El Nino Advisory And Outlook For The Southwest Monsoon Season

Singapore, 30 May 2014 – The Meteorological Service Singapore (MSS) is forecasting weak to moderate El Niño conditions to develop in the next few months, bringing drier and warmer conditions to Singapore and the region. Rainfall for Singapore over the coming Southwest Monsoon season between June and September 2014 could range between 10 – 40% below average, while the average daily temperature is expected to be about 1°C above average (refer to Table 1 for average values).

2The El Niño refers to the abnormal warming of the tropical Pacific Ocean and is known to disrupt normal weather patterns in various regions of the world. In Southeast Asia, the effect of the El Niño is prolonged drier and warmer weather in large parts of the region. (further information on the El Niño is given in Annex A).

3Since March 2014, the sea-surface temperature in the tropical Pacific has been warming steadily. This is a known precursor to an El Niño build-up. Based on the latest warming trend in the Pacific Ocean, as well as the computer model forecasts from various global climate centres, El Niño conditions could develop as early as end July. The strength of the El Niño is forecast to be weak to moderate and is likely to peak in the last quarter of the year. Typically, an El Niño which peaks late in the year will start to weaken in the first half of the following year.

4Based on past El Niño events of moderate strength, Singapore is expected to experience below average rainfall during the June to September period, which is also the traditional dry season in the region that is brought about by the Southwest Monsoon. In 1963, when an El Niño of moderate strength occurred, Singapore’s rainfall total over this four-month period was reduced by almost 40% compared to the long-term average. In the more recent occurrence of a moderate El Niño in 2009, the corresponding figure was about 20% below the long-term average. Average daily temperature for the same period in 2009 was 1.1°C warmer than the long-term average of 27.4°C. The relationship between El Niño strength and impact on rainfall is however not straightforward, as there are also other factors affecting local and regional rainfall patterns.

5Rainfall in May 2014 has so far been above average for most parts of Singapore. However, drier weather can be expected from the second week of June 2014 with the onset of the Southwest Monsoon. For the next four months (June-September 2014), rainfall is expected to be below average for most parts of Singapore, and average daily temperature is expected to be above average.

6Prolonged drier and warmer conditions during an El Niño will increase the risk of the occurrence of transboundary smoke haze from land and forest fires in the region. Depending on various factors such as wind direction and locations of hotspots in the fire-prone areas, Singapore could be affected by transboundary smoke haze during this period.

7MSS will continue to closely monitor the conditions in the tropical Pacific that lead to the development of the El Niño, as well as the regional weather and haze situation, and provide updates if necessary.

8In anticipation of the onset of drier weather, the Inter-Agency Haze Task Force (HTF) has already been activated and is co-ordinating their respective action plans in preparation for haze. Forecasts and advisories will take into account the new PSI system, as well as the revised Ministry of Health (MOH)’s health advisories and Ministry of Manpower (MOM)’s workplace guidelines. The public can access the latest issued advisories at the NEA website (www.nea.gov.sg), the haze microsite (www.haze.gov.sg), or follow NEA on NEA Facebook (www.facebook.com/NEASingapore) and NEA Twitter (@NEAsg).

9Reservoir stock levels will be impacted by drier weather and lower rainfall. In response, PUB will have to ramp up its production of NEWater and desalinated water to maintain reservoir stock and ensure water availability. To prepare for the drier months ahead, PUB strongly urges the community and businesses to continue to conserve water, and play our part to stretch our water resources.

Table 1: Long-term temperature and rainfall statistics of Changi Climate Station

June July August September
Average daily temperature(deg C) 27.7 27.4 27.3 27.2
161.0 158.6 175.0 169.3

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