Rare rains in Delta from coast, thanks to the UAC down south. Pondy-Cuddalore – Delta – South TN will see another great day, the UAC will fade away tomorrow.’
Chennai great heatless summer to continue for some few more days. Today lot of puffy clouds will be seen.
Next week options open – Semma Soodu ah illa some lucky rains ah, we will come to know in 2-3 more days. I assume all will be tracking the models and know the status urself
These are the scenarios
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Strong cyclone – we will miss the rains as it will move up
Curve away to Burma or Bangla – semma soodu awaits us.
Weak system – We have chance, as it will come close to TN before intensifying.
MJO is coming into our basin. SST is high, TPW is high. There is going to be a monster in bay. Our hope is it should not intensify in open waters, let it come close weak, give rains to us and then go somewhere else. If it goes straight up or curve away to Bangla or Burma, then we are in for frying.
We will know in few days. delay delay delay. Lockdown effects on models are seen.
From 8 to 12th March, 2021, there is chance of some rains in south India (South TN and South Kerala) such as Tuty, Nellai, Kanyakumari, Thenkasi, Virudhunagar and Theni distrct will get moderate rains from 8 -12th March. Some rains will be seen in parts of Coimbatore, Nilgiris and Valparai areas too. In Kerala, rains will be in Kollam, Trivandrum, Alapuzha, Pathanamthitta, Kottayam and Idukki districts. Wayanad and Mallapuram district too has some chance for rains in this period.
These rains will not be significant ones and will happen here and there.
Kingmaker coming into our Basin in the last week of month
The MJO is likely to come into our basin in the last week of March, this will make things interesting in Bay of Bengal / Arabian Sea and it is possible that the MJO might spin something. Its too early to confirm, lets wait and see how the MJO plays things out in our basin. Either way, things look good for both South TN and Kerala to get good rains from March end and April.
Note: Athigara porvamana vanilai arikkaiku, neengal official agenyin, forecast ai nadavum. Post podran podran solli, i have made you wait and i should not put a mokka post, so a big post. This post is pure interpretation with personal capacity. To be honest, this has been one of the difficult cyclone to interpret even with all the high end numerical models available. From bottom of my heart i want to appreciate IMD officials for sticking with their track of close to south of Pondy. Will try to answer most of the common man question in this post. If there are grammatical mistakes, please ignore, compiled in half sleep.
1. Where is the cyclone now and what intensity it is in ?
We can see here that the Cyclone is still over 300 kms away from our coast line (as of mid night on 24th) and is parallel to delta coast above north east of Sri Lanka. It has just moved above 10 N latitude moving in W-NW direction. The intensity is around 50 knots and pressure is 991 mb with wind speeds of already close to 100 km/hr.
2. Cyclone Nivar is expected to cross which are in Tamil Nadu and Why?
There is still no consensus among the models in the crossing area. But ippadiya wait panna, then i have to put post only after the cyclone crosses the land. The Europeans ECMWF, British UKMET and German ICON are more favorable for Nivar to cross towards Pondy to Chennai coast somewhere close to Mahabs. While the North Americans USA GFS and Canadian GEM are making the landfall close to Karaikkal / Parangipettai belt. Nammathaan USA ethu sonnalum keppom la, so IMD GFS model also takes it to Delta. Such a large divergence seen among the models with just 24 hours to go in to landfall and lot of katchi thavalas till today evening.
My interpretation of the above, the steering ridge from the pacific still controls the movement of the Cyclone with firm grip and until this Pacific Ridge steers the cyclone can take only W-NW path if it becomes strong. If it is a weak cyclone it can be pushed directly to Delta from east with pure west movement. And even in strong cyclones for it to move pure west, it has to be steered by Arabian Ridge which is very far away. The cyclone has already crossed 10 N latitude (please refer the 1st image above), there is very little chance for it to move pure west and crash into Delta like the American says and the Teacher from Delta says. So those who are in Delta, there will be some rains but Cyclone Nivar is not for Delta.
What is steering in simple layman i will try to explain this – Cyclones are pallam (low) and High pressure are medu when ur inside u can traverse only around the ridges of the medu (high pressure). That is steering. No apply ur mind on the above image and you can understand why Nivar is moving – W-NW. There are many other complex factors too. But will stop with this. Further, the Ensemble members of ECMWF also favors a track of crossing Pondy to Chennai around Mahabs (+ or – some kms).
So the conclusion is that Cyclone Nivar is expected to cross between Pondy and Chennai near Mahabs-Kalpakkam areas with some + or – some kms on the night of 25th to morning of 26th. The difference is not much between Mahabs and Chennai, if some little deviations occur, there are slight chances that cyclone might even land over Chennai.
4. Will Cyclone Nivar become stronger than Gaje Cyclone ?
Wind Shear of 5-10 knots and it is ideal for the Cyclone to intensity. We have seen in the past a wind shear 40 knots will destroy a strong cyclone into a skeleton within few hours. This low shear for Nivar path ahead with further decreasing trend will make one of the ideal conditions for intensification.
Next let come to the outflow. In simple terms, at lower levels (1-4 kms height) the inflow winds will come (converge) into the Cyclone, thes winds coming inside cant be trapped inside the cyclone itself, the winds coming at lower levels will have to escape out (diverge) at higher (10-12 kms height) levels. Let make it simple its nothing but breathing, we inhale and exhale to keep our-self alive. Like that Cyclone inhale (inflow) and exhale (outflow) to keep them alive. If outflow is not good what happens, winds keep on coming and at one point they collapse.
Those these are not the only parameters but these two as of not outweigh all others, with MJO in basin, optimal TCHP, good SST of 28-29 C and no dry air intrusion, i cant see any negative reason to weaken this Cyclone Nivar. High chances that this will become stronger than Gaje Cyclone.
5. What will be sustained wind speeds and gusts
We follow 3 min average for sustained winds and gusts (small burst of winds at times). With nothing negative to stop this cyclone we can expect this cyclone to intensify on par with Thane Cyclone (140 km/hr) or even better. The northern side of the cyclone crossing areas will get good winds too the ECR belt can expect 100 km/hr winds. So 26th morning will be a gusty morning for us.
140 km/hr – Pondy – Marakannam- Mahbas coasts (mid-night to morning of 26th)
100 km/hr – Cuddalore coast (midnight of 25th)
100 km/hr – Chennai Coast (26th morning)
100 km/hr – Chengalpet and Kancheepuram (26th morning)
80-90 km/hr – Ranipet, vellore and Tiruvallur (26th Noon)
6. What will be Rainfall and what are the districts ?
For accumulated rainfall till 26th evening,
Extreme Rainfall might happen around Cuddalore, Pondy, Villupuram and Chengalpet areas.
Very heavy rains might happen in – Chennai, Kancheepuram, Tiruvallur, Ranipet, Kallakuruchi, Tiruvannamalai and Vellore.
The interiors will get on 26th November while the coastal areas will get on 25-26th November. We will never know which spot among these districts where a big event might occur, which is always associated with Cyclones.
The rains will be intermittent to start with once we are close to the centre, we might see non stop rains for few hours when the centre passes the areas in above districts.
7. waves
The areas north of crossing will have the waves very rough. So right from Cuddalore to Nellore Coast dont venture out into seas or even go near the sea shore while crossing. The storm surges might come and wash you away.
Namma post na stats illama irukkathu, lets see the past cyclones in Tamil Nadu and wind speeds in Chennai and we will know where Nivar will stand.
9. Why Chennai (KTCC region rocked today) while others places did not even get rains
The concave coast is one major reason and the location of Chennai and spin of bands resulted in clouds right over KTCC. And our Chella Kutty Radar is back working overtime. Tomorrow the rains will be intermittent and as we near the landfall time, few hours before that we will get good non-stop rains when the centre is close to us.
14. Highest 24hrs rainfall in Tamil Nadu from Cyclones in North East Monsoon in last 10 years
Cyclone Phyan – 820 mm in Ketti, Nilgiris in November 2009
Cyclone Nisha – 656 mm in Orathanadu, Thanjavur in November 2008
Cyclone Ockhi – 451 mm in Papanasam Dam, Tirunelveli in
Cyclone Vardah – 382 mm in Shollinganallur, Chennai in December 2016
Cyclone Nilam – 240 mm in Yercaud, Salem in November 2012
Cyclone Gaja – 197 mm in Kodaikanal, Dindigul in November 2018
Cyclone Thane – 180 mm in Kallakuruchi, Villupuram in December 2011
Cyclone Jal – 160 mm in Gingee, Villupuram in November 2010
15. Do and Dont’s during Cyclones for Public.
After Nivar avaroda brother follow panni varar. ‘Tamil Nadu cant rest so soon, it needs to be vigilant.
Good morning to all. Intha post padikkama, next post epponu ketta semma gaandu ayuduvan !!! Will put up next post if there is some change in the above. Will switch off the phones and enjoy the rains.