Forecasting and nowcasting convective weather phenomena over southern peninsular India – Part I: Thunderstorms

Abstract

A few case studies of thunderstorms over Chennai and its neighbourhood have been discussed with its antecedent thermodynamic stability indices and parameters that are usually favourable for the development of convective clouds. As the forecast based on upper air data (radio sonde / radio wind and /or GPS sonde) is not time as well as location specific, data obtained from Doppler Weather Radar, Chennai have been used to issue location / time specific thunderstorm warnings especially for the aircraft operations from Chennai airport. Monitoring of sea breeze front propagation and velocity spectrum width data may help the forecaster to nowcast the development and movement of thunderstorms. Rainfall variability has been analysed using the radar reflectivity data based rain rate estimation and precipitation accumulation over a period of time. It is well understood from this analysis that fully calibrated radar and aptly fine tuned radar reflectivity (z) – rain rate (R) relationship will address the problem of inadequacy of rain gauges besides giving a better quality hydrological data (than that is being obtained through sparsely located surface rain gauges) which may be quite useful for the administrators and water resources managers.