Churn in Arabian Sea makes forecasters sit up

A remnant circulation from cyclone Laila has waded into the Bay of Bengal and set up a fresh low-pressure area on Monday.
The system is not seen as intensifying appreciably to exert further “pull” pressure on the monsoon, currently regrouping over the southeast Arabian Sea.
This part of the Arabian Sea is showing signs of some churn, but would need to be watched for likely formation of a system and its subsequent strengthening.

ONSET DYNAMICS


System formation and its strengthening just before the onset of monsoon could have an adverse impact over associated dynamics along the Kerala coast, as witnessed in the past few years.
A strong system (or an untimely cyclone) in the Arabian Sea before the monsoon flows have settled into the ideal pattern could see itself being driven north either along the west coast or away from it, and rob mainland India of precious moisture.
Otherwise, conditions are evolving for the onset over the next two-day period, according to Dr C.K. Rajan, Professor-in-charge, Chair for Climate Change at the Kochi-based School of Communication and Management Studies (SCMS).
The system behaviour would become clear in 12 to 24 hours after the Laila remnant in the Bay expectedly dies a natural death and its impact on the monsoon flow wanes, Dr Rajan told Business Line.
Prof Paul Roundy at the University of Albany has been alluding to the development of a system in the southeast and east-central Arabian Sea and, in the latest update of May 20, he has maintained the outlook.

CONVECTIVE CLOUDS

An India Meteorological Department (IMD) update said that satellite imagery showed convective clouds over parts of northeast, east-central and adjoining west-central and southeast Bay of Bengal, the Northeastern States, Gangetic West Bengal, Kerala and south Arabian Sea.
The satellite picture update for aviators put up by the International Civil Aviation Organisation also showed convective clouds massing around the region late on Monday evening.
Winds in the south Arabian Sea are southwesterly becoming westerly to the north of 5 degree Latitude, and this wind profile would need to extend north to the 10 degree N latitude for onset conditions to generate.
The US National Centres for Environmental Prediction showed a calibrated rise of rain activity along the southwest coast during the course of this week.

RAIN SPURT

The International Research Institute for Climate and Society at Columbia University saw a spurt in rainfall around the extreme southern peninsular point around Wednesday and Thursday.
Meanwhile, the IMD said in its forecasts valid until Thursday that fairly widespread rain or thundershowers would occur over Kerala, Lakshadweep and the Andaman and Nicobar Islands.
Fairly widespread rain or thundershowers have been forecast also over the Northeastern States during this period as moisture incursion continues under the effect of strong southwesterly flows from the Bay of Bengal.
A western disturbance is expected to cause isolated rain or thundershowers over Jammu and Kashmir, Himachal Pradesh and Uttarkhand during the next 24 hours.
Isolated dust storm or thunderstorms may occur over Haryana, Delhi, Uttar Pradesh and Rajasthan in the northwest and over east India and Karnataka.