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Erin B. Munsell, Jason A. Sippel, Scott A. Braun, Yonghui Weng, and Fuqing Zhang

1. Introduction This study examines sources of forecast uncertainty and error for Hurricane Nadine, a long-lived North Atlantic tropical cyclone that occurred in 2012. Simulations initialized at 0000 UTC 20 September 2012 with a convection-permitting hurricane forecast and analysis system [the Weather Research and Forecasting (WRF) Model and an ensemble Kalman filter (EnKF), collectively WRF-EnKF] are examined to better understand the large forecast uncertainties and errors that occurred during

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Hui Christophersen, Altug Aksoy, Jason Dunion, and Kathryn Sellwood

1. Introduction Unmanned aircraft systems (UAS) have emerged as an alternative method of collecting weather observations to improve understanding of the tropical cyclone (TC) environment and the accuracy of TC forecasts ( Braun et al. 2016 ; Cione et al. 2016 ), particularly in hazardous conditions where it is too dangerous to operate manned reconnaissance aircraft. The Global Hawk (GH) is one such aircraft that can fly for up to 24 h at an altitude of 60 000 ft (18 288 m) and was first

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Alan Brammer, Chris D. Thorncroft, and Jason P. Dunion

the short-term spinup of the vortex, creating large ensemble spread in vortex strength that continues to amplify through the forecast ( Torn and Cook 2013 ). Ensemble-based sensitivity analyses for forecasts of AEWs over West Africa, as well as tropical cyclogenesis events that are linked to AEWs, have shown significant correlation between moisture west and north of the AEW trough in the initial conditions and the forecast intensity of the disturbance ( Torn 2010 ; Rios-Berrios et al. 2016 ). The

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Erin B. Munsell, Fuqing Zhang, Scott A. Braun, Jason A. Sippel, and Anthony C. Didlake

structure throughout the troposphere and lower stratosphere. The overall goal of this study is to investigate the evolution of the inner-core temperature structure of Edouard prior to and throughout its period of significant intensification by using both the unusual variety of observations and a 60-member convection-permitting ensemble simulation generated by the Pennsylvania State University (PSU) real-time Atlantic hurricane analysis and forecast system. In particular, the ensemble simulation provides

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Erin B. Munsell, Fuqing Zhang, Jason A. Sippel, Scott A. Braun, and Yonghui Weng

1. Introduction Over the past 5 years, considerable effort has been directed toward improving tropical cyclone (TC) intensity prediction. Despite this effort, the operational prediction of tropical cyclone formation and significant changes in intensity, such as rapid intensification (RI) or decay, remain particularly challenging ( Elsberry et al. 2007 ). These TC forecasts are typically characterized by considerable uncertainty, though past studies have demonstrated the ability of ensemble

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E. P. Nowottnick, P. R. Colarco, S. A. Braun, D. O. Barahona, A. da Silva, D. L. Hlavka, M. J. McGill, and J. R. Spackman

. 2015 ; Randles et al. 2017 ; Buchard et al. 2017 ). Additionally, Nowottnick et al. (2015) describes the GEOS-5 lidar signal simulation capability. Owing to these forecasting and data assimilation capabilities, GEOS-5 forecasts were a valuable resource for guiding mission operations and flight planning involving dusty SAL outbreaks during HS3, and the same modeling system forms the basis of the subsequent scientific analysis presented here. Aerosols are simulated in GEOS-5 with an online

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Zhining Tao, Scott A. Braun, Jainn J. Shi, Mian Chin, Dongchul Kim, Toshihisa Matsui, and Christa D. Peters-Lidard

Unified Weather Research and Forecasting (NU-WRF) modeling system ( Peters-Lidard et al. 2015 ; Tao et al. 2016 ) to investigate the 24–25 August SAL outbreak. The radiative and microphysical effects of dust and other aerosols on the SAL structure are analyzed. The paper is organized as follows: section 2 provides a brief description of the observational data and model used in this study, section 3 describes briefly the SAL event, section 4 describes the model configuration and experiment setup

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Sergio F. Abarca, Michael T. Montgomery, Scott A. Braun, and Jason Dunion

storm growth ( Maclay et al. 2008 ), there is great interest in developing secondary eyewall forecasting tools. Today, the valuable and sophisticated forecasting tools tend to rely on empirical relationships (e.g., Kossin and Sitkowski 2009 ) and do not necessarily directly incorporate the physical processes of secondary eyewall formation. Secondary eyewall formation dynamics have been the subject of intense contemporary research and contrasting views of the azimuthally averaged dynamics prevail

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Scott A. Braun, Paul A. Newman, and Gerald M. Heymsfield

associated with the strong environmental shear impinged on the entire western flank of the storm, with the driest air wrapping around the southern side of the circulation. It is not yet possible to determine the impact of the SAL and upper-level dry air from these observations. However, ensemble simulations with the Weather Research and Forecasting Model with coupled aerosol–cloud–radiation physics are being used to quantify the role of the SAL and dry air in this case. Fig . 10. Equivalent potential

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Jonathan Zawislak, Haiyan Jiang, George R. Alvey III, Edward J. Zipser, Robert F. Rogers, Jun A. Zhang, and Stephanie N. Stevenson

1. Introduction The question of whether or not a tropical cyclone (TC) will intensify remains a challenge for both the forecasting and research communities. A diverse array of processes, spanning the environmental, vortex, convective, turbulent, and microphysical scales, can play a key role in determining the likelihood of intensification ( Marks and Shay 1998 ; Rogers et al. 2013a ). In terms of processes occurring on the vortex scale and smaller, these mechanisms can be grouped into

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