PRESS RELEASE
New Delhi, 24 April 2006
INDIA
METEOROLOGICAL DEPARTMENT
Long
Range Forecast for 2006
South-West
Monsoon Season (June-September)
Rainfall
1. Operational Models
The India Meteorological Department (IMD)
has been issuing operational long range forecasts of the south-west monsoon rainfall for a
number of years using statistical methods. In 2003, IMD adopted a two stage
long range forecast strategy. In the first stage, forecasts for the south-west
monsoon season (June-September) rainfall for the country as a whole is issued
in April using the 8-Parameter Power regression and Probabilistic models. In
the second stage, update forecast for the seasonal rainfall over the country
as a whole is issued by the first week of July using the 10-Parameter Power
Regression and Probabilistic models. In the second stage, separate forecasts
for the July rainfall over the country as a whole and for south-west monsoon
seasonal (June-September) rainfall over 4 broad homogeneous regions of India
(NW India, NE India, Central India and south Peninsula) are also issued.
IMD's Long range Forecast for the 2005 south-west
monsoon season over the country as a whole based on these models was
in agreement with the actual value.
In addition, IMD has also taken into account the experimental forecasts
prepared by national Institutes like Indian Institute of Tropical
Meteorology, Pune, Indian Institute of Science, Bangalore, Space
Applications Centre, Ahmedabad and Centre for Mathematical Modelling
and Computer Simulation (CMMACS) Bangalore and operational/experimental
forecasts prepared by international institutes like National Centers for
Environmental Prediction, USA, International Institute for Climate and
Society, USA, UK Meteorological Office, European Center for Medium Range
Weather Forecasts and Experimental Climate Prediction Center, USA.
As a part of IMD's consistent efforts to improve the long range
forecast capabilities, new statistical models and a dynamical prediction
system have been developed and being validated.
IMD is now ready with the first stage forecasts for the 2006 south-west
monsoon rainfall over the country as a whole.
2. Near Neutral conditions over the Equatorial Pacific
The weak El Nino conditions that prevailed in 2004 abruptly ended in
the first half of 2005. Sea surface temperatures were close to normal
over the equatorial Pacific region during the second half of 2005,
which became colder during the beginning of 2006. However, during the
past two months, equatorial Pacific region has warmed up again to return
to near neutral conditions. A majority of the statistical and coupled
model forecasts indicate higher probability (around 65%) for near neutral
conditions to prevail over the equatorial Pacific during the monsoon season.
3. Operational Forecasts for 2006 South-West Monsoon Season Rainfall
over the country as a whole
IMD's operational Long Range Forecast for the 2006 South-west
Monsoon season (June-September) is that the rainfall for the
country as a whole is likely to be 93% of the Long Period Average
(LPA) with a model error of ± 5 %.
Estimates also suggest that the probability for the 2006 South-west
monsoon season rainfall over the country as a whole to be deficient
(below 90% of LPA) is only 22%.
IMD will issue update for the above forecasts by the first week of
July, which will also include forecast for the July rainfall over
the country as a whole and seasonal (June-September) rainfall over
the four broad homogeneous regions of India.
--------------------