Planning & Mitigation | VOL. 14, ISSUE 86, September-October 2014

Numerical Weather Prediction Techniques

Numerical Weather Prediction (NWP) technique uses mathematical models of the atmosphere to predict weather based on current conditions. During the last two decades, weather forecasting all over the world has greatly benefited from NWP models. Significant improvement in accuracy and reliability of NWP products has been driven by sophisticated numerical techniques (advanced data assimilation algorithms, new observation systems, improved modeling techniques, physical parameterisations, advancements in computing power allowing for higher spatial resolution) and by the phenomenal increase in satellite observations. The objective cyclone prediction system (CPS) is a collective approach to address various components for improving cyclone forecasts (Fig 1). The CPS comprises five forecast components, namely, prediction of cyclogenesis by cyclone genesis potential parameter (GPP); multi-model ensemble (MME) technique for cyclone track prediction; intensity prediction by statistical cyclone intensity prediction (SCIP) model; rapid intensification (RI) prediction by RI-Index; and, prediction of decay of a cyclone after landfall by a statistical model. [caption id="attachment_1377" align="aligncenter" width="515"] Fig. 1: Cyclone prediction system[/caption] [caption id="attachment_1378" align="aligncenter" width="498"] Fig. 2: Multi model ensemble track forecasts along with various NWP model track of Phailin[/caption] A cyclone genesis parameter, termed the GPP for the northern Indian Ocean (NIO) is developed based on four variables—vorticity at lower level, middle tropospheric relative humidity, middle tropospheric instability, and the vertical wind shear. A number of low-pressure systems form over the NIO, but not...

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