The monsoon has been declared as having broken over north-west India, but at the cost of a largely dry Uttar Pradesh upstream to the east.
As if this is not enough, international agencies also point to the probability of monsoon entering into yet another brief lull phase from July 11.
‘CONVERGENCE' RAIN
The pattern of the ongoing heavy to very heavy rain over parts of the rest of northwest India suggests they are borne out of ‘convergence' between easterlies and a prevailing western disturbance.
One view is that these rains may last only for as long as the western disturbance is active in the region.
Meanwhile, a decisive change in ambient wind conditions helped monsoon easterlies establish themselves over large parts of northwest India.
They have also managed to bring the rains, though not in a pattern or quantum identified with normal monsoon.
The good times may not last beyond the next six days since flows over the Arabian Sea may once again weaken from July 11 onwards, says Dr Akhilesh Gupta, leading operational forecaster and Advisor to the Department of Science and Technology.
The lull phase is likely to hold until July 14, subsequent to which they are expected to revive gradually.
MONSOON ADVANCES
On Monday, the India Meteorological Department (IMD) said that monsoon has further advanced into Madhya Pradesh, Bihar, Uttar Pradesh, most parts of east Rajasthan and entire Haryana, Delhi, Punjab, Uttarakhand, Himachal Pradesh and Jammu and Kashmir. The IMD, too, conceded that the advance of monsoon over east Uttar Pradesh was feeble at best.
The northern limit of monsoon passed through Jawai Dam, Ajmer, Churu and Sriganganagar — all in Rajasthan.
Conditions are favourable for its further advance into the remaining parts of Rajasthan during next two days.
At no time in the recent past have monsoon flows been subjected to as many frequent ‘stops' as have happened this year, Dr Gupta told Business Line.
This requires a careful examination of conditions prevailing in the upstream domains, especially the southern hemisphere from where the flows originate.
According to him, the quick turnaround in the northwest over the past day or two was facilitated by the re-orientation of flows over North Arabian Sea.
QUIET BAY
That it draws little from an ‘attitudinal change' in the Bay of Bengal climes helps expose the weak link in the monsoon chain.
Explaining the change in the welcome wind pattern, Dr Gupta said the winds over North Arabian Sea changed from being south-southwesterly (heading straight into northwest India) to southwesterly-to-westerly.
This opened up a crucial sluice valve towards the east of the country, allowing easterlies to rush in to the plains in the north.
Had the re-oriented flows sustained for a longer time than is forecast, they would have initiated a proper low-pressure area in the North Bay and piloted the monsoon in.
Given this, it is likely that Uttar Pradesh would continue to a pose a stumbling block for the IMD even as monsoon finds its way in fits and starts to the rest of the north-west.
An IMD warning valid for the next two days said that isolated heavy to very heavy rainfall would occur over Konkan in Goa, coastal Karnataka, Telangana, coastal Andhra Pradesh, Madhya Maharashtra, Vidarbha, Gujarat, East Rajasthan, West Madhya Pradesh, Punjab, Haryana, West Uttar Pradesh, Uttarkhand and Himachal Pradesh.
Outlook until Thursday suggested that widespread rain/thundershowers would occur over west coast.
Fairly widespread rain/thundershowers would occur over Andaman and Nicobar Islands, the Northeastern States, sub-Himalayan West Bengal, Sikkim, Orissa, north Andhra Pradesh, Gujarat, Vidarbha, Chhattisgarh, Madhya Pradesh and
Lakshadweep.
Fairly widespread rain/thundershowers are likely over Haryana, Punjab, Chandigarh, Delhi, Rajasthan, Jammu and Kashmir, West Uttar Pradesh, Uttarakhand and Himachal Pradesh during the next two days and decrease thereafter.
Extended outlook until Saturday said that only scattered rainfall activity is likely over the plains of northwest India. But rains may scale up over Uttar Pradesh, Bihar, Sub-Himalayan West Bengal, Sikkim and the Northeastern States.
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