These reports are the views, study and observations of Vagaries. Estimates and forecasts are also the calculation of Vagaries, and may/may not tally with any other estimates/nodels. This may not be used for commercial purposes. Vagaries of Weather is not responsible for any commercial loss from this article, or these series of articles.
The Monsoon developments, as they unfold, will be analysed , discussed and explained in Vagaries.
Vagaries follows the developments(parameters) that emerge during the summer (Apr/May) which lead to the monsoon.
Vagaries believes the expertise to predict the monsoon in it's entirety during early summer itself (early April) is not feasable. The parameters themselves develop in April and May.Quantum of rain forecasting in April for June right through September is an impossible task. Things get clearer by last week of April. Vagaries' (in MW) normally remains true to estimates around early May.
😎Otherwise the charm of chasing the monsoon parameters as they unfold during the summer , is lost.
As of 24th April, the South West Monsoon is just about 21 days away from its normal date of arrival from the shores of India ! Yes ! it's just 21 days from the First touch of shores...Southern most point of India on the South Andaman Islands, Indira Point, where the normal arrival date is 15th May.
➤Further Analysis of the parameters as discussed in MW-1...
In this initial stage, we will observe the basic root and foundation, the initial 5 parameters only, and the initial seed of the monsoon. From these parameters, later a few more develop.
1. Cross Equatorial Winds from Southern Hemisphere and Mascarene high.
2. Pre monsoon showers / LWD.
3. Seasonal low over Indian subcontinent.
Situation as on 23rd April 2020:
1. Cross Equatorial Winds and Mascarene high :
i)The cross equatorial wind flow, has deteriorated compared to MW-1 in the Western sector Southern Indian Ocean. SE Winds, now are not striking the East African Coast below the equator because of a low off the Madagascar coast . The Northward movement of the ITCZ will surely hasten and strengthen the winds.
ii) In the Eastern sector, in the Bay Branch, the Cross equatorial winds are not organised Westwards towards the Sumatra Coast. The winds hitting Sumatra coast are not Westerly (as required), and also need to gather strength soon.Thunder clouds(Cb) developments are seen near the equator in eastern Indian ocean.
And that is exactly where the start should be for the SWM to arrive at the Andamans.
We prefer the Bay Branch to be better organised, as the SW Monsoon is normally expected there in less than a month.
This is considerable deterioration compared to the high reading of 1036 mb observed during MW-1.The power house of monsoon is behind schedule as of now.
The sea surface temps in the region of Mascarene High formation are lower than normal .This should help in strengthening the High.
In 2017, Barmer had approached 46 c and recorded min temp above 30 c. April heat records had tumbled at many locations over the Indian subcontinent.
Temperatures of more than 45 c had already been recorded in many states of India . Even at Srinagar (Kashmir),Shimla (Himachal) temperatures approached around 29 c in April 2017 . Delhi AP was 44.9 c on 20th April 2017.
In 2017, Most of India was 4-7c above normal range.
Earlier than normal,the night temperatures had also crossed the 30c mark ! Barmer in Rajasthan recorded 30.4c as minimum on 15th April ,Kurnool (Andhra) saw a low of 31 c on 19th morning and Jhansi (UP) saw a low of 31.6 c on 21st morning.
Jaipur,Kota,Bundi,Alwar,Bikaner,Churu,Pilani (Rajasthan), Cuddapah(Andhra) saw lows of/above 30 c on 21st April 2017 morning.
Comparison with previous years shows the difference this year. In 2010, the first 45c touched on 10th April, and on the same day Nagpur was 44c, Delhi 42.8c. Soon on 15 th April 2010, Simla was 28.2c on 16th, Ganganagar, Akola and Hissar soared to 46c.
2015...Into the 3rd week of April , it had just topped 44.6c in Barmer on 19th April.
2016....touched 46c in Bankura on 16th April...and was constantly hot in Eastern region with almost daily ,a place touching 46c.. Bhubaneshwar and Titlagarh in India had touched 46c. Several large regions in Vidharbh, Telengana and MP were in the 44/43c range.
But, in 2011, 2012, 2013 and 2014, till date in 2020, temperatures were yet to reach 45c anywhere over the Indian Sub-Continent .
In 2018 and 2019 also , significant heat waves were not seen by this time in April.
23 April 2020- Max /Min temps in c of some cities/towns :
iv) The 30 day Southern Oscillation Index (SOI) is calculated using the pressure differences between Tahiti and Darwin.It is in neutral range currently.
(sustained values below -7 indicates El Nino and above +7 indicates La Nina)
|SOI values for|
|Average SOI for last 30 days||-3.05|
|Average SOI for last 90 days||-2.86|
|Tahiti hpa - Darwin hpa (23 Apr 2020)||1013.75 hpa - 1011.10 hpa|
Latest weekly value is -0.09.
But as the second half of summer progresses , the high over the Bay of Bengal should collapse and give way to the formation of lows over the Bay of Bengal / Andaman sea.
Now south of the equator (5S) over western Indian ocean and near the equator over the eastern Indian ocean.
Time schedule of arrival and strength/quantum is normally indicated in subsequent MW series in May.