Monsoon pattern catches meteorologists unawares

Monsoon pattern catches meteorologists unawares

New Delhi: The cloudburst over Leh in Ladakh, floods in Pakistan and China, and a crippling drought over Russia have left meteorologists poring over weather models and historical data to make sense of why conventional monsoon patterns aren’t playing out over India and its neighbours.

The anomalous conditions that salvaged monsoon rains in India this year could be responsible for the floods over Pakistan as well as droughts in Russia, they say.

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“There is a common thread to all these events, though none of the dynamical models (an approach where scientists use computer programmes to simulate the atmosphere and forecast the weather) seemed to have predicted these patterns of weather," said Madhavan Rajeevan, a senior meteorologist at the Indian Space Research Organisation (Isro). “This heavy rainfall over the country is still not explicable."

The cloudburst in Leh, a Himalayan district in Jammu and Kashmir, and the resulting flash floods on 6 August have claimed 166 lives and injured 73, PTI reported. Some 400 are still missing.

“Mountainous regions do contribute to cloudbursts, but Leh is so arid that enough moisture, that too capable of causing such heavy rains, simply doesn’t accumulate. There are cloudbursts in the Himachal region frequently, but this is strange," said Ajit Tyagi, director, India Meteorological Department (IMD).

The occurrences would spark off several research papers over the next few months, including those from IMD-funded institutions, he added.

This year’s monsoons were weak until mid-July, but have surpassed expectations since.

Typically, rain-bearing depressions, a precursor to cyclones in the Bay of Bengal and originating along the east coast of India, bring rains to rice, oilseed and wheat-growing regions such as eastern Uttar Pradesh, Jharkhand, Madhya Pradesh and Orissa.

The depressions this year came from central Asia and the Arabian Sea, and such anomalies may threaten the dependability of the monsoon.

“There have been no depressions and few low pressure systems over the Bay of Bengal," Tyagi said. “If such a situation persists for a few more years, then the whole monsoon itself will be affected. Why all of this is happening is still an open research question, and we, too, are trying to understand this."

Other experts said that barring El Nino (a heating of waters in the central Pacific region associated with droughts over India), monsoon conditions this year were similar to last year, which saw India’s worst drought in 37 years and worsened food price inflation. El Nino did not recur this year.

D.S. Pai, director, forecasting, at IMD’s Pune unit, said all these weather conditions could be little more than a coincidence. “Usually, when it rains in China, showers weaken over north-west India. But historical data shows that it has simultaneously rained substantially in both regions before. It’s rare but not unprecedented."