Monsoon Update - Less than expected rainfall

Hitches in the making of a full-blown La Nina event (cold counterpart of El Nino) in the equatorial Pacific has forced India Meteorological Department to peg back the expected monsoon realisation this year to 93 per cent of the long-period average (LPA) with a model error of plus or minus 4 per cent.

The first long-term forecast made in April had assessed the rainfall to be 95 per cent of the LPA. This year's monsoon would suffer mostly from what looks like a below-par July, the IMD said in its updated long-range forecast on Friday.

July rains have a crucial bearing on the overall performance of the monsoon, with huge stakes for farm production.

Rainfall over the country as a whole in July is likely to be 95 per cent of its LPA with a model error of plus or minus 9 per cent. Over the four broad geographical regions of the country, rainfall for the season is likely to be 90 per cent of the LPA over northwest India, 98 per cent over northeast India, 96 per cent over central India and 94 per cent over the south peninsula, all with a model error of plus or minus 8 per cent.

'LOW' ACTIVE

A deep depression that crossed the Orissa coast on Friday is expected to be active until July 5 bringing large parts of the central India and the north peninsula under wet cover. Another low-pressure system is expected to spring up in the Bay around July 6 that should hold sway over more parts of the northwest India for another four to five days.

The monsoon would have covered the entire country by then, ahead of schedule. But, going by the IMD forecast, a lull would follow, with implications for farmers who have used the ongoing and preceding rains for sowing purposes. Transplantation, which should take place after four weeks from sowing, would be mired in trouble in this manner.

CONTRA VIEW

But a contra view is that an active monsoon phase is always followed by a 'break-monsoon' situation when the rainfall is confined to the northeastern and extreme southeastern parts of the country. Monsoon revives with activity picking up next in the Bay of Bengal, which helps bring back the northwest-southeast monsoon trough to its usual alignment, and thus rainfall.

Sources in the IMD, who did not want to be identified, were even more circumspect and said they would be happy if the monsoon performance did not dip any further than the latest level forecast on Friday. They even went to the extent of drawing a parallel with the year 2004 when the deficit amounted to 13 per cent.

MODEL DIFFERENCE

Most statistical models show ENSO-neutral (with no bias to either El Nino or La Nina) conditions persisting through August 2007, while most dynamical models indicate La Nina will develop within the next three months. However, for the past few months, the dynamical models have been predicting a stronger and more rapid cooling than has actually occurred.