This work was funded by the NWS Aviation Weather Branch via Grant DG133W06CN0182, under the direction of Kevin Johnston, Cynthia Abelman, and Curt Neidhart and through the NextGen program under the guidance of Mark Miller. The success of this demonstration was due to the six years of support provided by the FWD staff in entering boundaries and monitoring the products in real time, and to Dan Megenhardt at NCAR who provided numerous engineering enhancements and excellent real-time support. Steven Fano, Gregory Patrick, William Bunting, Ted Ryan, and Lance Bucklew provided us with valuable and insightful feedback throughout the demonstration. Thomas Amis and the Fort Worth CWSU staff provided helpful commentary on the nowcast fields. Collaboration with Stephan Smith, Mamoudou Ba, Kenneth Sperow, Scott O’Donnell, Xuning Tan, John Crockett, and Lingyan Xin of NWS MDL made it possible to completely integrate this system into the WFO environment and provide the forecasters with tools on AWIPS, including the boundary tools developed by Dave Albo at NCAR. Karen Griggs provided terrific assistance with the figures. The three formal reviewers provided detailed, discerning, thoughtful reviews that really helped make the paper much more complete.
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The Nowcasting Working Group of the World Meteorological Organization (WMO) World Weather Research Program has defined nowcasting as follows: forecasting with local detail, by any method, over a period from the present to a few hours ahead; this includes a detailed description of the present weather.
In lieu of lightning data, which were not available in the FOTL-ANC system, convective storms are defined as storms reaching radar echo intensities ≥35 dBZ. This designation is based partially on studies by Dye et al. (1989) and Gremillion and Orville (1999), who have shown that the onset of storm electrification generally occurs >5 min after storm echoes of 30 dBZ or greater have reached subfreezing levels.
All times are listed in UTC; subtract 5 h for Fort Worth, TX, central daylight time.
Storm extrapolation nowcasts of existing storms are obtained using the radar-based TITAN (Dixon and Wiener 1993) algorithm. Storm extrapolation and persistence are the typical benchmark nowcasts against which all other short-term precipitation nowcasts are compared (e.g., Mueller et al. 2003; Ebert et al. 2004, Pierce et al. 2004; Wilson et al. 2004; Saxen et al. 2008).
Hereafter, FOTL-ANC (ANC) notations are used to represent human (no human) involvement in producing the nowcasts.