Hitting the Bullseye - SW Monsoon Rainfall: 94% of LPA: Our forecast 94%!
July 3rd
2012: Revised Forecast
Monsoon Forecast: Give the Met Dept a break. They are
still on target and so are we!
Forecast
94.5 of LPA (91-98% LPA) Confidence Level 95%
Our
revised rainfall forecast of 94.5% of Long Period Average (LPA) or 91-98% of
LPA range was made at a time when rainfall deficiency in the country was over
32% and the Indian Meteorological Department
(IMD) was being castigated for their revised forecast of 96% of LPA.
Apart from being published in our blog, it was re-published in the financial
magazine, Moneylife. Read here At the time we made
the forecast, because of media going overboard with their drought hysteria, not
many took our forecast seriously.
While
we kept this revised forecast unchanged thereafter, the IMD presumably caving
to pressure of a very bad press and politicians, revised their forecast downwards
to first 90% of LPA by beginning of August and within a week, revised it even lower
to 85% of LPA. Nearly all major global models forecasted even earlier a
deficient monsoon viz below 90% to 80% range.
With
rainfall at 94% as of date and expected to end the season within the 96-98% of
LPA range, this makes ours among those published their forecasts, the only one who
hit the bulls eye.
April 10th,
2012: Early Forecast
Normal Monsoon Forecast: Indian Ocean Dipole (IOD), the
Wild Card
Forecast 100%
of LPA (96-104% LPA) Confidence Level 70%
There
were practically no difference in outlook between our April early forecast and
our revised July forecast in terms of how we saw critical climatic events
influencing the monsoon expected to pan out except in relation to the
assumption how an El Niño would pan out.
In
early April when we made our early forecast, it was not certain whether an El Niño
event will occur this year. By July, El Niño threshold values were observed in
the Central Equatorial Pacific Ocean. We
however treated the El Niño
would have no impact on the Indian Monsoon and if at all it does, September,
the last month of monsoon would be hit somewhat.
This
El Niño outlook we shared with only those of the IMD but differed with most
global models that forecasted drought in the country because of the El Niño
impact. Our confidence in ruling out the El Niño impact was on account of two
major assumptions that was validated:
a. The
Central Equatorial Pacific Ocean had
experienced a back-to-back La Niña
during 2010-2011 and 2011-12. Logically two years of cooling should result in the
Central Equatorial Pacific Ocean accumulating little heat during this
period and at the most we should have a very weak El Niño if any
b. Even
if there is a strong El Nino, as seen in
the above graph, there is a lot of cold water circulating from Alaska down the
west coast of Canada, the US and Mexico. This cold water is mixing with
equatorial Pacific waters and keeping SSTs in equatorial Pacific down. That
ruled out a strong El Niño event emerging this season.
Though
there are several factors that condition the Indian Monsoon, our hypothesis was
that in each monsoon, one climatic factor emerges as the main driver of the
monsoon for each season. This could be the El Niño in one season, the La Niña
in other season or the Indian Ocean Dipole (IOD) etc.
In
our April early forecast, we identified the IOD as the wild card. Even in our
revised first week July forecast, when most models were assuming the El Niño as
the wild card, we continued to consider the IOD as this season’s wild card. The
Japan Meteorological Agency (JMA) forecasted a negative IOD which was
detrimental to rainfall while the IMD forecasted a neutral IOD. We had in
contrast forecasted a positive IOD which in addition to be favourable for
rainfall can also swamp the effects of an El Niño.
This
El Niño outlook we shared with only those of the IMD but differed with most
global models that forecasted drought in the country because of the El Niño
impact. Our confidence in ruling out the El Niño impact was on account of two
major assumptions that was valid
Though
there are several factors that condition the Indian Monsoon, our hypothesis was
that in each monsoon, one climatic factor emerges as the main driver of the
monsoon for each season. This could be the El Niño in one season, the La Niña
in other season or the Indian Ocean Dipole (IOD) etc.
In
our April early forecast, we identified the IOD as the wild card. Even in our
revised first week July forecast, when most models were assuming the El Niño as
the wild card, we continued to consider the IOD as this season’s wild card. The
Japan Meteorological Agency (JMA) forecasted a negative IOD which was
detrimental to rainfall while the IMD forecasted a neutral IOD. We had in
contrast forecasted a positive IOD which in addition to be favourable for
rainfall can also swamp the effects of an El Niño.
For
the whole of June-July, the IOD demonstrated neutral values with a negative
bias which saw rainfall being affected in the country. But by beginning of
August, it switched to its strongly positive mode that saw very heavy rainfall
all over the country.
We
had also assumed once the main driver of the season’s monsoon falls into place,
all other elements follow. Such a hypothesis is not backed up by any scientific
literature but that is exactly what apparently happened this season. Once the
IOD turned strongly positive, other key elements like the Madden Julian
Oscillation (MJO) and the North Atlantic Oscillation (NAO) turned
positive, whether coincidence or not. Their combined effect saw the western
trough of the monsoon which was weak during June-July strengthen from August beginning
onwards one-hand and increased and stronger western disturbance (westerlies) on
the other-hand that together brought rainfall to the heavily parched
north-western regions of our country.
This
had been the first monsoon forecast. We undertook for basically two reasons.
The first could be traced to yielding to the temptation of monsoon forecasting,
considered one of the most challenging of climatic events. For years I
religiously followed the forecasts of my friends within the independent
community of weather, particularly Rajesh Kapadia’s blog - Vagaries of the Weather, where I picked up some of the
fundamentals to weather forecasting. Rajesh is not only a good teacher but
possibly one of the best weathermen in the country today. Then there are others
like young Akash Deoras and his blog Metd Weather and Ashok
Patil and his blog Gujarat weather.com whose
blogs and inter-actions with helped be pick up the fundamentals of forecasting.
Secondly,
I had been a harsh critic of NGO climate smart agriculture (CSA) programmes.
The monsoon is the single most significant element of climate with respect to
agriculture. And yet, none of these NGOs whether Oxfam; ActionAid; Gene
Campaign etc do not even come out with their own monsoon forecasts. When NGOs
are not able to even able to forecast the Indian Monsoon, their claims to CSA remain
thoroughly bogus. As a member of the NGO fraternity, by publishing my monsoon
forecasts I was actually throwing down a gauntlet at them to publicly prove
their climate smartness claim by their publishing monsoon forecasts.
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