Verification of Nowcasts from the WWRP Sydney 2000 Forecast Demonstration Project

Abstract The verification phase of the World Weather Research Programme (WWRP) Sydney 2000 Forecast Demonstration Project (FDP) was intended to measure the skill of the participating nowcast algorithms in predicting the location of convection, rainfall rate and occurrence, wind speed and direction, severe thunderstorm wind gusts, and hail location and size. An additional question of interest was whether forecasters could improve the quality of the nowcasts compared to the FDP products alone. The nowcasts were verified using a variety of statistical techniques. Observational data came from radar reflectivity and rainfall analyses, a network of rain gauges, and human (spotter) observations. The verification results showed that the cell tracking algorithms predicted the location of the strongest cells with a mean error of about 15–30 km for a 1-h forecast, and were usually more accurate than an extrapolation (Lagrangian persistence) forecast. Mean location errors for the area tracking schemes were on the ord...

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