Why have monsoons been fierce so far?

June 16, 2018 09:31 pm | Updated 09:57 pm IST

 A man walks on the beach as lightning lights up the night sky in Mumbai. File

A man walks on the beach as lightning lights up the night sky in Mumbai. File

 

What is the status?

In the fortnight since the start of the monsoon, India has recorded nearly 55 mm of rain, or 16% more than what’s usual for this time of the year. The bulk of it has been over south and central India, with the northeastern States so far registering a 24% deficit. After an early onset and quick advance, the monsoon has stalled and will remain so for at least a week, say meteorologists. However, several parts of northeastern India are expected to receive substantial rain, according to the latest weather outlook from the India Meteorological Department (IMD). Because the southern branch of the monsoon has stalled, it is causing heavy rain in Goa, coastal Karnataka and Kerala. The latter has seen 44 cm, nearly 49% more than what it gets in the first fortnight of June. This has led to widespread havoc.

Has lightning activity been high?

Lightning, according to the National Crime Records Bureau (NCRB), is the leading cause of accidental deaths in India attributable to the forces of nature. The NCRB’s most updated report, from 2015, says that of the 10,510 accidental deaths attributable to natural causes, 25.1% were due to lightning, 18.2% due to heat/sun stroke and 10.9% due to exposure to cold. Therefore, in any given year lightning is a serious killer. This year, however, May — which is not a monsoon month — saw nearly 300 deaths due to lightning in Uttar Pradesh, Bihar, Jharkhand and West Bengal. Because of unusual convective activity, Andhra Pradesh in April recorded nearly 36,000 lightning strikes in a single day. Typically that is what the State suffers in an entire pre-monsoon month. Therefore, even pre-monsoon rain can contribute to massive cloudbuildups and trigger widespread lightning strikes. Despite all that lightning, no more than 10 deaths were reported. Thus, there is no one-to-one link between the strength of the monsoon in one year and lightning deaths. Given that 2,000-2,500 deaths occurring due to lightning annually is ‘normal,’ (going by the NCRB figures that go back to 2005), and there is a delay in how quickly lightning death records are made publicly available, it is yet early to understand if this year has seen an unusual spike.

Can lightning forecasts be improved?

Lightning and thunderstorms are an extremely ‘local’ phenomenon with impact spreading no more than a few kilometres. Also they tend to occur rather suddenly and are therefore beyond the range of the weather radars. It is possible for the meteorological department to warn of the likelihood of thunderstorms and lightning over a district or a city about a day in advance but street-level or area-wise accuracy remains a stretch. While the build-up of clouds is known to be a factor, much more improved weather modelling is required to give accurate warnings about an impending strike in, say, a small town or village. The best way around this is precaution. State- and district-level disaster management agencies routinely issue advisories asking people to refrain from using mobile phones or handling electrical equipment plugged to sockets. That lightning strikes disproportionately affect the poor is also a fact noted by experts. So poorly built houses, staying out in the open during thunderstorms, being in places that aren’t properly electrically insulated, and the mere fact of working in open fields substantially increase the risk of death from lightning.

What’s in store?

The IMD said in May that India would get 97% of the 89 cm it gets during the monsoon months. Rainfall is expected to be normal in July at 101% of the historical average and 94% in August. However, this does not quite capture the extreme variability of the monsoon. Like most years, some parts of the country are going to see dangerous floods and some regions a crippling drought. Though the monsoon has stalled for a while, experts have said that because there is no threat from major climate factors — like an El Nino — there are no large-scale deficiencies expected. So far, the monsoon has advanced into parts of Odisha and the Gangetic West Bengal, parts of northwest Bay of Bengal, all of Arunachal Pradesh and most parts of Assam, Meghalaya and Sikkim.

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