Concerned over the erratic behaviour of the South-West monsoon, the Met department is planning to make forecasts of regional rainfall distribution patterns. The forecasts are likely to be released this week.

Global forecast models have predicted heavy rainfall concentration over the western and southern parts of peninsular India and the foothills of the Himalayas. The probability of emergence of the La Nina phenomena — that is, cooling of Pacific waters below normal — has been raised to 55 per cent. La Nina usually causes heavy rainfall, while the opposite phenomenon, the El Nino or warming of Pacific waters, causes drought. Global models predict that the El Nino may not take effect this monsoon.

Though the progress of the monsoon has been delayed over major parts of central and north India, rainfall distribution in June, the first month of the season, has been almost even with only Gujarat, east Rajasthan, Jharkhand and the Andaman Islands receiving deficient to scanty rains.

Northern, central and northwestern parts of the country received good rains due to factors other than the monsoon, which has not yet reached these regions. Punjab, Haryana, western Uttar Pradesh and western Madhya Pradesh received excess rainfall. The average cumulative rainfall over the country till June 20 was only 2 per cent below the normal of 89.3 mm.

The delay in the progress of the monsoon, however, is still a matter of concern.