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Joel K. Sivillo, Jon E. Ahlquist, and Zoltan Toth

atmospheric predictability. He demonstrated that weather, even when viewed as a deterministic system, may have a finite prediction time (1963). Further, predictability varies with different weather situations in a way not easily discernible by naked eye examination of weather maps (1965). He also calculated that the average limit to atmospheric predictability at planetary scales is on the order of 10 days (1969). More recent estimates ( Simmons et al. 1995 ) suggest that a 10-day average forecasting limit

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David E. Jahn and William A. Gallus Jr.

anticyclonic flow. Forecasting LLJ location and strength is thus important for forecasting convective precipitation in the Great Plains. Challenges remain, however, in the use of mesoscale models for LLJ forecasting. LLJ evolution is influenced by the turbulent mixing of the boundary layer ( Hu et al. 2013 ; Klein et al. 2016 ), the parameterizations and effects of which differ among planetary boundary layer (PBL) schemes. Local PBL schemes, such as the Mellor–Yamada–Nakanishi–Niino (MYNN) PBL scheme

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Xiaoyu Chen and Liguang Wu

domains. The other physics options include the Rapid Radiative Transfer Model (RRTM) longwave radiation scheme ( Mlawer et al. 1997 ), the Dudhia shortwave radiation scheme ( Dudhia 1989 ), the Yonsei University scheme for planetary boundary layer parameterization ( Noh et al. 2003 ), and the Noah land surface model. The National Centers for Environmental Prediction (NCEP) Final (FNL) operational global analysis dataset with a resolution of 1.0° × 1.0° at every 6 h is used to initialize the simulation

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Song-You Hong, Jung Choi, Eun-Chul Chang, Hoon Park, and Young-Joon Kim

1. Introduction At present, global numerical weather prediction models run with horizontal resolutions that cannot typically resolve atmospheric phenomena smaller than about 10–100 km. Many atmospheric processes have shorter horizontal scales than these scales and some of these “subgrid scale” processes interact with one another and affect the larger-scale atmosphere in important ways. Atmospheric gravity waves are one such unresolved process. The dissipation of these waves produces synoptic

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Shengjun Zhang, Tim Li, Xuyang Ge, Melinda Peng, and Ning Pan

systems at the Naval Research Laboratory/Fleet Numerical Meteorology and Oceanography Center (NRL/FNMOC) and the National Centers for Environmental Prediction (NCEP) apply different TC initialization schemes, respectively. The Navy Operational Global Atmosphere Prediction System (NOGAPS) includes synthetic data to represent TC vortices treated as convectional dropsonde data, while the NCEP Global Forecast System (GFS) uses a relocation method without adding synthetic data. Regardless of the

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William A. Gallus Jr.

not supported by the observations. It is interesting to note that even small steps in the model, like those occurring near the right edge of the cross section, act to block the flow. This blocking occurs despite generally low static stability in the lowest 1–2 km of the atmosphere. As in the 2D simulations of Gallus and Klemp (2000) , spurious horizontal vorticity generation, particularly due to strong vertical wind shear, appears to be responsible for the flow separation, and can be inferred

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Xiaogang He, Hyungjun Kim, Pierre-Emmanuel Kirstetter, Kei Yoshimura, Eun-Chul Chang, Craig R. Ferguson, Jessica M. Erlingis, Yang Hong, and Taikan Oki

from the very high quality in situ observational data from rain gauge stations provided by African Monsoon Multidiscplinary Analysis (AMMA) Land Surface Model Intercomparison Project Phase 2 (ALMIP2; Boone et al. 2009 ), which is supported by the AMMA–Coupling the Tropical Atmosphere and the Hydrological Cycle (CATCH) observing system ( Cappelaere et al. 2009 ; Lebel et al. 2009 ). The data are provided at a 0.05° resolution with a 30-min temporal resolution using the Lagrangian kriging

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Rebecca M. Westby and Robert X. Black

, those associated with CAOs ( Loikith and Broccoli 2012 ). In the accounts presented thus far, it is clear that synoptic-scale circulations are critical to ATR development; however, it is also possible that these smaller-scale circulations may be embedded within larger planetary-scale circulation patterns that may persist for much longer ( Konrad 1998 ). Therefore, circulation on a variety of scales may contribute to the formation of ATRs, ranging from frontal-scale features up to hemispheric low

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David S. Nevius and Clark Evans

with elevated mixed layers (EMLs) from the NSSL-WRF [e.g., Coffer et al. 2013 ] and 2.2 km Operational UM (Unified Model [ Walters et al. 2014 , Wood et al. 2014 ]) at sites where observed raob [rawinsonde observation] data is available. With a focus on sounding structure in the PBL [planetary boundary layer] and depiction of any capping inversions, which model has the best forecast sounding?” From the 89 responses, 67% answered the UM was better than the NSSL-WRF, 10% answered that the UM was

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David J. Stensrud and Steven J. Weiss

the spacing of sigma levels reduced near the ground surface to simulate better the evolution of the planetary boundary layer (PBL). The model is initialized for each day at 0000 UTC using the National Centers for Environmental Prediction (NCEP) Eta Model ( Black 1994 ) forecast fields available at 25-hPa vertical intervals and with 40-km grid spacing, bilinearly interpolated to the MM5 grid points at selected pressure levels. A static initialization is performed, in which the pressure-level data

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