Rains in Pettimudi was historic with massive 616 mm in 24 hrs, on the sad day landslide occurred

With MJO in our Basin, it is inevitable to avoid Low Pressures / Depressions / Cyclones in our seas. Presently, the kingmaker MJO is in very favorable phase in our basin and it is very conducive for development of Cyclone.  The 1st system (system here defines low pressure as of now) is fully home grown baby of Bay of Bengal thanks to MJO. MJO is presently

1. Two Scenarios for the 1st MJO Baby (Nivar) – 1st Scenario (Weak Cyclone = Delta Landfall)

1. Landfall – Vedaranayam to Karaikkal
2. Dates : 24-25 November (Crossing date 25th)
3. Likely Wind speeds – 70 km/hr
4. Gusts – 80 km/hr
5. Probability of Delta Landfall (Vedaranayam to Karaikkal) – 20%
6. Extreme Rainfall – Tiruvarur, Nagai, Thanjavur, Perambalur, Ariyalur and Karaikkal
7. Very Heavy Rainfall – Tiruvarur, Trichy, Namakkal, Salem, Viluupuram, Tiruvannamalai, Kallakuruchi, Vellore, Cuddalore, Pondy, Chennai, Tiruvallur, Kancheepuram, Ranipet, Chengalpet
8. Conclusion – Widespread heavy rains from Delta to Chennai and extreme rains to Delta.

2. 2nd Scenario (Strong Cyclone – Karaikkal to Chennai)

1. Possible Landfall – Karikkal to Chennai
2. Dates : 24-25th November (Crossing date 25th)
3. Likely Wind speeds – 120-140 km/hr (As a result of little bit of more time available coming to North TN coast than going to Delta coast, it intensifies more moving north than as a weak cyclone to Delta belt)
4. Likely Gusts – 150 km/hr
5. Probability of North TN Landfall (Karaikkal to Chennai) – 80%
6. Extreme Rainfall – Cuddalore, Pondy, Villupuram Chennai, Kancheepuram, Vellore, Tiruvannamalai, Ranipet, Chengalpet will fall in path of extreme rains
7. Very Heavy Rainfall – Kallkuruchi, Nagai, Karaikkal, Permablur, Ariyalur
8. Conclusion – Massive Rains to Cuddalore-Pondy-Villupuram belt and destructive winds of over 100 km/hr. KTC (Chennai) will get very heavy rains.

3. South and South West will miss rains

In both Scenarios, south and South West TN like Nellai, Ramanathapuram, Thoothukudi, Kanyakumari, Virudhunagar, Madurai, Tenkasi and Dindigul.

Note: The above are just two likely scenario’s once there is model consensus on intensity in a day, we can freeze many things. Just 24 hours we can get 90% clarity.

4. Steering – Why North Tamil Nadu ?

Why cyclone is moving towards North Tamil Nadu, as you can see majority of our Cyclone will be steered by the Pacific ridge with upper steering and very rarely they take Arabian Sea ridge (Gaja in 2018) in under steering. The outflow in upper steered ridges are always allow the cyclones to breath well while under-steered systems are choked and does not intensify a lot (Gaja was an exception due to nil wind shear). Namma MJO baby is an upper steered system through the ridge extending from Pacific side.

5. Favorable parameters for Cyclone to intensify

Positives

1. Wind Shear – Ideal wind shear of 10-15 knots and shows decreasing trend (refer image below)
2. TCHP – 60-80 KJ cm2 (refer image below)
3. No dry air intrusion (refer image below)
4. Sea Surface Temp is warming up and ideal (refer image below)
5. MJO is in Phase 2 and with strong amplitude (refer 1st image)
6. Steering ridge to NE of low allows good outflow or breathing (refer the steering image)

Negatives

1. It is very close to coast – Time is short
2. Very fast movement

6. Delta People – No wind threat for Delta, please dont cut the trees

Heard Delta People in Nagapattinam and Tiruvarur are cutting Coconut trees based on news spread by someone . Just a kind request for the bloggers, when it comes to cyclone, it is not time to see who post 1st and who gets name or who gets most likes what are you going to do with that name ? It was heart breaking to see photos of people doing this to Coconut trees and waste of money because of too early posts and videos in youtube on the cyclone. The models are started to shift from Delta to northwards, one should not be mundari kottai when it comes to cyclone. Model consensus is very important and there will be always a twist. 1 bad blogger will bring bad name to all the good work done by many of the bloggers. Please do this as a service and not for anything else.

7. What will be the Cyclone Name for our MJO Baby

The next name in the cyclone list is Gati but Gati name will be given to the Somalia system. Remember the circulation near Maldives which gave awesome rains to South TN indirectly that circulation has now moved west and has become a beautiful cyclone.

This is more than a Deep Depression strength with a well defined eye and IMD will announce Cyclone Gati soon.

8. Our MJO baby will be named “Cyclone Nivar” and Cyclone avoid Sri Lanka for unknown reasons. Strangely the cyclone which try to avoid Sri Lanka and move towards TN coast are all with Coincidence starts with letter “N” – Nisha in 2008, Nilam in 2012 and now the expected Nivar which was shown crashing into Sri Lanka is now avoiding Sri Lanka and moving W-NW towards North TN coast.  It is not the 1st time, all cyclones try to avoid Sri Lanka only very handful cyclones have crossed Sri Lanka.

9. Fishermen

Fishermen from Tamil Nadu, Pondy and Andhra are not requested to venture into sea from today. This will be followed by another low pressure / system within few days. So be cautious in going into Deep Seas.

10. Tamil Translation Courtesy  Tami l Hindu online

https://www.hindutamil.in/news/tamilnadu/604174-mjo-s-1st-baby-nivar-growing-in-bay-two-scenarios-favorable-one-is-between-karaikkal-to-chennai.html

The above interpretations are personal and are for guidance – Please follow the official agency and Tamil Nadu State Disaster Management agency for authenticated updates.