For the cool summer so far, thank the frequent spells of rain

Subject :Geography

Section: Physical geography

Context:

India was bracing for a record hot summer. However, western disturbances have brought some much-needed rain and surprisingly pleasant weather.
Despite a few heat waves, India has had an unusually pleasant summer so far. Temperatures in most places have been 1 to 4 degrees Celsius below normal, going against predictions of a very hot summer.

Predictions & portents:

2023 is predicted to be extremely hot both globally and in India. Indeed, the January to March period was globally the fourth warmest start to a year ever. March was the second warmest ever, behind only 2016; April was fourth warmest.
In India, there was a heat-wave like situation in February — a month for which heat-wave conditions are not even defined because heat waves are expected only in April, May, and June.
Despite the IMD’s forecast of a normal monsoon, apprehensions remain. The developing El Niño in the equatorial Pacific Ocean is expected to get very strong in the coming months, and has the potential to spoil India’s monsoon.

Rain and cool weather:

The first five months of the year have been far from being uncomfortably hot, the few heat waves notwithstanding.
Only parts of east and north-east India, and some parts of Gujarat and Maharashtra, have experienced slightly higher than normal temperatures.
The average maximums have remained well below normal almost everywhere except parts of Bihar, Jharkhand, West Bengal, and the Northeast. (Some of these areas are facing heat-wave conditions even now.)
At the same time, rainfall has been higher than normal in most parts of the country. For the three-month period from March to May, India as a whole received 12% higher rainfall.
The rain has been the most important reason that has kept temperatures in check.

Western Disturbances:

Most of the rainfall activity in the last three months happened over north and northwest India, and central India, and were caused by what are called Western Disturbances.
These are east-moving rain-bearing wind systems that originate beyond Afghanistan and Iran, and pick up moisture from as far as the Mediterranean Sea and even the Atlantic Ocean.
These are examples of extra-tropical cyclones that are a result of low-pressure areas formed due to the interactions between polar and tropical winds.
Western Disturbances frequently influence weather over India, particularly the northwestern regions.
There were seven Western Disturbance events in March, five in April, and eight in May, causing frequent, sometimes heavy, rainfall over large parts of India.
A fresh Western Disturbance is expected to bring more rain to northwest India. Southern India is also expected to get rainfall over the next couple of days because of a different low-pressure system.
Kerala is likely to receive some rain until Sunday, while some places in Karnataka, Andhra Pradesh and Tamil Nadu could receive rain over the next five days.

No pointer to monsoon:

The current weather conditions are the result of short-term local interactions that do not have a bearing over long-term weather. How the monsoon turns out remains to be seen.
Several scientists have predicted an unusually strong El Niño this year. The IMD has said that a positive Indian Ocean Dipole (IOD), a phenomenon similar to El Niño in the Indian Ocean, could offset the impact of the El Niño to an extent. However, El Niño is known to have a much stronger impact on the monsoon than the IOD.