Since the start of Northeast Monsoon season it has been a wonderful couple of weeks for Interior Tamil Nadu. The current seasonal performance for TN & PDC stands at 208.3 mm 53% excess than normal rainfall. Among weather bloggers though above average always brings a certain bit of scepticism about overall seasonal performance. A scepticism triggered by more recent memories of years like 2017 to 2019. Years when Chennai saw nearly 300 mm by the time October end but struggled for the rest of the season. The prospect of a dry Diwali pretty much adds to the nervousness as well.
Around the same Diwali period during the year 2019 a spell of dry weather brought about similar cynicism. It is common knowledge when a north moving pulse happens there is likely to be a spell of dry weather. The movement of Cyclonic Storm Dana to Odisha / West Bengal was picked up fairly well by weather models. In all this one should also not forget the overall NEM performance so far has been good. Nagappattinam, Tenkasi and Thoothukudi are the only districts currently in deficit. Tirunelveli, Virudhunagar and Puducherry though not in deficit but show negative anomaly.
With possibly a spell of 7 to 10 days of dry weather the murmur about poor NEM 2024 will start getting louder. Having tracked weather for so many years the dry spells are not unusual during Northeast Monsoon. To add a context we have had very good NEM years like 2015, 2020 in recent times despite onset happening late October. While it is essential to keep a more grounded perspective it should not be at the cost of dropping the guard. Sub seasonal weather outlooks continue to show a fairly strong couple of weeks during November. A period which may coincide with favourable transit of MJO over the Indian Ocean.
Once the current circulation over Odisha fades away the drier Northerlies will be replaced by westerlies over Peninsular India. Easterlies though will take some time to return back to Bay of Bengal. Tropical storm Trami over Indo China Peninsula is expected to hold back the return of Easterlies. Later next week we can expect the Easterlies to gradually make a return once Trami weakens. The remnant pulse of Trami may then play a beneficial role moving in as a circulation into South Bay. This could potentially set off what could be the 1st active phase of NEM 2024 for the coasts.
Until then it is likely to be dry weather for most of Tamil Nadu. Places like Chennai may see warmer than normal conditions. Diwali will remain relatively dry across Peninsular India except for parts of South TN which may benefit from westerlies. The westerlies will possibly bring a spell or two of heavy rains for the next couple of days. Kerala and adjoining Ghats of TN, parts of Kanyakumari, Tirunelveli and Tenkasi may see heavy rains today and tomorrow. Starting from tomorrow we can see the intensity of the rains reduce.
The season still has two months to go. Under La Nina conditions there is always a possibility of late season flourish. Overall there is no reason yet to panic about a below par NEM year.