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Burkely T. Gallo, Jamie K. Wolff, Adam J. Clark, Israel Jirak, Lindsay R. Blank, Brett Roberts, Yunheng Wang, Chunxi Zhang, Ming Xue, Tim Supinie, Lucas Harris, Linjiong Zhou, and Curtis Alexander

. Resultant mesoscale boundaries were also abundant from convection the previous day. Subjective ratings of model performance within the daily domain of interest were mixed, with the HRRRv3 performing best according to the nine survey respondents (not shown). Surrogate severe fields designed to optimize the ROC area, FSS, and the reliability component of the Brier score show how different a forecast from the same model can look, simply by adjusting the UH threshold and σ value used to generate the

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Siebren de Haan, Gert-Jan Marseille, Paul de Valk, and John de Vries

ECMWF focusing on the midterm (5–10 days) and HIRLAM X11–H11 focusing on the short range (0–24 h). This might and most probably will lead to a different deployment of the observations in global and mesoscale models, as is further discussed in section 5 . Results of the assimilation of scatterometer observations is discussed in section 4a by comparing forecasts of wind and pressure from the H11 and X11 experiments with available independent observations from buoys, ships, and ASCAT. We focus on

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Dan Bikos, Daniel T. Lindsey, Jason Otkin, Justin Sieglaff, Louie Grasso, Chris Siewert, James Correia Jr., Michael Coniglio, Robert Rabin, John S. Kain, and Scott Dembek

analysis of the convection-allowing model output and offered a unique perspective on the main features of the day, if they were synoptic in origin. Of course, the converse is true as well; if the imagery indicated very little discernible large-scale impact on the region of interest, then this alerted the forecasters to the importance of mesoscale details on the subsequent convective evolution. The length of time for analysis of this specific forecast field was typically less than 10 min (including

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Logan C. Dawson, Glen S. Romine, Robert J. Trapp, and Michael E. Baldwin

mesoscale and convective processes provides qualitative information about the expected convective mode, which aids forecasters in anticipating predominant severe weather hazards ( Kain et al. 2008 ; Weisman et al. 2008 ; Kain et al. 2010 ). Even with horizontal grid spacings of 1–4 km, convection-permitting forecasts are still too coarse to fully resolve smaller-scale convective features and severe weather phenomena such as mesocyclones and tornadoes. In an effort to overcome this limitation of grid

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Xuejin Zhang, Sundararaman G. Gopalakrishnan, Samuel Trahan, Thiago S. Quirino, Qingfu Liu, Zhan Zhang, Ghassan Alaka, and Vijay Tallapragada

frictional drag in very high winds . Geophys. Res. Lett. , 37 , L07802 , doi: 10.1029/2009GL042206 . Hendricks, E. A. , Peng M. S. , Ge X. , and Li T. , 2011 : Performance of a dynamic initialization scheme in the Coupled Ocean–Atmosphere Mesoscale Prediction System for Tropical Cyclones (COAMPS-TC) . Wea. Forecasting , 26 , 650 – 663 , doi: 10.1175/WAF-D-10-05051.1 . Hong, S.-Y. , and Pan H.-L. , 1996 : Nonlocal boundary layer vertical diffusion in a medium-range forecast model

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John D. McMillen and W. James Steenburgh

greatly impacted the Wasatch Front urban corridor south and east of the Great Salt Lake (GSL), including Salt Lake City ( Carpenter 1993 ; Steenburgh et al. 2000 ; Alcott et al. 2012 ; Yeager et al. 2013 ). Exacerbating the forecast challenge is the inherently low predictability of convective systems and the small-scale phenomena that influence mesoscale precipitation features ( Lorenz 1982 ; Anthes 1986 ; Stamus et al. 1992 ; Emanuel 1994 ; Mullen et al. 1999 ); the sensitivity of GSLE systems

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Myunghwan Kim, Hyun Mee Kim, JinWoong Kim, Sung-Min Kim, Christopher Velden, and Brett Hoover

1. Introduction In numerical weather prediction (NWP), an analysis can be produced through assimilation of observations into a “background” or first-guess state, often from a short forecast from the previous analysis. The updated analysis can then be used to continue the forecast–analysis cycle, as well as serve as initial conditions for a medium-range forecast. While the number and types of observations have increased, due largely to the growing availability of satellite data, the impact of

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Charles M. Kuster, Jeffrey C. Snyder, Terry J. Schuur, T. Todd Lindley, Pamela L. Heinselman, Jason C. Furtado, Jeff W. Brogden, and Robert Toomey

1. Introduction National Weather Service (NWS) forecasters consider a vast amount of information during the warning decision process, including scientific conceptual models that help them anticipate impending hazardous weather (e.g., Andra et al. 2002 ; Lindley and Morgan 2004 ). The recent dual-polarization (dual-pol) upgrade to the Weather Surveillance Radar-1988 Doppler (WSR-88D) radar network provides an additional suite of variables and derived products that could be integrated into

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John D. McMillen and W. James Steenburgh

–averaged max vertical velocity. (b) MP subdomain max vertical velocity at available forecast hours during the GSLE period. All simulations are cold start initialized at 1800 UTC 26 October 2010 and run for 24 h. Initial atmospheric and land surface conditions, as well as lateral boundary conditions, are derived from 6-hourly operational North American Mesoscale Model (NAM) analyses obtained from the National Oceanic and Atmospheric Administration (NOAA) National Operational Model Archive and Distribution

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Burkely T. Gallo, Adam J. Clark, Bryan T. Smith, Richard L. Thompson, Israel Jirak, and Scott R. Dembek

CONUS throughout the period of interest. Ongoing thunderstorms were expected to limit the instability across the central High Plains. A sharpening dryline and remnant boundaries from the morning convection were anticipated as the focus of the subsequent severe convection. Such mesoscale detail poses a forecasting challenge to humans and NWP alike, making this a difficult day to forecast. Effective bulk shear was noted by the SPC as being sufficient for supercells with a tornado threat east of the

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