The Australian monsoon may well have ended, the country’s national forecaster said on Tuesday, which removes a potential irritant to the orderly evolution and progress of the Indian monsoon.
Monsoon Down Under staying put beyond April could mean a spanner in the works for the Indian monsoon. An active monsoon trough located there topped with a weather system (depression/cyclone) will repel flows bound for India.
MJO aiding summer showers
The Australian Bureau of Meteorology said that a Madden-Julian Oscillation (MJO) wave is active over Central Indian Ocean on Tuesday, helping with cloudiness and possibly fuelling the summer rain regime over South India.
The MJO wave is a low-pressure belt that sets up clouds and rain as it circumnavigates the tropics periodically from East to West. A wet MJO phase brings rain, triggers low-pressure area/depression, even onset of monsoon.
On the contrary, a dry MJO phase means opposite conditions including dry weather and even ‘break-monsoon’ conditions in which rains shut out for a week or longer midway through the season. On Tuesday, the Equatorial West Pacific was bereft of any significant clouding, which meant that the MJO would weaken before it reaches Australian longitudes. So there is less chance of another monsoon burst this season, the Bureau said.
Top heat down under
In fact, parts of the southern continent have been in the grip of a record-breaking heat spell. Several locations set records for consecutive days above high thresholds. The Bureau also said that the Equatorial Pacific is expected to witness ‘neutral’ conditions over the coming months as most oceanic and atmospheric indicators do not suggest anything to the contrary. As for the Indian Ocean Dipole (IOD), which refers to see-sawing temperatures in the western and eastern basins of the Indian Ocean, the value is currently neutral.
Neutral IOD phase seen
A positive IOD with the western basin warmer , aids a concurrent Indian monsoon and vice-versa. Most models indicate a neutral IOD.But two of six models indicate a negative IOD during June to August, the Bureau said.It, however, But cautioned that climate model outlooks for the Pacific and the Indian Ocean have lower accuracy during March to May than at other times of the year.
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Published on April 17, 2018
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