Chennai gets mid-night rains from the clouds moving from sea because of Upper Air Circulation (UAC) in the Bay of Bengal

By Tamil Nadu Weatherman on 09 Sep 2017 | read
Delta belt is seeing monsoonish like morning rains right now.
Normally only during our north east monsoon, clouds will move from sea to land or else there should be UAC or low pressure area very close to our coast. There is UAC which is formed now (refer the pic enclosed) This is not a low pressure area but a circulation which exists in atmosphere. If the circulation comes down to mean sea level then we call it as a low pressure area. But this one is not going to develop as a low pressure area.

How has this UAC formed - Its due to Equatorial Rossby waves
When ever there is system forming south of equator as a result of ER wave it will spin a counter part circulation in the northern hemisphere or vice versa. Now refer the pic enclosed eg and the present one. You will get and idea. This UAC will not intensify into Low pressure in Bay of Bengal but will bring good rains to the interiors as the winds from sea will clash with the opposing monsoon winds from west from Arabian sea side. So awesome september is going to continue for Tamil Nadu.

Awesome rains in Tamil Nadu. Rainfall ending 8.30 am on 09.09.2017
Delta got smashed with Kumbakonam topping with 162 mm heavy rainfall. Ponneri in North part of Chennai got smashed with heavy rainfall of 65 mm rainfall from the mid night / early morning spell,Thoothukudi dt got good rains with upstream areas of Maniyachi getting 62 mm and flash floods happened. (refer pic) No wonder Madurai got flooded yesterday with Tallakulam 108 mm and Madurai South 85 mm. Avinashi in Tiruppur has recorded 89 mm. So awesome season for Tiruppur continues too. Tirunelveli town got 40 mm too....which is rare considering its location. Pamban in Ramanathapuram got smashed with whopping 114 mm rainfall, Most of it happened in morning. Kodaikanal in dindigul smashed too with 104 mm heavy rainfall.

Rainfall ending 8.30 am on 09.09.2017 in Tamil Nadu. Awesome day for entire TN. Pamban broke its all time record set on 27th September 1901 when it recorded 108.5 mm
in mm (min 40 mm)

Kumbakonam (Thanjavur Dist) - 162
Pamban (Ramanathapuram Dist) - 113.5
Talakulam (Madurai Dist) - 108
Kodaikanal (Dindigul Dist) - 104
Avinasi (Tiruppur Dist) - 89
Madurai (Madurai Dist) - 85
Thoockanaickenpalayam (Erode Dist) - 79
Aravakurichi (Karur Dist) - 70
Manjalar (Theni Dist) - 70
Chinnakalar (Coimbatore Dist) - 68
Kallakudi (Madurai Dist) - 66
Ponneri (Tiruvallur Dist) - 65
Tirumangalam (Madurai Dist) -63
Periyakulam (Theni Dist) - 62
Maniyachi (Toothukudi Dist) - 62
Hosur (Krishnagiri Dist) - 60
Paramathivelur (Namakkal Dist) - 60
Tiruppur (Tiruppur Dist) - 58
Kodumudi (Erode Dist) - 54
Mettupalayam (Coimbatore Dist) - 53
Gobichettipalayam (Erode Dist) - 52
Valparai taluk office (Coimbatore Dist) - 50
Namakkal (Namakkal Dist) - 50
Upper Kodayar (Nilgiris Dist) - 49
Shoolagiri (Krishnagiri Dist) - 48
Perundurai (Erode Dist) - 47
Annur (Coimbatore Dist) - 46
Sathyamangalam (Erode Dist) - 45
Thiruthuraipoondi (Tiruvarur Dist) - 44
Karamadai (Coimbatore Dist) - 43
Parambikulam (Coimbatore Dist) - 43
Ottapadiram (Toothukudi Dist) - 43
Kothagiri (Nilgiris Dist) - 42
Glenmorgan (Nilgiris Dist) - 42
Dharapuram (Tiruppur Dist) - 40
Sholavandan (Madurai Dist) - 40
Natham (Dindigul Dist) - 40

All areas which were under drought are getting good rainfall in last two months. Some pics enclosed.