Rains To Reduce Across Southern Peninsula

The cyclonic circulation over Bihar-West Bengal border would persist, bringing in heavy showers over the mountainous regions of West Bengal, Sikkim and Meghalaya. This in combination with the upper air circulation over North Bay of Bengal, embedded in the monsoon trough, would instigate scattered thundershowers over the states of Orissa and West Bengal in the evening with a few places experiencing heavy rainfall. Across north India, along the monsoon trough, solitary thundershowers would occur in the afternoon/evening especially in Punjab, Haryana and Uttar Pradesh.

Light rain would continue in parts of the west coast. Southern Peninsula will see reduced rainfall and TN needs to contend with isolated thundershowers.

Chennai – A warm and sultry day with a maximum temperature around 35 C. Isolated showers might occur at night.

Coimbatore – A rather dry day in store with little rainfall. The mercury will not rise above 32 C.

Madurai – A hot day in store with probable thundershowers in the evening. Temperatures would peak at about 35-36 C.

445 thoughts on “Rains To Reduce Across Southern Peninsula

  1. Traffic is very less in blog today so far. I dont like this attitude, people return only when its rain is not a good habit. The spirit should be high always, either it rain or shine. Lets celebrate both occasions.

    Comeback guys wherever you are…

  2. Tibetan high for the last one week has been gradually shifting down latitude…but stays close to mean position for this time of the year….

  3. In Agumbe , the houses were covered with plastic sheets on many sides. We found it new, but with the damp and moist conditions that is a necessity….

  4. rajeshhrd, smart answer. Pity for august even the charts are not showing anything, Jupie can come here and there put spot on..lol….rajesh being a expert, can u tell whats is store for August last week so that i can comment on the same.

  5. We have completed 2 months of providing forecasts DC. I would like to thank all the bloggers who are involved in this initiative. You can see all the forecasts in the Kea-DC page

    If you do have any suggestions on how to improve please do let me know. We always want to improve further. Any suggestions will be welcome.

  6. Ehsan u dont know to ready wind barb and now u proved again that u can niether read precipitaion charts and u are saying cloudy skies. I dont know u get to interpret cloudy skies from precp charts. Hats off to your talent

    • ha ha. You are trying to be funny.
      August + September team expected good rainfall in Chennai end of last week. It didn’t materialise. How can you be so sure 8days in advance Nunga or Meena will get the September rains?
      History says that Nunga beats Meena in September. So you can rule out Meena to score big.

      • i am really getting angry. It rained in most of the places. U have to be god to predict rains exactly for nunga. For 4 days we got rains, what else u want.

        You have lot to learn a lot. We cant predict weather for pinpoint location.

      • yes i am least bothered about august. And when i say rains, its not nunga specific. Do DC readers or public reside only at nunga.

        Please look at wider angle.

  7. PJ,

    TS chances still exists between 27th and 31st date. I have already said it, not changing till date.

    I am not saying every day we have a chance, but between 27th and 31st we have a chance.

    Also Positive Anomaly likely to dominate entire September. I am not competing here, just saying the forecast. I dont believe Precipitation charts, i left taking it as basic 6 months back.

  8. We all know that cyclones weaken in presence of wind shear..
    Here is a sequence of processes that weaken a cyclone in such a case….

    1) Development of strong inner core asymmetries.
    2) Asymmetries in upper core become strong enough to mix heat and PV outwards, along the shear to ventilate eye.
    3) Loss of upper warm core causes surface pressure to rise.
    4) Downshear advection of weakened upper levels causes downshear tilt of storm.

    Courtesy :
    Vineet Kumar , Vagaries of weather.

    Source :

    Global perspectives on TC s by Johnny C . L Chan and Jeffrey D. Keppert …

  9. @ PJ Sir and @ KEA , Please do not comment like this na.. PJ mocking KEA and KEA mocking PJ.. Vidunga Boss..

  10. Today’s dip in share market gives oppr to buy.

    Buy Srikalasthi pipes at 276
    Buy Borosil glass at 2525
    Buy Vardhaman Textiles at 907

    Bounce back expected soon. If not it can be part of ur investment.

  11. Selvan and GTS,

    Since it is going to be dry days, just a question to you.

    We are seeing the position Tibetan High at 200 HPA, since SWM winds influence is only up to 600 HPA levels, why are we seeing this level, also how it influences the lower level TEJ. I am asking in general for all seasons.

    • both hav “n” number of relation when monsoon get into active state.. both upper level winds and lower level winds increases during active phase of monsoon… lower level helps in bringing moisture for TS development where as upper level helps in maintaining the life of tat TS..

      • u mean during the overshooting of TS the upper level supports?
        if yes, then the moisture at upper level should be high, what about the wind speed, it is always high at upper level, how a TS overshooting can sustain?

      • not only during the overshooting stage,it helps even bfore tat..we can see the anvil spreading out when TS reach above 10-12km..OVERSHOOTING is the scenario when storm pierces into tropopause

      • Yes thunderstorms extending into upper levels form anvils, but a proper one occurs near tropopause , where there is huge temperature inversion. It may form below that level also in case of mid to upper level warming..

      • the rising air must diverge before reaching the tropopause .tat diverging action results in anvil. tis normally happens at 300-200mb and tat divergence is aided by UPPER LEVEL EASTERLIES

      • But I think the wind speed and moisture at higher levels always affect the equilibrium level and also the maximum parcel level.
        I mean..though the overshoots of thunderstorms are mainly due to updrafts(lifting of warm air from lower levels),the condition at upperlevel may have the parameters which may enhance or restrict or supress the overshooting.
        So upperlevel may support or may not support the overshooting

    • Partha,
      Winds in SWM season move northward inland towards Indian subcontinent and the surrounding South Asian low pressure belt at lower levels to mid levels , may be up to 600 hPa as u said. This entire inward rushing northward air flow is due to the meridional pressure gradient between south Indian ocean and south Asian land mass in general. So this flow completes the lower part of Hadley cell. And so what went in towards India will have to diverge at upper levels to maintain the inflow. This outflow takes place near Tibet mainly, comprising of this high pressure area, and these outflows tend to move down to south Indian ocean and sinks down , thus completing the meridional Hadley circulation. This entire process is somewhat similar to a Cyclone , wherein , inflow and outflow balance is essential for the engine to live and work. So , similarly if upper level clogging appears by way of improper ventilation in Tibetan High region , it may indirectly affect the lower level inflows, beginning from where the entire life cycle of Monsoon convection would depend on , and the vice versa case do exist. And as Selva said , T’storms life is getting supported by upper level shear, and enhancement of lower level convergence too, by way of displacing air from upper levels , to induce updrafts from surface

  12. IMD Rainfall Update Today

    Dindigul (Dindigul Dist)


    Tiruchengode (Namakkal Dist)


    Chinnakalar (Coimbatore Dist), Mylam AWS (Villupuram Dist), Valparai taluk office (Coimbatore Dist), Arantangi (Pudukkottai Dist)

    3 each

    Cholavaram (Tiruvallur Dist), Peravurani (Thanjavur Dist), Alangudi (Pudukkottai Dist), Thali (Krishnagiri Dist), Marakkanam (Villupuram Dist), Anjatti (Krishnagiri Dist), G Bazar (Nilgiris Dist), Red hills (Tiruvallur Dist), Tindivanam (Villupuram Dist), Gingee (Villupuram Dist)

    2 each

  13. why the metro water department not utilizing veeranam as the tank is filling up fast. this can at least solve water shortage for south chennai. any news on this from any one.


      • No Mr. John. please see the veeranam in website. they are only stating 70 cusecs outflow. if your statement is 180 MLD then half of chennai at least would get sufficient water. but reality is not so. They are not using the veeranam water in full for the past few months, the reasons not known to public. Most of the south chennai areas catered by veeranam water for the past 15 days, the sumps and pumps are dry./

      • ss, the maximum they are tapping is 100 mld per day due to operation issues and the design is for 180 mld.

      • Mr. JOhn. Thanks for your reply.
        if you see the web site you can find only 70 cusecs of water released per second which works out to 17 MLD whereas the stipulation for chennai is 180 million liters daily or alternate days. so this works out to only 6 % of the stipulated level. so my finding is they are not utilizing veeranam to the maximum extent. i think they expect some more healthy inflow to improve the outflow. One cusec equals 28.32 liters 28.32 X 60 X60 x 24 hours x 70 outflow = 17.12 MLD. My feeling is veeranam water is used only by 15 %

      • please check. it works out to only 17.1 milions. not 171. so only 10 % of 180 million stipulated level from veernam is drawn. if remaining 90 % used, half of chennai there may not be any water shortage.

    • Yes of course it will change …the wind flows shift according to the center position of 200 hPa ridge , as it will slowly move SE wards from Tibet >> Burma >> Malaysia and then further SE wards going ahead

      • If the ridge center is more to the east we may see near southerlies to SSE ,,but even that depends on the blowing out and contracting in process of the ridge

      • Position of Ridge and ENSO is somewhat defined , with this STR a bit south in El Nino events , but the rainfall pattern would be more related to seasonal position to STR s , which in tern are associated to global circulation patterns.
        But, this can definitely give an average mean path and steering of cyclones in NEM…
        For example in 2013 , the mean average position of upper level ridge was a bit north , and so the systems took a WNW track right away near SE Bay and moved towards AP coast , whereas , in case of 2005 , the position of ridge was a bit lower and further extending westwards ,,favoring tracks to TN and S.AP

  14. Relation between TEJ and SWM

    TEJ stream extends f at to the north of Tibet and airflow is roughly along the kolkata-Bangalore axis.These upper air easterlies descend into the permanent high pressure area formed over the southern Indian ocean.This intensifies the highs present over there (Mascarene Highs) which are responsible for our SWM

  15. Interesting point about Tibeten High

    Just like the TH there always exists an anticyclone over North America Sector (Mexican High)
    The interesting part is that in between the TH and MH there exists two troughs in mid pacific and mid atlantic oceans
    The clockwise flow around TH contains easterly jet stream

    • I am totally out of scope on this, IOD could not be predicted by any model.
      If I go with past scenario like IOD coupled with ELNINO, I would say the SST anomaly counts more than IOD values. SST anomaly over eastern part of IO is also not cooling enough to get IOD Positive perfectly.

      We need negative anomaly over Eastern Part to get IOD in September.

      Overall, IOD values should keep increasing in September when comparing to August and should stay in October, this values should not come down in between. If this happens i feel we have very good NEM. Otherwise it can stay in Neutral until NEM onset, this will bring Normal rainfall.

  16. Sel and GTS,

    Thanks for the info and patience shown as usual to my silly questions.
    Now bloggers have to think that during dry days, there will be more scope for learnings, they should not be away. If they are free they should login during these days, not to miss the opportunity.

  17. This Day In Weather History

    Vostok, Wilkes Land, Antarctica (1960)
    About 1,176 kilometers from the Indian Ocean, the mercury fell to minus 127 degrees F (minus 88C). This was the lowest recorded temperature ever on the face of the earth, until July 21, 1983, when the temperature reached minus 128.6 degrees at the same location.

    Virginia (1906)
    Cloudburst at Guinea, VA – 9.25 inches of rain in only 40 minutes.

  18. Parth my northern side balcony is getting away from sunlight (other day we were talking about this)…and more Northerly and NW wind blowing…these are like september conditions

    • Yes someone posted yesterday(I think u only) about Godzilla elnino, I think elnino ll not attain full fledge status according to BOM,what’s ur take?

  19. During coming NEM, Chennai may get excess rainfall and TN normal rainfall( similar to 1918 NEM, Chennai got excess rainfall around 1270 mm but TN got only normal rainfall around 486 mm).

    • Lol 1918?? Almost 100 year comparison nothing… will not materialaize… Things have changed, Better to expect near normal/normal at best.. No scope for expecting excess n disappointed later. Every year same story expectation like 2005…

      • even experts( Joe Bastardi and few others) considering 1918 as analog for this year. IF you analyze QBO and IOD vlues of this year with 1918 values, they are very similar and also el nino showing similar trend to 1918 event.

      • There are few years(1943, 1976, 1960..) in which Chennai got excess rainfall but TN got normal rainfall. So similar thing can happen again.

  20. Recent study of models performance during cyclone season in north indian ocean basin from 2010-2014 shows NCEP GFS outplayed ECMWF& UKMO.. The ensemble means track forecasts errors of
    NCEP, ECMWF, UKMO models at 72 hr were 252, 322, and 374 km respectively.. ECMWF had better skills over bay of bengal compared to arb sea.. worst performance is from UKMO which showed very high negative skill over both arb &bay

  21. partha ji u told Exactactly 19 to 22 good rains may be places and intensity differ but he is correct observer hats of to him

  22. Check out the pattern which is in the right side of the below diagram. Current el nino will have the same pattern.( 1957, 1965, 1972, 1997 pattern) during NEM.

  23. Positive IOD and Jupi’s Connem,

    I know Jupi has not completed it yer, but what Jupi was saying in his initial draft was if SWM is excess then NEM will below normal.

    1. So far SWM is excess, if Positive IOD emerges then I feel drastic reduction in rainfall in September over Chennai, this will bring Chennai’s accumulated rainfall from June to September below normal or normal. Then NEM will be an excess. This will make Jupi’s CONNEM to successful.

    2. If Positive IOD does not emerge, then Chennai will get more rainfall in September, then we will be here to see excess rainfall from June to September, hence Neutral IOD + ELNINO is also good for NEM, the rainfall from October to November will become Normal. Then Jupi’s theory might prove wrong?

    Even the second option happens, Jupi’s theory may not be proven wrong, since during ELNINO years we have seen Excess SWM rainfall and Excess NEM rainfall in the past, Deficit SWM rainfall and Deficit NEM rainfall.

    Hence Jupi you need to wait till next year to conclude your theory.

  24. South west monsoon rainfall over chennai
    Nungambakkam – Actual- 301, Normal- 284 ( 17mm excess)
    Meenambakkam- Actual- 357,Normal – 311 ( 46mm excess)

    Nungambakkam having high chances to enter deficit category in next 2-3 days

  25. also a possibility if winds support. a thundershower can move from sea towards city. but the month of august, little chance.


  26. Good evening all.

    Today again going to be Pondy to Marakkanam day . A small intense Pop has emerged North east of Thiruvannamalai.

  27. is there any one guess a thundershower might move from sea towards city in few minutes time, as i noticed quite a lot of convection takes place due to interaction of strong sea breeze near chennai port.


  28. chances for more popups near the coast. the one which we saw few minutes back entered sea and gained lot of strength. if winds favors this might as well move back to city.. let us keep track.


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