We are seeing possible early
signals of an emerging El Niño. Large swathes of land within the country are
already facing drought like conditions. Meanwhile in Peru, scientists are
perplexed over the mystery death of over 3,000 dolphins. What causes marine
mammals to die en masse? The US climatic agency, NOAA notes a number of
possible causes, including infectious disease, parasite infestation, starvation
(associated with El Niño events), pollution, injuries and algal blooms that
release bio-toxins. The El Niño remains their primary suspect.
Asked whether he was
worried about the El Niño playing spoil sport with the Monsoon, the India
Meteorological Department (IMD) Director General LS Rathore told the media
that:
"Yes there are chances
of El Nino phenomenon emerging in the Pacific which may not favour rains in the
month of August-September. But overall monsoon is likely to be normal. El Niño
is just one of the parameters being considered while forecasting".
As if news on the El Niño
front is bad enough, those of the Indian Ocean Dipole (IOD) is no better. The POAMA
IOD forecast indicates a negative IOD right through Jun-Sept, with the period Jun-Jul
it being expected to be relatively stronger. As in the case with the El Niño,
the saving grace is that it is likely to be a weak event. However, when this POAMA IOD forecast is
juxtaposed with their El Niño forecast, this could result in a below average
monsoon rainfall this season, if these models are right.
Besides seasonal rains
should break in less than a month over the south-west coast, but they need a
temperature/pressure gradient to propel into the north of the country.
Sustained heating of the north-west and lower pressure over land provides just
that, but the process has been delayed for almost a month now.
And this happens to be the other
major problem that goes against the expectation of a normal monsoon season.
Weather models had indicated a small window for heating to begin this week, but
an incoming western disturbance appears to have closed it somewhat. Rain
inducing western disturbances (WD) is passing low-pressure waves which set up
thunderstorms, thunder squalls, dust storms, rain, thundershowers and even
hail. All these serve only to put a cap on the heating process, which normally
sets up heat waves to severe heat waves over north-west, central, east and east-central
India.
Asked how serious this problem
is, the IMD chief said the comparatively lower temperature in April will not
have any impact on monsoon:
"Heat low has started
little late. But it's intensifying fast which is a good signal. Heating of the
land mass has started in Maharashtra, which will generate a low pressure area. The
heat low pressure is now migrating to North Rajasthan which is a good sign.
This will result into building up of North-South pressure gradient along west coast
of the country."
“Farmers will be able to
sow crops on time in June-July, which means field crops will be at the maturity
stage by the time El Nino makes its impact felt," said Jai Shankar
Mishra, an agri-scientist.
So is the IMD’s optimism of
a “normal” monsoon warranted? They (and so is this blog which predicted a normal” monsoon”) maybe on the way to be
proved wrong. The IMD has an awful track record but much better than the UK’s Met
Office. This hardly helps in retaining a modicum of confidence in their forecast.
But the success rates of dynamic
models of international climatic agencies is not anything much to write home about, though
the Japan Agency for Marine-Earth Science and Technology (Jamstec) has a fairly
decent track record of predicting the monsoon in recent years. Jamstec
predicted that North-West India, parts of Central India and East-Central India
will have below normal monsoon rains between June to August this year, a period
during which the bulk of the country’s rice production grows. According to them
“an unexpected developing” Indian
Ocean Dipole (IOD) is the reason for the forecast for a monsoon rain deficit.
The IOD replicates the El Niño-La Niña phenomenon but on a smaller scale, and
is likely to reduce rains at the monsoon this year. But models like POAMA otherwise
indicate the El Niño as the primary danger to the monsoon this season.
Amidst these conflicting
forecasts, it is best to keep on tracking the Monsoon. Like they say, the
weather has the ability to surprise you when you least expect it. This gives almost every model an even predictive
probability of getting it right. Who knows the IMD may have the last laugh? And me to??
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