This year, the India Meteorological Department (IMD) is likely to issue fortnightly forecasts of the monsoon’s arrival in States, once it begins its onset over Kerala. Typically, the IMD only forecasts the monsoon’s arrival over Kerala — around mid-May — and then gives a three or five-day heads-up as it journeys northwards.
This year, it will tweak one of its models to generate a 15-day lead time. “It’s a difficult task but we hope to make a beginning this year,” said Madhavan Rajeevan, Secretary, Ministry of Earth Sciences (MoES).
The IMD is an organisation under the MoES.
Climate meet ahead
Mr. Rajeevan would be detailing plans later this week in Pune at the South Asian Climate Outlook Forum — an annual conference of climate and monsoon experts from Afghanistan, Bangladesh, Bhutan, India, Maldives, Myanmar, Nepal, Pakistan and Sri Lanka.
While the IMD, on Monday, said that India would experience a ‘normal’ monsoon — or 97% of the 89-cm average — it hasn’t indicated how this would distribute geographically.
Farmers are interested in when the monsoon will arrive at their fields and a longer lead time means decisions, such as what seeds to sow, furrowing, etc. can be better planned hence, the interest in an improved-forecast system.
IMD chief K.J. Ramesh told The Hindu that the organisation already issued weekly forecasts — each valid for two weeks — on the likelihood of significant rains in any region.
Historically, meteorologists have identified mile-markers: the monsoon system reaching Maharasthra within 10 days of landing in Kerala, and the whole of the country being covered by the 15th of July. However these schedules are increasingly getting erratic.
Last year the monsoon arrived in Kerala on the 30th of May; precisely when the IMD said it would arrive. After that it stalled and didn’t reach north Karnataka, Telangana and central Andhra Pradesh until 11th June, instead of the traditional 5th June.
Though every monsoon has its own quirks — regarding the pace of its progress — meteorologists say the last few years the monsoon has been moving along slowly and even stays on until mid-October instead of its traditional September-end exit.
“A reduction in depressions (supporting cyclonic-like winds from the surrounding seas) slows down the monsoon patterns and climate change does seem to have a role,” said Mr. Rajeevan. The IMD’s Monsoon Mission Climate Forecasting System (MMCFS), or the ‘dynamical’ model that simulates the weather on supercomputers, is being employed for these forecasts.
Another scientist familiar with the exercise said 7-day forecasts were better captured by the MMCFS but any earlier, harder to capture.
Published - April 18, 2018 12:15 am IST
