Monday, 18 May 2015

S W Monsoon 2015 outlook for Goa - as per the Weather Blog "Vagaries of Weather"

Every year beginning mid April, the well known weather blogger Mr Rajesh Kapadia publishes in his blog "Vagaries of Weather" at, a series of posts aptly named as Monsoon Watch, analysing the synoptic conditions affecting the setting in of the S W Monssons over the Indian Sub Continent.

The fourth part of the series was posted on May 17 and gives a clearer picture of the onset of the monsoons. The article can be accessed here.

The main highlights of the monsoon onset this year according to Vagaries of Weather are reproduced below:

Synoptic Situation as on May 17, 2015:
(1) South West Monsoon advances into South Andamans
(2) Season's first  low pressure area in Arabian Sea Branch formed off Kerala Coast and neighbourhood on 15th
(3) Rajasthan and Gujarat in India and Sindh and Balochistan in  Pakistan start heating up ..and reach 49c (Pakistan)
(4) Pre-monsoon convective activity increased over central and peninsular India due to presence of wind discontinuity

Based on his experience and deep understanding of the various parameters affecting the onset and quantum of the S W Monssons, as detailed by him in his blog post, Mr  Rajesh Kapadia gives his estimate for the onset of monsoons and quantum of rains up to July 2015 as under:

In his blog Mr Kapadia also mentions the 50:50 chance of full blown El NiƱo in July - August this year, resulting in possible break in monsoon and reduced precipitation in the second half of Monsoon.

For Goa the analysis presented in Vagaries of Weather would imply:

1. Onset of Monsoon by June 9, and
2. Normal quantum of rain during June and July.

For the record, while Vagaries of Weather estimates that Monsoon will reach Kerala by 3/4 June, IMD in its press release of May 14, forecasts the date of arrival of Monsoon at Kerala as May 30 +/- 4 days, ie any time from May 26 to June 3! Also the Preliminary forecast of IMD dated April 22, 2015 estimates the quantum this year as below normal (93% of LPA).

Expected Onset Dates and Actual Advance of SWM 2015 as per IMD (18-05-2015)

Being the premier meteorological body in India, one would have expected from IMD, a more precise date for onset of Monsoon over Kerala than the 8 day window! Normally Monsoon reaches Goa one week after reaching Kerala.

The weather in Goa over next week is expected to remain hot and humid, with few isolated showers accompanied by thunder in the evenings, mostly towards the interior. Monday/ Tuesday/ Wednesday the offshore trough will weaken off Goa coast, hence there will be decrease in rains. After Thursday a slight increase in thundershowers is expected.

Maximum temperatures would be restricted to 34 - 35 C, due to sea winds blowing from the west, but with heat index of 40 - 42 C due to the high humidity. This effect would be more pronounced in the coastal belt of Goa, while interior areas of Goa could get hotter as one moves away from the coast. Alternately mornings would be cooler towards the interior forest and mountain areas than the exposed coastal belt.Minimum temperatures would be around 27C. Expect lot of Sunshine with development of Cumulus Clouds over the next week.

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