Tuesday, May 09, 2017

Monsoon Watch -3... 2017 (Additional)...May 9th 2017.
Monsoon Arrival Estimate.

The arrival date is calculated seeing today's position.Further from today, we presume the normal rate of progress/developments. This initial estimated dates are subject to some changes, and will be finalised around mid-May, when the puzzle pieces get better arranged.
(Dates in brackets are the normal dates of arrival).

As of today, there seems to be a slight delay in both, Arabian Sea and Bay Branches of the Monsoon. There continues to be a doubt on the timely arrival of the Monsoon in the Bay branch.

Arabian Sea Branch: The LWD parameter is strong, and developed well. Otherwise, There is not much improvement in some of the parameters, there is still much to be achieved, and most parameters are still lagging behind time, and are -ve.
The Arabian Sea branch, now affected by the "getting organised" Somali current winds and the equatorial winds at the equator. They can recover provided the winds regroup fast.

On these calculations, Vagaries would estimate the Monsoon to reach Maldives around the 22nd of May 2017 (20th May), Sri Lanka around 27th/28th of May (25th May).
Kerala by the 2nd/4th June (1st June).
Hence, maintaining and presuming the normal rate of progress, As the Seasonal Low strengthens, Monsoon could "slide " up the coast to be in Goa should get Monsoon rains by around 8th/10th June (5th June). NE States can also see Monsoon resume around that date.

 Mumbai by 12th/14th June (9th June). Pre Monsoon thunder showers could start from around 3rd/4th June 2017.

Bay Branch: A weak Western Disturbance  was active the Northern regions of the sub continent.

Bay branch needs to wait a few days for the the pulses from the East in the Bay to resume for Low formations. 

SWM should hit South Andaman Sea around 17th.May (12/15th May), and rest Andaman Islands by 20th May 2017.
Generally moves up (normally) the Bay at a sustained speed, and Kolkata should see Monsoon arrival by the 11th/12th of June.

We stop at this initial progress, and work out further region wise progress at a later date  (as is the usual practise in Vagaries' MWs).

These Dates are worked out and estimated as per my personal calculations and may not be used for commercial purposes.The dates are not binding on anyone and no responsibility is taken if used for any purposes.

A reader had asked me how Vagaries' Estimate compared with the actual Dates...well, here are some yearly comparisons from MW-3 of that year (Estimated in Early May of that year).

Estimated:  4th/5th June  v/s  Actual : 8th June
Goa (Southern Touch): Estimated: 10th June v/s   Actual: 10th June
Mumbai: Estimated: 14th June   Actual: 20th June.

Kerala: Estimated  3rd/4th June  v/s  Actual 5th June
Goa: Estimated 10th June  v/s Actual  8th June
Mumbai: Estimated 13th/14th June  v/s  Actual  12th June

Kerala: Estimated  31st May  v/s   6th June  Actual
Goa: Estimated 5th June  v/s   11th June  Actual
Mumbai: Estimated  9th June  v/s  15th June  Actual

Kerala: Estimated 3rd June  v/s Actual 1st June
Goa: Estimated  8th June  v/s Actual 3rd June
Mumbai: Estimated  12th June  v/s Actual 8th June.


Unknown said...


Srikanth said...

Sir if you remember during your first two Monsoon Posts I was mentioning about the possibility of a slow onset. There could be a possibility of a Arabian Sea disturbance under the influence of MJO around 3rd / 4th week of May which could possibly play spoilsport as well in my opinion. What is your take on the possibility of an Arabian Sea disturbance evolving under MJO & monsoon surge Sir

NilaY Wankawala said...

As always great sir. It's indeed a commendable job to provide estimated dates of arrival at this juncture based on parameters prevailing as of now. Rajesh sir has been doing since years.

Vijith Menon said...

Great detailed info sir
What's EL Nino affect as now models say it may decline?

Cumulus arjun said...

So, this year, Monsoon will reach Mumbai on 12-14 June.

NilaY Wankawala said...

Credit Econmic Times

India facing higher monsoon rains than forecast: Weather office chief

By Reuters | Updated: May 09, 2017, 10.22 PM IST

NEW DELHI: India looks likely to receive higher monsoon rainfall than previously forecast as concern over the El Nino weather condition has eased, the chief of the weather office said on Tuesday, raising prospects of higher farm and economic growth. 

The state-run India Meteorological Department on April 18 forecast this year's monsoon rains at 96 percent of the 50-year average of 89 cm. 

"Things have changed for the good since then," said K.J. Ramesh, director general of the state-run India Meteorological Department, told Reuters in an interview. 

The monsoon delivers about 70 percent of India's annual rainfall, critical for growing crops such as rice, cane, corn, cotton and soybeans because nearly half of the country's farmland lacks irrigation. 

"We assessed 96 percent based on theclimatological conditions up to March. Now, conditions are becoming favourable for an improvement over our April 18 estimate," Ramesh said. 

Australia's Bureau of Meteorology recently said there were signs of concerns easing over El Nino. 

El Niño, a warming of ocean surface temperatures in the eastern and central Pacific that typically occurs every few years and was linked to crop damage, fires and flash floods, faded in 2016. 

The establishment phase of the monsoon north of the equator has already started, and the Indian Ocean Dipole phenomenon - which counters the impact of an El Nino - will have an incremental positive effect on the Indian monsoon, Ramesh said. 

Pre-monsoon showers have already hit certain dry areas in the southern part of the country, he said, bringing much needed relief to farmers ahead of the start of the four-month monsoon season beginning June. 

India defines average, or normal, rainfall as between 96 percent and 104 percent of the 50-year average. 

Jettisoning a statistical method introduced under British colonial rule in the 1920s, theIndia Meteorology Department has for the first time relied on the so-called dynamic model to improve the accuracy of one of the world's most vital weather forecasts. 

The new system, based on a U.S. model tweaked for India, requires large computing power to generate three-dimensional models to help predict how the monsoon is likely to develop. 

Experts say better forecasting could help India raise its farm output by nearly 15 percent, by helping farmers tweak the best time to sow, irrigate or apply fertiliser and if rains fail, plan state-wide measures. 

This would be a major boon for a country already either the world's biggest or second-biggest producer and consumer of rice, wheat, sugar and cotton. 

Higher farm output will raise the income of some 600 million people, who depend on farming for their livelihood, and boost demand for an array of goods and services.

Cumulus arjun said...

Now IMD is forecasting that there will be higher rainfall than the previous forecast in April because of easing of El Niño. Good news for Indian farmers. IMD is also predicting above average rainfall.

Cumulus arjun said...

IMD is now predicting 100% of the LPA (long period average) of rains this year. Earlier IMD predicted 96% of the LPA.

Abizer kachwala said...

Wow...,but surprised to see IMD changimg statements by getting influenced by International weather forecasting agencies

NilaY Wankawala said...

@ abizer kachwala- I guess it's parameter el nino that has made them changed their statement, the probability of which has been reduced as compared to what it was on April 18 when they issued 1st L R F SWM 2017.

Rajesh said...

Nilay: We should bear in mind that El Nino or La Nina is one of the parameters in gauging the rain quantum...it is not the ONLY parameter. There are 6/7 others.How will one parameter change the forecast ?

Dattaraj said...

Nice write-up and forecast sir. IMD is saying monsoon likely to advance in SE of Nicobar sea by 15-May. Fingers crossed.

Thanks for considering my request of putting comparison between vagaries forecast v/s actual.

NilaY Wankawala said...

Noticed lightening Eastern skies borivali arrd 7 45. Noted 3 of them. Vagaries rocks.

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