The Hindu Business Line : US, Asian models see normal rains during July

India is likely to have a normal monsoon during the agriculturally crucial July-August-September quarter, with surplus precipitation indicated for the north Madhya Pradesh-east Rajasthan-Uttar Pradesh belt.

This is according to the latest update from the International Research Institute (IRI) for Climate Prediction at Columbia University. The September-October-November quarter that coincides with the north-east monsoon later this year will see above normal rains for southwest Rajasthan, northwest Madhya Pradesh and east Gujarat.

A similar forecast has been put out by the Busan, South Korea-based APCC, a climate model, developed by member-countries of the Asia-Pacific Economic Cooperation (APEC). It said that India’s west coast and adjoining central provinces, Uttar Pradesh, and Bihar may get surplus rainfall during June-July-August.

Reasonably good precipitation has been indicated for Rajasthan, Gujarat and adjoining Pakistan too. The monsoon would be normal over the southern peninsula, while the north eastern States are likely to turn in a deficit.

IOD-MJO IMPACT

Several international models now agree that a prevailing positive Indian Ocean Dipole (IOD) event and a passing pulse of active convection heralded by the Madden-Julian Oscillation (MJO) wave have been instrumental in triggering the onset and progress of the India monsoon that has run up a surplus of 45 per cent as on date.

A positive IOD, in which a warming anomaly sits over the west equatorial Indian Ocean in relation to the cooler seas to the east, has a more direct and favourable impact on the prevailing Indian monsoon than El Nino/La Nina has. In particular, the country’s west coast and peninsular north receive above normal rainfall during a positive IOD.

The La Nina (cold counterpart of El Nino) may be dying, but the equatorial Pacific has more or less slipped into what looks like a prolonged ‘neutral’ mode. While this may not boost a concurrent Indian monsoon, it is not known to harm it either. No conclusive cause-effect relationship between the two has been established.

According to the IRI, neutral conditions may last still March-April-May 2009, leaving open equal chances for an El Nino or La Nina event with implications for that year’s monsoon. But the Australian Bureau of Meteorology (BoM) was more circumspect, saying these events can evolve quite rapidly even later during this year.

FRESH MONSOON ‘LOW’

Back home, the National Centre for Medium Range Weather Forecasting (NCMRWF) has predicted the formation of a monsoon ‘low’ over northwest Bay of Bengal during the next week. It is tipped to intensify to another monsoon depression and move in a typical northwest direction.

But the European Centre for Medium-Range Weather Forecasts (ECMWF) seems to suggest the south coastal Andhra Pradesh-north Tamil Nadu coast for the landfall to take place. In any case, this would be interesting since a monsoon system in the northwest Bay crossing the Orissa-Andhra Pradesh-Tamil Nadu coast would normally busy up monsoon over the peninsula and the west coast.

Meanwhile, Thursday’s ‘low’ over north-east Madhya Pradesh and adjoining east Uttar Pradesh persisted on Friday. Widespread rainfall with isolated heavy to very heavy fall will likely prevail over Madhya Pradesh for another day. The activity will subside over west Madhya Pradesh and increase over Chhattisgarh, adjoining Orissa and north Andhra Pradesh.

This eastward shift of the ‘low’ is being masterminded by the western disturbance that has crossed in afresh from the international border. The ‘low’ might keep moving to the east for a while bringing back moderately heavy rains into the region. On Friday, the seasonal trough over land passed through Anoopgarh, Agra, Kanpur, the centre of the ‘low’, Keonjhgarh and into the east-central Bay.

Forecast for the next two days said that isolated heavy rainfall is likely over the north eastern states, West Bengal, Sikkim, the Andaman and Nicobar Islands, north Chhattisgarh and Bihar. Isolated thunder squall is likely over Punjab. Three days from Monday will see an escalation of rainfall along the west coast and over east India and adjoining north peninsula.

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