New Delhi, Monday June 18 The southwest monsoon has covered entire coastal Maharashtra, south Gujarat, Vidarbha, south Chhattisgarh, east Orissa and some parts of West Bengal, including Mumbai and Kolkata in one big sweep over the last weekend.
Interestingly, the southwest monsoon has been delayed by at least a week in both the mega cities. The monsoon lag was being attributed to feeble southwesterly wind flow over the Indian peninsula. Notably, southwesterly winds are the harbinger of monsoon over the India sub-continent.
The southwest monsoon has been vigorous over Konkan & Goa, sub Himalayan West Bengal and Sikkim during the past forty eight hours. Monsoon was active over rest west coast.
An off-shore trough along the west is being sustained by a steady moisture feed from the Arabian Sea. The trough where northwesterly winds are turning into southwesterly was quite strong along the Konkan & Goa coasts but might change as the trough weakens during the next few days.
Another north-south trough extends from sub-Himalayan West Bengal to the Bay of Bengal, though the weather formation remains strong in the Himalayan sector for now.
Troughs are places where winds from opposing directions meet (or winds turn) and atmospheric pressure is low while the turbulence caused by such interaction (or turning) leads to rain, thundershowers and storms.
The monsoon is expected to swallow some more parts of Gujarat, entire Maharashtra, some more parts of Chhattisgarh, Orissa, entire West Bengal, east Bihar and east Jharkhand during next two to three days. A cyclonic circulation has developed over Jharkhand and adjoining Orissa and it will give a fillip to monsoon’s further advance in east/east-central India.
The weakening trough along the east coast would reduce rainfall over the region in general albeit leaving enough southwesterly impetus to take monsoon further north in the west.
Intensity of monsoon is likely to decrease over west coast particularly over coastal Maharashtra. Rainfall activity will increase over interior Orissa, Chhattisgarh and east Madhya Pradesh. Rains over Mumbai will also show a marked decrease during the next two to three days (due to trough’s weakening).
North and east India are reeling under severe heat wave conditions for many days now. The onset of monsoon over east yesterday may ease the discomfort here but no respite is in sight for north for this week. Weekend thundershowers might relax most of north including Delhi, Haryana, south Rajasthan and west Uttar Pradesh (Punjab will be excluded for now).
Temperatures are soaring due to the dominance of hot westerly winds while some respite from heat is expected in north including Delhi due to inception of southwesterly and easterly winds. But the resultant increase in humidity may lead to discomfort, still leaving Delhiites in oppressive environs.
Light rainfall likely during the weekend would be supported by moisture incursion by southwesterly and easterly winds. Heat wave conditions would also abate from east Uttar Pradesh during the next 2-3 days as the onset of monsoon has brought in a change in wind direction in east India.
Chances of monsoon to reach Delhi on time are frugal as the yearly rain phenomenon is already running late by 5-6 days though much would depend on its progress during the current few days.
