The India Meteorological Department (IMD) has declared that the North-East monsoon has commenced over south peninsular India on Friday.
Tamil Nadu, Kerala and adjoining areas of Andhra Pradesh and Karnataka have been receiving consistent showers over the past few days.
CONVECTIVE CLOUDS
The 24 hours ending Friday morning saw rainfall or thundershowers being reported occurred at most places over Tamil Nadu and Kerala.
Many places over Andaman Nicobar Islands and a few places over south coastal Andhra Pradesh also witnessed wet spells.
Afternoon cloud imagery showed the presence of convective (rain-bearing) clouds extensively over the south peninsula and adjoining seas.
These clouds could be seen rising over south Andhra Pradesh, Tamil Nadu, Kerala, south interior Karnataka, southwest Bay of Bengal, Comorin area and South Arabian Sea.
A trough (elongated area of lower pressure and, hence, rain-friendly) lay extended from south-west to west-central Bay of Bengal.
HEAVY FALLS
The trough also featured a cyclonic circulation over southwest Bay of Bengal, which helps pump in moisture-laden easterly winds into the peninsula. A weather warning for the next two days said that heavy to very heavy rainfall would occur at one or two places over Tamil Nadu.
Heavy rainfall has been warned for one or two places over Kerala, south coastal Andhra Pradesh, Rayalaseema and Lakshadweep during this period.
An extended outlook by the IMD for the next seven days indicated a decrease in rainfall intensity over south peninsular India. This would come about after a circulation expectedly forming over southeast Arabian Sea digging a course away west into open Arabian Sea.
CHILL IN NORTH
A couple of global forecasts had suggested that this could instead stick to a path close to the west coast and travel north.
Meanwhile in the North-West, the ongoing rainfall/snowfall activity over the hilly regions may reduce in intensity as a prevailing western disturbance moves away to east.
Given this, minimum temperatures also would fall by 2-3 deg Celsius over parts of north-west and Central India from Wednesday.
Rain or thundershower would occur at one or two places over sub-Himalayan West Bengal, Sikkim and the Northeastern States from Tuesday.