Friday, October 14, 2011

Vagaries Estimate October weather forecaste Reproduced v/s actual (in green)

Black Print is original Forecast, and Green is actual performance.

Vagaries Estimate for October for the Sub-Continent:

-As we see the SWM still prevailing in the Indian peninsula and Eastern regions, we shall first discuss its possible retreat.

The current signs and parameters suggest a withdrawal of the SWM from Maharashtra and A.P, and Orissa by the 1st week of October.

SWM withdrew from A.P.and Orissa, still prevailing in S.Maharashtra.

-Further withdrawal from the Southern states of Karnataka, T.N. and Kerala will be between 7th and 12th October.

Not yet thru.

-Formations of UACs or a low pressure in the South Bay around 16th can herald the advance of the NEM. Initially, as a weak MJO prevails in the Indian Seas, NEM may remain weak till the 22nd.

UAC formed in South Bay on 14th, and could become a low by 16th. NEM can adveance.

-ENSOconditions remain within neutral conditions, but both atmospheric and oceanic indicators show a trend toward La Niña. More importantly, for a La Niña event to occur, these indicators must remain above the threshold and persist for at least a few months.

Hence, NEM could be moderate to avarage after setting thru October.

No major W.D. is seen crossing the Northern regions in the first half of October. However, as the westerly upper winds gain strength and stabilise, a W.D. is possible in the second half of the month. The middle hills (Gulmarg, Pahalgam, Kalpa, Keylong) could get the first snowfall during the 2nd half of this month, and here will see the temperature touch 0c by the 15th of October. Leh, in Ladhak will freeze a week before.

A weak W.D. moved across Northern sub-Continent in the 1st week, and brought snow to the higher reaches. Middle hills snow possible as forecasted.

-Northern plains of India, Delhi, Gujarat and Rajasthan will be hot in the day. Day temepratures in these areas will hover between the 32-37c range till the 15th October. Cooling will take effect in the 2nd half.

Days will be around 33-35c in interior Maharashtra cities till around 18th October.

Delhi, Pune, Aurangabad and Nasik will drop to below 15c (night ) after the 20th.

Northern Plains are currently in the 33-37c day range, with 38c as the highest. Maharashtra interior cities are in the 33-35c range. Night temperature in the North are around 20-23c range, and drops should be on schedule.

-There could be a possibility of a depression forming, and strengthening, in the East Arabian Sea off the west coast of India around the 20th of October. This is based on certain assumptions, and such long time predictions could change.

Waiting. Date not arrived !

-For Nepal, the surface winds have almost become westerlies to NW. Indicative of SWM withdrawal. SWM still holds sway in the central and Eastern parts, but likely to retreat by the 1st week.

Local weather phenomena always holds the key over the Mountainous areas, which in turn effects the nearby plains. Thunder cells could form in the mountains, and drift over the nearest plains areas. Specially in the next few days, as the region is predominantly saturated with moisture.

In general, we can expect the nights in Kathmandu to get cooler after the 10th. Presently at around 17c, will start dropping to around 14/15c and gradually go lower.

The average rain for October is around 57 mms, and most of it could be from local phenomena, meaning no etc.

Do not expect any W.D. to have any great effect in October.

SWM withdraws, and Kathmandu nights get cooler, after the 10th. Nights went down to 13-14c, and now is around 15/16c.

-Sindh regions of Pakistan will initially heat up in the first half of October. The days will be in the 35-39c range in many cities of Sindh, with cooler nights dipping to around 18/19c in the interiors. Days will drop to below 34c after mid October.

Northern regions will experience the normal cooling, with a couple of W.D.s in the Northern most regions preicipitating rains, after 20th of this month.

Days in Sindh are around 35-38c range, with the highest showing 39c. Nights are still warmer than expected in Sindh in the 22-24c range.


junaid said...

today was unable to comment as there was a major power problem in panvel due to thunderstorm activity,,,unlike the storms of the two days todays storm wasnt very squally like yesterday,,,but in rain amounts todays amount wud definitely be more,,,as unlike yesterday the shower continued for a longer duration i am waiting to see panvel figures,,,,as today was the rainiest of the previous three days,@rajesh the clouds wich i saw during thunderstorm were towering thunderstorm clouds...todays thunderclaps were very ferious as severe lightening struck ...all this started at 4:30 wen the sunny sky began to get overcast and heavy rains startrd at 5:20 wich countinued for more than an hour the rain rate was high and also the duration....

junaid said...

@rajesh the imd is predicting fairly widespread rain to continue over west coast,....what are your views

Shitij said...

Whether the forecasted depression will form in Arabian sea?

Pavan said...

Sir,Some of aws and arg stations in maharastra are working inefficiently so the we can't get data for temp and rainfal, another query is can we instal a rain gauge at our place if yes then hw it can be from where we get these gauge, and hw abt wet bulb and dry bulb th'meter

Rajesh said...

sridhar: As you say, all the maps, from 22nd Sept to 5th October, showed Mumbai possibly getting rainfall, while my views were somewhat hesitant. But, where is the reasoning, when during these 10-12 days, models go on mentioning rain, and vagaries sees no rain, and it does not rain during these days. In fact, during this period, vagaries daily explained the SWM withdrawing parameters were activated.
yes, when the rains did pop up in Mumbai, Shridhar, I have explained the thunderstorms events in Mumbai. What my point is, it eventually rained as a sort of "post monsoon" event. All parameters are non monsoonish, and convectional rainfall is generally withdrawing monsoon or post monsoon types.

junaid: yesterday Panvel had 23 mms as mentioned. For Mumbai I had estimated the clouds to come by 6 pm, and they did. The towering clouds form an anvil, which moves East over Mumbai..that is what was expected today. Mumbai had 20 mms at Colaba and 4 mms at SCruz. Rainfall decreasing after Saturday in our regions.

pavan:i shall send you the link where u can get the aws installed.

sridhar said...


Viravanalluran said...

What my point is, it eventually rained as a sort of "post monsoon" event. All parameters are non monsoonish, and convectional rainfall is generally withdrawing monsoon or post monsoon types.
Dear Rajesh,
You are extremely correct. This type of TS activity is common during SWM withdrawal period in the east coast. Of late the signatures of SWM has been changing and withdrawal phase too is felt in western coast of India during Sept / Oct. Generally the withdrawal phase is infested with TS activity only. {The relevance of "Ganapathy papa moria" with SWM withdrawal is to be studied then]
Secondly, the shift in Mascarene High or shift in Tahiti - Darwin ENSO [NORTHERN oscillation ???]
towards North latitude in Southern hemisphere.
The less active Bay branch is indicator and Cherrapunji rainfall is the evidence.[And also Kollur, Agumbe,& Mah. rainfall.]

Viravanalluran said...

Pavan said:
Some of aws and arg stations in maharastra are working inefficiently so the we can't get data for temp and rainfal, another query is can we instal a rain gauge at our place if yes then hw it can be from where we get these gauge, and hw abt wet bulb and dry bulb th'meter
9:25 PM, October 14, 2011
Any one can install rain gauge and other meteorological instruments for self study. But for effective comparison of data, WMO or IMD recommended standard instruments have to be procured and installed with adherence to WMO / IMD procedure.
Secondly observations need to be taken at standard times stipulated by WMO. [i.e from 00GMT which corresponds to 0530 hrs IST and at 03,06,09,12,15,18,21 GMT]

This involves commitments and some times extra care. Meteorological instruments can be had from M/S Lawrence and Mayo (Met division) Hindustan clock works, etc.

But if volunteers or organisation come forward and if money is not a criteria, one can go for AWS with limited sensors.
Globally reputed company Vaisala is selling AWS[with limited sensors]costing from INR 70,000.

similarly I wish to put my request to these weather enthusiasts that interested volunteers or reputed organisations must come forward to install AWS or extend support to maintain AWS at very vantage meteorological locations like Agumbe and other high altitude stations where solar powered battery back up during SWM period fails because of want of sunlight.There will be continuous cloud cover for more than 15 days with no sun shine in these regions. Volunteers from Agumbe or from respective hill station must take care and maintain by giving proper power back up. This will ensure quality data .

emkay said...

seems the depression in arabian sea is in forming now. big cloud mass off south maharashtra coast. Rajesh, what wuld be track

Rajesh said...

viravanalluran: Absolutely correct. The ENSO and MJO effect expected on NEM is also mentioned by me in October estimates.
Actually SWM will be "converted" to NEM within a week now, as systems, albiet weak initially will come in the Bay.
AWS must be used and placed with utmost care and sincerity..half knowledge is dangerous.

emkay:You seem to be in a hurry -:). First let the kid be born, then we see which career he chooses, whether it bcomes a metman or a magician !Who can say from now at this stage ?

NT said...

Lots of Thunder cells have formed in the ghat areas as per the latest Doppler image, looks like the daily soap opera will continue for Mumbai today as well. This rainy season is becoming a never ending saga. Is it the longest rainy season yet for Mumbai?

Anonymous said...

@NT Last year the last rain fell on 16th november in mumbai (borivali)!!!

Anonymous said...

@NT Very sorry!! I checked the photos. Last year the last rain fell on 23rd/24th november in mumbai (borivali)!!!

NT said...

@Anonymous .. I meant the official SW Monsoon season. The rain that fell in November last year was not from the SW Monsoon which was declared over by October 24 (I think). That way Mumbai has had rains even in December and many times in November. Remember the cyclone that crossed south of Mumbai 2 years back?

This year the first rains started in SCZ on 2nd June (early onset) and are still continuing.

Anonymous said...

@rajesh bhai :the climate is building up,but will there be any thundershower today.

Anonymous said...

can we say a storm to hit in mumbai from ghatkopar mumbai

Anonymous said...

The drums are beating and getting darker at Ghatkopar!!! ..........potey

Anonymous said...

gusty winds from east-southeast at borivali. no thunder yet!

sridhar said...

heavy rains lashing thane now ... with little bit of thunder

Anonymous said...

rain started in borivali now but still no thunder!

Anonymous said...

thick drizzling in sakinaka andheri east but no thunder till now

Anonymous said...

Ghatkopar, clouds getting thinner, no rain.

Anonymous said...

i think there is a scattered rain in all over the area.on top floor,i see on one there is a heavy rainfall and on other side the skies are clear (from sakinaka andheri east)

NT said...

Are we done for tonight in Mumbai or is there a surprise in store? Rajeshbhai, your forecast for today has come right.

Pavan said...

Its pouring pouring in pune bcos SPAIN s very far and lil tomy does'nt wan t to play

junaid said...

@nt panvel received 5cm yesterday (imd mumbai ) report,,,yesterday was the day which gave the maximum amount of rain at panvel in the last three also the weather turned out like last three days but todays cloud lacked depth and they were spread out clouds,,,,,,and there was also little thunder,,,,@rajesh plz update about the weather of the coming says!!!

Anonymous said...

@rajesh bhai please forecast the weather for sunday.

Rajesh said...

anonymous: Forecast for which place ??

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