After torrential rains along the west coast in July, and intense spell in Northwest India on July 31, the southwest monsoon is now approaching its break-phase. According to the India Meteorological Department (IMD), the seasonal rains are likely to be ‘Normal’ in August.
The weather department defines ‘Normal’ as rainfall between 94-106 per cent of the long-period average (LPA), which is roughly 255mm. “We expect good rains over the next week, but after that the activity will decrease, as the monsoon could enter a break-phase around August 10. It will pick up again towards the end of the month, and could improve significantly in September,” said IMD chief Dr M Mohapatra on Thursday.
Except for the intense heavy rains on July 31, which also triggered cloudbursts in the hills, Northwest India has so far seen a subpar performance of the monsoon as the rainfall deficit touched nearly 14.3 per cent this month — contrary to the IMD’s initial forecast issued earlier.
“Normally, we get a lot of western disturbances. But this time, they have been very week. Unlike last year, there was also no major interaction of the WD storms with tropical easterlies of the monsoon, hence the scarce rains,” added Dr Mohapatra.
As of July 31, as many as nine states continue to reel under deficient rains — Jammu and Kashmir, Punjab, Haryana, Eastern Uttar Pradesh, Bihar, West Bengal, Jharkhand as well as Tripura, Nagaland, Manipur and Nagaland. The deficit has touched nearly 45 per cent in Punjab, and 41 per cent in Haryana and West Bengal — all crucial paddy-growing states.
WHAT LED TO HEAVY RAINS OVER SOUTHERN INDIA?
However, heavy rains continue to lash the southern peninsular states which have witnessed 36 per cent surplus rains this month. Meteorologists also pointed to a trend of above-normal rains for Southern India in July for the last five years, while it is just the opposite for North-east India where the rainfall remains Below-Normal yet again.
The IMD chief said the weather department had alerted for heavy rains along the west coast in its Extended Range forecast (valid for two weeks) on July 18 and 25. “We had also issued an orange alert for heavy rains for Kerala on July 29, and red alert on July 30. Orange alert means the local administration should take immediate action, and not wait for red warnings,” he added.
Over 340mm rains fell over Vadakkancherry (Thrissur), 300mm in Alathur (Palakkad), and 280mm in Vyttiri (Wayanad) on July 29-30, triggering a massive landslide in Wayanad that took over 250 lives. According to IMD, the monsoon trough was south of its normal position for most days of July, which led to heavy rains over southern India.
The Arabian Sea arm of the monsoon remains very active throughout the month. As many as three low-pressure systems developed over the Bay of Bengal and all of them moved across Odisha towards the west coast. These moisture-laden winds got an additional boost from the westerlies from Arabian Sea, increasing the rains along the west coast. “None of these systems, which together lasted for 11 days, moved north-westwards, which explains why states like Uttar Pradesh, Bihar, Jharkhand did not get as much rain,” he added.
INTENSE RAINS HIT NORTHWEST INDIA
Several cities across Northwest India from Himachal Pradesh to Punjab, Haryana, Delhi and Rajasthan recorded over 100-180mm rainfall on July 31. Over 183.2mm rains lashed Dharamshala in Himachal Pradesh, 163mm in Dehradun (Uttarakhand), 146mm in Jaipur (Rajasthan), 145mm in Noida (Uttar Pradesh), 141mm in Ambala (Haryana). Delhi’s Safdarjung recorded nearly 107mm rains — nearly 79mm of which fell during two hours from 5.30pm-7.30pm, while it was highest at 147mm in Mayur Vihar (Delhi).
EMERGENCE OF ‘LA-NINA’ DELAYED TO AUGUST-END
The IMD DG said the temperatures over the equatorial Pacific Ocean continue to remain near-normal so the emergence of La-Nina has been delayed to August-end. This is an ocean phenomenon characterised by cooler waters in the equatorial Pacific which strengthens the monsoon current. La Nina in September is likely to boost monsoon rains, and overall, and favour above-normal rains for the second-half of the monsoon season from August to September, said IMD.
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