Feels like the year-end wet season? You're right

Victoria Vaughan Straits Times 26 Aug 10;

RAINFALL in Singapore over the last few months is closer to the volumes seen in the monsoon season at the end of the year. And the wet weather is set to continue.

The total monthly rainfall for June was 240.5mm and it was 298.5mm for last month - figures which are almost double the long-term average rainfall for these two months, which are typically the country's driest after February. This month's figures are already at 146.5mm, currently below the average of 151.9mm, but there are still six days till the end of the month.

The average rainfall recorded in the traditional wet months of November and December is 262.4mm and 329.5mm respectively.

The huge deluge of rainwater in the last two months also resulted in three major reports of flooding, affecting areas such as Orchard Road, Bukit Timah, Newton Circus and Telok Kurau.

From June to Tuesday, 34 heavy-rain warnings have been issued by the National Environment Agency (NEA).

This tops the total number of warnings issued during June, July and August in the last three years with 19 issued in 2007, 13 in 2008 and 20 last year.

There is a silver lining, however, to the deluge - haze has not darkened Singapore's horizons as the weather has been too wet for forest burn-offs in Sumatra.

The haze has been an almost yearly problem in the past years, with the air quality index sometimes hitting the unhealthy range.

In the last three months, the PSI - a measure of air quality - has only slipped above the good range three times.

Experts here point to La Nina for the damper conditions. The weather pattern brings unusually cold ocean temperatures in the eastern Equatorial Pacific and increases in vertical air currents in this region, resulting in more clouds and therefore more rain.

A spokesman for the NEA's Meteorological Services Division said: 'From June to August, Singapore has experienced above average rainfall and the trend is likely to continue till September. La Nina will enhance the intensity of the afternoon thunderstorms and Sumatra squalls seen during the south-west monsoon and inter-monsoon months,' he added.

The unexpected heavy rainfall here is being mirrored in other countries in Asia, such as Pakistan where the jetstream - a cold wind travelling from west to east - is exacerbating the monsoon season there, causing the worst floods in 80 years.

Closer to home, Indonesia's weather experts say the country is experiencing extreme weather causing torrential rain and floods in Jakarta in what is usually the dry season. It is the same story in Malaysia, where the gloomy forecast of heavy rain, lightning and thunderstorms is predicted up to early next year.

La Nina conditions are expected to continue until early next year and NEA predicts next month will have a higher than average rainfall but will not be as wet as previous months.