Why Burevi is taking a South West Dip and goes down
Nivar oda brother “Burevi” moves W-NW for few more hours under the Pacific Ridge and then the grip of the pacific ridge weakens over Burevi. Then it stall over Gulf of Mannar for a day and then the steering ridge from West (Arabian Ridge) steers the system W-SW and makes it move into Arabian as a very weakened system most probably a Depression or a well marked low.
In the above image, we can see why Burevi moves down (W-SW) because of the under steering of the ridge from the west.
Rare cyclone for Sri Lanka
Even during Nivar, i had mentioned that very few cyclones have made landfall as cyclone over Sri Lanka, not sure what may be the reason, may be the position of the pacific ridge (most likely reason) or the cyclone fear the rugged terrains (just kidding). Would you believe if i said the last three cyclones which made landfall in Sri Lanka are in 1978, 1992 and 2000. So after 20 years a Cyclone is moving into Sri Lanka as a Cyclone.
1st Landfall and Winds
The cyclone Burvei has already started weakening a bit and as the cyclone moves into Sri Lanka it will weaken further and make landfall evening to tonight close to Trincomalle. The area from Trincomalle to northern regions of Sri Lanka till Jaffna will witness winds of 60-70 km/hr tt
2nd landfall, stalling (due to ridge change) and winds in South India
After crossing it moves into Rameswaram belt in Gulf of Mannar later tomorrow morning. Ramanthapuram to Rameshwaram island to Pamban and the near by areas will witness winds of around 50-60 km/hr. Particularly the winds will be high in Pamban to Rameswaram belt compared to other areas. The Cyclone is weaken a lot by now and will become Deep Depression in Gulf Mannar after which it stays in same location for almost a day because it is not in the control of pacific ridge anymore and shift in steering ridge happens. Then on 4th morning it will further weaken into Depression and will cross coast between Kanyakumari and Pamban close to border areas of Ramanthapuram – Thoothukudi district (plus or minus some kms) as a weakened one with wind speeds of 30 km/hr on 4th morning to noon.
So wind threat of 50-60 km/hr is mostly in the areas Tondi, Ramanthapuram, Pamban to Rameshwaram belt.
South Kerala and Kanyakumari will also see moderate wind speeds of 30 km/hr. Manjolai in Nellai and Kodaikanal in Dindigul will see gusty winds being higher in elevation and with east opening valley.
Stalling for day and Very Heavy to extreme rains in South and South West Tamil Nadu
Because of the ridge change, weakening and caught in no-mans land over Gulf of Mannar on entire 3rd December, the weakened Burevi stays in Gulf of Mannar (GoM) over a Day and as a result Very Heavy Rains will be in Southern and South western districts such as Ramanathapuram, Pudukottai, Sivagangai, Madurai Theni, Kanyakumari, Thenkasi, Virudhunagar, Thoothukudi, Tirunelveli, Dindigul districts. Coonoor, Kodaikanal, Papanasam and Manjolai areas needs closer watch for very heavy to extreme rains as the valley opens from east and are locked valleys. from 3-5th December Delta districts (Nagai, Thanjavur, Tiruvarur) will also get very heavy rains from tonight – 5th December.
As it stalls over GoM for a day, it will send bands after bands up north upto Chennai and Kancheepuram, Tiruvallur, Chennagalpet (KTC belt) and cts will also get rains from tonight for next 3 days, even Pondy, and Cuddalore will get good spells. Even interiors such as Ariyalur, Permambalur, Trichy, Karur, Tiruppur will all get good rains. Salem, Tiruvannamalai, Namakkal, Villupuram, Vellore, Kallakuruchi will also get good rains atleast for 1-2 days.
Western districts such as Nilgiris, Coimbatore and Tiruppur will also get good rains for a day or two, though they are not capture by the models. 3-6 th December will the days for chance of rains.
Only area to get Moderate rains will be in districts very far away in Erode, Dharmapuri, Krishnagiri and Tirupattur.
There will be some storm surge in areas in Ramanthapuram and Thoothukudi coast where some areas are on par with mean sea level and even below mean sea level.
Overall conclusion – Weakened Cyclone – Heavy rains are threat in South Tamil Nadu, winds are not a problem.
The above is done based on personal interpretation of charts and also based on experience. Follow the official agency and disaster management for any precautions.
Tomorrow a special post on neglected Historic South Tamil Nadu Cyclones.