Active spell for northwest as La Nina returns

Indian Meteorological Department (IMD) has forecast an active wet spell for northwest India during the next five days and over east and adjoining central India during the next three days.

This came about on a day when Japanese scientists assessed that the predicted return of La Nina conditions may already be happening.

Scientists at the Regional Institute for global Change (RIGC) based in Tokyo have been hinting this possibility from many months ago.

US OUTLOOK

Recently, the Climate Prediction Centre at the US National Weather Services too had officially changed its outlook for the Pacific into a ‘La Nina watch.'

La Nina is an alter-ego to monsoon-killer El Nino, and refers to the see-sawing of sea-surface temperatures in the equatorial Pacific.

Cooling of east equatorial Pacific waters induced by La Nina has been traditionally found to favour the prospects of an ongoing Indian monsoon as was proved last year, though without direct cause-effect relationship. But the jury is out this year, at a stage when the monsoon may just be peaking out with the season having entered the last month-and-half. But the very fact that an El Nino tendency is increasingly being ruled out is sufficient to provide some stability to the remainder of the monsoon, some experts feel.

LA NINA BACK

Dr Jing-Jia Luo, Senior Scientist with the Climate Variation Predictability and Applicability Research Programme Research at RIGC, wrote to Business Line on Friday that the La Nina condition is currently on the way back.

This condition is forecast to persist until early next year, Dr Jing-Jia says, adding that a weak positive Indian Ocean Dipole (IOD), which mimics EL Nino-La Nina in the Indian Ocean, also may occur during the next few months.

Positive IOD refers to the warming of seas-surface temperatures in the western part of the Indian Ocean, and vice versa. Positive IOD has been found to favour a concurrent monsoon. Regional forecast from the RIGC said that the La Nina would bring cool to wet conditions over southern Africa, Australia, and Brazil during the southern hemisphere summer.

WET FOR INDIA

The La Nina would also help reduce the surface temperature over many parts of the globe except the northern Eurasia and southern US during this period. Wet to flooding conditions have been forecast Indonesia, India, eastern Africa, and eastern China, Korea and western Japan during this autumn.

Meanwhile, back home, a weather warning by the IMD said that isolated heavy to very heavy rainfall would occur over Orissa, north Chhattisgarh, east Madhya Pradesh and Gujarat state during the next two days. Isolated heavy rainfall would occur over Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Punjab, Haryana, Jharkhand, Gangetic West Bengal, Konkan, Goa and coastal Karnataka during this period.

‘LOW' INTENSIFIES

Thursday's low-pressure area in east India has intensified into being ‘well-marked,' and was traced to over Orissa and Jharkhand on Friday. This has led the counterpart ‘low' to the west over south Rajasthan lose some steam and weaken as an upper air cyclonic circulation.

The axis of the monsoon trough over land passed through Bikaner, Bharatpur, Allahabad, Daltonganj, the centre of the well-marked ‘low' before heading south-eastwards into east-central Bay of Bengal. The offshore trough runs from Gujarat coast to Kerala coast.

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