Jakarta experienced on Tuesday night its worst rainfall in over a decade, with heavy rain pouring over the city nonstop until Wednesday morning, causing severe flooding in the capital and its satellite cities on the first day of 2020.

The Meteorology, Climatology and Geophysics Agency (BMKG) recorded rainfall intensity on New Year’s Eve at 377 millimeters per day, according to an observation conducted at Halim Perdanakusuma Air Force Base in East Jakarta.

Meanwhile, observations at Taman Mini Indonesia Indah, also in East Jakarta, and Jatiasih in Bekasi recorded rainfall intensity at 335 and 259 mm per day, respectively.

The figures are the highest in the city since 2007, when rainfall intensity reached 340 mm per day.

“The rain falling on New Year’s Eve in the western and northern parts of Java was very extreme and triggered floods in [Greater Jakarta] and Cikampek [in West Java]. This rain is not ordinary rain,” the agency wrote in a statement.

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The BMKG said the nearly record-high rainfall intensity was due to several factors, including the occurrence of a monsoon. According to the United Kingdom’s Met Office, a monsoon climate is characterized by “a dramatic seasonal change in direction of the prevailing winds of a region which brings a marked change in rainfall”.

“Wind moving from the northeast of Java Island met with another wind blowing from the south of the island. Such an encounter has led to the massive formation of clouds in the sky above Java Island,” the head of the BMKG’s public meteorology center, Fachri Radjab, said in a video uploaded by the agency’s official YouTube account.

He added the weather conditions had been worsened by a high amount of water vapor caused by the high temperatures of the Indian Ocean, especially in areas south of Java Island. “The water vapor later affected cloud formations over Java,” Fachri said.

The BMKG predicted heavy rain to continue in Greater Jakarta until Saturday as a result of the atmospheric conditions. (nal)