The Meteorology, Climatology and Geophysics Agency (BMKG) has issued a warning for potential extreme weather predicted to occur on 15 to 20 August 2021 in a number of provinces.
According to BMKG Deputy for Meteorology Guswanto, the provinces that are expected to experience moderate to heavy rain are Aceh, North Sumatra, Riau, Riau Islands, West Sumatra, Jambi, Bengkulu, South Sumatra, Bangka Belitung Islands, Banten, West Java, Central Java, West Kalimantan, Central Kalimantan, East Kalimantan, North Kalimantan and South Kalimantan, North Sulawesi, Gorontalo, Central Sulawesi, West Sulawesi, South Sulawesi, Southeast Sulawesi, North Maluku, Maluku, West Papua, and Papua.
Guswanto said the potential for rain cloud growth is the impact of increased activity from the Madden Julian Oscillation (MJO) and the Equatorial Rossby wave.
“The MJO and the Equatorial Rossby Wave are atmospheric dynamic phenomena that indicate the potential for the growth of rain clouds on a wide scale around the area they pass through,” said Guswanto.
He explained that the MJO phenomenon moves from the Indian Ocean to the Pacific Ocean through Indonesia over a cycle of 30 to 40 days. Meanwhile, said Guswanto, the Rossby Wave phenomenon moves from the Pacific Ocean to the Indian Ocean by passing over Indonesia.
“Just like the MJO, when the Rossby Wave is active in Indonesia, it can contribute to increasing the growth of rain clouds in several parts of Indonesia,” he explained.
BMKG also observed the presence of confluence areas and a slowing of wind speed (convergence) that extends to the western waters of West Sumatra and from Riau to North Sumatra, which can contribute to the increase in the growth of rain clouds.
“The existence of these atmospheric dynamic conditions has the potential to increase the growth of rain clouds in the next one-week period in several parts of Indonesia,” he explained.
In addition, Guswanto continued, BMKG also warned of potential hydrometeorological disasters for the next five days.
“The disaster is in the form of floods or flash floods due to heavy rains in Riau, West Sumatra and Jambi,” concluded Guswanto.