The western end of the land-based monsoon trough too has shifted southwards signalling the possibility of rainfall spreading into central and adjoining north peninsular India.
The eastern end had shifted to the south on Monday itself, and an upper air cyclonic circulation has since formed over west-central Bay of Bengal.
OFFSHORE TROUGH
The offshore trough along the west coast has extended overnight its reach from Gujarat coast to Kerala coast.
A weather warning issued by India Meteorological Department (IMD) on Tuesday said that isolated heavy rainfall is likely over south Orissa and coastal Andhra Pradesh on Wednesday.
But Telangana, Vidarbha and south Chhattisgarh are expected to receive isolated heavy rainfall on both Wednesday and Thursday.
Subsequently, rainfall activity would scale up over northwest India. Maharashtra and Gujarat are also expected to make major gains from the emerging wet session.
MAJOR DEFICITS
Major deficit Met subdivisions in the peninsula (deficit in percentage figures) are Marathawada (50 per cent); Telangana (39); coastal Andhra Pradesh (24); Rayalaseema and Tamil Nadu (22 per cent each).
Most of these are expected to receive precipitation in varying amounts during the current spell, although Tamil Nadu and Rayalaseema may possibly have wait until July 15 for the same.
The two met subdivisions with scanty rainfall fall in Gujarat, where the western end of the northern limit of monsoon has been stuck for a long time now.
But even here, some rains are expected during this current spell when these regions come under the footprint of a trough conjured up by the cyclonic circulation over the Bay of Bengal in combination with the original land-based monsoon trough.
RAINS FORECAST
A short-term forecast valid until Friday said fairly widespread rain would lash Madhya Pradesh, Madhya Maharashtra, Marathawada, Lakshadweep Islands, Andaman and Nicobar and the west coast. But IMD sees Rajasthan getting only meagre rains during this round.
Meanwhile, global models indicated that the southern peninsula might start getting its share of the second spell of monsoon from around July 15.
These models do not see any low-pressure area/depression spinning up in the Bay of Bengal for this week and the week after.
But the monsoon would need to brace itself for the possibility of a fresh tropical storm erupting over the northwest Pacific Ocean and tracking a north-northeast track for onward movement.
PACIFIC STORM
These away-moving storms are normally considered a drag on the monsoon flows directed towards the subcontinent but models see the monsoon system largely remaining in tact.
If fact, it is during this very phase that southern peninsular India is shown to be benefiting from the second spell, post ‘break-monsoon’ phase.
(E.o.m.)