Excess rainfall recorded during the week ended yesterday (Wednesday, November 21) has helped Tamil Nadu get into the 'normal rainfall' category so far during the ongoing North-East monsoon season.
But only just, since the normal rainfall category as per IMD parlance (between -19 per cent and +19 per cent of long-period average). As of yesterday, the rainfall deviation amounted to -19 per cent.
Deficit districts
The highest deficit (in percentage figure) posted by a district so far is -61 (Dharmapuri), followed closely by Chennai and Krishnagiri (-60 each); Vellore (-57); Tiruvallur (-54); and Perambalur (-56).
Puducherry has returned a more respectable figure of -11 per cent, with the district of Puducherry at -25 per cent and district of Karaikal recording +12 per cent.
These figures were much worse to begin with, since the North-East monsoon made an onset delayed at least by 15 days due to an unseasonal very severe cyclone 'Titli' straying from Tamil Nadu.
It took very severe cyclone 'Gaja,' and a well-marked low-pressure area that followed, to lend some respectability to the rainfall figures, delivering 49 per cent excess rainfall during the last week.
This morning, India Met Department (IMD) located the well-marked 'low,' which is live and kicking, over the South-West Bay of Bengal and adjoining Tamil Nadu.
The system should continue to deliver more rain during the couple of days, which might help further improve the record for Tamil Nadu.
Meanwhile, the North-East monsoon was more benevolent to Kerala, which has a deficit of only four per cent so far during the season, with a surplus of 115 per cent delivered during the last week alone.
Systems under watch
The respective figures for Lakshadweep were -15 per cent and 44 per cent, making for a much improved show after it had to contend with a a very poor South-West monsoon earlier this year.
With another week to go, forecasters are watching with interest a couple of tropical depressions in the North-West Pacific for any signs of downstream impact on the Bay of Bengal.
Only one of these can be of any significance given its track to the west and a landfall over Vietnam, while the other is forecast to move north-north-east and further away into the open Pacific.
While the IMD is watching the behaviour of a persisting cyclonic circulation over the Malay Peninsula, other models swear by a tropical storm entering the South China Sea.
It is here that a 10-day outlook posted on November 18 by the the Department of Meteorology and Hydrology, Myanmar, assumes some relevance.
This outlook (for November 18-28) says a low-pressure area may form over the Andaman Sea and the Bay of Bengal and may further intensity into a depression.
In which case, credit should go to the anticipated tropical storm in South China Sea for generating the required 'pulse' for the 'low' to form.