Note on Withdrawal of SWM this Year:

Several models are recently showing absolute dry and "no precipitation" conditions in major parts of Pakistan and adjoining Rajasthan.
And, consequently, I have received several queries on this forecast, such as "is it an early withdrawal of the SWM "?
Does it necessarily mean or indicate a monsoon retreat ?

Let us first study , and understand for ourselves what actually are the parameters and conditions for SWM withdrawal. On monitoring, and following these, we can ourselves decipher and judge whether it is a withdrawal.

Parameters for withdrawal from Pakistan and Rajasthan region:

-1. Let us initially keep a watch on the 200 hp jet streams. During the monsoon , they are Easterlies approximately below the 30N line.This is the Southern periphery of an anticyclone at 200 hp, with the core between 30N and 35N at 150 hp. Peak winds at core exceed 100 knots. Westerlies are to the North of the Himalayas. 
Now, when the withdrawal process starts, we may see a deviation, gradually  from the Northern regions. The anticyclone in the Northern most regions vanishes, and westerlies start taking over below the 35N.
-2. A trough, in the westerlies, in the Afghanistan/ North Kashmir region, would mean the movements of WDs in the upper atmospheres. The frequent movements of these troughs and WDs would hasten a withdrawal.
-3. High temperatures prevail over Tibet till August End. This normally provides the ascent for the Hadley Cell. Falling temperatures over Tibet weaken the Heat source for the Hadley Cell.
-4. The Seasonal Low starts weakening with the formation of a high pressure in the Pakistan /Rajasthan region at the 850 hp level, or below. This would start "crippling" the axis, and its strengthening would regulate how fast the axis moves Southwards. The Southward moving axis, shifts and takes the upper limit of the Monsoon southwards with it.
As the axis reaches Karnataka and TN, the NEM conditions like wind and humidity get established  So, a direct link between SWM withdrawal and NEM setting.
-5. Relative Humidity reduction is observed in the NW parts of India. As the winds change direction, we see reduction in SW winds in the NW regions, thus reducing Humidity.
-6. UTH shows a marked and steady reduction.

Now, where are we placed this year as on 18th August ?

Currently, we do not see any of these parameters showing a withdrawal signs.
AN UAC/Low will be tracking thru Central India next few days. I would rule out any indication or parameter of withdrawal revival till the life span of this system. 

Possibly, this system may push in extreme Coastal and Eastern Sindh region around 24th/25th August.Rainfall. whatever amounts, is possible from Central India thru N/NW India from this system from 20th August-24th August. Good rainfall possible next 2 days in Northern Pakistan.
In fact, Northern India can get more rains for a couple of days after 30th August. (This is not a detailed Forecast report, but just a hint that withdrawal is not immediate).

x-------------------------------------x--------------------------------------x-------------------------------------x
Specific Forecast for Monday/Tuesday/Wednesday:

Chennai has a chance of a regional /local thundershower popping up on Monday evening, in some parts. At the most a remote chance on Tuesday with a local area getting a convective uprising shower. Later, as the trough weakens, Tuesday onwards, the chances of rain are negligible. Warm days later.

Mumbai sees the 2/3 passing showers reminding of the monsoon season on Monday. upto 10 mms possible.
A slight increasing trend from Tuesday night, will possibly see a sharp shower on Tuesday night, and some frequent rains on Wednesday. 20 mms/day.

Delhi NCR will continue to receive the spotted regional showers it is receiving. Regional or parts of the region will get showers next 3 days , with some downpours amounting to upto 30 mms on a day.


Jayeshbhai sends Last years Vagaries Lake Levels comparison (as put on vagaries with today's

See Pradeep's Page for...
Super Heavy 10 day Spells This Monsoon...And What Spells ! 
Also Pradeep's effort in working out Normal Goa Averages.

The withdrawal line of SWM moves South.

The Bay UAC has moved a bit to the SE, but not yet descended to sea levels.

Moisture drawn from the  TN and Karnataka regions is being drawn towards the system, resulting in some thunderstorms along the route in TN and Pondicherry today (Wednesday) evening.

And for Maharashtra, vagaries had mentioned : Direct Quote from Yesterday's blog:: " Thundershowers will be trying to "pop up" in Maharashtra on Wed 26th/Thursday 27th/Friday 28th/Saturday 29th, as the monsoon current weakens fast over the state."

Today, few thundershowers have commenced from the Vidharbha and Satara regions. Lets see tomorrow.

And guys , For Mumbai,  what was said was :Direct Quote: "Two or Three thunderstorms at the most, between Wednesday and Sunday." 

Patience is the Virtue which few Enjoy,  

we still have another 4 days to look forward to..after all otherwise, without a break, how can 2/3 storms occur in 5 days -

Thundercloud pic from South Mumbai on Wednesday..interactive Page..and many other thundercloud formations from various readers on vagaries fb page..

Further Withdrwawal of SWM from Rajasthan, Haryana, Kashmir, Delhi, HP, Utteranchal and West UP Tuesday, 26th night...Daily UTH,OLR and winds confirm.

Now for the next phase of axis moving towards N.Mah to trigger the thunder activity (see prevoius blog) and further retreats from regions    "alloted" by Vagaries for Friday seems to be on schedule. ( including Nepal) .


Sticky mini vortex mentioned brings the Saurashtra and Eastern Gujarat rains, with Surat getting 36 mms and Amreli 16 mms.  Another 2 days, and Monsoon withdraws ! 

But, unexpectedly, vortex moving west into Kutch and SE Sindh..light rains there ??

Bay UAC maintains position, and may drop to sea level to form a low today. Then track away from coast.

Mumbai pressure rises to 1014 mb today, highest since end April ! Now look out for towering cumulus clouds till Sunday...

Retreating SW Monsoon:

The anticyclone over Rajasthan and adjoining regions has all  but  dis-integrated  the seasonal low, and with a vengence, is all set to "wipe it off"  from the Western region by Friday. 
The seasonal low, if we can now call it so, over the Rajasthan region is 1004 mb, and soon will be a huge region of "high" at 1010 mb. 

Favourable conditions will withdraw SWM out of Rajasthan, Haryana, Kashmir, Delhi, HP, Utteranchal and West UP by Wednesday 26th.

The axis moves towards Northern Maharashtra by Thursday, 27th/Friday 28th, and the SWM is all set to call it a "season" from Gujarat, MP and UP by Friday 28th.

Resultantly, once the above scenario takes shape, the Westerlies winds in the NW and Northern India will become N/NW, and will cover all of Northern and Central India, down South upto the Vidharbha region. 


These Northerly winds, will change direction South of the Monsoon axis over Maharashtra. 
For convienance, I'll call this region "Region A", where the North winds cease and line of dis-continuity starts, and where the axis will be located. 

Now, South of this, the axis line diverts the wind, and in the State of Karnataka, a line of wind dis-continuity can form, creating turbulent weather.

Please note, that this "Region A" may occur slightly North or South of Vidharbha, cannot be too sure today.

Rains anywhere? 

As the anticyclone grips the Northern and Central States, the winds go "haywire" and turn a drastic Northerly in Northern and Central India upto Vidarbha.

Thundershowers will be trying to "pop up" in Maharashtra on Wed 26th/Thursday 27th/Friday 28th/Saturday 29th, as the monsoon current weakens fast over the state.

A sticky local mini vortex aloft brings some rains to Saurashtra and Eastern Gujarat Tuesday 25th/Wednesday 26th. 
A weak Low forms in the Bay on Wednesday 26th, and rapidly moves into Jharkhand/W.Bengal (Heavy rains).

Mumbai: For many of Vagaries' Mumbai readers, it will be a short lived monsoon farewell (compared to what we have seen last few years). Two or Three thunderstorms at the most, between Wednesday and Sunday.

SWM retreat will be somewhat "stuck" for some time after retreating upto Karnataka.

Immiedietly, on the withdrawal line reaching coastal Karnataka, the shortened "pigmy" off shore trough strengthens, and the strong "diverted " inland winds may give rise to an UAC/Low off the Karnataka Coast by Saturday 29th, and heavy rains likely in coastal Karnataka Saturday 29th/Sunday 30th.(Again, since this is a long term estimate, the UAC/Low may form a bit North or South).

Thats not all ! The rainfall moves eastwards into Karnataka, and even Bangalore can expect heavy rains for a couple of days early next week.

So, the SWM will not move away from the Southern Indian Peninsula till mid week next, at least. 

Presuming it retreats after the 5th of October, NEM can be, in calculable probibilities, NEM can start its advance between 16th October and 20th October...as of the situation today.


btw, IMD annonced Monsoon withdrawal from extreme west Rajasthan and Kashmir....on 24th, as hinted by vagaries a few days ago..

SWM Withdrawal Watch:

1. We can presume the core of the seasonal low, the main factor "fulcrum" of the monsoon axis has started vanishing. Latest map shows a very weak elongated low over the Balochistan region at 1004 mb.

2. The prevailing anti-cyclone over Sindh has "elongated" and extended westwards into the Westren Rajasthan region. Low humidity and clear skies are prevailing there and the UTH has also extended its grip North-Westwards today (Friday).

3.Corresponding OLR readings of over 300 w/m2 are seen in the Kutch and Rajasthan regions.

4. 200 hpa jet streams have steaied themselves above the 30N line.

Vagaries will withdraw (and make corresponding announcement) the SWM from Rest of Pakistan, Western Rajasthan, Punjab, Haryana and Kashmir on Saturday, 22nd September.
(*Withdrawal is announced after the parameters are established, and 90% of the region recieves no rain).
But, by IMD standards, for withdrawal, there has to be no rain in these regions for 5 continuous days, hence the official withdrawal from them will come later. 

Saturday, 22nd/Sunday 23rd: 

There will be "triggered" storms in Interior Maharashtra and Northern Karnataka. Gujarat, barring Kutch, will get rainfall in some areas, including Gujarat region (Eastern) and Saurashtra.
Surat, Ahmadabad, Baroda, Surat and Bharuch can get showers. 

Heavy thundershowers possible in pockets of Marathwada, Vidarbha and Madhya Maharashtra.
Rainfall also possible in South MP (Indore), and extreme South Rajasthan adjoining Gujarat.

A trough runs along the East coast of India, from the UAC over Orissa, embedded in the axis. Will result in heavy rains in Orissa, Coastal AP, parts of Interior AP, and Northern regions of TN coast. 
Chennai will get the odd thundershower "popping up" on the weekend. The trough shows a reasonable "dent" along the southern AP/TN coast on the week end. Possible heavy localised showers in some parts including Chennai.

Mumbai:
Saturday/Sunday: Cloudy morning, with rain in some areas. Getting clear by late morning. Clouds re-grouping by afternoon. Thunderclouds developing by evening, with heavy thundershowers possible. 

Pune: 
Saturday/Sunday: Partly cloudy, with thunery developments from afternoon. Thundershowers, heavy in certain parts, possible.   

Delhi NCR: Few clouds. Day temperature will be around 33/34c, and nights will be at a low of 24c. SW Monsoon withdrawal in next phase after Haryana*. 

Kathmandu may get a light thundershower, with clouds developing over the ranges. But, rainfall decreases after Sunday. Currently the temperature range will be between 30-18c, but nights will drop from Monday by 2c. 


Cherrapunji Annual Total crosses 12000 mms, at 12150 mms till 21st september 2012....

South West Monsoon is retreating Southwards. Parameters like OLR and UTH observed from IMD images indicate the SWM to have vacated regions above 25N. And approaching fast towards Maharashtra.

For Maharashtra and Mumbai, the only positve factor favouring "last farewell" rains is the "Maximum Lifted Condensation Level". Still favourable at 1000-1500.

A thunderstorm lashed Pune in the evening on Wednesday. Rainfall recorded was 22 mms.Shivaji nagar (Pune) measured 33 mms till evening. Unconfirmed reports of thunder rain at Lonavala.

SWM should be withdrawing from below the 20N line by October 1st week.

Would expect NEM to set in around 15th October. One thing is for sure, next system coming from South Bay will be from the NEM "family".

The other parameters are slipping ! The anti monsoon, withdrawal parameters are moving Southwards. Today,Tuesday, on observing the OLR map, we find the "browns" creeping towards Maharashtra, and the UTH also shows a reduced humidity (blue)ribbon sweeping across Mah. and totally covering the areas north of the state. 200 mb jet streams are westerly above the 25N line.

According to vagaries, SWM is done with (in addition to regions given previously) from North Gujarat, Rajasthan, North and Central M.P, and East U.P.

Next would be all of Gujarat, North Mah, Utterakhand, rest U.P, and M.P. Besides, Eastern and Central Nepal would see withdrawal in the next 2 days.

And the ridge ? Has it moved away northwards again? On the contrary ! A high pressure area has established itself right over the state of Mah. at sea level. Even at 850 mb, it is seen over the Western Mah.region. So,a high pressure is seen from sea level (1012 mb) to the upper atmosphere over western India.

It seems, that the withdrawal signs and criterea are "catching up" fast on Maharashtra.

Too fast for a last shower in Mumbai ??

Can the hills of Matheran, Mahableshwar and Lonavala still see a farewell thundershower ? Yes, its possible.

One can never say with the weather !

Vagaries analysis indicate withdrawal of SWM completely from Sindh, Kutch, Central Rajasthan and Punjab.

Very clearly depicted in the current OLR image.

Totally indicative of withdrawal conditions from these regions, the withdrawal stage is all set to cover rest of Rajasthan, Haryana, Delhi and Northern Gujarat in the next 2 days. A fast forming La-Nina may/can push for a speedy SWM retreat.

Due to the adverse conditions, we cannot expect any rains in this week in the above regions which have seen/will see SWM retreat soon.

Days have started heating up in the Rajasthan region, with 36c as the highest, but will rise more.Delhi is expected to touch 36c soon.

Across the border, Sibbi in sindh was 39c. Karachi is still maintaining its day at 33c.

See some rainfall again increasing nominally from Thursday for Kathmandu, as BB-8 advances North.

In the eastern front, BB-7 is gone and BB-8 has formed South of Kolkatta. At 1000 mb, its moderate at this stage, and would soon track NNE into W.Bengal by the 22nd/23rd. By 24th, it could move into Bangladesh. The anti cyclone and "dry" resistence pushes it Northwards.

Anyway, we can expect heavy precipitation in W.Bengal, Sikkim and parts of Jharkhand on Wednesday. Kolkata will again get good rainfall next 2 days.

Thundershowers are expected in Maharashtra this week. A formative easterly trough can bring some rains to coastal A.P./ T.N. on Wednesday/Thursday. Chennai could see some showers. Do not see any meanigful rains in interior Karnataka this week.

See Mumbai Page for latest…

The expected process of Monsoon Withdrawal has commenced from the North Gujarat and west Rajasthan regions. The parameters indicating this are the low humidity in the mentioned areas (see IMD map alongwith), and day temperatures have begun to rise appreciably in northwest Rajasthan due to post monsoon conditions. The mercury has touched 40 deg C at Jaisalmer and a few other places.
And the nights have started getting cooler in the extreme north (thats where it starts from).

Like, places in Ladhak have dipped to -3c ( Chushul) and Srinagar reached 8.8 c yesterday.

Also, the western end of the monsoon trough (axis), normally fixed across the border, almost near Arabia, has now shifted into India. The exrtreme western low is in Rajasthan, as the MSLP map from IMD indicates.

Its a matter of these conditions persisting for another couple of days, and the monsoon can be considered withdrawn from this region.
The next W.D. will result in this winter's first snowfall in the higher reaches of Kashmir and H.P.
For furhter progress of the monsoon shifting southwards, we will wait for the current low to fizzle out.

The deep depression has been degraded as a well-marked low-pressure area and moved from west into Madhya Pradesh.

Meanwhile, the Bay has a fresh upper air cyclonic circulation on Tuesday. But, as per my last blog, I do not see it gaining much.

The IMD update said that Monday’s offshore trough from Maharashtra to Kerala had weakened, reducing the intensity of the rains over the region.

Next 2 days, i see rain only along the path of the weakening low. Wednessday rains can be expected in M.P/ north Maharashtra (Nasik and Jalgaon regions and Aurangabad). And on Thursday lesser rains in eastern regions of Gujarat, and in south Rajasthan to some extent.

After Thursday, rainfall will decrease markedly in Gujarat, Maharashtra, Goa and Karnataka and most of the southern region, till the end of this week.

For Mumbai: A few showers in some parts on Wednessday evening. Rain decreasing from Thursday thru Saturday. As rainfall will be meagre, tendency to gat warmer after Thursday.

kapadias@gmail.com