IMD models hint at monsoon revival after June 21

PUNE: Monsoon is likely to revive over parts of the state and central India after June 21.
The India Meteorological Department (IMD) weather models indicated the monsoon revival was likely over south peninsula and adjoining central India, including Maharashtra, Odisha, Chhattisgarh and south Madhya Pradesh. But subdued rainfall is likely to continue over northwest India, north Madhya Pradesh and north Gujarat.



The models indicated that the ongoing weak monsoon pattern was likely to continue at least up to June 20. During the period June 15 to 21, no further advance of southwest monsoon is likely, while the rainfall may remain below normal during this period over Maharashtra, Andhra Pradesh, Telangana, West Bengal, Sikkim, Madhya Pradesh, Gujarat, Uttar Pradesh, Uttarakhand, Bihar, Jharkhand and Odisha.

A source said, based on these models, the gradual revival of monsoon might begin during the week June 22 to 28, starting from south peninsula. Models are showing normal to above-normal rainfall during this period over interior Maharashtra, south Madhya Pradesh, Odisha, Assam, Rajasthan, south peninsula states like Kerala, Karnataka, Tamil Nadu and Puducherry among others.

Rainfall, however, may be below normal over Himachal Pradesh, Uttarakhand, Uttar Pradesh, Bihar, Jharkhand, north Madhya Pradesh and Gujarat among other states between June 22 to 28. Though the official monsoon onset over Delhi is around June 29, only later forecasts will indicate when it is likely to make an onset there.

Active and break spells in monsoon are associated with monsoon intra-seasonal oscillations (MISOs). These are oscillations in the sub-seasonal scale, manifesting as spells of heavy rainfall and periods of inactive rainfall instead of a continuous deluge. These oscillations develop in the ocean and travel northward to land — their northward movement is associated with active rainfall conditions.

Sources stressed the ongoing break in monsoon was a result of the intra-seasonal variability in monsoon. “Monsoon rainfall works in such a way, with active and break spells — based on soil, land and atmosphere feedback. Monsoon cannot remain active for an entire month,” a source said.