Strengthening Positive Indian Ocean Dipole Intensifies Australian Drought

Discussion: The positive phase of the Indian Ocean Dipole continues to strengthen and rivals 2001 and 1997 as the strongest on record. Strong trade winds are evident north of Australia and into the eastern tropical Indian Ocean up-welling cool waters while the western tropical Indian Ocean remains somewhat warmer than normal. The influence on climate has been profound causing the latest retreat of the wet Indian Monsoon on record and accelerating drought in Indonesia to Australia while East Africa is very wet. Interestingly, the surface pressure at Darwin is unusually high compared to near normal at Tahiti and driving a persistent negative southern oscillation index common only when El Nino is in-place. The –SOI pattern along with +IOD will continue to produce worsening drought in Australia ahead of the summer season. Despite lack of an official El Nino episode, most commonly related to harsh Australian drought there is no El Nino now and Australia may observe one of their worst drought’s on record as summertime arrives. The latest 15-day rainfall forecasts indicate chance of up to 0.75 in. of rain in central Western Australia by the GFS and CMC ensembles while the ECM ensemble is dry (nationally). The dry ECM ensemble is favored.