La Nina sustains in the Pacific; strong negative Indian Ocean Dipole predicted
Cyclone Asani lay centred about 30 km East of Machilipatnam and 40 km South-West of Narsapur in Andhra Pradesh buffeted by winds speeding up tp 65-75 km/hr and gusting to 85 kmph on Wednesday evening. The weakening storm will bring light to moderate rainfall over Coastal Andhra Pradesh and coastal areas of Odisha and West Bengal and heavy rainfall over parts of Coastal Andhra Pradesh on Thursday, India Meteorological Department (IMD) said in an update. .
Asani is expected to lose cyclone status and weaken into a deep depression by Wednesday night as it drifts along Yanam, Kakinada and Tuni coasts and heads into the West-Central Bay of off the North Andhra Pradesh coast by Thursday by when it would weaken further into a depression.
A heatwave may re-emerge over North-West India (in white and ash colours) even as erstwhile severe cyclone Asani has cooled down the East Coast and the South Peninsula.
La Nina, negative IOD
Australian and Japanese agencies have indicated that La Nina conditions in the tropical Pacific have sustained or strengthened a bit, and expect these conditions to sustain into June-August (winter in the southern hemisphere).
The Application Laboratory of the Japanese national forecaster Jamstec is the more confident among the two, while the Australian Bureau of Meteorology cited only one of the models it surveyed as suggesting that the La Nina may last until August.
A La Nina (cooler to the East while warmer to the West of the equatorial Pacific) has complemented a concurrent India monsoon for the most part, unlike alter ego El Nino, which has heralded poor monsoon or drought, though with honourable exceptions.
Australia, Indonesia to benefit
What the Indian monsoon may have to confront with instead is the threat of a negative Indian Ocean Dipole (IOD) that mimics the El Nino-La Nina tango in the Indian Ocean. A negative IOD warms up the eastern basin of the ocean relative to the West, and apportions a part of the monsoon flows to itself.
The immediate beneficiary in terms of the heavy rainfall would be Indonesia and Australia, which lie within the immediate vicinity to the East of the Indian Ocean basin. The Australian Bureau notes that all climate models suggest a negative IOD may develop, despite the low forecast accuracy at this time of the year.