Showers expected along coastal central and South TN

Most parts of Indian subcontinent apart from southern peninsula and some parts of east India is getting filled in by the continental dry air gradually, which indicates the exit of south west Monsoon (SWM) from most parts of the country. Conditions are favorable for further withdrawal of SWM from remaining parts of east India during the next 3 days.
Meanwhile, a trough in the easterlies running from south west Bay up to west central Bay off Andhra coast may trigger some rainfall across coastal parts of Central and South TN. Also, isolated parts of Kerala and Lakshadweep will experience some rains during the next 24 hours, from the westward moving Upper Air Circulation (UAC) near Comorin area.
Chennai will see a partly cloudy sky with some haze. Maximum day time temperature will hover around 33 C.

Coimbatore to see mostly clear skies with few cloud patches. Maximum temperature will stay around 32 C.

Vellore is in for another comfortable day with day time highs just settling about 31-32 C.

Madurai will have sunny day with maximum day time high settling around the low to mid-thirties. Possibility of isolated light rains persists.

Trichy is in for a sunny day with maximum inching close to 33-34C.

1,158 thoughts on “Showers expected along coastal central and South TN

  1. This is Vagaries’ second article on the NEM introduction…
    El-Nino: North East Monsoon: Quantum:
    “Whether El Niño gets slightly stronger or a little weaker is not statistically significant now. This baby is too big to fail,”

    Read full article on

  2. Vagaries. had put up their first write up on NEM on WEDNESDAY, OCTOBER 14, 2015
    Have just posted it again here to co relate with the 2nd write up on NEM 2015 posted yesterday night here.

    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.

  3. Understanding Mother Nature is very difficult for our human brains. Till today no one explained how SWM succeeded in strong Elnino year 1997, which also a strong +ve IOD year. Similarly no one explained how NEM failed in strong Elnino year 1982, which also a strong +ve IOD year. So in conclusion it’s premature to claim the logical reasons for nature’s sins in 100%.👍😆

  4. Oh..thank GOD…3rd WP system (after Champi) will not be taking shape, which is a good sign fro our NEM. So overall it looks WP will be going to sleep mode after this Twin systems (Koppu & Champi). So slowly Indian ocean-Lion will wake up.

  5. With almost inching close to the victory for 2D-Gyrci map model in case of Koppu’s LF and track prediction, I would like to share 3D-view of 2D-Gyrci map model.

    1. With success in estimating the Northern recurve for Koppu, this model becoming more accurate day by day.
    2.Only need to practice more in case of mid-latitude influenced N/NE turning systems.
    3. Need to find the ways to foresee the system’s intensity with this model apart from track estimation.

    3D-view of 2D-Gyric map model:

  6. Massive rains Reported in Kanyakumari again. This time Ramanathapuram joins in.

    Kancheepuram has also got rains.

    In Kanyakumari –

    Rajakkamangalam – 76 mm
    Thovala – 64
    Munchirai – 63

    Nagapattinam, Tirunelveli, Theni, Thoothukudi dts have reported rains.

  7. See the gfs forecast for 200 mb on Nov 2nd, this very good for tn as any circulation that forms south of andaman it would drive towards us even if it becomes cyclone and second image is ecmwf forecast a low forming south of andaman on Oct 27th so wet end and wet Nov confirmed

    • ha..ha..1st system of NEM-2015 season must target SAP/NTN (Chennai or just surroundings) at any cost. No change in my opinion even in sleep also 🙂

    • vignesh, when cyclone forms near Andaman. It would be maximum a low. How will 200 mb steer it. it will low level steering.

      • Yep sir, but I am saying low forming there and when it further moves and develop into a cyclone it will come towards us as 200 mb support is good and also middle level steering also favourable

  8. Good Morning all.

    Radar looks good for pre monsoon showers in Chidambaram, Cuddalore, Nagai, Tondi. As day progresses, CTN coast may get more such showers signalling the precursor of incoming monsoon.

    Our only enemy is TY Koppu which stands far away in the way altering the wind pattern in SCS. Hope it makes way for our much awaited monsoon at least by next weekend. This October cannot end up in deficit.

  9. Flash…NEM-Onset alert… I am expecting NEM-onset will be in October (between 24 & 26) only due to progress in forward movement of MJO and weakening of ER-suppressive mode.

    Theses favorable developments in equatorial waves taking shape due to weakening of WP-systems.

  10. NEM rainfall already touched 91 mm for TN. The average is 438 mm for 3 months. I think with ease TN as whole will move in to above normal category.

  11. Good article in vagaries.. clearly indicates how an el nino year will impact the Indian monsoon (both SWM and NEM)

      • He forecasted NEM to strike on 27 is there any possibility IMD will declare onset if ctn and stn gets ws rain in coming days

  12. Super Typhoon Koppu makes landfall over northern Philippines and had Wind gusts up to 295 km/h (180 mph) while making Landfall over Philippines. Koppu intensity was similar to that of a Category 4 hurricane in the Atlantic Ocean.

  13. Reading this blog day by day only gives me tension and sad feelings. Only negative news are staring us. But things should change soon.

  14. Nem peak frm oct end to dec early in general.. Take away 2-3 weeks of dry weather in tat.. rest of which is not safe frm betrayal cyclones.. Idhula onset withdrawal vera… :p

    • we were happy without these predictions, technologies when rains will start in october. now all these predictions giving tension to mind.

    • We can’t have a fixed onset line for NEM. Sometimes S TN alone gets rains from first spell, sometimes N TN alone. It can be from both south to north as well as north to south, there is no fixed pattern like SWM

  15. The current rain wave over the peninsula is well marked till 850 hPa and poorly marked at 700 hPa with no major atmospheric effect at 500 hPa except for the moisture it’s carrying.

    A circulation is seen from surface upto 0.9 km a.s.l in Laccadive Sea, directly south of Thoothukudi and west of Colombo. This circulation is part of a larger easterly wave seen clearly at the 850 hPa level, whose trough extends across TN coast through GOM and Palk Strait. However dry air is spoiling rains for N TN

  16. Models showing bad Oct and we are following them and the same why everyone not believing in Nov model forecast be positive everything will change soon

  17. Instead of looking things from a “positive” or “negative” point of view, change your perspectives to “realistic” and “unrealistic” ones.

  18. Back in Chennai after a few weeks of travel.Happy to feel the easterlies.Rains are not far away.Elnino is poised to give us a normal/excess NEM through normal easterlies / persistent LPAs.Dont worry too much about the onset and long dry days.These are the characteristics of NEM.

  19. Gfs run half completed let’s see what in store for us during late Oct and also it is expecting ty koppu to move in nw direction instead of ne which ecmwf predicted

  20. Had call from dad saying Nellai is having rain since morning unofficially NEM started that too in first day of iypassi

  21. This is not a surprise in November. What we need is something this October! – kalai

    we are fighting for poor child october to get pass marks by giving regular tuition. will he succeed

      • Yes, he realised just now and trying to look himself for improvements and it will show up in his performance in a week’s time!

    • Kalai is just too worried about October as though his life depends on it.. once again I am saying.. brace yourself.. historic November ahead.. forget October

      • Your being negative when it comes to Chennai Rains :p
        I feel from oct last week till dec end its going to be very wet. November will be more wetter with lesser dry days.

  22. Good rains reporting all over central adj stn tamilnadu…. Nem almost started…don’t wait for poor onset….enjoy these rains…

  23. never seen such a positive news from vagaries….lets enjoy the NEM…hats off to Partha as well for releasing it from KEA behalf 2 months back…(just a minor miss in onset)

  24. Conditions are favourable for further withdrawal of southwest monsoon from remaining partsof east & northeast India and peninsular India during next 48 hours

  25. As models were quite persistently expecting symmetric cyclonic circulations straddling close to the equator near the western eq. indian ocean, has actually come into reality and has been there since 3 or 4 days not sure though on the exact no. of days

  26. The upper air cyclonic circulation  over southeast & adjoining southwest Bay of Bengal now lies
    over south west & adjoining southeast Bay of Bengal  and extends upto 1.5 km above mean sea

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