(Map by Tejas Baxi.)
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MONSOON REPORT (01-9-2016 TO 30-9-2016)
TOTAL ALL INDIA RAINFALL (as on 30-9-2016)	862.0 mm
SEASON +/-	-2.87%
RAINFALL PER DAY this season	7.07 mm
SEPTEMBER RAINFALL (2016)	168.9 mm
AVERAGE SEPTEMBER RAINFALL (1966 TO 2015)                                                              #	168.1 mm
SURPLUS	+0.5%
TOP FIVE SUBDIVISIONS THIS MONTH	mm
A & N ISLAND	604.3
KONKAN & GOA	600.2
ARUNACHAL PRADESH	530.1
SHWB & SIKKIM	514.4
BIHAR	357.9
BOTTOM FIVE SUBDIVISIONS THIS MONTH	mm
JAMMU & KASHMIR	44.5
EAST RAJASTHAN	40.2
PUNJAB	16.9
HAR. CHD & DELHI	15.5
WEST RAJASTHAN	11
TOP FIVE SUBDIVISIONS ABOVE NORMAL THIS MONSOON
EAST RAJASTHAN	32%
KONKAN & GOA	22%
MARATHWADA	21%
WEST RAJASTHAN	20%
TELANGANA	19%
BOTTOM FIVE SUBDIVISIONS BELOW NORMAL THIS MONSOON
LAKSHADWEEP	-25%
HAR. CHD & DELHI	-27%
PUNJAB	-28%
ASSAM & MEGHALAYA	-30%
KERALA	-34%
TOP FIVE STATES THIS MONTH	mm
SIKKIM	632.6
ANDAMAN & NICOBAR (UT)	604.3
ARUNACHAL PRADESH	530.1
MIZORAM	417.2
MANIPUR	405.3
BOTTOM FIVE STATES THIS MONTH	mm
JAMMU & KASHMIR	44.5
CHANDIGARH (UT)	41.5
RAJASTHAN	24
PUNJAB	16.9
HARYANA	13.6
TOP FIVE STATES ABOVE NORMAL THIS MONSOON
RAJASTHAN	28%
DADAR & NAGAR HAVELI (UT)	26%
TELANGANA	19%
MADHYA PRADESH	19%
MAHARASHTRA	16%
BOTTOM FIVE STATES BELOW NORMAL THIS MONSOON
PUNJAB	-28%
HARYANA	-28%
KERALA	-34%
CHANDIGARH (UT)	-46%
MEGHALAYA	-48%
TOP TEN DISTRICTS THIS MONTH	mm
UPPER SIANG (arunachal pradesh)	1169
WEST SIKKIM (sikkim)	1021.1
EAST SIANG (arunachal pradesh)	925.5
LOWER DIBANG VALLEY (arunachal pradesh)	793.4
RATNAGIRI (maharashtra)	793.1
RAIGARH (maharashtra)	788
SOUTH ANDAMAN (a & n Island)	770.9
IMPHAL WEST (manipur)	737.6
MUMBAI CITY (maharashtra)	733.4
PAPUM-PARE (arunachal pradesh)	714.6
BOTTOM TEN DISTRICTS THIS MONTH	mm
BADGAM (j & k)	2.2
TUTICORIN (tamil nadu)	1.9
BHIWANI (harayana)	1.3
JAISELMER (rajasthan)	1.2
SANGRUR (punjab)	0.9
BATHINDA (punjab)	0.9
ROHTAK (harayana)	0.7
TIRUNELVELI (tamil nadu)	0.4
HISAR (harayana)	0.2
LEH AND LADAKH (j & k)	0.1
(TARAN TARAN, SIRSA, MUKTSAR, MORBI, MOGA, MANSA, KAITHAL, JIND, FATEHABAD, FARIDKOT, BARNALA all had 0 mm rainfall)	0.0
TOTAL ABOVE AVERAGE RAINFALL DAYS this month (subdivision data)	13  (43%)
TOTAL BELOW AVERAGE RAINFALL DAYS this month (subdivision data)	17 (57%)
# IMD figures are different as this is 50 year average	source -IMD

 

Estimate for Next 2 days Wednesday 28th and Thursday 29th September for :-

Delhi NCR: As monsoon withdraws by month end, Region may experience very hot days. Day may rise to 38c.

Mumbai: Partly cloudy with a couple of passing showers in some parts of city. Days likely to be hotter.

Kolkata: Warm, but a shower or thunder shower expected on Wed/Thursday.

Chennai: Cloudy, with showers on Wednesday and Thursday. Around 10-20 mms of average rainfall per day.

Bangalore: Expecting a thundershower on Wednesday and Thursday.

Hyderabad: Partly cloudy. May get windy on Thursday. Light drizzle in some parts.

Posted Monday Night:
Mumbai will get periods of sunshine with a few passing showers on Tuesday, maybe upto 10 mms in the day/night. Rest of the week will be seeing periods of sunshine with a few showers in some parts. Decreased rain continues till month end. 

Mumbai's Evening thunder showers (from East) may start by next month.

Mumbai Rainfall Stats:( 25th September)

Seasonal Totals:
Colaba: Mumbai Colaba crosses 2500 mms for this season...2507 mms As on 26th September.
Recent crossing 2500 mms was in 2011 when Colaba measured 2879 mms ( Full Season) and in 2010 when this station saw 3291 mms till Monsoon withdrawal.
Highest ever Seasonal total for Colaba is 3482 mms in 1954.
Santacruz:  Total on 26th September for this season stands at 2893 mms.
Recently in 2010, SCruz measured 3392 mms till Monsoon withdrawal. Highest ever at Scruz is 3785 mms in 1958.

September Totals;
Colaba: This year 2016, as on 25th September, this Month has recorded 731 mms , while wettest ever September was in 1988 and 1993, when 832 mms was recorded.
Santa Cruz:2016 September, Scruz has received 703 mms, still short of the record september of 1993 when the month saw 905 mms.

Incidentally,  2011 had the Longest Monsoon Season for Mumbai, when the Monsoon withdrew on 24th October, after lasting 141 days !

Posted Saturday Night:

BB-13 persists over Telengana/Vidharbh. Expected to remain in region next 2 days. Heavy rains continue in parts of Telengana and Vidharbh. Hyderabad next 2 days : Some heavy showers.

Mumbai sees a sharp reduction in rains....Sunday thru Tuesday will be partly cloudy with sunny periods. 4/5 passing showers in parts of city. Major decrease in rains from Monday.

Sunday thru Tuesday:Light rains (upto 5 mms) occurring along South Gujarat coast (Valsad and Surat).

Jaipur had a heavy "end of season" shower of 59 mms Friday night and Churu received 38 mms on Friday night.
As mentioned, South West Monsoon all set to withdraw from Saurashtra, North Gujarat and East Rajasthan by Monday 26th September.
Days will be over 40c in Rajasthan and Kutch.

Yesterday in the comments section I gave a brief analysis of "Peninsular" rainfall for the period 1871 to 2014 during the monsoon months, June to September.

Today we look at the same set of data ((via IITM under the All India and Macro Regional data set. (It includes six subdivisions namely Coastal Andhra Pradesh, Rayalseema, TN & Pondicherry, Coastal AP ,S I Karnataka and Kerala)) of the "Peninsular" rainfall for the period October to December.

This period is normally classified as the NEM and this is what IMD Chennai says about it..

"The period October to December is referred to as Northeast Monsoon season over peninsular India. Earlier   this period was also referred to as 'Post-Monsoon Season' or 'Retreating southwest Monsoon Season'.

Northeast Monsoon season is the major period of rainfall activity over south peninsula, particularly in the eastern half comprising of the meteorological subdivisions of Coastal Andhra Pradesh, Rayalaseema and Tamilnadu-Pondicherry. For Tamilnadu this is the main rainy season accounting for about 48% of the annual rainfall. Coastal districts of the State get nearly 60% of the annual rainfall and the interior districts get about 40-50%  of the annual rainfall. 

Though the principal rainy season for  Interior Karnataka, Kerala and Lakshadweep is the Southwest Monsoon season, rainfall continues till December in these sub-divisions, the period October-December (Northeast Monsoon ) contributing about 20 % of the annual total. " 

First we look at a graphical representation of the raw data from 1871 to 2014..

As can be seen the rainfall varies from as low as 93mm in 1876 to 585mm in 1946. Those are the extremes. The average for the entire 144 years is 345mm.

Now we look at a smoother version of the above data which has been averaged every three years..

 As can be seen there is a cyclical behavior that seems to swing between highs and lows every few decades. The lows are formed every 35 to 45 years and since the last one was in 1990 the next can be expected around 2025 to 2035 (since it is averaged for the previous three years the actual lows might form from 2022-25 or 2032-35).

An even more smoother version (9 years) gives us this ;

 Here too we get the same 35 to 45 year lows in rainfall.

We now compare the Peninsular Oct to Dec rainfall to the Annual Peninsular rainfall for all the years;

(smoothed every nine years)

Same conclusions as above!!! Also the range varies from 35% (1888) to 25%(1955).

And finally we compare the Peninsular Oct to Dec rainfall with the Peninsular Monsoonal rainfall;

(smoothed every nine years)

Again the same conclusions as far as the lows are concerned. The range varies in this case from 65%(1888) to below 45%(1912,1955).

Conclusions: The Peninsular rainfall from Oct to Dec shows a huge variation from 93mm to 600mm and ranges between 25% to 35% of its annual rainfall averaging around 29.5%. As compared to the south west Monsoon it varies from below 45% to almost 65% averaging around 54%. A cyclical behavior is very evident in the charts above and the current century shows nothing unusual.

The fact that some kind of regularity has been seen in the trend for the last 144 years does not suggest at all that a new trend might not emerge in the future..weather is too complicated for any one to truly predict accurately a hundred per cent all the time. I personally feel a time period of 150 years is too short for any kind of definitive trends to be emerge.

 

((Thanks to IITM for the data and IMD Chennai for the NEM introduction)) 

Posted Tuesday Night:

Mumbai received intermittent showers on Tuesday Night and Wednesday. From 8.30 am - 8.30 pm IST on Wednesday, Colaba measured 99 mms and Scruz 57 mms. 

On Thursday, Mumbai city will get marginally less rains as experienced on Wednesday. Less frequency passing showers, not continuous,  will measure around 40-60 mms from Thursday Morning - Friday morning. (Less Compared with Wednesday figures). 

Northern Outer townships have received the brunt of the heavy rains recently. They will get much reduced rainfall next 2 days.

Friday: Frequent showers, some heavy. Though not intermittent or continuous, the rainfall will be almost the same as Thursday amounts.

Pune: Few light showers on Thursday, rain frequency increasing to 15-20 mms on Friday. Cool days.

All Lakes supplying water to Mumbai on the brim now, 99% full. Mumbai has water storage for 385 days, i.e. till 11th October 2017 !!..Lakes Info from Vagarian Jayesh Mehta.

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A low from the Bay will cross the AP coast on Thursday/Friday. An extended upper air trough from the system will cross the South Konkan coast , forming by Saturday. Increasing rains in South Konkan and Goa from Saturday. More on this later.

South West Monsoon may withdraw from Saurashtra by 24th September.

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Mumbai: From Tuesday mid night till  Wednesday mid night, Colaba received 113 mms and Scruz 75 mms.Vagaries measured 89 mms.

Estimate given for 24 hrs ended midnight Wednesday was "More rains for Mumbai Tuesday Night...70-90 mms from Midnight Tuesday next 24 hrs...Posted Tuesday Night"

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South West Monsoon ...How Vagaries works out the Withdrawal...(18th September 2016)

Explanation:

South West Monsoon Criteria for Withdrawal as per IMD:
Withdrawal of SW Monsoon

a) Withdrawal from extreme north-western parts of the country is not attempted before 1st September.

b) After 1st September:

The following major synoptic features are considered for the first withdrawal from the western parts of NW India.
i)        Cessation of rainfall activity over the area for continuous 5 days.
ii)       Establishment of anticyclone in the lower troposphere (850 hPa and below)
iii)      Considerable reduction in moisture content as inferred from satellite water vapour imageries and tephigrams.

Parameters for Withdrawal considered by Vagaries:

a)*A Primary factor  is the 200 hp jet stream. This is one of the main and assertive parameter. The Easterly winds at 200 hp, gradually become Westerly starting from the Northern regions as the Monsoon withdrawal line moves South.An anticyclone High forms in the jet streams around the Sindh coast by 1st week of September, thereby creating Westerly winds almost throughout the region of Pakistan and Rajasthan. In fact, these winds bring down the axis and the withdrawal line.

b)**As the Monsoon withdrawal commences, the seasonal Low weakens, and the core (then becoming around 1000 mb during initial withdrawal ) moves to North Pakistan region.

c) Another factor, connected is the Outgoing Longwave Radiation (OLR). As the norms touch 290 W/m2 or rise above ...

d)***Also, the Upper Troposphere Humidity plays an important part in supporting and "holding " the Monsoon. The current humidity position indicates a weak situation for Monsoon sustenance in North/North-West.(Below 10%).

Position Parameter wise as on Sunday 18th September

* The West winds (at 200 level) are firmly above the 30N line. An Anti Cyclone will form along the 27N line, roughly in the Sindh/Rajasthan region in a couple of days.Jet Streams North of the Anti Cyclone will be firmly West.

**The Seasonal Low is weakening, with the core around the Central Sindh Region at 1002 mb. Will move and merge with the other Low in North Pakistan, also at 1002 mb.

***OLR and UTH Map shows the immediate withdrawal possible from Rajasthan and Punjab.( From 19th as mentioned in yesterday's Post). 

At the 850 level, a weak anti Cyclones prevails over NW India and adjoining Regions. But conditions are apt for a Ridge formation over the Region in next 2 days.

Mumbai Water Supply Lakes are now 98% full, and City has a year's Stock available as on today..data from Vagarian Jayesh Mehta 

compiled by Vagarian Tejas

Posted Saturday Night:

1*. The UAC off the Mumbai coast, descended to sea level on Saturday. The Low is expected to dissolve by Sunday evening. Rainfall decreasing in Konkan and Interior Mah from Sunday evening.

2**. Another Low is expected to form off the North Konkan/Saurashtra Coast around the 24th/25th of September. Seeing the developments possible, this may develop and deepen, and as AS-1, track Westwards into the Arabian Sea.
3. South West Monsoon will withdraw from Rajasthan and Kutch by 19th of this month. And subsequently from Punjab in the next 2 days.
Monsoon may withdraw from NCR around 26th of September.

*1(a): Mumbai: Vagaries had clarified, that depending on the exact location of the UAC, 100 kms North/South of Mumbai cold be the range of rainfall along the coast. 
As shown in maps ( In Vagaries) on Friday and Saturday, this trough and embedded UAC has produced rainfall upto 100-350 mms. In the  North (Dahanu 120 kms had 345 mms) and South (Murud 120 kms had 230 mms) of Mumbai.

Mumbai received an average rainfall of 23 mms as on 15th morning, 68 mms on 16th and 76 mms on 17th.
Rains will persist in the Mumbai region on Saturday night and Sunday. Frequent showers on Saturday night and Sunday.Next 24 hrs, from Saturday mid night- Sunday mid night Mumbai can bring up 60-80 mms. 
Saurashtra had good showers on Friday and Saturday(mentioned in LTF on Tuesday). 
South Gujarat region coast and Coastal Saurashtra will get thunder showers on Sunday. 
Surat: Chances of a couple of heavy showers on Sunday. Next 24 hrs,30-50 mms till Sunday night.

**2(a): On forming, AS-1 may bring rains again to North Konkan around 23rd.(If on schedule, Mumbai may get another spell on 22nd or 23rd). Showers will also cover the South Saurashtra Coast.

Mumbai Water Position see Mumbai Page

Rain Frenzy around Mumbai continues into Saturday Morning....
Mumbai was predicted to get average between 60-80 mms for Friday...actual received Map below:

 and Ghat and other stations around the region map (below)...

Posting Fresh Report for next few days Saturday evening...

Posted Thursday Night: Mumbai Follow Up:

Due to a slight weakening of the divergence in the winds at the 200 levels, there could be some delay in the formation of the expected UAC over the Mumbai region.Not much though, Heavy showers expected Thursday Night and...
Friday will see showers post noon, and may still measure upto 60-80 mms on Friday. 
Saturday will be seeing heavy rains , again potential for flooding. With strong winds, Mumbai may see around 150 - 170 mms on Saturday.

Pune, getting fairly frequent showers on Friday (around 35 mms) with the day around 23c.


On Saturday, heaviest rains spreading Northwards along coast upto Gujarat coast.Surat may get heavy showers.

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Posted Thursday Evening...
We had mentioned the formation of an east-West trough thru Mumbai going towards the interior Maharashtra region. This formed on Thursday, resulting in an initial commencement of rains around Mumbai.
Some rainfall amounts from 8.30 am -5.30 pm on Thursday: Mumbai Colaba 20 mms, Vagaries 55 mms and Mumbai Scruz 76 mms.

Pune was cloudy with occasional rains, 4mms, the day's high being 24.2c (AP) and 24.9c (City). In Marathwada, Parbhani recorded 47 mms in the same period.....more on the situation tonite 11 pm IST

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Follow up to Mumbai Rains : Posted Wednesday Night:
A Brief Explanation:
On schedule, the Arabian Sea UAC at 65E, and now its on stream to form an Upper Air Trough from This UAC to theUAC of BB-11...East-West Upper Trough. And the 200 level divergence will help in the formation of UAC around Mumbai by Friday...So,

Expect thunder showers on Thursday around Mumbai. Mumbai can get about 40-50 mms on Thursday, increasing substantially on Friday to 140-160 mms. Watch out for flooding.
Stormy Saturday expected.

As mentioned, rains will wet Pune next 3 days , with thunder.Around 25 mms on Thursday and 30-40 mms on Friday.
Pune must be ready for cool days at 23c.

Posted Tuesday Night:

Mumbai Special:Wet and windy Spell ahead !
Starting Thursday 15th September, next 4 days are going to be very wet and windy for Mumbai and all surrounding townships.

Thursday 15th will be the commencement of the wet spell, being cloudy with a few showers. 

Showers start increasing in intensity from early Friday 16th morning, and the day will see heavy rains . Watch out for flooding also. Vagaries would expect between 150-170 mms in 24 hrs (Friday). Fairly frequent showers with thunder.

Rains continue into Saturday 17th, with frequent intermittent showers in the day. Again, another 150 mms expected in next 24 hrs.Watch out for flooding.

Heavy rains on Sunday 18th, though less then intensity of Friday/Saturday. will add to flooding.Sunday will see let up only after evening.

As the reason and cause for this expected heavy rains is an embedded UAC in an East-West Upper Air trough, its outreach may be restricted. Heavy rains will roughly cover the region round 100 kms North and South of Mumbai along the coast, and around 50 kms inland.
The ghats between Mumbai and Pune region will also experience heavy rains, along with the stations in Mahableshwar and Koyna regions. May get more than 300 mms. in 2 days.

Pune will also witness a wet spell,from Thursday thru Sunday. Thursday will be rainy and wet (40-50 mms), but The peak rainfall (of around 80-100 mms ) will be on Sunday.Cold days ahead the weekend, with the days not exceeding 23c.

Posted on Sunday 11th Night:
Vagaries works out  a Medium/Long Term Forecast for its reference thrice a week .Long Term Forecast is hardly ever put up on Vagaries due to uncertainty and varying changes., but 
Judging form the anxiety about the rains, Vagaries is today deviating and putting up a "rare Medium Term forecast".(Subject to revision).

1. South West Monsoon likely to withdraw from West Rajasthan and Sindh by 13th September. Temperatures likely to rise in Sindh.

2. 12th Monday - 14th Wednesday, rains likely in Vidharbh, South Chattisgarh, Odisha. Kashmir and HP get rains from a WD.

3. From Thursday 15th/ Friday 16th-Sunday 18th ...Rains likely in Interior Maharashtra, Konkan, NI Karnataka, Southern Peninsula, Central India (M.P.) and Southern U.P. Substantial increase in rains in Madhya Maharashtra (Pune/Nasik) and Goa, Konkan (Mumbai and towns around).
Thunder showers in Mumbai Friday-Sunday.

4. From Saturday 17th, for a copule of days, rains in Saurashtra and rest Gujarat except Kutch. Rains increasing Saturday/Sunday in West Bengal/Odisha.

This will reduce the All India Monsoon Deficit after 20th September....Current deficit -5%

Mumbai Lakes Position: 97% full, and having storage of 1405 Mcum out of full capacity of 1441 Mcum. Translating, we have 1 year water stock, i.e. upto 15th September 2017. Lakes Info credit Vagarian Jayesh Mehta.

Posted Saturday 10th Night:

BB-11 is expected to form on 11th as expected. It may track W/NW into Telengana and clouding in Western segment will bring rains to interior Mah next week. Rainfall expected in A.P./Telengana and Vidharbh next 2 days. It may track NE later and weaken further...

Conditions for Monsoon withdrawal may commence from West Rajasthan and adjoining South East Sindh from 13th September.

Chennai received heavy rains on Saturday, and between 5.30 pm and 8.30 pm, 52 mms were recorded at Minambakkam.
Hyderabad received 8 mms till 8.30 pm IST Saturday.

Southern Indian Peninsula Deficit at -13%:
The monsoon axis has remained in the far north, or more North than normal for a very long time now, almost a month (or more). When this happens, naturally, the seasonal low in the Kutch region becomes weak, or also moves North.
Now, as i have stated, the off shore trough along the west coast in monsoon season "pivots" and is anchored from the seasonal low in Kutch. If this gets weak, the off shore trough (west coast) weakens also. This has caused weak and deficient rains along Karnataka Coast (-31%) and Kerala (-31%) this year. 
Also, the position of axis (in North) prevented the formation of a trough or LWD in the Central Peninsula region this year. We have not heard of a trough forming North -South this year from any system positioned in MP, even though BB-6,7 and 8 went thru MP. With the syetems from the Bay, only the Eastern side of axis came Southwards, while the Western end remained far North.The Arabian Sea and Bay sytems are also "instigated" by favourable MJOs.
Thus South Interior Peninsula got less rains...NI Karnataka 0%,SI Karnatak -13%, 
Though Interior Mah (Maratwada -2% and Madhya Mah +7%) got rains from the BBs over MP.