All good things should come to an end goes an old saying. Peninsular India may not have seen the classic winter this year due to prevailing La Nina. But even the mild winter conditions have pretty much come to an end for the plains. Over the past few days night time temperatures have slowly started to climb up over the plains. Even the interior areas of Peninsular India and the slightly elevated Deccan Plateau region have also seen nights get less cooler.
Weather models indicate pretty much the entire plains of Tamil Nadu may start seeing minimum temperatures move North of 20°C. While this is due to winter ending partially. The other reason is the arrival of moist Easterlies from Bay. Under the influence of the East to West moving Equatorial Rossby wave a cyclonic circulation may form in South Bay. There is still some uncertainty in terms of its movement though models expect a WNW movement. This movement may decide on the eventual rainfall prospects for Peninsular India though South TN and Delta have a high chance for moderate rains.
The Extended Range Outlook of IMD also indicate the possibility of cyclonic circulation over the Equatorial Waters. It may make sense to wait for a couple of days before coming to a conclusion on the upcoming rainfall episode. One may wonder if it is unusual to expect rains at this time of the year. With La Nina prevailing it is not entirely unusual. As recently as 2022 we saw two depressions in Bay of Bengal during the month of March. It is also worth mentioning most circulations tend to move South to North during the month of March unlikely the predominantly WNW / NW movement during NEM season.
Meanwhile it is also essential to keep a tab on the day time temperatures over North Tamil Nadu. Weather models indicate North TN may see hotter than normal afternoons for the next few days. Interior areas of the old composite Vellore dt, Tiruvannamalai may see day time temperatures stay 2 – 4°C above normal. While coastal areas may benefit from the moderation provided by the Easterlies they may still be warmer than normal.
A detailed update on the upcoming rainfall episode will be put up in a couple of days time with better inference from weather models.