Monsoon and Lightning

What is the issue?

In recent period, certain states of India witnessed a worrying number of lightning related deaths.
It is essential in this backdrop to understand the association between lightning and monsoon, if any.

How has rainfall distribution been?

What is IMD's prediction?

After an early onset and quick advance, the monsoon has stalled and will remain so for at least a week.
However, several parts of north-eastern India are expected to receive substantial rain.
Because the southern branch of the monsoon has stalled.
It is causing heavy rain in Goa, coastal Karnataka and Kerala.
These have seen 44 cm, nearly 49% more than what it gets in the first fortnight of June.
This has led to widespread havoc.

How has lightning activity been?

This year saw nearly 300 deaths due to lightning in UP, Bihar, Jharkhand and WB.
This was however in May which is not a monsoon month.
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.
Despite all that lightning, no more than 10 deaths were reported.
Therefore, even pre-monsoon rain can contribute to massive cloud buildups and trigger widespread lightning strikes.
Thus, there is no one-to-one link between the strength of the monsoon in one year and lightning deaths.
2,000-2,500 deaths occurring due to lightning annually is ‘normal,’ as per the NCRB figures.
It is thus early to understand if this year has seen an unusual spike.

Why is lightning a serious concern?

Lightning is the leading cause of accidental deaths in India attributable to the forces of nature.
Nearly 25% of accidental deaths attributable to natural causes were due to lightning.
That lightning strikes disproportionately affect the poor is also a fact.
So poorly built houses, staying out in the open, being in places that aren’t properly electrically insulated, etc are some driving factors.
The mere fact of working in open fields substantially increases the risk of death from lightning.

What is the challenge in early warning?

Lightning and thunderstorms are an extremely ‘local’ phenomenon.
The impact spreads no more than a few kilometres.
Also they tend to occur rather suddenly and are therefore beyond the range of the weather radars.
However, it is possible for the meteorological department to warn of the likelihood of thunderstorms and lightning.
This can be given for a district or a city, about a day in advance.
But street-level or area-wise accuracy is a tough challenge.

What could be done?

Build-up of clouds is known to be a factor which can help predicting.
However, much more improved weather modelling is required to give accurate warnings.
State- and district-level disaster management agencies routinely issue advisories.
It includes asking people to refrain from using mobile phones or handling electrical equipment plugged to sockets.

Source: The Hindu