The North-East monsoon is expected to set in by Monday, way in advance of its normal timeline, helped in no small measure by storms brewing in the Arabian Sea and the Bay of Bengal.
The normal window of onset, marked by escalation of rainfall along the Andhra Pradesh and Tamil Nadu coasts, is between October 15 to 20. Depending on how one looks at it, its arrival this year will be early by eight to 12 days.
S-W monsoon withdrawal
The India Met Department (IMD) announced the expected date of onset on a day when the predecessor South-West monsoon withdrew from most parts of North and East India and the withdrawal line prepared to enter Peninsular India.
On Friday, the withdrawal line passed through Kalingapatnam, Sironcha, Washim, and Dahanu with parts of Maharashtra, all of Gujarat and the North Arabian Sea having been covered.
Conditions are becoming favourable for further withdrawal from Chhattisgarh, Maharashtra, most of Andhra Pradesh, Telangana and Central Bay and some parts of Karnataka and some more parts of the Arabian Sea during next the three days.
This would prepare the ground for its exit from the entire country, leaving space for the ‘monsoon in reverse’ (North-East monsoon) to set in over Tamil Nadu, Puducherry, Kerala and adjoining parts of Andhra Pradesh and Karnataka by Monday.
‘Low’ over Arabian sea
Meanwhile, an expected low-pressure area spun up over the South-East Arabian Sea on Friday, which is expected to become ‘more marked’ (a well-marked ‘low’) by Saturday and further concentrate into a depression by Sunday.
The IMD has stuck to the view that the system would move in a north-westerly direction and intensify into a cyclonic storm by Monday and head towards the Oman coast.
A counterpart ‘low’ would form over the South Bay by Monday, become ‘more marked’ and move towards the Odisha and North Andhra Pradesh coasts. Extended forecasts suggest it could become a depression.
Given this context, the IMD has given out a forecast for heavy to very heavy rain for disparate regions in the South Peninsula, which normally falls under the footprint of the North-East monsoon. The spell could variously last until October 12 (Friday next).
The outlook for Saturday said heavy to very heavy rain is likely over Tamil Nadu, Puducherry, Lakshadweep and Kerala while heavy rain is seen over the Andaman & Nicobar Islands, Coastal and South Interior Karnataka.
Thunderstorms accompanied by lightning and gusty winds may break out over Tamil Nadu, Kerala, Coastal Andhra Pradesh, Telangana and Coastal Karnataka.
Sea conditions may remain ‘rough’ to ‘very rough’ (wave heights between four ft to 20 ft) over the South and Central Arabian Sea, the Comorin and Lakshadweep areas. Fishermen are advised not to venture into these areas.
Forecast for Sunday
Heavy to very heavy rain with extremely heavy falls have been predicted for Tamil Nadu and Kerala. Heavy to very heavy rain is seen for Lakshadweep and heavy rain for the Andaman & Nicobar Islands, Coastal, and South Interior Karnataka.
Thunderstorms accompanied by lightning and gusty winds are forecast over Tamil Nadu, Kerala, Coastal Andhra Pradesh, Telangana and Coastal Karnataka.