A Gridded TCM to Support Forecast Operations at NHC and WFOs

A new gridded representation of the Tropical Cyclone forecast advisory Message (TCM), generated by the GWAVA (gradient wind asymmetric vortex algorithm; Mattocks and Forbes, 2008) parametric wind model, is being experimented with for implementation at the National Hurricane Center. Currently undergoing evaluation during the 2017-2018 hurricane seasons, it provides a consistent starting point for local and marine forecasters at multiple WFOs and national centers to enable them to create more realistic renditions of the inner-core structure of hurricanes and more realistic characterizations of the tropical wind field at landfall and inland that are consistent with official forecasts. With the objective of making this process even simpler, longer term plans also include evaluating the feasibility of including the gridded TCM in the national blend of models.

Congruent with the Hurricane Specialists' OFCL forecast track parameters, these high quality depictions of the surface wind forcing will be used to drive the Nearshore Wave Prediction System (NWPS; Van der Westhuysen, A. J. et al., 2013, 2014) at coastal WFOs and the Regional Wave Prediction System (RWPS; Padilla-Hernandez et al., 2017) at national centers during tropical cyclone events. Envisioned as a replacement for the current labor-intensive TCMWindTool in AWIPS, the gridded TCM will ameliorate the extreme product preparation and delivery stress that operational forecasters face when preparing tropical cyclone wind forecast inland or across multiple ocean basins.

Results from the gridded TCM for hurricanes Harvey, Irma, Maria, and Nate (2017) will be presented and assessed using statistical metrics. Upgrades and improvements planned for 2018 will also be described.