Although tornado forecasting has remarkably improved over the last two decades with advanced forecasting techniques, weather satellites, numerical forecast models and Doppler weather radar, there is much about tornado forecasting that still remains a mystery.

CNN: STORY HIGHLIGHTS

Throughout most of its history, weather forecasting has been done by national governments, although, since any rain forecast for London incorporates data collected from as far away as Fiji, they have to co-operate.

ECONOMIST: Weather

Mr McCallum admitted in a news conference in April that seasonal forecasting was still in its infancy - a cross between climate change prediction and tomorrow's weather forecast.

BBC: Met Office cools summer forecast