Category Archives: 2013

March 13, 2015

Thunderstorms with Hail in Singapore

An intense thunderstorm in the afternoon over western Singapore brought hailstones the size of small pebbles to the Bukit Batok area on 25 June 2013. The thunderstorm developed following strong solar heating and convergence of winds over western Singapore. Moderate rainfall of 31.8 mm over half an hour was recorded at Corporation Road between 2.50pm and 3.20pm.

The intense thunderstorm (in red and pink colours) as detected by weather radar and hailstones sighted at Bukit Batok around 3pm on 25 June 2013.

In 2014, hail was observed during an intense thunderstorm event on 14 October around the Turf Club Road area.

The previous reported occurrence of hail in Singapore was on 12 September 2009.

Severe Transboundary Smoke Haze during Southwest Monsoon 2013

In the second week of June 2013, hotspot activities escalated in central Sumatra as a result of the relatively dry atmospheric conditions in the region. Westerly winds over the equatorial Indonesia then blew the moderate to dense smoke haze in central Sumatra towards Malaysia and Singapore. Slightly hazy conditions was experienced in Singapore on 13 June 2013, but the condition deteriorated rapidly on 17 – 18 June 2013, with the 24-hr PSI readings breaching the Unhealthy and Very Unhealthy levels within the next few days. The 3-hr PSI reached a record high of 401 on 21 June 2013, and the 24-hr PSI reached a record high of 246 on 22 June 2013, making this the worst transboundary smoke haze occurrence ever experienced in Singapore.

The smoke haze situations on 18 – 19 Jun 2013 were shown in the following NOAA-18 satellite images.

A change in wind direction on 25 June 2013 then brought an end to the haze in Singapore.

The unseasonal westerly winds were partly attributable to the presence of an unusually strong low pressure area to the southwest of Sumatra in Indian Ocean and also to the presence of the two tropical storms near Philippines during the period.

Northeast Monsoon Surges 2013

A moderate Northeast Monsoon surge affected the region on 18 – 22 January 2013 during the wet phase of the Northeast Monsoon season. The surge was due to the strengthening of winds over the South China Sea. The rain was prolonged and widespread, intermittent and heavy at times with occasional windy conditions. The surge was most intense on 19 January, with the highest total rainfall of 134.7 mm recorded at Changi area.

Another surge occurred quite late into the Northeast Monsoon on 12 – 14 February 2013. This surge was weaker and brought moderate to heavy thunderstorms over Singapore on 14 February, with the highest rainfall total of 117.6 mm recorded at Seletar area.

March 12, 2015

Warm Temperature in March and April 2013

Singapore experienced warm conditions in March and April 2013, due to the weakening of the winds coupled with strong convective heating in the day, which is typical during this time of the year as the sun is almost overhead at the equator and the Northeast Monsoon transitions into the Inter-Monsoon season. During this period, the winds are weak and variable, and hot afternoons are common.

The highest daytime maximum temperatures for March and April 2013 are 33.8 °C and 36.2 °C, recorded on 30 March and 16 April respectively.

The highest temperature ever recorded at our climate station in Changi is 36.0 deg C on 26 Mar 1998. The highest temperature recorded at any station in Singapore so far is 37.0 deg C on 17 April 1983.

October 6, 2013

Sumatra Squalls during Late Southwest Monsoon 2013

Singapore experienced Sumatra squalls on multiple occasions during the late phase of Southwest Monsoon in 2013 from August to early October. A particularly severe squall affected Singapore during the early and predawn hours of 6 October 2013. As a result of the passage of the squall, strong winds were experienced around the island with the strongest gust of 77.7 km/h recorded at West Coast Highway.

Sumatra squalls are common during the Southwest Monsoon which typically last from June to September/early October.

Sumatra squall brought strong gusty winds to Singapore on 6 October 2013.