‘Good rains’ for India in Aug-Sept, say Japanese experts

Japanese researchers have concluded that the 2010-11 La Nina, which brought a normal monsoon last year marked by occasional flooding events, faded out fully in June.

La Nina is the periodical ocean phenomenon marked by cooling of the east-equatorial Pacific waters and warming of the west, and has mostly coincided with a good Indian monsoon, though without direct cause-effect relationship.

TO RETURN

But researchers at the Tokyo-based Regional Institute for Global Change (RIGC) have maintained their forecast for the return of La Nina conditions towards the autumn.

The Climate Prediction Centre of the US National Weather Services too had come out with an outlook recently suggesting the return of La Nina later this year.

In what is a good sign for the Indian monsoon, the RIGC has also said that the La Nina would be accompanied by a ‘weak positive Indian Ocean Dipole’ from August to November.

The India Ocean Dipole (IOD) is a seesawing of ocean water temperatures in west and Indian Ocean, closely resembling the El Nino-La Nina phenomenon in the equatorial Pacific but with more direct and immediate impact on Indian monsoon.

‘GOOD RAINS”

When the ocean water temperature is high in west Indian Ocean relative to the east, it is said to be a positive IOD phase, and vice versa.

A positive IOD is seen as boosting the prospects of a concurrent Indian monsoon and hence the RIGC outlook for good rains, despite the ‘weak’ IOD credentials.

In its draft outlook statement, the RIGC said most of India would have good rains, even flooding events, during late summer (August-September-October) associated with the influence of La Nina and the emerging positive IOD.

The IOD event may be related to current sub-surface cooling condition in the eastern equatorial Indian Ocean.

This would also mean that warmer-than-normal sea surface temperatures would persist west of Australia during the following months.

‘LOW’ IN BAY

In other regional forecast outlook, the RIGC said that ‘cool’ to ‘wet’ condition would return to southern Africa during late southern spring. Many parts of Australia would witness similar conditions during late spring to summer.

Dry conditions are expected to emerge over southeast China to western in August but with above-normal autumnal rain in September. Northeast China is likely to witness flooding conditions in August, the RIGC outlook said.

Meanwhile back home, the surge in monsoon flows triggered by an intensifying storm, Ma-on, in central Pacific has tossed up a low-pressure area over west central Bay of Bengal on Wednesday.

The day also saw the overall rain deficit for the country as a whole creep up to four per cent (two per cent as of Tuesday) as the ‘base effect’ caused by the high July normal caught up with monsoon.

DEFICIT CUT

However, the active monsoon conditions over the past couple of days have drastically reduced the deficit in the worst-affected Gujarat State, with Saurashtra and Kutch just managing to get within ‘normal’ range (a deficit below 20 per cent).

The monsoon surge has also helped improve the conditions in Andhra Pradesh, Maharashtra, Orissa and Chhattisgarh, with more rains forecast during the next few days.

A weather warning valid for the next two days said that isolated heavy to very heavy rainfall would occur over Konkan and Goa, coastal Karnataka, Kerala, Telangana, north interior Karnataka, Marathawada and Madhya Maharashtra.

Isolated heavy rainfall would occur over north coastal Andhra Pradesh and west Madhya Pradesh on Thursday.

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