Possible Shift in the Indian Ocean Dipole?

Fig. 1: Northwest Africa drought is developing and expected to intensify.

Discussion: The Indian Ocean SSTA is somewhat warmer than normal (Fig. 1). In the tropics, anomalous warm SSTA in the western Indian Ocean associated with positive phase Indian Ocean dipole (+IOD) has spread eastward during recent weeks. The tropical Indian Ocean is now slightly warmer in the eastern tropics (compared to the western tropics). The IOD pattern is neutral. However, the anomalous warmth in the tropics is impressive. Looking back 30 years for the month of February, similar widespread warm SSTA in the tropical Indian Ocean occurred in 1998, 2010, and 2016. Each analog year was following the mature stage El Nino similar with 2024. The Indian Ocean basin is warmer this year due to marine heatwaves (MHW) west and southwest of Australia and off the Southeast Coast of Africa. Based on the analog years mentioned, the MAR/APR/MAY climate pattern for India and Southeast Asia to Australia is mostly hotter than normal (Fig. 2) with a sharp divide between heavy rains developing in the eastern tropical Indian Ocean due to the warming SSTA extending to Northern Australia while areas to the north are drier than normal including Southeast Asia to the Philippines (Fig. 3). The rainfall forecast pattern identifies a shift in wet anomalies across tropical Africa/Western Indian Ocean tropics from Q4/2023 associated with +IOD toward a potential -IOD scenario.

Fig. 2-3: Based on an analog, the temperature and precipitation anomalies for MAR/APR/MAY 2024 across the Indian Ocean basin and vicinity and eastward.