Heavy to very heavy rain lashed isolated places over Telangana, Kerala and Mahe during 24 hours ending on Wednesday morning as the monsoon appeared to revive over parts of South Peninsula on the back of a building activity over Bay of Bengal.
The monsoon is expected to advance into more parts of Central and adjoining East India around Saturday.
Extremely heavy rain
Extremely heavy rainfall is warned over Kerala and Mahe for three days from Saturday; coastal and south interior Karnataka for five days from Thursday; north interior Karnataka on Thursday; and Tamil Nadu, Puducherry and Karaikal on Saturday and Sunday. Isolated heavy rainfall is likely over coastal Andhra Pradesh and Yanam for four days from Thursday; very heavy rainfall over Tamil Nadu, Puducherry and Karaikal for six days; Kerala and Mahe for two days; and Karnataka, for seven days.
South, East battered
India Meteorological Department (IMD) said in an evening update heavy overnight rain was also reported on Wednesday from Nagaland, Manipur, Mizoram, Tripura, Odisha, Uttarakhand, Chhattisgarh, coastal Andhra Pradesh, Yanam, Tamil Nadu, Puducherry, Karaikal and coastal Karnataka with a western disturbance bracing to interact with an incoming western disturbance.
Western disturbance
The IMD said the disturbance was unchanged from its location over southern Iran and adjoining Afghanistan for past couple of days, and is now expected to affect North-West India from Friday while dipping south to interact with monsoon easterlies whipped up from Bay. It may be too early to expect a low-pressure area to spin up from the melee just yet.
Pacific depression
This is because a depression within the larger monsoon trough over West Pacific is currently intensifying, aiming to hit south-west China around the same time as the western disturbance starts affecting North-West India. The larger system away from Indian waters might divert a bulk of the monsoon flows to itself, denying the Bay circulation a favourable window to gain traction.
Myanmar sees ‘low’
But his has not stopped Myanmar Department of Meteorology and Hydrology from posting an outlook for a low-pressure area to develop over the Andaman Sea and adjoining Bay during next 10 days. The IMD doesn’t appear to rule out the possibility either, with its numerical models indicating deferred activity building over Odisha coast by next week.
MJO not active
US Climate Prediction Centre does not anticipate a rain-supporting Madden-Julian Oscillation (MJO) wave playing any role in the global tropical convective pattern (including Arabian Sea-Bay of Bengal) during next two weeks. This explains why the monsoon over India might have had to wait for a western disturbance to dip south and activate a circulation over the Bay.
Rainfall predictions
The US agency indicates the possibility of above-normal monsoon over for Central and North-West India next week (June 18 to 24) except in Rajasthan, Punjab, Himachal Pradesh, Delhi, Chandigarh, Haryana, Jammu-Kashmir-Ladakh as well as southern parts of North-Eastern States. Rain pattern will likely revert to climatological normal during week that follows (June 25 to July 1).