Mumbai's weather forecast may just get better

For the first time, the weather bureau here need not depend on 24-hour forecasts of rain during the monsoons. The Indian Meteorological Department (IMD) on Tuesday began the installation of a Doppler radar at Navy Nagar.

The radar, which will replace a decade-old system, will issue heavy rainfall and cyclone warnings quicker, and with greater precision, to avoid a repeat of the July 26, 2005, deluge. Hours before the 944mm deluge, weather forecasters had only warned of very heavy rainfall: 70mm to120mm.

Even cyclones couldn’t be accurately forecast by the department. The technology, used successfully in Vizag, Kolkata and Chennai, will alert the bureau every five hours about monsoon clouds.

Manufactured by Bharat Electronics Ltd, the radar, which reached the city last month, is larger and cheaper than a Chinese version, which was rejected for security reasons.

“It is more of a monitoring tool than a forecasting tool. It’s called a ‘now casting’ tool which helps make the forecast accurate. It can trace and locate rain clouds five hours before,” said Dr RV Sharma, IMD deputy director-general.

It detects wind direction and speed, precipitation intensity and provides estimates of rainfall amounts. It gives forecasters the capability of early detection of thunderstorms that may bring with them large hail, heavy rain, strong wind and tornados.