The aftermath period of any extreme weather event is always fraught with fear. Any fresh update triggers anxiety for the affected people. One needs to strike a fine balance between providing clear update without triggering panic. It is also essential not to underplay any potential extreme event coming up so that people are better equipped. Weather Anxiety is becoming a more common phenomenon with the social media arrival. The upcoming period of Northeast Monsoon also pretty much falls into a similar category. With large parts of Tamil Nadu battered by Cyclonic Storm Fengal there is a visible anxiety among common public. With IMD announcing the formation of LPA in South Bay yesterday talk in mainstream media has also increased.
But it is essential to separate the wheat from the chaff while providing an inference during critical times like now. Yes there is an LPA now currently over Southeast Bay of Bengal. There is increasing convergence among weather models it may move NW towards Sri Lanka / Coastal TN. Not to forget increasing convergence among models about possible rainfall event next week. But there are a few crucial differences that needs to be highlighted. One of the biggest difference is the state of ocean temperatures around South Bay. While the temperatures still remain abnormally. warm there is a fair bit of cooling due to the slow / near stationary movement of Cyclonic Storm Fengal. This could potentially mean significant intensification may be less likely.
Similarly weather models seem to be in convergence about this LPA / WML not moving across Peninsular India and resurface into Arabian Sea. One of the biggest challenges with Fengal was its movement across Peninsular India as a significant disturbance. This enhanced the rains over interior Tamil Nadu bringing in floods over basins like Then Pennai. A weaker disturbance could potentially mean heavy rains may be restricted to coastal areas of Tamil Nadu. Additionally unlike Fengal which brought it very heavy rains continuously for a period of 3 days this event may be shorter.
One other reason this rainfall episode code during the upcoming week may be shorter is the arrival of a fresh disturbance. Sub seasonal weather models were consistently picking up a mid December disturbance over South Bay. This is now gradually reflecting in operational weather models as well. Unlike the current LPA that is closer to Equator the incoming one next week may come in around 10N latitude. The arrival at 10N latitude could mean a WNW movement may bring the WML / Depression closer to North TN coast.
We will cross the bridge when it comes as far as next disturbance goes. Just to reiterate the current LPA may become Well Marked over the next 24 to 48 hours. In all probability this could be the peak intensity for this disturbance. There is a 50:50 chance it may become a depression when it reaches ENE of Sri Lanka. But overall the upcoming week may see fairly widespread rains over Coastal Tamil Nadu. The stretch between Pondicherry and Delta may be the hotspot for heaviest rains. Some models indicate a potential WSW movement of the LPA / WML in the last leg. If this materialises then parts of South TN could see some much needed rains later next week.
Next couple of days until the LPA moves closer to Tamil Nadu less rains likely in the state. Drier and cool weather likely to prevail until Tuesday with rains gradually returning subsequently.