Possible delay in Monsoon dynamics

The Heat over North Tamil Nadu does not seem to be in a mood to go away any time immediately. The IMD observatory at Nungambakkam crossed 41°C for the second time this year after 2nd May 2019. The airport observatory crossed 41°C for the fourth day in a row recording 41.6°C yesterday about 0.6°C higher than the previous day.

Today also weather models indicate day time temperatures to remain similar to yesterday with the city areas of Chennai likely to see day time maximum temperatures around 41°C while the western & Southern suburbs will be a tad hotter around 42°C. The stretch between South AP & Villupuram district could remain the hottest area of the state.

Weather models indicate a pseudo circulation feature over the Comorin Sea area. This is likely to strengthen the Easterlies at lower level of atmosphere providing thunderstorm opportunities for places along the Western Ghats. Additionally the moisture brought in by these Easterlies on interacting with the rising air particles through extreme heat over North TN could trigger isolated thunderstorms in the region.

While heat seems to be the overall theme off late it is essential to keep a tab on what is happening south of Equator too. As we mention many times the trigger for Southwest Monsoon dynamics happen over the Southern Hemisphere. One indicator on the development of monsoon dynamics is the evolution of Cross Equatorial Westerlies that are responsible for the Bay Branch of Southwest Monsoon.

While Kerala is the more universally popular destination as the first Port of Call for Monsoon in the Indian Mainland, it is Andaman & Nicobar islands that is the first Port of Call for Indian Sub Continent as the Cross Equatorial Westerlies, as Bay Branch, bring monsoon into these areas. The wind charts indicate a scrambled Easterlies south of Equator which possibly is reflecting in poor Cross Equatorial Westerlies as things stand. While the normal window for Monsoon to hit A&N Island is 15th to 20th May it appears we could see a slight delay in monsoon reaching A&N Islands. It is too early to say if this may have a bearing on the monsoon onset over Kerala too.