41% more rainfall during between October 1-21: Weather office
New Delhi, Oct 22: India received 41 per cent more rainfall than normal during October 1-21 with Uttarakhand alone recording more than five times its normal precipitation, India Meteorological Department (IMD) data showed on Thursday.
Providing a numerical perspective to the unusually heavy rains ravaging several parts of the country, particularly the hill state of Uttarakhand in the north and coastal Kerala in the south, the IMD said the country received 84.8 mm against the normal 60.2 mm this month, PTI reported.
Of the 694 districts in the country, 45 per cent (311 districts in 16 states and union territories) recorded rainfall in "large excess" and 14 per cent (96 districts in six states and UTs).
Uttarakhand, where rains have claimed the lives of more than 54 people, recorded 192.6 mm against the usual 35.3 mm during October 1-20. The monsoon has wrought huge damage in the state, triggering floods and landslides that have blocked highways and smaller, key roads. Figures for the state were available till Wednesday, October 20.
Kerala received 445.1 mm of rainfall until October 20 as against the usual 303.4 mm. More than 40 people have been killed in Kerala, where videos of a house being swallowed by a swollen stream and landslides give a sense of how brutal the lashing was.
Heavy rains have also hit Sikkim, sub-Himalayan West Bengal and Uttar Pradesh, displacing people and damaging property.
Experts attribute the extreme weather events to various causes, including warming of the seas, unabated development and delayed withdrawal of the monsoon.
Balaji Narsimhan, professor at the Civil Engineering department, IIT-Madras, said it was undoubtedly an "unusual October" and pointed to "infrastructural challenges and unabated development".
"Many of these extreme weather events have taken place earlier. But now places are more densely populated which amplifies the impact," Mr Narasimhan, who also studied the 2015 Chennai floods, told PTI.
In December 2015, Chennai received its highest rain in 100 years in which more than 250 people were killed.
Discussing the situation in Kerala, Mr Narsimhan said the state gets bountiful rainfall both during the Southwest monsoon and the Northeast monsoon but this year has been different.
Explaining the heavy rainfall, IMD Director General Mrutunjay Mohapatra said October saw the formation of two low pressure areas (cyclonic circulations that bring in rainfall and strong winds).
In Uttarakhand, he explained, the interaction between western disturbance and the low pressure area resulted in heavy rains this week.
The
western
disturbance
over
north
India
is
a
phenomenon
typically
observed
in
non-monsoon
seasons.
"The
interaction
of
cold
winds
of
western
disturbance
and
the
warm
winds
of
the
low
pressure
area
bring
in
thunderstorms
and
heavy
rainfall,"
Mr
Mohapatra
said,
adding
that
such
interaction
had
taken
place
during
the
deadly
deluge
in
Uttarakhand
in
2013
in
which
hundreds
of
people
were
killed.
M Rajeevan, former Ministry of Earth Sciences secretary who has been studying the Southwest monsoon for more than three decades, said there is a delayed withdrawal of the monsoon.
Since the retreat has been late over the last few years, the IMD in 2020 had revised the withdrawal date from northwest India.
This year, the withdrawal of the Southwest monsoon from northwest India commenced on October 6, the second-most delayed withdrawal since 1975. In 2019, it had started on October 9.
The IMD said its complete withdrawal from the country is expected around October 26.
"More
importantly,
the
active
conditions
of
Southwest
monsoon
which
began
in
September
have
still
not
ended.
Usually,
such
an
active
phase
does
not
last
for
a
month,
but
this
time
it
has,"
Mr
Rajeevan
said.
Warming
of
seas
around
India
is
another
factor,
Mr
Rajeevan
pointed
out.
He said the warming of the Bay of Bengal and Arabian Sea helps in forming a cyclonic circulation. This year, it is aided by La Nina conditions - the phenomenon is associated with the cooling of the Pacific waters and usually results in good rainfall activity - and some remnants of cyclonic circulation from the Pacific Ocean.
Once
these
remnants
enter
the
Bay
of
Bengal,
the
warm
water
aids
in
formation
of
cyclonic
circulations.
In
a
paper
published
earlier
this
year,
Mr
Rajeevan
along
with
other
meteorologists,
said
from
1970
to
2019,
7,063
extreme
weather
events
killed
1,41,308
people
in
the
country.
(PTI)