The weak monsoon season in August pushes rainfall across India to 10% below normal
A prolonged period of weak monsoon seen throughout August this year pushed rainfall across India to 10 percent below normal as on Wednesday.
Over the four monsoon months, July and August account for nearly 70 percent of the country’s seasonal rainfall. This year, July rains across India ended with a 1% rainfall deficit and it looks like August, too, will follow with an even larger deficit margin. Like Wednesday, it stood at -10 percent.
There is no immediate recovery likely, as the Indian Meteorological Department (IMD) said on Wednesday that moderate rainfall would continue over the center, northwest and along parts of the west coast of the country until August 30.
IMD officials pointed out that an extended period of moderate rainfall was due to the weak monsoon season this month. Favorable weather systems – either in the form of a low formed in the Bay of Bengal or a trough off the coast of the Arabian Sea along the west coast – were largely absent.
Normally these two elements contribute to monsoon currents and cause rainfall over the central monsoon area covering Gujarat, Maharashtra, Madhya Pradesh, Chhattisgarh, Jharkhand and Odisha. The two-depression systems, formed earlier this month, weren’t strong enough.
Until July 31, the country had recorded 449 mm and over the next 25 days to Wednesday, the amount of precipitation added to that total was only 154.1 mm. In July, precipitation over 12 states or union territories was “deficient” compared to 14 states or UTs this month. Last month, 18 states or UTs ended up receiving “normal” precipitation while 21 fell into this category in August.
With prolonged dry conditions now lasting more than three weeks, the Standardized Precipitation Index (SPI) values increase negatively, indicating an increase in drought during the monsoon season. SPI is a value assigned to measure drought in a locality based solely on rainfall and is used to predict possible droughts.
Gujarat, Odisha, Jharkhand, western and eastern Madhya Pradesh, Nagaland, Manipur and northern Maharashtra are experiencing extremely dry conditions with SPI values of around -1.99, according to IMD data (until August 18). Along with southern and central Rajasthan, Himachal Pradesh and Punjab, these large geographic areas experience mild to severe dry conditions, with SPI values ranging from – 0.99 to -1.49.
Among the states or UTs with the lowest rainfall are Manipur (- 58%), Ladakh (- 51%), Gujarat (-48%), Chandigarh (- 38%), Lakshadweep (-35%), Odisha (-31 percent), Jammu and Kashmir (-29 percent), Kerala and Mizoram (-28 percent each), Nagaland (-25 percent), Arunachal Pradesh (-24 percent), Punjab (- 21 percent), Himachal Pradesh and Assam (-20 percent each).
Until the end of this month, precipitation is expected to remain largely concentrated over the eastern and northeastern regions of India.
“With the probable formation of a low pressure system in the Bay of Bengal on Thursday, strong southerly and southeasterly winds are likely to prevail. This will bring precipitation to sub-Himalayan West Bengal, Sikkim and the northeastern region. until Saturday, ”the IMD forecast said.