iCAST: A PROTOTYPE THUNDERSTORM NOWCASTING SYSTEM FOCUSED ON OPTIMIZATION OF THE HUMAN-MACHINE MIX

A prototype thunderstorm nowcasting system, tentatively named iCAST (interactive Convective Analysis and Storm Tracking), is being developed at Environment Canada with an emphasis on optimizing the ‘human-machine mix’. The prototype aims to build on the strengths of the human forecaster in the thunderstorm nowcasting process while making the best use of machine computing capabilities. iCAST is being prototyped on a platform developed at Environment Canada called Aurora. Aurora is an object-oriented conceptual modeling system that allows forecaster interaction with graphical objects such as grids, areas, lines, points, and time links. Aurora also ingests NWP (currently the Canadian GEM and US RUC models), high-resolution satellite data, radar data (Canadian and US), surface station observations, and lightning network data. iCAST employs a three-stage approach to nowcasting. First, NWP model output, past weather, current observations, and conceptual models are used to generate a mesoscale prognosis for the T+6 timeframe. The forecaster identifies and creates objects for both synoptic-scale features (such as fronts and jets) and mesoscale features (such as lake-breeze fronts and outflow boundaries). In addition, the forecaster identifies areas where convection may be expected to occur at that time. Next, mesoscale analyses are performed hourly by the forecaster to verify the existence and locations of the mesoscale features using mainly observations, but also some NWP guidance. The forecaster must use pattern recognition and conceptual models to build a coherent depiction of the weather, despite any missing or conflicting data. Lastly, once thunderstorms are present or imminent, storm-scale nowcasting is undertaken. We are currently experimenting with storm track modification and filtering as a way to achieve an optimal humanmachine mix at storm-scale. The forecaster may use conceptual models, analyzed/nowcast mesoscale feature information, current observations, and NWP model output to modify cell tracks and convective trends for the highest priority storms. In the prototype phase, iCAST will help to assess the value of human input to the convective nowcast problem via an automated verification process. In addition, we will test whether a semi-automated warning generation interface leads to more efficient and effective warning generation. It is anticipated that successful components of the iCAST prototype will be proposed for transfer to Environment Canada’s national forecaster workstation presently under development (NinJo). iCAST will be used in a real-time, operational setting during the summer of 2009 via a Research Support Desk at the Ontario Storm Prediction Centre in Toronto. Preliminary results will be presented at the symposium.