Yesterday saw one of the stormiest days of the Pre Monsoon Thunderstorm season 2020. It is no coincidence that it is at a time when the King of Tropical Waves, MJO, has been travelling over the Indian Ocean. The day started with North Coastal TN coming under a batch of rampaging storms that hugged the East Coast all the way from North AP / Odisha for more than 24 hours and ended up with lighted skies over the West Coast in Kerala & South Karnataka.
April rains are always welcome for coastal places like Chennai, more so when the previous day was the hottest day of the year. Many parts of the city & suburbs recorded moderate rains before the storms moved SW towards interior TN reaching all the way up to West Interior districts of Erode & Tirupur.
The satellite image indicates the influence MJO is playing with increased convective activity seen over the Eastern Indian Ocean which could see a possible Low Pressure develop in the next couple of days over the Equatorial waters in Bay of Bengal. While MJO is expected to remain over the Indian Ocean for the next few days, its subsequent Eastward movement into Maritime Continent will still allow it to pull the strings over Bay of Bengal.
The role of MJO in increased amplitude of thunderstorms both in terms of intensity & spatial spread cannot be discounted. Over the next couple of days interior areas of Tamil Nadu will continue to benefit from these thunderstorms triggered by both convective process through day time heating and also the wind instability created by converging winds. While the most intense thunderstorms of the sub continent will happen over North Coastal AP & Odisha few places in Peninsular India will also see high intensity thunderstorms under right conditions.