A WEIGHTED CONSENSUS APPROACH TO TROPICAL CYCLONE 96-H AND 120-H TRACK FORECASTING

1. A WEIGHTED CONSENSUS APPROACH TO TROPICAL CYCLONE 96-H AND 120-H TRACK FORECASTING 1Lt James Hughes (Mar 2007)Advisor: Prof. Russell Elsberry 2nd Reader: Mark BootheBeneficiary: JTWC and DoD • A long-range (96 h – 120 h) weighted position consensus for tropical cyclone tracks is evaluated for 24 western North Pacific storms in 2006. • The first weighted position technique simply weights the 96-h, 108-h, and 120-h dynamical model positions inversely to their distances from the 60-h, 66-h, and 72-h consensus positions, which yields modest improvements over an unweighted position consensus • The second weighted consensus technique uses the same weighting factors but is applied to the forecast motion vectors to assess 96 h – 120 h track errors, which yields reductions in track errors of 9.9% at 96 h and 5.6% at 120 h relative to unweighted postion consensus errors. • The 96 h – 120 hweighted position consensus (grey stars) indicates an improvement over an unweighted consensus (blue asterisks). • Improvement is due to assigning the NOGAPS model (NGPI) the largest weighting factor (0.75), since the NOGAPS model is closest to the consensus from 60 – 72 h.