On the three days of 7–9 August 2012 unusually strong rains poured almost a meter of rain on Manila, the capital of the Philippines, causing widespread flooding in the city. The city is often struck by heavy rains during the wet season that peaks in August, but these are usually associated with tropical cyclones and do not last as long. The rains on 7–9 August were very strong monsoon rains that lasted for three days. The intensity was increased by two tropical storms passing to the North of the Philippines. Comparing with historical data over 1947–2010, the amount of rain on a single day was the third largest recorded, implying a return time of around 20 year. However, as the rains lasted three days, the total amount has a return time of more than 600 years. In general, greenhouse warming will produce more intense short-duration rain events, but the contribution of global warming in intensifying this specific event is still an open question.
Siswanto, GJ van Oldenborgh, G Lenderink. Floods in Manila August 2012
published, KNMI Kenniscentrum, 2012