Tamil Nadu’s tryst with thunderstorms during the break in monsoon period continues unabated as yesterday saw many parts of Chennai hit by moderate to heavy spells of rains in the evening. The Western and Northern suburbs of Chennai saw the better spells of rains as places like Puzhal, Red Hills were hit by intense burst of rains around 5 in the evening.
One can consider yesterday as a prelude to what most of Tamil Nadu is likely to see over the course of the next couple of days. Not often one is likely to see wide spread rains in the coastal areas during Southwest Monsoon unless a lot of factors come in place at the same time. The next couple of days is likely to see a combination of factors which is likely to work favorably for Tamil Nadu in terms of thunderstorm prospects.
While the convective storms are mostly called “Veppa Salanam” or heat induced rains one should possibly not discard the role played by winds at lower and upper levels in creating the necessary instability in the atmosphere for the thunderstorms to thrive. Today is likely to be one such day with Mid Tropospheric Instability expected to come into equation during the later part of the day.
Adding fuel to the combustible atmosphere is the likely hood of Off shore convergence near North Coastal TN at lower levels and the probability of a strong sea breeze front which could interact with the thunderstorms moving in from the interiors towards the coast.
As always the case its futile to just blindly go by model outputs and point a single place of interest in terms of possible impact. Overall it appears the coastal TN along with parts of South AP between Delta & Nellore is ideally placed to benefit out of the thunderstorms moving in from the interiors. As always the case expect the thunderstorms to intensify closer to the coast, but lets not forget the genesis will more often than not be the interiors and possibly triggered by in many cases mechanical lifting by the broken Eastern Ghats.