On the lookout: Rescuers with a search and rescue dog searching for missing flood victims at Felda Kerteh 3 in Dungun, Tererengganu. — Bernama
PETALING JAYA: The floods on the east coast of the peninsula are driven by the “monsoon surge” which pushes the rain belt further inland, says a climatologist.
National Antarctica Research Centre climatologist Prof Datuk Dr Azizan Abu Samah said flood patterns can differ from year to year.
However, he said major floods such as the one in 2014 and currently taking place in 10 states will only occur once during “a particular northeast monsoon season”.
Currently, the states affected by floods caused by the northeast monsoon are Kelantan, Terengganu, Kedah, Perlis, Perak, Negri Sembilan, Melaka and Johor.
However, the east coast states are the worst affected.
“It’s difficult to compare or define how different each flood is, as there are similarities and differences. Most major floods tend to occur during neutral El Nino/Southern Oscillation (Enso) or La Nina years, but not during El Nino years.
“For example, in 2013, major flooding happened in southern Thailand, while in 2014, it was worse in Kelantan. However, both were caused by the same monsoon surge,” Azizan said, referring to a cold surge.
He defined monsoon surge as one of the main drivers of rainy weather, with a strong surge during the northeast monsoon capable of triggering continuous rain that lasts 48 to 72 hours.
“A strong surge is defined as one with wind speeds exceeding 20kph, with the current surge reaching speeds of 40kph.
“Typically, a major flood happens only once during a particular northeast monsoon season. If another major flood occurs before the end of December, it would be unusual.
“The west coast is also affected depending on the speed of the surge. If the surge is stronger, the rain belt is pushed further inland, and the surge can move over the main mountain range.
“This causes heavy rainfall on the west coast of Peninsular Malaysia and the east coast of Sumatra, as seen during the 2021 floods.
“All floods during the northeast monsoon are driven by the cold surge, with its strength influencing the intensity of rainfall. If the surge is weaker, the rain is less heavy,” said Azizan.
