SWM withdrawal in progress

An upper air cyclonic circulation (UAC) over South TN is now seen centered over Comorin Sea & adjoining Maldives. So under its influence one or two areas along Kerala, South Tamil Nadu might see some showers. Another UAC over North Bay of Bengal seen pumping moisture over Northeastern states providing some showers to one or two areas.
Moving to the North, western disturbance induced UAC is seen near Indian border. This would bring some showers in few areas over the states of Jammu & Kashmir, Punjab, Uttarakhand and Himachal Pradesh. Rest of the country would see dry weather conditions as monsoon withdrawal in place.
ezindia1_day202. India_Sat (1)
Chennai – Clear skies along with warm conditions expected. Max temp may settle near 34-35C.

Madurai – No change expected. Warm, uncomfortable weather likely to continue with temperature around 34-35C.

Trichy- Humid day expected with max temp peaking to 33-34C

Vellore – City might see fair weather with clear sky. Thermometer would see 32-33C

Coimbatore – Another clear day on cards. Temp may stay close to 29-30C

971 thoughts on “SWM withdrawal in progress

  1. I think after 2011 we are going to see NEM well past normal date of oct 20. In fact we had very good rainfall in 2009 10 11, hoping that this year also will be similar to that three years.

  2. Flash..be patience alert…please be firm just like me about our forecasted system. Still long way to go for this system. So request everyone to be in patience and no need to change emotions just like our model runs of ECMWF/GFS/etc.πŸ˜†πŸ˜†πŸ˜†πŸ‘πŸ‘

  3. in line with Mr. Maiush comment, Foreca shows light rains daily from 17th for Chennai, hope it sustains and we get rains as predicted by him,

      • according to my study, the monsoon was over above 15 north latitude by last sunday the 11th and now except for southern tip of india, it has already exited in total till 6 north latitude covering almost all states, except some pockets of kanyakumari & Trivandrum. I am confident some showers would start in coastal districts by this sunday – tuesday.


  4. Promising signs seen over southern parts of bay. Easterlies which made a breakthrough over parts of south-s.east bay seen pushing moisture from east.. there is an area of convection over south east bay along 4N,90E under very low shear zone.BUT there is no proper upper level support for this system to develop but still this could maintain a weak circulation and affect srilanka adj s.tn in next 3-4 days..this system might hav developed if there was no pacific system..

  5. Good morning.. Dew around 5.30am today. Clear skies making it, but not gud for rain right now.. But it happens in every year of nem.

  6. β€œThis is an El Nino year. Any activity over the Pacific Ocean region is affecting weather patterns in the Bay of Bengal region.
    Because of this, the monsoon has stopped withdrawing and has got stuck over Jharkhand. It hasn’t withdrawn an inch over the past 10 days. Right now, we have a cyclonic circulation over Bay of Bengal,” B Mukhopadhyay, senior climate
    scientist who heads the Indian Meteorological Department in Pune, said.
    β€œA typhoon has developed over the Pacific Ocean. Its tail, if it manages to reach the Bay of Bengal after crossing South
    China Sea, could develop into a cyclone. In 2013, very severe cyclonic storm Phailin had formed in a similar way from the tail of a cyclonic circulation over South China Sea,” Mukhopadhyay said

    β€œIt would take another 2-3 days for the weather system over Bay of Bengal to fade. We expect monsoon to start withdrawing from October 16. It would bid adieu to Kolkata and south Bengal by October 18,” said BP Yadav, who
    heads the National Weather Forecasting Centre at IMD Delhi.

    But scientists in both Pune and Delhi are more concerned about something else. They have spotted an ominous sign over the Pacific Ocean which could well turn into a nightmare for many after the Pujas..

  7. 2 more days to go for aippasi (tamil) month to start. Oct 18th..As per our tamil astro, rains should start to commence from sea..

  8. NEM onset around 25th will be triggered by Mr MJO.

    It is likely to emerge in Phase 2 by 20th and strengthen by 23rd. This would be the main reason for NEM onset. Also month end system is getting triggered by Mr MJO since it moves towards Central EQ IO during that time. That system will surely move towards TN.

  9. Vagaries’ Note: a brief Summary of the North East Monsoon.

    As the south-west monsoon draws to a close, the direction of the surface winds change and the stage is set for the north-east monsoon. Much of the country is heavily dependent on the south-west monsoon for most of its annual rainfall. However, many parts of southern India also receive considerable rain from the north-east monsoon.
    Tamil Nadu, in particular, typically gets nearly half its annual rain during this monsoon. In fact, as much as 60 per cent of the rain that the State’s coastal regions receive in a year is from this monsoon.

    Salient Features:
    -The SWM onset is well defined, and follows a well coursed out Northward progress. And can be discerned with reasonable accuracy on charts.
    For the NEM, it is not so.
    In fact, on many occasions, there is no clear indication between the widhrawing SWM and setting NEM. Often one tends to merge into another.
    So, setting a date for the commencement of NEM is difficult, and sometimes not possible.
    -The main has its origin, its “Power House”, is at the Mascrene Highs off Madagascar. The NEM has its origin round a large anti-cyclone over Siberia.

    -The Upper winds during the NEM across the Bay are in a clockwise direction.That is an anti-cyclone is formed. At a level of 500 mb, the centre of the anticyclone shifts to central Burma region.
    -The Upper Air temperatures show a Northward gradient in the NEM. Near 10N it is normally warmest, and dropping by 8c at 30N.
    -Jet streams at 200 hpa are common to both the monsoons.
    In the SWM, the Tropical Easterly Jet stream dominates the Peninsula, while the Sub-tropical Westerly Jet Stream is the feature of the NEM.
    – The Sub Tropical Ridge (STR) in the stream determines the track of cyclones during the NEM months.The STR osscillates East-West, and shifts along the North Bay.

    -The normal Sea Level Pressure during the NEM is a large system of low pressure over the Central Bay. It can extend into the Indian Peninsula as a trough.Towards the end of November,there is a shift southwards of this extended low.
    -The general variations and fluctuations in intensity of this low pressure, governs the rainfall. When the trough is well defined, and the low is well marked, rainfall over the southern peninsula is good.
    -During the NEM, an occasional burst of cold air from the Siberian High develops a low pressure systems over the Equatorial regions of the South China Seas. These systems move slowly westwards thru Sarawak/Eastern Malaysia coast, and remnants of these cross over into the Bay and form depressions.

    Most of the NEM rains depend on depressions and cyclones from the Bay towards the East Coast of India.

    The advent of the NEM is getting delayed this year.
    Vagaries predicts its advance by the 24th. taking into considerations the withdrawal of the SWM. The SWM lingers on, and even today, on the 14th, is still prevailing over parts of Karnataka and T.N.

    The overall delayed actions, beyond forecast estimates, is mainly attributed to the stubborn SWM, and to some extent the weak MJO not “supporting” the fast formation of NEM currents in the Bay. Cooler SSTs are prevailing west of Java and Sumatra.

    But, the upper winds are showing signs of “resigning” and changing. The Mascrene highs have lost their grip, and are seasonal and weaker, and the Tibetan/Siberian High is taking shape ,though late.

    Courtesy: Vagaries blog

    • That was a fantastic report from Rajesh Sir. Very typical of him.A Threadbare and detailed one. Very easy to understand. Simplicity has always been his forte. .One has to make the common man understand the technical jargon used widely in a subject like weather.
      Kudos Sir, look forward to your posts here in Kea blog during the season.
      Thanks for sharing Vel.

  10. Very cool here in vellore… Looks like typical winter…
    Temperature going 21 c today morning records 21.6 c…
    Lowest in tamilnadu except hilly areas like ooty, kodai….

  11. KEA

    Your views on showers from 18th ?? most of the bloggers say only by 25th the rains would start. If we miss even few days in october, difficult to compensate, as first week of december the shift of monsoon to lower latitudes. we actually need very good rains in october followed by november. already 15 days gone. even one week delay can bring down the rainfall quantum,unless repeated systems forming close to coast.


    • What can we do? If it has to rain from 25th, it will rain from 25th. We cant control nature. Chances or rain from 18th is very remote.

      • i remember decades back rains used to commence exactly on the last day of puratasi. i.e on october 14th. Certain years even it crossed 50 centimeters within october itself. now those are gone. We have to get rains only when the system moves closer to chennai latitude. it is really unfortunate. all lakes are totally dry. we need at least 6 TMC to get water up to next season. if it does not rain, i think by february, we might face a very big water crisis.

    • SS, If have to tell the fact..Not a single day has gone so far this NEM. I’m aware you are counting the days that has passed in October and you are well aware that our actual rain season starts only from 17th or 18th in October. In all probability, not a single day has gone waste this season.

    • already we could fee easterly winds though not strong or for longer duration. compared to yesterday, today there is some change.


  12. please see the area east of srilanka close to west of south andman islands. we could see some disturbance taking place. to keep track of its development.

  13. October last week (27-31) will always help chennai to get rid of deficit previous years. Nilam crossed Chennai during this time.

  14. Latest run of CFS is consistent it indicates that Aech circulation to develop and move towards us. First easterly wave striking TN coast on 19. It is consistent with its forecast since past week

  15. Dharmapuri at 19c and Tirupattur at 19.4c wer cooler than Bangalore at 19.7c this morning!! I Wonder wat if our towns are at an elevation of 920mts like B’luru , the mercury might dip to 15 to 16c!!

  16. In 2005, between systems during november and december, dry air prevailed in Chennai and morning mist was there. Only last system, moved south west towards Nagapatinam during december and NEM was withdrawn after that.

  17. year 2005 was one of the best NEM in the last 50 years. 2006-2011 considered to be very good. 2012 was some what OK, 2013 was poor, and 2014 slightly better. so going by the law of averages, this year there could be a repeat of 2005.


      • during 2005, i remember rains commenced on 12th october itself followed by lot of systems close to the coast. that was one of the best and even chennai rainfall overtook mumbai.


      • during first week of december all lakes over flown and water diverted to bay of bengal. there was huge crowd witnessed water flowing in adyar near kotturpuram. more than 5 TMC of water let down to sea. which is almost 9 months water supply to chennai.


  18. A weak circulation approaching SL and S.TN is consistent with the recent ecmwf run. Moves in closer to SL on 19th Oct, With decent positive vorticity field , expect some showers more prominent across SL and quite average for S.TN..

  19. My only concern now is dry air and how this easterly wave on 19th is going to materialize as rain for Chennai as we have seen over previous years, dry air dissipated the band when it inches towards coast and we get only drizzles at the end.

  20. GTS/Selva,

    I know you have patience.

    This weak circulation is forming due to E-W shear zone forming in GOM due to westward movement of Koppu in WP.

    I could see that surface level easterlies setting tomorrow and becoming more prominent from 17th.

    Anyway On 18th we have the weak circulation near Srilanka and then by 20th it will be in GOM.

    This circulation bringing some rainfall activity along the coast of TN and in interiors of STN.

    Why not IMD declare the onset of NEM by 20th or 21st?

    • from tomorrow the easterly winds at surface level can prohibit dry air entering from north west andra & north interior karnataka. once easterly winds gets some more strength the dry air will be limited up to cuddpah-kurnool pockets.


    • u remind me of our past swm seson now we guys are struck in between those two season which we are not enjoying the evening ts and even our belowed NEM is struggling to enter bay ;( what a year this is . such huge gaps of dry and then continues ts days .

  21. With high and koppu in action then how cfs expecting onset on 19. My pressure rising πŸ˜‚πŸ˜‚πŸ˜‚πŸ˜‚πŸ˜‚πŸ˜‚πŸ˜‚πŸ˜±

  22. I hope this nem denounce all man made and machine made predictions and strike with its own will and making fun of superstitions

  23. The UAC above 3.1 KM above mean sea level over North Bay is the reason for IMD not declaring further withdrawal, also another UAC over West Central Arabian Sea still exists. Both these systems should dissipate to declare further withdrawal.

    Bay UAC likely to dissipate by tomorrow. Hence we can be sure of IMD announcing further withdrawal by tomorrow.

  24. Guys.. This October is going to mimic 2012 October…
    During 2012, weak easterly wave affects central tamilnadu on October 18…
    But chennai got decent rains…..
    Imd struggled to announce that was onset…
    Even most of our bloggers had huge discussion about oct 2012 which I saw in kea archive….
    Then on oct 25 strong easterly wave formed then results in nilam….
    Same onset confusion ll arise this year too I guess

  25. ecmwf consistent and rules out any major re curvature scenario for TY Koppu . It expects westward movement up to Luzon and then NW movement and LF along SE China coast to the E of Hong Kong ..

      • I had lots and lots of learning this October.
        Yes if i did not made that mistake of predicting NEM onset, then i would have not learnt, now i know where i did the mistake, from now on my prediction will become more stronger than past.

        Also lots of learning about SWM withdrawal, it was totally different this time. No WS or FWS rainfall across the country, it remained weak for longer time, but not withdrawing, also the interruption from WP for NEM.

  26. Good monsoon showers in titucorin, thirunelveli districts..
    But it can’t be swm rains…. Tuticorin is full rain shadow in swm..
    It was pre nem showers sure

  27. We have introduced a new section called Bloggers Travelogue. This will feature bloggers travel tales. More details can be found on the page.

    GTS as already contributed the first write up from his Agumbe trip in August

    We encourage many more such contributions from bloggers in the future.

  28. IMD has notified SWM monsoon withdrawal up to northandhra as expected. They have also notified an UAC over south andaman. probably by tomorrow they might announce total withdrawal of SWM. Now south andaman system we need to keep track. now it is strange how they said no formation of any weather systems in bay when West pacific is prevailing. contradictory reports by IMD.


  29. Friends Tuticorin not get single amount of rain in past 5 days… My village is located in 35km north of Tuticorin.. Near ettaiyapuram….. Parts’ of Tuticorin get good rain

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