Conditions are expected to become favourable for advance of the 2020 South-West monsoon into some parts of the South-East Bay of Bengal, the South Andaman Sea and the Nicobar Islands in three days (May 16, Saturday), followed by the onset of the seasonal rains thereafter.

What is seen as aiding the denouement is the formation of a low-pressure area over the South-East Bay and adjoining Andaman Sea, as per the two-day outlook of the India Meteorological Department (IMD). The low will help consolidate the south-westerly monsoon flows across the Equator, incremental westerly bands of which would precipitate the onset of seasonal rains sequentially over Sri Lanka, an intermediate port of call, and Kerala in mainland India, over the subsequent fortnight.

Build-up over Maldives

Before the rains can arrive over the Bay of Bengal, they report at an important pit-stop over the Maldives Islands, farther to the West-South-West and closer to the Equator. The Maldives Meteorological Service said this morning that scattered showers and thunderstorms are expected over the country, with showers likely being heavy over the Central and Southern atolls. Importantly, winds are becoming increasingly monsoon-friendly from the previous day.

The Maldives agency said that surface winds will prevail from the south-west/west at 21-37 km/hr across the Southern atolls and West/North-West at 12-29 km/hr elsewhere. Winds may gust up to speed of 72 km/hr during showers. Winds are expected to turn more Westerly/South-Westerly and pick up speed in time for the actual onset of the monsoon over the Maldives, normal period for onset of which is around mid-May. On Wednesday, clouds hovered over the Maldives as well as over South-East Bay of Bengal.

Pre-monsoon thunderstorms

The IMD said in a morning bulletin that a cyclonic circulation persists over the Comorin area. This apart, a pre-monsoon trough extends all the way down from West Madhya Pradesh to Interior Karnataka across Vidarbha, Marathawada and North Interior Karnaka. These are the two features driving the pre-monsoon thunderstorms over the South Peninsula and Central India. Satellites pictures showed clouds massing up over the Gulf of Mannar and across the Lakshadweep Islands and along the Kerala coast.

Isolated to scattered rain/thundershowers have been forecast over Central and South Peninsular India during the next three days. According to the IMD, thunderstorms accompanied with lightning and gusty winds (speed of 30-40 km/hr) are likely at isolated places over these regions. Heavy rainfall is forecast at isolated places over Kerala, Coastal and South Interior Karnataka and Lakshadweep during May 15-16 while squally weather is likely over the Lakshadweep and Andaman & Nicobar Islands during May 14-16.

North-West, North-East India

North-West India, East India and North-East India too are under the grip of typical pre-monsoon with an approaching western disturbance from across the Pakistan border preparing the ground. Scattered to fairly widespread rain/thundershowers are forecast for the hills (Jammu & Kashmir, Himachal Pradesh and Uttarakhand) as well as adjoining plains of North-West India (Punjab, Haryana, Delhi, Rajasthan and West Uttar Pradesh) during the next two days. Isolated thunderstorms accompanied with hail, gusty winds and lightning may lash these regions.

Similarly, the North-Eastern States may continue to witness spells of scattered to fairly widespread rain/thundershowers during the next five days. Isolated to scattered rain/thundershowers are forecast over parts of adjoining East India (West Bengal, Odisha, Chhattisgarh, East Madhya Pradesh) during this period. There could be isolated thunder squalls and heavy rain over Assam and Meghalaya today (Wednesday) and gusty winds, lightning and occasional heavy rainfall over the rest of the region during the next five days.

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