Goa Monsoon 2014 Analysis - Happy Ending!

The South West Monsoon Season brings the bulk of the rains to Goa every year.

The Monsoon season lasts from June 1 to September 30th.

Monsoon season 2014 started with the scary prospect of deficient rains! There was a talk everywhere of an El Nino in August - September. And to compound the problem, arrival of the rains in Goa was delayed by 5 days. From June 1 to June 30 Goa received nearly 46% deficient rains. But it was the copious rains that Goa received in July and August which turned the tide! Check these blog posts for details of June 2014 Monsoon Analysis,  July 2014 Monsoon Analysis,  August 2014 Monsoon Analysis

In 2014 in the final analysis, from June 1 to September 30, Goa received Area Weighted Average Rainfall of 3057.2 mm (120.36 inches) against normal of 2971.7 mm (117 inches) showing a surplus of 3%! The pattern of rain during the four months is brought out in the IMD Goa prepared daily average rainfall graph in Figure 1, the Monthly Rainfall and total Rainfall graph in Figure 2 and the cumulative rainfall graph in Figure 3 below.

Figure 1

Figure 2

Figure 3

IMD Goa maintains daily records at 13 Rain Stations across Goa. It was again Valpoi at the base of the Western Ghats in the Eastern Interior Goa which retained the title of the wettest place in Goa for 2014! Valpoi received 4111.4 mm (161.87 inches) of seasonal rains. It was closely followed like last year by Sanguem, also at the base of the Western Ghats but more to the South. Sanguem received 3950.2 mm (155.52 inches) of seasonal rainfall. Margao, Canacona and Sakhali also made it to the top 5 wettest spots. See Figure 4.

Figure 4

The rains decreased from the interior towards the coast and the Port town of Mormugao with 2460.3 mm (94.74 inches) and the Airport town of Dabolim with 2337.8 mm (92.04 inches) occupied the bottom of the table. In fact these two places were the only places which did not cross the Century of Seasonal Rainfall in inches. Rest all places crossed 100 inches of rainfall.

A graphical depiction of the seasonal rainfall in Google Earth shows the variation quite well.

Figure 5

Rainfall in September 2014 was almost entirely restricted to the first half of the month.

Vagaries Goa Rain Gauge which is located at Margao brought this out well as seen in the daily rainfall readings in Figure 6.

Figure 6

The last few days of September witnessed  thunderstorms in the late afternoons associated with retreating monsoon. The thunderstorms which start in the interior from the east and proceed towards the west and the Arabian sea, brought increasing rainfall in the interior. Figure 7 shows the September 2014 rainfall pattern across Goa.

Figure 7

Margao monthly rainfall in Figure 8, is representative of the rainfall pattern this year across the state of Goa.

Figure 8

So even though the seasonal monsoon rains in 2014 were less than 2013, the fears of El Nino did not materialize and the copious rains in August were just enough to turn the deficit into a 3% surplus rainfall season for Goa!

Just for comparison Figure 9 shows the Sub-division wise average rainfall across India. Thus India as a whole showed a deficit of 12%! For a more detailed look at the performance of Monsoons in India for 2014 check this post at the weather blog www.vagaries.in.

Figure 9

Though the Monsoon season ends on September 30, the withdrawal of monsoon from Goa usually gets prolonged till mid October. And so the monsoon magic continues!

 

Likelihood of rains this week - posted Monday September 22, 2014

Goa continues to enjoy a fine mid September spell of occasional rains and plenty of sunshine as forecast in the last post !

However things may change later this week. Retreating monsoon season would see late afternoon and evening showers accompanied with thunder from Wednesday 24th onwards till around Friday 26th. This would be particularly true towards the hills in the interior of Goa. Coastal areas may experience overcast skies. As explained by the weather blogger Mr Rajesh Kapadia in his blog The Vagaries of Weather at http://www.vagaries.in  in THIS POST a Line of Wind Discontinuity (LWD) will form on 23rd from around Satara in Maharashtra to interior Karnataka, and a low will form at the same time in interior Karnataka. This low is expected to travel west and fizzle out in the Arabian Sea off the coast of North Karnataka.

Goa will be benefitting from the rains from this system!

Quoting further from the Blog Vagaries of Weather "Monsoon has withdrawn from west Rajasthan and Kutch and begin gradually withdrawing from Punjab and (rest of) Rajasthan by 23rd".

Goa has received normal rain with just 4% excess as seen in this graphic from http://imdgoa.gov.in

However overall deficiency for SWM 2014 over India remains -11%

Things are not expected to change much over rest of the monsoon season which officially ends on September 30!

Update September 15, 2014 - Monsoon Withdrawal Symptoms?

Update September 18,2014, 1800 hrs:

Break Monsoon like conditions returned on September 17 and Vagaries Goa recorded zero mm in 24 hrs ending 0830 September 18. Check here. September 19 saw heavy downpours in some parts mostly towards the interior, but largely the coastal belt remained dry. Vagaries Goa recorded zero mm during 0830 - 1800 on September 19.


Update September 16, 2014, 1800 hrs

 

As if to prove wrong the GFS forecast mentioned in the post below, most parts of Goa remained heavily overcast from September 16th morning and experienced scattered heavy downpours throughout the day. Vagaries Goa recorded 20 mm from 0830 to 1800 hrs on September 16th, and the rains continued at the time of this update. This development tied up with formation of low pressure area in westcentral Bay of Bengal and adjoining Coastal Andhra Pradesh and Associated upper air cyclonic circulation.

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Last year in 2013, September saw an almost dry period in Goa for the first 15 days, followed by one of the wettest 15 days period in September in recent years. Checkout this post on September 2013 Monsoon Revival

However this year in 2014, the last fortnight may well signal that the Monsoons are finally withdrawing.

GFS forecasts for Goa are all pointing to atleast a dry week ahead till September 21/22. The SW Arabian Sea winds are also weak with low moisture.

These Rains in First half of September have helped Valpoi cross the 150 inches mark and retain its role as the wettest place in Goa. Sanguem is however, not very far behind:

Mapusa, Mormugao and Dabolim are the only rain stations in Goa which have not crossed the Century rainfall mark in inches as of 15th September.

As of September 15, 2014 the Area Weighted Average rainfall for Goa has reached 2961.9 mm (116.6 inches) against normal of 2845 mm (112 inches), which is a surplus of +4% as on September 15!

You can check out the pattern of Rainfall in Goa from June 1 to September 15, 2014 in Google Earth and also monthwise graphically HERE

And you can check the daily rainfall pattern for my hometown Margao HERE

Are we going to end Monsoon 2014 in surplus after all? Watch this space!!

August 2014 Rainfall Analysis - Ending with a Big Bang!

Heavy to very heavy record downpour in the last 6 days of August was the highlight of the rains in August 2014 in Goa. The rains wiped out the rainfall deficiency, yielded 50 to more than 60% of the total rains for the month and created flooding in low lying areas of many towns and villages of Goa.

The deficiency which was -49% in June '14 and -17% in July '14 turned positive to +1% with Area weighted total rains from June 1 to Aug 31, 2014 measuring 2721.4 mm ( 107.14 inches) against a normal of 2691.5 mm (105.96 inches).

Seasonal rainfall at Panjim, which IMD had been giving out as Goa's rainfall, before the present system of Area weighted average started also showed a similar trend:

South Goa recorded more rainfall than North Goa in August 2014, with Sanguem receiving the highest rainfall.

In fact Goa as a whole received more rainfall in August 2014 than in August 2013, as seen the comparison for top five wet places in Goa (Rainfall figures in inches):

At the end of August 2014, Valpoi continues to remain the wettest, but for how long into September before Sanguem overtakes it will be interesting to watch! The ranking as on August 31, 2014 is as below:

 

 

Comparative figures for top 5 stations over last year are as below:

 

 

 

However this excellent performance in August was characterized by a 13 days monsoon break like period from August 12 to August 24, with extended sunshine and day's high climbing to 32-33 C, +4C above normal! This is brought out clearly in the daily rain chart for Margao:

 

 

 

But the intensely heavy rainfall which started on August 26 and continued till August 31 contributed to 50 to 60% of the month's total rainfall in just 6 days:

 

In fact Panjim received a record rainfall of 228.7 mm (9 inches) in 24 hr period ending 0830 hrs on August 30, just missing by a whisker the record for highest one day rainfall in August set on August 1, 1981 with 242 mm. However it was the highest in a decade and wreaked havoc in low lying areas of Panjim and Taleigao with flooding, mud slides and house collapses. Fortunately no loss of life was reported.

 

So we enter September on a happy note as the rainfall deficiency has been wiped out. Let's see what September has in store!

A Wet Ganesh Chaturthi 2014 - Updated August 28, 2014

Monsoon has become vigorous over Goa since last three days and will continue to remain very active with very heavy to heavy downpour over the next three days coinciding with the popular Festival of Ganesh Chaturthi from August 29 to August 30th!

A low has formed in the Bay of Bengal off the coast of North AP / Odisha around 17N and under its influence the monsoon trough has become active in the Arabian Sea off the West Coast. This low is expected to track westward over land as a strong UAC, bringing rain to most parts of India.

The IGES/COLA forecast for the next fifteen days indicates very heavy rains on the west coast till 5th September and reducing thereafter as indicated below:

The Daily rain chart for Margao Goa reflects the increase in rain since August 25th:

The weekly analysis by IMD Goa, for week ending August 27, 2014 clearly indicates the above normal rains this week, particularly in South Goa.

Over the Ganesh Chaturthi Festival Days of August 29 and 30, the days are expected to remain heavily overcast and most parts of Goa will experience 60 - 100 mm rainfall per day. The maximum temperature will remain between 25-26C and minimum will come down to 23C.

For regular updates checkout www.vagaries.in

Margao crosses Century mark and other intersting statistics for SWM 2014

On August 26, 2014 Margao became only the third Rain Station in Goa to have crossed the Century mark in inches during 2014 SWM so far! Rainfall measured 119.8 mm during 24 hrs ending 0830 hrs on Aug 26th, helping Margao reach this milestone after Valpoi and Sanguem.

While Valpoi and Sanguem are at the base of the Western Ghats, the SWM performance in Margao this year has been remarkable.

While it appeared that Margao may be reaching the century mark by mid August, the monsoon break like situation which developed after August 15 meant Margao received just 108.6 mm of rainfall during 14 days from August 12 to August 25, less than what it received in a single day on Aug 26, 2014!

However rains have performed slightly better in Margao this year in August than in 2013. As seen in the chart below, till August 26,  Margao has received 26.72" compared to only 19.18" for the whole month of August in 2013!

However by August end 2013, the total rainfall for Margao had reached 114.82". Margao will have to receive 11" in the next 5 days to surpass it this year!

The overall situation of SWM for Goa as on August 26, 2014 is as below:

While the monsoon trough on the west coast is still active, the wind strength is low. While coming days may remain overcast, rains are forecast to be isolated and only occasionally heavy!

It will take a courageous weather forecaster to predict that Margao will surpass last year's total by August end!

All India Monsoon Performance Snapshot - August 11, 2014

For once the dreaded 'D' word seems to be receding!

The performance of Monsoon in July and now continuing so far into August, has managed to bring down the National deficiency to -17%.

The All India Monsoon performance chart released by IMD for August 11, 2014 looks like this:

In fact, Odisha shows excess rainfall, thanks to BB5 and BB6. The flood situation is a real threat here!

The normal and deficient sub-divisions are almost evenly balanced.

Goa has a deficiency of -13%.

However the forecast released by Indian Institute of Tropical Meteorology, Pune, India had bad news for NW India for the remainder part of August.

Hopefully Goa will continue to receive its normal quota of August Rains!

August 2014 start promises to wipeout rainfall deficit

The start of the month of August 2014 has brought copious rains to all parts of Goa.

Aided by the activation of monsoon trough on the west coast and a deep depression BB6 travelling from Odisha westwards and now at the border of Rajasthan and M.P. the week ending August 6, 2014 saw nearly 50% excess rainfall in Goa as this chart from IMD, Goa Center indicates:

With this the seasonal rainfall deficit has come down to 15%. In IMD parlance normal rainfall is defined as +/- 19%! Thus this spell of rainfall has helped Goa reach the Normal monsoon range!

The daily Area weighted rainfall for Goa, also prepared by IMD Goa is helpful in gauging the daily variance:

The top three wettest places in Goa continue to remain:

1. Valpoi - 2722.9 mm (107.2 inches)
2. Sanguem - 2251.9 mm (88.7 inches)
3. Margao - 2159.7 mm (85.0 inches)

From Aug 1 to Aug 6 rainfall recorded at Valpoi and Margao was:

Valpoi - 411.4 mm (16.2 inches)
Margao - 201.7 mm (7.9 inches)

The trough is expected go remain active at least till Aug 8, bringing isolated heavy downpour in most parts of Goa, interspersed with bouts of cool sunshine!