The circulation is still well away from TN coast and elongated one and one end of the circulation is creating convergence close to North TN coast thats why we are seeing monsoonish feel. Still this is clouds from N-NW and not from east from sea side like our monsoon.
The startiform clouds associated with the intense bands are giving steady rains to KTC and Chennai from the morning. This will continue throughout the day with varying intensity at times. If some of the intense bands are pushed in by luck like a water ripple then the intensity of rains will pick up. Mostly we will see steady rains troughout the day with increase in intensity later in the evening / night.
What will happen to this new circulation / low
As you can see the circulation is very far away but on October 20th, one of the vortex in the circulation comes close to SAP and North TN coast, we can get good rains on 20th. Then the circulation is caught in the westerly trough and dragged up north towards West Bengal / Bangladesh. When it moves up North TN and South AP falls in the interaction zone of the westerlies trough and the circulation and models show enhanced rains when this even pans out on October 23/24.
Meanwhile, what a day it turned out to be, Thanjavur got the heaviest rains of the year. The list so huge so limiting the rainfall to 40 mm.
Rainfall in Tamil Nadu on 18.10.2020
————
in mm (min 40 mm)
Pudukottai
———-
Perungalur – 134
Arimalam – 80
Adanakottai – 75
Illupur – 73
Malaiyur – 65
Kariayur – 64
Aranthangi – 62
Keeranur – 52
Gandarvakottai – 40
Thanjavur
———
Vallam – 125
Thanjavur – 95
Echanviduthi – 80
Grand Anaicut – 62
Thanjavur PTO – 57
Thirukkattupalli – 56
Manjalaru – 54
Budalur – 53
Thiruvaiyaru – 43
Thiruvidaimaruthur – 43
Tiruvannamalai
———–
Kilpennathur – 106
Thandrampattu – 73
Chengam – 53
Tiruvannamalai – 48
Trichy
———
Samayapuram – 81
Lalgudi – 76
Ponnaniyar Dam – 63
Nandhiyar Head – 58
Viralimalai – 57
Koppampatti – 43
Devimangalam – 40
Thuvakudi – 40
Villupuram
—–
Vanur – 75
Valathy – 52
Nemoor – 50
Avalurpettai – 44
Kedar – 44
Mugaiyur – 43
Marakannam – 40
Mailam – 40
Kallakuruchi
————–
Moongilthuraipattu – 70
Tirukkoilur – 45
Manalurpet – 42
Erode
——-
Perundurai – 64
Bhavani – 62
Erode – 48
Tiruvarur
———
Kudavasal – 67
Valangaiman – 42
Ariyalur
——-
Thirumanur – 67
Jayakondam – 54
Cuddalore
———
Tozhudur – 49
Cuddalore Collectorate – 43
Others
———
Kariyapatti, Virudhungar – 83
Chettikulam, Perambalur – 65
Paramakudi, Ramanathapuram – 47
Manamadurai, Sivagangai – 47
Yercaud, Salem – 44