Predictability studies of genesis and non-genesis using global model ensembles

During the 2010 PREDICT field campaign and also in 2011, new real-time probabilistic products pertaining to tropical cyclogenesis were provided based on ECMWF and NCEP ensemble forecasts. Using quantitative metrics based on critical values of circulation, local thickness anomaly, and mean sea level pressure to define the onset of genesis, probabilistic verifications of these ensemble forecasts are provided. To complement these forecasts, aspects of error growth for 0-10 day forecasts on the synoptic- through to meso- scales are quantified for cases that do and do not develop into tropical cyclones. The reasoning behind why predictability is lost at longer forecast lead times is investigated through an examination of perturbation growth and scale interactions in the ensemble forecasts.