Easterly wave boosts weather over south Tamil Nadu

The northeast monsoon has been active over south Tamil Nadu during the 24 hours ending Sunday morning as an easterly wave buffeted extreme southern peninsula.

An update by the Chennai Regional Met centre said that rainfall occurred at most places over south Tamil Nadu and Lakshadweep and at a few places over Kerala, north Tamil Nadu and south interior Karnataka.

Isolated rainfall occurred over coastal Andhra Pradesh, Rayalaseema, coastal and north interior Karnataka.

Disturbed upstream


A warning of disturbed weather over the Andaman Sea and the Gulf of Thailand upstream has been extended until Monday by the Thailand Meteorological Department.

Easterly winds speeding up to between 20 to 35 km/hr, heavily overcast conditions and scattered thundershowers have been warned of over the Andaman Sea during this period.

A two-day forecast issued by the Chennai Met Centre said that rain or thundershowers are likely at many places over south Tamil Nadu, Kerala and Lakshadweep.

Isolated thundershowers have been forecast over north Tamil Nadu, Puducherry, Rayalaseema, coastal Andhra Pradesh, coastal and south interior Karnataka. Isolated rain is likely over north interior Karnataka and Telangana.

Heavy rainfall warning has been issued for south Tamil Nadu, Kerala and Lakshadweep during the next 24 hours.

Outlook by India Meteorological Department (IMD) said that isolated to scattered rain activity would continue over south peninsular India until the end of the week, which is in agreement with that of most international models.

What is currently engaging the minds of weather watchers is the possibility of any organised convection taking place in the south and adjoining south-central Bay of Bengal during the week.

Almost the entire Bay basin has warmed up sufficiently – except along the coast of India - to be able to host a weather system.

In fact, the European Centre for Medium-Range Weather Forecasts (ECMWF) had late last week hinted at the possibility of a weather system shaping up over south-central Bay of Bengal.

On Sunday, however, the IMD picked a cyclonic circulation each over southwest Bay of Bengal and adjoining Comorin region. Satellite imagery showed convective clouds over parts of south Andaman Sea and southeast Arabian Sea.

The Canadian Meteorological Centre model hinted the possibility of formation of a low-pressure area over the south Tamil Nadu coast during this week.

The UK Met Office, as did a few other international models, saw a cyclonic circulation patrolling the southwest coast (off coastal Karnataka-Kerala) during this week.

The Climate Prediction Centre (CPC) of the US National Weather Services has said that rain or thundershowers are possible over the southern peninsula during the week with southeast Bay of Bengal and adjoining east Indian Ocean continuing to be very active.

Meanwhile, the Empirical Wave Propagation method employed by the CPC to track the movement of weather-causing Madden Julian Oscillation (MJO) wave has projected that the next wet phase would be active over equatorial Indian Ocean from December 11.

The wave would be particularly active around Sri Lanka and the southern Indian peninsula from December 16 to 26. This could favourably impact the northeast monsoon that normally runs until the end of December.

MJO TRACKING


The MJO wave travels in the upper levels of the atmosphere periodically from west to east and can set up weather over ground depending on its alternating wet or dry phase.

Back home, towards the north of the country, maximum temperatures were below normal by 2-4 degree Celsius over parts of Punjab, Haryana, Uttar Pradesh and Gujarat during the 24 hours ending Sunday morning, the IMD update said.

Minimum temperatures too were below normal over parts of central, east and north east India, Punjab, north Haryana, east Uttar Pradesh and Telangana. The lowest minimum of 3.5 degree Celsius was recorded at Meerut.

Colder northwesterly winds continued to prevail over Indo-Gangetic Plains in the lower levels. No significant change in minimum temperatures is likely over northwest India during next 24 hours but a slight rise is seen thereafter.