IMD predicts early arrival of monsoon
The southwest monsoon is likely to advance into the south Andaman Sea, some parts of the southeast Bay of Bengal and the Nicobar islands around May 19
The southwest monsoon is likely to advance into the south Andaman Sea, some parts of the southeast Bay of Bengal and the Nicobar islands around May 19, ahead of its normal onset date of May 22, the IMD (India Meteorological Department) said on Monday.
The monsoon normally advances further to Kerala around June 1; thereafter it advances northwards, usually in surges, and covers the entire country around July 15.
Monsoon rainfall over the country between June to September is likely to be “above normal” at 106% of the long period average (LPA) with a model error of +/-5%, the IMD said in its long-range forecast on April 15. An updated forecast will be provided during the last week of May, which is also expected to provide probabilistic forecasts for seasonal rainfall over the four homogenous regions of India (northwest India, central India, the south peninsula and northeast India) and the monsoon core zone (MCZ). Around the same time, the IMD will announce the likely monsoon onset date over Kerala.
“The southwest monsoon is very likely to advance into the South Andaman Sea, some parts of the southeast Bay of Bengal and the Nicobar islands around 19th May, 2024,” the IMD said on Monday, adding that light-to-moderate rainfall accompanied by thunderstorms, lightning and squally winds (40-50kmph) is likely over sub-Himalayan West Bengal, Sikkim and the Andaman & Nicobar Islands during the next seven days while widespread rainfall, lightning and squally winds are expected over Tamil Nadu, Puducherry, Kerala, Mahe and Karnataka in the same period.
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The LPA for the season as a whole for the period 1971-2020 is 87cm. Last year, the monsoon was “below normal” at 94.4% of the LPA. The IMD had forecast a “normal” monsoon last year at 96% of the LPA with an error margin of +/-4%. Before that, the 2022 monsoon was “above normal” at 106% of the LPA; 2021 recorded a “normal” monsoon at 99% of the LPA and the 2020 monsoon was again “above normal” at 109% of the LPA.
A cyclonic circulation is lying over south interior Karnataka and a trough is running from it to northwest Madhya Pradesh at lower tropospheric levels. Another cyclonic circulation is lying over the Comorin area at lower tropospheric levels. Under their influence, there is a lot of pre-monsoon activity over central India -- isolated to scattered light-to-moderate rainfall accompanied with thunderstorms, lightning and squally winds is very likely over Madhya Pradesh, Vidarbha, Chhattisgarh, Madhya Maharashtra and Marathwada during the next five days apart from thunderstorms, lightning and gusty winds (30-40kmph) over the Gujarat region on May 14.
Isolated hailstorm activity is also likely over Madhya Pradesh on May 14.
The IMD has also forecast a fresh spell of heatwave over northwest India starting May 16. There is likely to be a gradual rise by about 3-5 degrees Celsius in maximum temperatures over many parts of northwest and east India during the next five days.
“Models are indicating good rainfall over the Andaman Sea region on May 19, 20 and 21. They are also showing that cross-equitorial flow of winds will be established over the region around that time. It normally takes around 10 days for the monsoon to reach Kerala after reaching the Andaman region. But every year is different. Also there is an anticyclone persisting over the Arabian Sea and the monsoon will not advance over Kerala until that moves away,” said Mahesh Palawat, vice-president, climate and meteorology, Skymet Weather.
“Temperatures are expected to rise over northwest India, including Delhi, now. We are not expecting any pre-monsoon activity immediately again over this region. Hot, dry northwesterly winds are expected to blow over the region; clear skies will also increase the heat,” Palawat said.
On Sunday, maximum temperatures were in the range of 40-42 degrees Celsius over many parts of west Rajasthan, east Madhya Pradesh and Vidarbha, Chhattisgarh, the Gujarat and Rayalaseema region, and in isolated pockets of east Rajasthan, Saurashtra, Kutch and Telangana.
