JAKARTA, KOMPAS — The climatic phenomenon of El Niño is said to be active again this year, even though it is still weak compared to 2015. Its impact on heightening the dry season in Indonesia must be monitored until April 2019.
The United States National Oceanic and Atmospheric Agency (NOAA) confirmed this weekend the formation of El Niño. The NOAA Climate Prediction Center announced, "A weak El Niño has formed and is expected to continue to be active in the northern hemisphere until spring 2019," referring to the months of March, April and May.
El Niño occurs naturally when the waters of the Pacific Ocean grow warmer than the annual average temperature, which greatly affects the weather conditions in many countries, including Indonesia. NOAA data shows that the waters of the Pacific Ocean increased +0.8 degrees Celsius in early February, although the temperature increase has now fallen to +0.5 degrees Celsius.
Climate information and air quality head Siswanto at the Meteorology, Climatology and Geophysics Agency (BMKG) said in Jakarta on Sunday that the agency was monitoring El Niño-related activities.
"We are still formulating a draft forecast for the 2019 dry season. For the time being, we expect the dry season to be normal in most of Indonesia, although some will progress or reced [faster], but it will not be dominant. There will be a national meeting this week for climatology stations throughout Indonesia to finalize the seasonal forecast," he said.
The current El Niño was predicted to end in June-July, so it was less likely to affect the country’s dry season. "However, we can only become certain of this in April, because the temperature of the ocean waters in the Pacific is largely determined by conditions in the spring, around April," said Siswanto.
During normal conditions (El Niño–Southern Oscillation/ENSO), warm winds from eastern waters flow to the western Pacific Ocean near Australia and Indonesia. When the warm ocean waters trigger deep atmospheric convection, extensive rainfall will occur in June-August in some parts of the country. However, during El Niño (positive ENSO phase), the wind currents weaken or reverse and pools of warm water in the central and eastern Pacific head toward the eastern Pacific near South America, and rainfall and storms also head away from Indonesia.
Chance of rain
The BMKG weather analysis shows that the Asian monsoon dominated almost all areas of Indonesia during the past week. Changes in wind currents were seen around the equator. Winds from the northern and southern hemisphere converged from along the west coast of Sumatra, across the south of Java and to East Nusa Tenggara, contributing to rain cloud formation in the area.
Siswanto said that high daily rainfall of more than 100 millimeters was predicted to occur in several regions, including: along the western coast of Sumatra, in West Java, Central Java, Yogyakarta, East Java, Bali, North Sumatra, Southeast Sulawesi, South Sulawesi, Buru Island and Papua.
Meanwhile, parts of Java (11 percent of all subdistricts) had a forecast of low flooding, especially coastal areas in the north and south. A small area along the northern coast of East Java in Probolinggo regency had a potential for high floods. (AIK)