The waxing and waning phase of rains is an inbuilt characteristic of the Monsoon season. This has been observed during the month of July this time.
The first 10 days of July have been poor with the daily deficiency being between -10 and -20%. The deficiency of July coupled with rolled over deficiency of 5% in June, mounted to a -10% Pan India deficiency on July 10.
Thereafter, a week of extended wet spell resulted in heavy rains and flood like situation over some parts of the country which caused the deficiency to improve at -2% on July 17.
The month of July and August are core monsoon months with an average of 289 mm and 261 mm respectively.
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The month of August contributes 30% of total season’s rainfall. Skymet’s Monsoon forecast which was issued in April specified that the month of August will be the most deficient of the season. Numerical models also suggest that August will commence on a dry note and will be prolonged up to the first two weeks of the month.
The first week of August will see scanty rains over most parts of the country especially West Coast, Central and Northeast India.
The second week will also see poor rains over North West India, West, South and Central India along with the Northeastern region of the country.
There are several reasons attributed to these upcoming deficient rains:
Firstly, unlike the month of July where a series of Monsoon systems in the form of cyclonic circulation and low-pressure area were seen, August will see fewer such systems.
Secondly, a break in Monsoon is generally seen during the month of August and conditions are conducive for such a break which could last for a week to 10 days. In this case, rains usually get limited to some parts which result in deficiency across the country.
There are some other Monsoon drivers like MJO and IOD. However, both are not in a favourable position to enhance Monsoon rains.
MJO will not visit during the first half of the month and IOD will remain neutral. Therefore, rains will remain light.
On the El Nino front, equatorial sea surface temperatures are near to above average across most of Pacific Ocean.
Chances of El Nino increasing to about 65% during fall and about 70% during winter are quite likely.
To simply put this, Nino indices are on the rise which are not considered favourable for enhancing Monsoon rains in India.
Image Credit: ndtv
Please Note: Any information picked from here must be attributed to skymetweather.com
