Monday, June 25, 2012

Will the IMD monsoon forecast pip global models in hitting the bulls’ eye? Probably yes!

The IMD is reduced to a butt of jokes. Two years in a row, they failed to predict the monsoon.  During 2010-2011 monsoon season, they got the forecast wrong, failing to anticipate a looming La Nina. The next year, again they missed factoring in the re-emergence of a second year La Nina and ended up with mud on their faces.

Last week the IMD revised their May forecast last week.  While their forecast of a “normal” monsoon [(viz. 96-104% of Long Period Average (LPA)] remains unchanged, rainfall shortfall is now forecasted at 4% of Long Period Average (LPA), instead of an estimated 1% earlier in May. This makes their latest forecast a downgrade of their first in May this year.

The probability for a below average monsoon [viz 90-96% of LPA] increases by a whopping 9% while those of a normal monsoon decreased 5% from their May forecast.  Since the IMD model possesses a statistical model error rate of + 5%, there is now theoretically, almost an equal probability for a below-average and a normal monsoon occurring this year. 

Can they put their infamous past behind and hit a bulls-eye this year? Most probably yes!

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