India is witnessing widespread rainfall due to active southwest monsoon, with at least 80% of the country experiencing heavy to very heavy showers in Assam, West Bengal, Uttar Pradesh, Uttarakhand, Gujarat, coastal Maharashtra, Karnataka, Kerala and Lakshadweep.
The India Meteorological Department (IMD) has also issued warning that several parts of the country will experience significant rainfall over the next few days.
The monsoon is expected to be particularly active in Peninsular and central parts of the country over the next four to five days.
What is Causing Widespread Rainfall?
After a severe heatwave that engulfed almost the entire North India till around mid-June, the monsoon covered the entire country on July 2, much ahead of the scheduled date. The monsoon has been active over southern peninsular, east, northeast, and central India regions.
There have been two main contributors to the enhanced rainfall. One is the continuous incoming of moisture-laden strong westerly winds from the Arabian Sea.
The persistence of an off-shore trough (a shallow trough of low pressure, which develops along India’s coast during the monsoon) between south Gujarat and north Kerala for more than a week now.
The intermittent development of a wind shear zone — where winds move with different velocities and directions — along latitudes 20 ° N between central and peninsular India.
The development of a low pressure system over the west-central Bay of Bengal, off the Odisha coast, on Monday. The system moved over Chhattisgarh and adjoining Vidarbha on Tuesday, and over southeast Madhya Pradesh on Wednesday.
What is the La Nina Effect?
The above rainfall for July could also be due to El Nino-Southern Oscillation returning to neutral, and the cooler phase, known as a La Nina, is expected to form in the second half of the monsoon season. (August-September).
La Niña is characterised by the cooling of sea surface temperatures, and occurs every 3-5 years, occasionally in consecutive years, leading to increased rainfall and distinct weather patterns, which can result in floods.
As of 15 July, India has received 2% less than normal rainfall since the beginning of the four-month monsoon season (June-September).
Rainfall Forecast
Fairly widespread to widespread light to moderate rainfall, accompanied by thunderstorms and lightning, is very likely over West and Central India, Kerala & Mahe, Lakshadweep, Coastal Andhra Pradesh & Yanam, Telangana, and Karnataka over the next five days, IMD said. Isolated to scattered light to moderate rainfall is expected in Tamil Nadu, Puducherry & Karaikal, and Rayalaseema.
Light to moderate widespread rainfall, along with thunderstorms and lightning, is likely over the Andaman & Nicobar Islands, Sub-Himalayan West Bengal & Sikkim, and Odisha, IMD said. Scattered to fairly widespread light to moderate rainfall is expected over Bihar, Jharkhand, and Northeast India over the next five days.
Heavy to very heavy rainfall is anticipated in isolated places over the next five days in West Madhya Pradesh, Konkan & Goa, Madhya Maharashtra, Saurashtra & Kutch, Telangana, Coastal & South Interior Karnataka.
Isolated heavy rainfall over the next five days in East Madhya Pradesh, Vidarbha, Chhattisgarh, Gujarat Region, Kerala & Mahe, Coastal Andhra Pradesh & Yanam, North Interior Karnataka, as per IMD.