While the monsoon is stuck over the South Andaman Sea and South-East Bay of Bengal three days after India Meteorological Department (IMD) declared its arrival, an emerging powerful typhoon over the West Pacific may take centre-stage, intensify flows and help its cause over the Bay.
The typhoon is predicted to race initially West across the Pacific towards Taiwan from where it might recurve and drive itself away.
While the southern parts of the Bay may make some gains, the same cannot be said about the Arabian Sea off the Kerala coast where the monsoon strikes land first.
Arabian Sea averse
The short-term outlook of the IMD and global models indicates an unfriendly region of high pressure (anticyclone) will hold fort over the Arabian Sea at least until June 1, suppressing cloud formation or rain.
But parts of the West Coast, interior peninsula, East-Central, and adjoining North-West India may witness rain or thundershowers from passing western disturbances across North India.
Since monsoon flows would be conspicuous by their absence during this period (until June 1), these disturbances (waves of lower pressure) will be prompted to extend limbs in the form of weather-friendly troughs towards the South to Central India and the South Peninsula.
Moist air from the Arabian Sea will rush in as hot air expands over land, cool, and set up thunderstorms.
Lower day temperatures
Accordingly, maximum (day) temperatures may rise by 2-3°C over North-West India until tomorrow (Tuesday) and fall by 3-5°C with rain, thunderstorms, lightning, and even hail materialising thereafter.
No significant change in maximum temperature is seen over the rest of the country during the next five days.
Heatwave conditions may emerge over parts of South Haryana, Delhi, southern parts of Uttar Pradesh, West Rajasthan, East Madhya Pradesh, plains of West Bengal, and Jharkhand today.
Towards the East, almost similar conditions will emerge with the western disturbances continuing with their eastward journey over North and East India, lowering ‘payloads’ of volatile weather along custom-generated troughs as moist air from the Bay fill the vacuum left behind by the ascending hot air.
Rain, thunderstorms, lightning, and high winds will be the result here as well.
Rain, thunderstorms seen
The monsoon can enter these regions only after these troughs cease to exist over a land heated up suitably.
Western disturbance activity should also come to an end for the Bay arm of the monsoon to enter Central and North-West India (the monsoon has a since-like approach with the Bay and the Arabian Sea arms hitting the East and West Coast respectively for onset).
The IMD said this (Monday) morning the northern limit of the monsoon continued to pass through Nancowry in the South Andamans.
Conditions are favourable for its further advance into some more parts of the South Bay, the Andaman Sea, and the Andaman & Nicobar Islands during the next 2-3 days.
Strong south-westerly winds are blowing from the Bay to North-East India.
Fresh western disturbance
A prevailing western disturbance has reached North-East India even as a successor is likely to affect North-West India from Tuesday.
This too will be an active one and will hold sway variously until the month-end (May 30) even as another gets triggered over the Mediterranean and sets itself rolling in. It can hit North-West India with some intensity if the monsoon has not been established by then.
IMD outlook for the next few days is instructive. Fairly widespread to widespread rain, thunderstorms, lightning, and gusty winds are likely over the hills of North-West India and isolated to scattered rainfall over the plains from Tuesday to Friday.
Thunder squalls (wind speeds of 50-60 kmph), hail, and lightning are likely over Uttarakhand while heavy rain may lash parts of Jammu & Kashmir and Himachal Pradesh.
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Central, South India
Over Central India, light to moderate to isolated rain, thunderstorms, lightning, and gusty winds are forecast for Vidarbha and Chhattisgarh during the next three days and over Madhya Pradesh until Friday.
Over South India, light to moderate isolated to scattered rain is forecast during the next five days over many parts of the region.
Thunderstorms, lightning, and gusty winds are likely over Coastal Andhra Pradesh, Telangana, Tamil Nadu, Puducherry, and Karaikal until Friday; over Interior Karnataka until Tuesday (tomorrow); and over Kerala and Mahe during the next five days.