NEW DELHI: Summer monsoon, which ended on Monday in the ‘above normal’ category after recording nearly 8% higher than normal rainfall, is likely to fully withdraw from the country by mid-October and the winter monsoon will set in around the same time (by Oct 17) in the southeast peninsula, the IMD said on Tuesday. It also hinted at the possibility of a harsh winter in north India, specially northwest India, including Delhi-NCR and adjoining central region, as La Nina conditions are expected to form during Oct-Nov.
La Nina is a climate phenomena associated with the periodic cooling of ocean surface temperatures in the central and east-central equatorial Pacific. Though it is linked to good monsoon rainfall in the Indian sub-continent, it remained absent during the southwest (summer) monsoon months despite forecasts by different global models.
“There is a 71% chance that La Nina conditions will develop during Oct-Nov… The years when you have La Nina, temperatures in the northern part of the country, specially northwest India and adjoining central region, are below normal (colder than normal)… So, you can have cold wave conditions during winter months,” said IMD chief, Mrutyunjay Mohapatra.
He, however, underlined that its severity would be known only later as the La Nina condition is still weak and the Met department will have to monitor how much it will be strengthened in January or February. The IMD will follow it up and will be able to come out with a more precise forecast only in November.
Good rainfall this year, however, was mainly due to other factors including six depressions, 14 ‘low pressure systems’ in Bay of Bengal and one cyclonic storm ‘Asna’ in the Arabian Sea.