Monthly Archives: June 2015

Increased risk of hotspot activity and transboundary haze

 

Singapore, 26 June 2015 – Meteorological Service Singapore (MSS) is forecasting that Singapore and the surrounding region can expect a drier and warmer than usual Southwest Monsoon season[1] (June – September/early October) this year. This is partly due to the prevailing moderate El Niño[2] conditions in the equatorial Pacific Ocean, which are likely to further develop in the months ahead.

2         With fewer rain days experienced this month, the total rainfall for June 2015 (as at 25 June 2015) recorded at the Changi climate station is 38% below the long-term average. Warmer days and nights have also been experienced in recent days. The average daily maximum and minimum temperatures for June 2015 (as at 25 June 2015) are 31.9°C and 26.5°C, about 0.6°C and 1.7°C above the long-term average respectively .

3          Lower than usual rainfall is expected to persist for Singapore in the next few months. For July 2015 the total monthly rainfall is forecast to be 15-45% below average. The long-term rainfall and temperature statistics for July to September at the Changi climate station are shown in Table 1.

	July	August	September
Average Monthly Rainfall Total (mm)	158.6	175.4	168.8
Average Daily Maximum Temperature (°C)	30.9	30.9	30.9
Average Daily Minimum Temperature (°C)	24.6	24.5	24.3

Table 1: Long-term temperature and rainfall statistics for July-September

Impact of El Niño on Singapore

4          Most models from the major global climate centres project a high likelihood that the tropical Pacific sea surface temperatures would continue to warm over the coming months and possibly reach strong El Niño levels. During the 1997 El Niño which is the strongest on record, Singapore experienced a sharp 53% reduction in June-September rainfall. In the last occurrence of a moderate El Niño in 2009, Singapore’s rainfall total over the June-September period was about 20% below the long-term average. The average daily temperature for the same period in 2009 was 1.1°C higher than the long-term average of 27.4°C. The relationship between the strength of the El Niño and the impact on rainfall is however not straightforward, as there are also other factors affecting local and regional rainfall patterns.

Risk of Transboundary Haze

5          With the drier and warmer weather over the southern ASEAN region in the coming months, exacerbated by the prevailing El Niño, we may see an escalation of hotspot activities, particularly in the fire prone provinces in Sumatra and Kalimantan. This would increase the risk of occurrence of transboundary haze in the region. The impact of the smoke haze on Singapore is dependent on factors such as the proximity and extent of the fires, the strength and direction of the prevailing winds, and the incidence and amount of rain.

6          In recent days, sporadic hotspot activities with localised smoke plumes have been observed in Sumatra. In addition, drier and warmer weather conditions have prevailed over Singapore and the surrounding region, indicating the start of the traditional dry season in the southern ASEAN region.

7          MSS will continue to closely monitor the regional weather and haze situation as well as the development of the El Niño, and provide updates when necessary. Updates on haze information and the El Niño are available in the MSS website at

• https://www.weather.gov.sg/warning-haze-satellite-image/
• https://www.weather.gov.sg/climate-el-la/

Haze Preparedness

8          In anticipation of the onset of drier weather, the Inter-Agency Haze Task Force (HTF) is co-ordinating the agencies’ respective action plans in preparation for haze. NEA’s haze forecasts and advisories will take into account the Ministry of Health (MOH)’s health advisories and Ministry of Manpower (MOM)’s workplace guidelines. The public can access NEA’s 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).

PUB’s preparedness

9          Drier weather and lower rainfall will affect reservoir stock levels. To prepare for the drier months ahead, PUB strongly urges the community and businesses to continue to conserve precious water.

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[1] Southwest Monsoon season is characterised by prevailing winds that blow predominately from the southeast or southwest. The Southwest Monsoon months are generally the drier months of the year.

[2] The El Niño is known to disrupt normal weather patterns around the world, and in the ASEAN region, the El Niño could lead to prolonged drier and warmer weather over large parts of Southeast Asia. Singapore would normally experience drier and warmer conditions during moderate to strong El Niño events, especially during the Southwest Monsoon period. At other times outside of these months, the impact of El Niño on local rainfall is not as significant.

 

Sumatra squalls and slightly hazy conditions also expected on few mornings

 

Advisory

Singapore, 16 June 2015 – Southwest Monsoon conditions are expected to persist for rest of June 2015, and the low level winds are forecast to blow predominantly from the southeast or southwest.

2As compared to the first half of June 2015, the second fortnight of June 2015 could experience fewer rain days. Short-duration thundery showers due to strong solar heating of land areas are likely on three to five days, mostly in the late morning and early afternoon. In addition, thundery showers with gusty winds due to ‘Sumatra’ squalls can be expected on one or two days in the pre-dawn and morning. On some days, maximum day-time temperatures of 34 degrees Celsius and warm nights can be expected.

3Slightly hazy conditions can be expected on a few days, in particular in the early morning due to the accumulation of particulate matter under light wind conditions.

4Rainfall for June 2015 is likely to be below normal.

Review of 1 – 15 June 2015

5Southwest Monsoon conditions prevailed in the first fortnight of June 2015 with low level winds blowing predominantly from the southeast or southwest. In the first week of June 2015, Singapore experienced a few warm days, in particular over the north-western part of the island, where the maximum daily temperature recorded was around 35 degrees Celsius.

6During the review period, Singapore experienced thundery showers on several days in the late morning and afternoon due to strong solar heating of land areas and convergence of winds. The highest total rainfall of 68.4mm was recorded on 8 June 2015 over Jurong. On 12 June 2015, moderate to heavy thundery showers affected many parts of the island in the afternoon, and the highest total rainfall recorded that day was 65mm over Mandai.

7Between 1 and 15 June 2015, rainfall was above average in the western parts of Singapore, and below average in the central and eastern parts of the island. The highest rainfall of 140mm and 170mm (70% to 110% above average) was recorded around Jurong, and the lowest rainfall of 20mm and 40mm (50% to 75% below average) were recorded around MacRitchie and East Coast areas.

 

STATISTICS FOR JUNE since 1869 (CLIMATE STATION)

Average rainfall for the month — 160.4 mm
Highest rainfall ever recorded — 378.7 mm (1954)
Lowest rainfall ever recorded — 21.8 mm (2009)
Average number of rain days — 13
Average daily maximum temperature — 31.3 degrees Celsius
Average daily minimum temperature — 24.8 degrees Celsius

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The public can view if it is raining over the 28^th SEA Games 2015 venues by selecting the check box “SEA Games 2015 venues” in the Rain Areas page (as shown in the image below)

 

Sumatra squalls and slightly hazy conditions also expected on few mornings

 

Advisory

Singapore, 2 June 2015 – During the next fortnight, Southwest Monsoon conditions are forecast to set in and low level winds are expected to blow from southeast or south-southwest.

2In the first half of June, a few warm days with maximum temperatures around 34 degrees Celsius can be expected in the afternoon. In addition, short-duration thundery showers due to strong solar heating of land areas are likely on five to seven days, mostly in the late morning and early afternoon. Thundery showers with gusty winds due to Sumatra squalls can be expected on one to two days in the pre-dawn and morning.

3Slightly hazy conditions can be expected on a few days, in particular in the early morning, due to the accumulation of particulate matter under light wind conditions.

4Rainfall for the first fortnight of June 2015 is likely to be near-normal.

Review of 1 – 31 May 2015

5Inter-Monsoon conditions prevailed in May 2015. During the period, the low level winds were light and variable in direction for most parts of the month, and occasionally blew from the southeast or south-southwest in the last week of May 2015.

6Singapore experienced wet weather conditions on most days in May 2015. The thundery showers fell mainly in the late morning and afternoon with the highest total rainfall of 119.6mm recorded on 3 May 2015 over Bukit Panjang area. In addition, on 23 May 2015, moderate to heavy thundery showers due to a Sumatra squall affected many areas of Singapore in the pre-dawn and morning.

7In May 2015, most parts of Singapore received near-average rainfall. The highest rainfall of 352mm and 368mm (80% to 115% above average) were recorded over the western and northern parts of the island around Choa Chu Kang and Woodlands respectively. The lowest rainfall of 59mm and 67mm (50% to 80% below average) were recorded over the eastern and south-western parts of the island around Changi and Tuas respectively.

 

STATISTICS FOR JUNE since 1869 (CLIMATE STATION)

Average rainfall for the month — 160.4 mm
Highest rainfall ever recorded — 378.7 mm (1954)
Lowest rainfall ever recorded — 21.8 mm (2009)
Average number of rain days — 13
Average daily maximum temperature — 31.3 degrees Celsius
Average daily minimum temperature — 24.8 degrees Celsius

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