mallen, and Paul D. Reasor

Weather Research and Forecasting (WRF) modeling system (version 2.2; Skamarock et al. 2005 ) to conduct simulations of the genesis of Tropical Storm Gert. Four grids nesting down to 2-km horizontal grid spacing ( Fig. 1 ) are employed to adequately represent the convection. The outer grid has a horizontal grid spacing of 54 km and contains 150 × 90 grid points in the x and y directions. The grid is centered at 22.9°N, 91.1°W and uses a Mercator map projection. Two stationary nested meshes are

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