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Joshua M. Boustead, Barbara E. Mayes, William Gargan, Jared L. Leighton, George Phillips, and Philip N. Schumacher

associated with significant tornadoes near discernible boundaries and in the warm sector to nontornadic boundary and warm sector supercells. Thunderstorms occur on the meso-Γ scale, and forcing for their development generally occurs on the meso- α scale. Nevertheless, synoptic-scale environments can produce favorable conditions for convective initiation, and those times when both the synoptic and mesoscale environments are favorable for tornadoes are generally when the largest outbreaks occur ( Doswell

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Greg L. Dial, Jonathan P. Racy, and Richard L. Thompson

1982 ; 1984 ). Through three-dimensional idealized cloud model simulations, Weisman and Klemp showed that a spectrum of storm structures evolved when the thermal buoyancy and vertical shear were varied over an array of environmental conditions. The ratio of buoyancy to vertical wind shear, in the form of a nondimensional bulk Richardson number, was found to be useful in determining basic storm structures. Later observational studies using proximity soundings ( Rasmussen and Blanchard 1998

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Tong Zhu, Sid Ahmed Boukabara, and Kevin Garrett

, with the remaining 36% coming from the assimilation of surface-based observation types in the Met Office global NWP system. Regional modeling systems have been widely used for short-range forecast and regional climate modeling. However, the impacts of any physical scheme, advanced DA techniques, and new satellite data are difficult to evaluate in the regional NWP models, mainly because of the influence of the lateral boundary conditions (LBCs). The sensitivity to LBCs is widely acknowledged in the

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Adam J. Deppe, William A. Gallus Jr., and Eugene S. Takle

a level at which winds are strongly influenced by surface friction. Prior wind forecasting research in the western United States has focused on flow in complex terrain (e.g., Wood 2000 ; Ayotte et al. 2001 ) and is therefore not applicable in Iowa where boundary layer stratification, low-level jets (LLJs), and changing surface conditions are likely to be the dominant factors providing uncertainty in short-term forecasts at 80 m. Other modeling studies have taken a more statistical approach to

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Matías G. Dinápoli, Claudia G. Simionato, and Diego Moreira

. Model A is the lowest resolution/largest scale spanning from 59° to 26°S and from 69° to 46°W ( Fig. 1 , inset), with a horizontal resolution of 7.50′ and 5.25′ in the zonal and meridional direction (equivalent to approximately 12 km), respectively. This model is used to provide boundary conditions to a higher-resolution model focused on the RdP (model B, Fig. 1 ). Model B covers the region between 38.20°–32.60°S and 58.75°–52.50°W. Using the empirical criteria of 1/3 reduction from father to child

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Alex M. Kowaleski and Jenni L. Evans

the RMW (in the eyewall), entrainment at the top of the boundary layer ceases. This cessation, combined with large ocean–air moist enthalpy fluxes, causes relative humidity and θ e to increase rapidly. Within the classic PI framework, conditions beyond the eyewall determine the ocean–air entropy deficit under the eyewall and the balance between energy production and frictional dissipation there. If the actual TC boundary layer differs from classic PI theory (if temperature or relative humidity

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Kay Sušelj, Timothy F. Hogan, and João Teixeira

updrafts provide a countergradient subgrid mixing in the dry boundary or subcloud layer and are the roots of the moist updrafts. The vertical velocity and moist conserved variables within the thermal are modeled as in Sušelj et al. (2013) : where represents the buoyancy of the thermal; and where the constants are a = ⅔, b = 0.002 m −1 , and c = 1.5. The variable represents the lateral entrainment rate (defined below) and is one of the key closures of the parameterization. Boundary conditions

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Fan Zhang, Ming Li, Andrew C. Ross, Serena Blyth Lee, and Da-Lin Zhang

mesh, meteorological forcing, and initial/boundary conditions were used. These modeling studies typically focused on improving the hydrodynamic model prediction of tides, storm surge, and waves. For example, Kerr et al. (2013a) found that the storm surge generated by Ike was sensitive to the bottom friction parameterization, especially in shelf waters where a strong shore-parallel coastal current was a key to the storm’s geostrophic setup. To obtain accurate predictions of surge water levels

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John Lawson and John Horel

were performed with the Advanced Research version of the Weather Research and Forecasting (WRF; Skamarock et al. 2008 ) Model, version 3.4 (see LH15 for WRF configuration details). Each simulation used 12-, 4-, and 1.3-km nested domains, with feedback enabled between the nests ( Fig. 2 ). For the ensemble forecasts in this study, perturbed initial and boundary conditions were provided every 6 h by the Global Ensemble Forecast System Reforecast, version 2 (GEFS/R2), dataset [for the perturbation

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Bao-Fong Jeng, Hway-Jen Chen, Shwu-Ching Lin, Tzay-Ming Leou, Melinda S. Peng, Simon W. Chang, Wu-Ron Hsu, and C.-P. Chang

up to 48 h over the eastern parts of Asiaand the northwestern Pacific Ocean. The MFS has a resolution of 45 kin, uses RFS analysis and forecast asinitial and boundary conditions, and produces 24-h forecasts for Taiwan and its immediate vicinity. Modelconfigurations, numerics, physical parameterizations, performance statistics, and two significant weather casesof the two forecast systems are discussed. Future improvements and new plans will also be given.1. Introduction The island of Taiwan

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