Development of NWP Based Objective Cyclone Prediction System (CPS) for North Indian Ocean Tropical Cyclones — Evaluation of Performance

Abstract

ABSTRACT: An objective NWP based Cyclone Prediction System (CPS) has been developed and implemented at IMD for operational cyclone forecasting over the north Indian Ocean (NIO). The five forecast components of CPS are (a) Genesis Potential Parameter (GPP), (b) Multi-Model Ensemble (MME) technique for track prediction, (c) Statistical Cyclone Intensity Prediction (SCIP), (d) rapid intensification and (e) decay model to forecast intensity after the landfall.Verification shows GPP had higher probability of detection (0.98) and lower false alarm ratio (0.27) with higher critical success index (0.72). Mean track error of MME ranged from 74 km at 12 h to 200 km at 72 h and reduced by 27% to 52% for 36 h to 72 h forecast during 2009-2013. The mean forecast errors of landfall position ranged from 56 km at 24 h to 137 km at 72 h and landfall time error ranged from 3.6 h at 24 h to 6.1 h at 72 h. Mean intensity errors of SCIP ranged from 5.4 kt at 12 h to 16.9 kt at 72 h. The probabilistic rapid intensification forecast was skillful compared to climatology. The 6-hourly decaying intensity (after landfall) errors ranged from 3 kt to 4.9 kt. Results demonstrate the potential of CPS for operational cyclone forecast over the NIO. Keywords: tropical cyclone, Cyclone Prediction System (CPS), forecast verification, North Indian Ocean