The monsoon has entered a vigorous phase not witnessed till date during the season, with central and adjoining peninsular India too expected to come under enhanced rain cover from early this week.
This is despite the poor credentials of a concurrent rain-driving system developing in the Bay of Bengal, where model forecasts see no anchor 'low' materialising for another week.
But the strong flows ordained by a benign Madden-Julian Oscillation (MJO) wave are enough to sustain the monsoon strength until July 15, say model forecasts.
ARABIAN SEA 'LOW'
The west coast would continue to be battered by waves of torrential rainfall closing in one after the other, culminating in the formation of a 'low' over northeast Arabian Sea midway through.
The system may move away from coast for sometime, only to get snaffled by an expanding trough from a prospective and well-endowed 'low' materialising in the Bay by the end of the week (around July 12).
This phase could launch monsoon towards another peak replete with the prospect of a mid-tropospheric cyclonic (MTC) circulation, a prolific generator of sustained rainfall, revealing itself right above Gujarat.
An MTC is known to generate much more rain in time and space than a conventional monsoon 'low' or depression is capable of, eve while being blessed with enhanced staying power.
South Gujarat and Konkan coast, including Mumbai and central India, would do well not to lower its guard and ready themselves to deal with any situation likely arising from enhanced rains and flood conditions.
IOD BOOSTER
Monsoon rains from a friendly MJO wave may get further boosted in the context of signs of a positive Indian Ocean Dipole (IOD) event marked by positive sea-surface temperature anomalies for southwest Indian Ocean.
India Meteorological Department (IMD) said in an update on Sunday that the monsoon has been an 'active' phase overnight in sub-Himalayan West Bengal, Sikkim, Orissa, Konkan, Goa and coastal Karnataka.
But it was subdued over Bihar, west Uttar Pradesh, Haryana, Punjab, east Rajasthan, Telangana and Rayalaseema, which is reflective of how rain coverage can falter if no anchor 'low' is available in the Bay.
The IMD said that rainfall occurred at most places over the west coast, including Mumbai, and at many places over central and northeast India, interior south peninsula and Orissa during the past 24 hours.
In its outlook for the next few days, it said that the active/vigorous phase of the monsoon is likely to continue over west coast during the next 2-3 days.
Rains would become further entrenched over central and adjoining peninsular India from Tuesday onwards, apparently after an upper air cyclonic circulation spins over into land and moves west.
The wave of rains is likely to merge with a counterpart coming from the opposite direction and lead to sustained rainfall over central India, west Maharashtra and the west coast for the rest of the week.
This phase may also see the run-up to the initiation of the long-delayed anchor 'low' in the Bay by the weekend. It could get a move to the west-northwest along the seasonal monsoon trough over land, bringing monsoonal rains into the northwest.
On Sunday, the crucial monsoon trough over land lay extended from Anoopgarh, Alwar, Fatehpur, Daltonganj, Digha and southeastwards into east-central Bay of Bengal.
OFFSHORE TROUGH
To the peninsular west, the rain-making offshore persisted from Konkan coast to Kerala coast, and will continue to cause widespread rainfall with heavy to very heavy falls at a few places over west coast for another 4-5 days.
Numerical weather prediction models suggest fairly widespread rainfall activity with isolated heavy to very heavy falls for east India, especially West Bengal, Sikkim, Orissa, as well as for the northeast during the next 2-3 days.
A warning valid for the next two days said that heavy to very heavy rainfall are likely at a few places with isolated extremely heavy fall exceeding 25 cm over Konkan and Goa.
Heavy to very heavy rainfall has been forecast at a few places over coastal Karnataka also during this phase. Isolated heavy to very heavy rainfall is likely over the northeast, West Bengal, Sikkim, Orissa, Kerala and Lakshadweep.
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