Yesterday in a much needed development parts of Chennai and suburbs saw rains in a way that sort of set the stage for the onset of northeast monsoon 2022. Last week the development of Cyclonic Storm Sitrang through its movement towards north bay brought about winds from north over peninsular India bringing about a reduction in not only rains for the coastal areas but also thunderstorms over interior areas of Peninsular India. The rapid dissipation of the remnants of Sitrang sort off became a positive development for the return of moist easterlies from Bay of Bengal to set the stage of northeast monsoon 2022.
Satellite images indicate the gradual movement of easterlies from south China sea into Bay of Bengal in the form of convection moving east to west bringing moisture into coastal areas of peninsular India. If one were to look at the wind charts the winds at 1.5 kms above sea level indicate the coastal areas of north TN and south AP for the next 24 hours or so will possibly see slightly more drier winds from the NNE rather than the moist easterlies from the bay. This will gradually fade away as the easterlies from south China sea start to penetrate further west pushing the moisture across.
As the easterlies push further west bringing with it increased moisture conditions not only become conducive for the onset of northeast monsoon but also the wind convergence over parts of coastal peninsular India between drier northerlies and moist easterlies will become more pronounced triggering intense thunderstorm activity on account of abundant moisture at lower levels brought by the easterlies. While the actual location of this wind convergence will change based on real time conditions it is fair to estimate parts of north coastal TN and south coastal AP remain vulnerable for a spell of heavy to very heavy rains over a 24 hour period between during the first few days of November. Weather models indicate a weak disturbance in the form of a trough of low over south Bay providing support to the onset phase of this years NEM.
In the meanwhile today we can see moderate rains along the coastal areas of Tamil Nadu between delta districts and Chennai with tomorrow influenced by the easterlies pushing further parts of south TN may also come under monsoon conditions. Gradually rains are expected to pick up from tomorrow all across the east coast of peninsular India between Kavali in Andhra Pradesh and south TN. Northeast Monoon onset may be delayed this year but hopefully the delay will not have a bearing on its overall performance. Things can change drastically in weather dynamics and this year will possibly be an example of how these rapid swings change the monsoon dynamics hence it may make sense to take one week at a time.