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Jun-Ichi Yano and Joseph J. Tribbia

that the same could be true for the whole tropical planetary-scale circulations. Such a new perspective may have an immediate impact on global model initialization strategy over the tropics: the current basic strategy is an initialization based on a linear equatorial wave decomposition (cf. Žagar et al. 2005 ). The proposed MJO–modon theory suggests a nonlinear balance initialization ( Baer and Tribbia 1977 ; Kasahara 1982 ; Tribbia 1984b ) as the key for a successful MJO forecast. From a

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Y. Qiang Sun and Fuqing Zhang

Craig (2015a) . In their high-resolution simulation of a warm-season weather event over Europe, Selz and Craig (2015a) showed that 60 h after perturbing their operational forecast model with negligible initial small-scale error, the large-scale 500-hPa geopotential height error induced by upscale error growth was about half the spread of the European Centre for Medium-Range Weather Forecasts (ECMWF) 6-h ensemble forecast. This result suggests that the upscale error growth plays a nonnegligible

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Hua Chen and Sundararaman G. Gopalakrishnan

from the previous cycle that has been relocated and adjusted toward current pressure and wind observations ( Liu et al. 2006 ; Tallapragada et al. 2014 ). This study uses output from the 1800 UTC 26 August 2010 retrospective forecast, with vortex initialization and assimilation consisting of three major steps: 1) interpolation of the global analysis fields from the GFS onto the operational 27–9–3-km model grids; 2) removal of the GFS vortex from the global analysis; and 3) addition of the HWRF

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Chun-Chieh Wu, Guo-Yuan Lien, Jan-Huey Chen, and Fuqing Zhang

, the storm motion vector, and the axisymmetric surface wind structure. As is the case with the TC observed positions, the storm motion vector is available from the operational forecast center, which is mainly based on satellite analyses, while the axisymmetric surface wind structure (radial wind profile) is estimated based on the wind radii data from operational centers and the dropwindsonde data, such as those collected in the DOTSTAR program. The EnKF method and the settings of the Advanced

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Da-Lin Zhang and J. Michael Fritsch

periods up to about 18 hours. The results also suggest that significant improvementsin warm-season quantitative precipitation forecasts might be possible if numerical forecasts of the meso-f3 scalestructure and evolution of convective weather systems became operational.1. IntroductionAlthough numerical predictions of large-scale circulation patterns have improved markedly during thepast three decades, quantitative precipitation forecasts(QPFs) have proven to be a particularly stubbornproblem to solve

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T. N. Krishnamurti, M. C. Sinha, Bhaskar Jha, and U. C. Mohanty

difficult to see the maintenance of the monsoon from a string of analyzed fields. The spinup of the monsoon using a high-resolution global model appears to produce a better picture. A model run with reasonable forecasts is able to describe the above sequence very clearly. The budgets of the energetics are performed carefully, but they are not entirely residue free. Monsoon research has moved in several areas encompassing many time and space scales, ranging from the diurnal to the interannual. Energetics

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Richard A. Anthes

cooperation of the National Hurricane Research Laboratory and National Hurricane Center,Miami, Fla., and the Geophysical Fluid DynamicsLaboratory, Princeton, N. J. Because of the cost ofcomputing with fine-mesh (~60 km) models and theconsideration of the maximum benefits to be derivedfrom improved hurricane forecasting, this initial opera~tional model will be designed primarily for forecasts ona time scale of about 24 hr (Hovermale, personal communication). For such short-range forecasts, a majorproblem

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Erin B. Munsell, Fuqing Zhang, and Daniel P. Stern

weakened to a remnant low 6 h later as it passed to the south of Puerto Rico. Tropical Storm Erika reached its peak intensity at 0000 UTC 2 September 2009 with a minimum SLP of 1004 hPa and maximum sustained winds of 45 kt. The genesis of Erika was very well forecasted ( Berg and Avila 2011 ; Brown 2009 ). However, at the time of genesis of Erika (1800 UTC 1 September 2009) nearly all operational intensity models forecasted the tropical storm to intensify into a hurricane although the storm failed to

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Yizhe Peggy Bu, Robert G. Fovell, and Kristen L. Corbosiero

-derived radiation scheme that was long employed operationally in the Hurricane Weather Research and Forecasting Model (HWRF) (cf. Tallapragada et al. 2014 ) did not handle CRF properly, resulting in deep clouds that were effectively transparent. Testing revealed, however, that implementing an ostensibly superior radiation scheme degraded model skill (L. Bernardet et al. 2014, personal communication). Analysis of those results led us to consider how the planetary boundary layer (PBL) influences storm size, in

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Stephanie Evan, M. Joan Alexander, and Jimy Dudhia

0300, 0900, 1500, and 2100 UTC from 21 January to 12 February 2006. We use the data from the ECMWF operational forecasting system. In 2006 the operational model had a T511 spectral resolution, equivalent to a grid size of approximately 40 km. The model had 60 vertical levels from near surface up to 0.1 hPa. The vertical resolution is 1 km at the tropopause and 1.5 km at 25 km. The dataset comprises the ECMWF fields of temperature, zonal and meridional winds, and geopotential heights. Although

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