LPA in next 24 – 48 hours

Upper air cyclonic Circulation (UAC) over West Central Bay of Bengal persists. It is likely to intensify and descend as a Low Pressure Area (LPA) in next 24 – 48 hours. Heavy rainfall is likely to occur in almost all the places over Coastal Andhra Pradesh and Odisha.

A trough at lower level runs from Madhya Pradesh, Maharashtra to Lakshadweep persists. A shear zone is also running across 17N latitude. Heavy rainfall is likely to occur in some parts of Telangana, Rayalaseema, Karnataka and Kerala in the next 24 hours.

Meanwhile SWM withdrawal line continues to pass through Amritsar, Hissar, Ajmer & Barmer. Interestingly southern peninsular states, including TN, Kerala and Karnataka may record maximum temperature below average, because of the ongoing rainfall activities in the region and its associated cloudiness.

Chennai – Day temperature is likely to be around 33 C, rain or thundershowers are possible towards evening/night.

Coimbatore – Can expect a cloudy day with temperature around 32C. Sporadic showers possible in some parts of the city.

Madurai – Day temperature is expected to soar at 37C. Chances of rains appears less.

840 thoughts on “LPA in next 24 – 48 hours

  1. Gud morning blogerrs .today is the best chance of ws-vs TS in chennai .because LPA is going to form in WC BOB.so we can see one or two intense TS.;).keep fingers crossed.

  2. I expected rains in many places in early morning. It seems it didn’t rain any place. I hope in next 24 hours we will get rains!

  3. Heavy rains in kurnool and adjoining anantapur
    Kurnool deficit reduced to 28 percent.

    vajrakarur knl Atp border – 99 mm
    Pamidi – 96 mm
    Devankonda kurnool – 76 mm
    Peapally kurnool – 67 mm
    dibbanakkal Adoni knl – 63 mm
    imd kurnool – 27

  4. North-nw’ly winds associated with anticyclone dominating entire north and north central india..If RH values decrease further and next week system fails to move inland,withdrawal line might hav a massive jump

  5. Selva,

    I was also thinking about the upcoming system. The forecast about the upcoming one is getting downgraded in every update, also the HPA from NW is dominating Rajasthan, Gujarat, Punjab, Haryana, HP and West UP. There is no change in these states for the past one week, also the forecast from IMD suggests dry weather in these regions. Hence upcoming system is a doubtful one, also as far as it stays as LOW, it is good for AP and NTN.

  6. Despite monsoon activity in central Indian and southern peninsula regions early this week, there would be a rare chance of rains in Rajasthan, the state MeT Director O P Sreejith told PTI here.
    Any western disturbance might cause scattered rains later this month in a few regions of the state, the Director said, adding even no side effect of monsoonal clouds from Madhya Pradesh will give relief to Rajasthan.
    Read more at:

  7. Selva,

    In a Normal Arctic Oscillation period, there might be an HPA dominating 30N to Sub Tropic areas, hence WD will be weaker. WD weaker years, NEM might be strong. This is my thought, what do you say about it?

    • no idea partha..WD usually dip south than average position in elnino years affecting tropical systems .. To my knowledge when they dip south below 20N, they appear strong and strengthen further

  8. The Skies of Mumbai opened up yesterday as I was wading through the traffic.The huge deficits the city has accumulated is a huge cause for worry and yday’s return of the rains offer a feeble hope that some of the deficits can be scaled down in the next few days.

  9. sep late night rains rocks though a miss yesterday, today there is good chance to get some spell.. looking for a complete wet day.

  10. It Seems Scientist Dr.Sulochana Gadgil has made a statement mentioning the less significant relationship between Indian Summer Monsoon and IOD event in a seminar that took place in Tropmet Pune. Scientists at IITM, Pune though differ in their opinion.

      • Yes, exactly, even in her lecture videos she does explain the positive correlation between the WEIO OLR and Monsoon region’s low OLR. But, yesterday in her seminar to Tropmet students and scientists she had made this statement. Seems all of them were shocked by her statement. May be they are coming with any other factor dependent variable shortly.

      • interesting.. even pple in IITM scientist hav said the relation is not positive in all years. few say the relation has weakened in recent years and few say its strengthend…

      • Indian ocean hav such huge variability unlike pacific ocean..both atmosphere & ocean playing a key role in indian ocean.. maybe bcos of land locked at northern side

      • Yeah, the thermocline and subsurface waters in equatorial Indian Ocean just not responds to atmospheric wind stress immediately like the Pacific , that responds quite better.

  11. The process by which rains are generated along the west coast are largely related to curvature vorticity, whereas the Bay synoptic systems convection has a dependence of horizontal shear vorticity.

  12. Mumbai has recorded only a moderate rain, that too Colaba had some passing showers in the past 24 hours. I know that September cannot given Mumbai the respite, as the monsoon will at the weakest. They might record few CM’s but not heavier one.

    As of today morning:
    Santacruz – 31 MM
    Colaba – 3.6 MM

  13. The reason for 2005 massive rains in coastal N.TN, C.TN and north TN was asked by our Novak(Thala) on a live TV show that was conducted by Podhigai. It was answered by Dr. Balachander, IMD Chennai. He attributed it to the normal ITCZ position for a long time in SW Bay, and the associated seasonal composite horizontal shear vorticity being favorable.

  14. Sharing Vineet, Vagaries member & IITM student’s share on FB:

    Yesterday IITM has organized the sep. edition of monsoon discussion:
    Key highlights :- Talk by Dr. S. Gadgil:
    Main point of her talk was there is no significant relation b/w IOD & SW monsoon rainfall
    2:- Talk by P.hd student who said that SW MP heavy rain event on 21 aug was a mesoscale event
    3- Elnino peaking durig oct – dec
    First 2 r really controversial talk objected by some high profile scientists.
    There were 4 more talks on monsoon situation , synoptic features of aug, oceanic condition in aug & sep.

  15. Like the proverbial silver lining to every cloud, there’s good news at the end of this year’s disappointing monsoon season. A recent extended range forecast by the Indian Institute of Tropical Meteorology (IITM) mentions the formation of a system over the Bay of Bengal around mid-September, which may provide good rainfall over the entire country by the end of the month. The forecast mentions that MISO amplitude is becoming stronger over peninsular and central India. “The good rainfall activity, expected over the entire country, may therefore be a combination of the system over the Bay of Bengal and MISO activity. The forecast showed that large-scale active monsoon conditions are now in sight,” a scientist said.
    “With active monsoon conditions developing over India, it seems that the withdrawal of monsoon may stop immediately. However, more would be revealed in subsequent forecasts. The cyclones over the west Pacific have now dissipated and two monsoon systems have begun to develop over the Bay of Bengal and the maritime continent between the Indian Ocean and West Pacific. The system over the Bay of Bengal is expected to move towards central India in about 10 days, giving good rainfall over the southern peninsula and Central India after September 18,” the scientist explained.
    An official from the India Meteorological Department (IMD) said that a new pulse of monsoon is coming from the south, bringing rain in its wake. “Monsoon has been active over the south peninsula. Maharashtra too has received some rains in the last couple of days. The pulse is expected to move further upwards. This seems to be the last pulse of monsoon but it is expected to provide some rainfall over the country in the coming days,” he said.


  16. One more student had explained about the double branching of Monsoon axis, which the scientists at Tropmet, Pune and Dr. Gadgil had a doubt and difference of opinion. But the IMD had mentioned the branching in the past few days in their daily reports. Seems there exists a difference of opinion to the IMD analysis among the research community.

  17. we need clear sky with bright sunshine till afternoon to trigger a thunderstorm. this type of weather can only bring drizzling. not good for heavy shower.


  18. Novak,

    NEM 2005 Success Story: I feel this should have happened.

    Negative NAO in October and November. Which made a ridge to form over Eastern part of Europe and Gulf, which has weakened the WD movement. This has not stopped or weakened the easterlies.

    Arctic Oscillation, oscillating from Negative in the beginning of October and becoming Positive by end of October than again Negative in November. This has bought the mid level atmosphere humidity to increase. The moisture at all atmospheric levels were high below 15N latitude. The polar vortex extended till mid latitude’s when it turned negative.

    ENSO – Neutral till September and became Negative in October.

    Negative IOD – Negative IOD was the mail reason for NEM success and excess rainfall pattern.If you see the SST anomaly, there 0.5 C on the positive side over eastern indian ocean region, also the south eastern indian ocean anomaly was negative, this has ensured the long stay of monsoon axis to stay in northern hemisphere strongly. I have attached the pic for your reference. The wind anomaly at 850 HPA was from West to East over Equatorial Indian Ocean, this has pulled down the wind from mid latitude’s, which was strengthened over TN. This phenomenon has also bought the MSLP below average over SW Bay of Bengal. Due to this we had more low pressures forming in SW Bay of Bengal.

  19. One thing worrying me is that Oct forecast is getting progressively worse. With NEM expected to set in early this year, I don’t understand how Oct can end up in deficit.

  20. heavy showers ( long red thick lines) over bay of bengal south east of chennai resembles north east monsoon season. this looks like moving towards coast. there is a minor disturbance close to coast due to UAC prevails in west central bay. if low pressure slightly shifts to south, chennai will be benefited much from this evening.


  21. -22% deficit in august across the country was due to Easterly Wind Anomaly over Equatorial Indian Ocean, it was due to emerging Positive IOD time. This has suppressed the precipitation in August and bought big deficit.

  22. I don’t think we have a chance of rain today, might be some drizzles in the evening or early part of night, nothing much to be expected. Overnight dry air likely to occupy. The trough is weak over NTN.

    Also a temporary UAC likely to form over SIKTK and Rayalaseema, this will bring more rain to Coastal KTK, Interior KTK, Rayalaseema. Some parts of NTN closer to KTK border will get rainfall today.

  23. clouds move from north east resembles north east monsoon season. but very high clouds. to be tracked. radar continue to pick up showers south east of chennai. quite strange in middle of september.


  24. 3 ஆயிரத்து 231 மில்லியன் கன அடி மொத்த கொள்ளளவுடைய பூண்டி ஏரியில் 57 மில்லியன் கன அடியும், 3 ஆயிரத்து 300 மில்லியன் கன அடி கொள்ளளவு கொண்ட புழல் ஏரியில் 192 மில்லியன் கன அடியும், 3 ஆயிரத்து 645 மில்லியன் கன அடி கொள்ளளவு கொண்ட செம்பரம்பாக்கம் ஏரியில் 197 மில்லியன் கன அடி மட்டுமே (நேற்றைய நிலவரப்படி) தண்ணீர் இருப்பு உள்ளது.

    4 ஏரிகளின் மொத்த கொள்ளளவு 11 ஆயிரத்து 57 மில்லியன் கன அடி ஆகும். அதில், 446 மில்லியன் கன அடி மட்டுமே தற்போது தண்ணீர் இருப்பு உள்ளது. கடந்த ஆண்டு மொத்த ஏரிகளில் நீர்மட்டம் 2 ஆயிரத்து 357 மில்லியன் கன அடியாக இருந்தது குறிப்பிடத்தக்கது.

    The dam / lake levels around Chennai dwindles much,


    • What is the reason? Last year SWM and NEM didn’t fail that much..and SWM this year is normal so far..but why only 1/5th full compare to last year..
      Reason: Because of population increase and increase in water usage..
      Ini chennai ku evalavu mazhai penchaalum NEM munnaadi sep month storage kuraiva thaan irukkum..

    • Increase in consumption, Less Rainfall in catchment areas(TVL dist) for past 2 years and most importantly, Urbanisation. (Conversion of wet lands).

      • It also gives job opportunities for many people’s like mineral water companies and tanker lorries etc…many of them getting job indirectly behind this

      • Include Doctors, Nurses, Pharmacists, hospitals, Auto& taxi guys who also get job as people get sick after consuming the polluted water. It is a good business model.

  25. The cyclonic east- west shear zone running across 17 N might be a possible reason behind the storm that was seen north of Chennai today during the early morning hours. This shear zone is in partial association with the UAC in Bay. The region north of Chennai had good cyclonic vorticity field in the lower levels, which was eventually seen in the intensification of boundary layer convergence zone. This may go into the category of synoptic scale system induced one.

  26. Mumbai Indians cricketer Abhimanyu Mithun will be getting married to Tamil actress Radhika Sarathkumar’s daughter Rayane

  27. interesting : LLANFAIRPWLLGWYNGYLLGOGERYCHWYRNDRODWLLLLANTYSILIOGOGOGOCH, yep a town in wales,UK. longest name which was pronounced correctly by a weatherman in UK. courtesy: DC. now wonder how many bloggers will give a try hmm.

  28. This is the available latest 5.30 am IST derived 850 vorticity chart, clearly the cyclonic vorticity is more than 8 x 10^-5 s^-1 in association with the east-west shear zone which had induced quite intense boundary layer convergence. Although CAPE was less.

  29. Rains in Two extreme Ends of the State, Chennai & Kanyakumari ending 8.30 am on 10.09.2015
    Chennai recoded the wettest day of the year 2015 at 48 mm. A cyclonic circulation extending upto 2.1 kms a. s. l. lies over northeast and adjoining east central Bay of Bengal. The cyclonic circulation between 3.1 & 7.6 kms a. s. l over west-central Bay of Bengal and neighbourhood persists. Under its influence, a low pressure area may form during next 2 -3 days. The east-west shear zone now runs roughly along Lat. 17° N and extends between 1.5 & 5.8 kms a. s. l.

    A cyclonic circulation extending upto 2.1 kms a. s. l. lies over Lakshadweep area & neighbourhood

    in mm (min 10 mm)

    Chennai & Surrounding Areas
    Chembarabakkam – 80
    Chennai City (Nungambakkam) – 48
    Sriperumbudur – 41
    Anna University (Guindy) – 38
    Chennai AP (Meenambakkam) – 35
    Hindustan University (near Kelambakkam) – 32
    Kolapakkam (near AP) – 32
    Kelambakkam – 30
    DGP Office (Marina) – 29
    Taramani – 29
    Kancheepuram – 28
    Thirukalukundram (near Mahabs) – 28
    Katupakkam (near SRM University) – 28
    Tambaram – 27
    Thiruporur (near Kelambakkam) – 23
    Chengalpattu – 20
    Sathyabama University (Sholinganallur) – 19
    Mahabalipuram – 12
    Poonamalle – 10

    Killiyoor – 81
    Thuckalay – 72
    Anaikadangu – 65
    Adayamadi – 65
    Mambazhathuraiyaru – 62
    Rajakkamangalam – 61
    Kottar – 47
    Colachel – 47
    Koliporvilai – 41
    Mylaudy – 40
    Kannimar – 38
    Mullankivilai – 34
    Munchirai – 31
    Kurunthancode – 29
    Kuzhithurai – 28
    Boothapandi – 27
    Thovala – 27
    Nagercoil – 26
    Aralvoimozhi – 25
    Eraniel – 23
    Upper Kodayar – 20
    Kulasekharam – 16
    Agastiswaram – 16
    Kanyakumari – 16
    Suralode – 13
    Lower Kodayar – 13
    Puthen Dam – 10
    Pechiparai – 10
    Perunchani – 10

  30. Kanyakumari records heavy rainfall for 3rd day ending 8.30 am on 11.09.2015
    The upper air cyclonic circulation over westcentral Bay of Bengal, now extends upto 7.6 km above mean sea level. Under its influence, a low pressure area would form during next 48 hours. The shear zone runs roughly along Latitude 17.0°N between 1.5 & 5.8 km above mean sea level.

    in mm (min 10 mm)

    Chittar II – 86
    Koliporvilai – 41
    Mullankivilai – 36
    Kannimar – 35
    Rajakkamangalam – 31
    Chittar I – 31
    Kottaram – 27
    Adyamadai – 25
    Munchirai – 24
    Anaikadangu – 23
    Mylaudy – 22
    Suralode – 21
    Kulasekharam – 19
    Eraniel – 19
    Thovala – 18
    Neyoor – 17
    Nagercoil – 17
    Agastiswaram – 17
    Colachel – 17
    Thiruvattar – 14
    Kuzhithurai – 14
    Thuckalay – 14
    Karuthancode – 13
    Lower Kodayar – 13
    Pechiparai – 13
    Kanyakumari – 12
    Killiyoor – 11
    Upper Kodayar – 11
    Boothapandy – 10

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