Vinson Kurian

Thiruvananthapuram, July 3

BARELY have Gujarat and other flood-hit parts of central India recovered from the shock than comes the fresh warning about another low-pressure area, second of the season, taking shape in the Bay of Bengal as early as by Wednesday.

The National Centre for Medium Range Weather Forecasting (NCMRWF) has said that favourable conditions are building up for the formation of the `low' over northwest Bay of Bengal. It may be recalled that the centre had correctly predicted the first `low' of June 27, which later turned into a depression and helped the northern limit of the monsoon sweep the entire north and northwest in record time.

Very slow in its northwestward progression, this monsoon depression has dumped rain during the course of its tenure over central India bringing vast swathes of land under a massive sheet of water. Even after seven days, the depression had remained practically stationary at its latest location over north Madhya Pradesh and adjoining east Uttar Pradesh on Sunday.

Systems to interact: Speaking to Business Line, Dr Akhilesh Gupta, Director, NCMRWF, said the prevailing depression is now likely to move slowly in north-westerly direction and interact with the existing western disturbance over Jammu and Kashmir leading to widespread rains with isolated heavy rains in some parts of northwest India during the next two days.

Delhi, Uttar Pradesh, Himachal Pradesh and Haryana are expected to receive good showers for 24 to 36 hours under the influence of the interaction of the systems. The depression will use the feed from the westerlies to prolong its life after which it is expected to weaken further and die, preparing the ground for the new `low' to take form.

Explaining the dynamics, Dr Gupta said two monsoon-time systems do not co-exist due to the `updraft' and `downdraft/subsidence' effect of the core winds. Right beneath the `low', there will be pumping up of moisture but beyond this, for a distance of 500 km to 600 km, there will be subsidence of air, ruling out formation of a `low'.

Temporary respite? : The mid tropospheric cyclonic circulation over Gujarat and neighbourhood is likely to persist for another 24 hours and cause widespread rains with isolated heavy to very heavy rains over the region. The cyclonic circulation is expected to weaken hence, leading to decrease in heavy rainfall activity.

But, according to Dr Gupta, Gujarat has better be wary about the new `low' taking shape in the Bay on Wednesday. There are chances that it could herald a second spell of heavy rain in the region. A clearer picture on this would emerge only over the next 24 to 36 hours though.

East Rajasthan is likely to experience scattered to fairly widespread rains during the next three days. West Rajasthan may receive scattered rains during this period. Bihar, Jharkhand, West Bengal, Orissa and the Northeastern States are expected to receive widespread rain over the next 2-3 days, the NCMRWF forecast said.

(This article was published in the Business Line print edition dated July 4, 2005)
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