The Hindu Business Line : Circulation in west to decide N-E monsoon onset

The rogue upper air cyclonic circulation over south Konkan and Goa refuses to die down, and will now have an increasingly clear say on the arrival of the northeast monsoon over the southern peninsula.

The circulation will be active for another 24-36 hours, said Dr Akhilesh Gupta of the Department of Science and Technology, quoting model predictions. The resulting rainfall will impact the west coast varyingly over the next four or five days. Konkan, Goa and coastal Karnataka will be major beneficiaries.

LULL FROM OCT 11

This would be followed by a lull from October 11 to 14, the timeline up to when predictions are available. During this period, the projected atmospheric pressure regime is such that no major, organised rainfall event will become possible in the peninsula.

"Given this, it's likely that we will not get to see the northeast monsoon break in at any time during this period," Dr Gupta said. But northeast monsoon has been known to arrive even later, within a time band of October 15 to 20.

NEW CIRCULATION

The National Centre for Medium Range Weather Forecasting (NCMRWF) said in its update that a cyclonic circulation, remnant of erstwhile Typhoon Xangsane, was expected to form over the Andaman Sea by Saturday. This would concentrate into a `low' in due course.

But it has to grow to some strength in order that not to be impacted by invading northwesterlies and get sheared off in the process, said Dr Gupta. This is situation that bears some watching.

CYCLONE RULED OUT

Commenting on weather in western India, Mr Jim Andrews of AccuWeather.com says that the `ghost' of the former Tropical Depression 05B has re-emerged off Maharashtra and south of Kathiawar, Gujarat. "I do not see anything pointing to a tropical cyclone off west India, but I do believe that there is a real system here," he said.

This could drift southward offshore instigating heavy to excessive rains over a small area nearby. Coastal Karnataka and, later Kerala, are the likely sites for the heaviest rains.

RAINS IN NORTHEAST

The NCMRWF said that a north-to-south oriented trough persisted over the Northeastern states. Under its influence, fairly widespread rainfall with isolated heavy to very heavy falls are likely over these States during the next 2-3 days.

A western disturbance is likely to approach Jammu and Kashmir during the weekend and is projected to move eastward.

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