| Long Range Forecast Update for 2007 South-West
India Meteorological Departments (IMD) Long Range
Forecast update for the 2007 South-West Monsoon Season (June-September) is that
for the country as a whole the seasonal rainfall is likely to be 93% of the Long
Period Average (LPA) with a model error of ± 4%.
Rainfall over the country as a whole in the month
of July 2007 is likely to be 95% of its LPA with a model error of ± 9 %.
over broad geographical regions
Over the four broad geographical regions
of the country, rainfall for the 2007 South-West Monsoon Season is likely to be
90% of its LPA over North-West India, 98% of its LPA over North-East India, 96%
of its LPA over Central India and 94% of its LPA over South Peninsula, all with
a model error of ± 8 %.
the new 5-parameter statistical model, on19 April, IMD issued the following forecast
for the 2007 southwest monsoon rainfall over the country as a whole.
long range forecast for the 2007 south-west monsoon season (June to September)
rainfall is that the rainfall over the country as a whole is likely to be 95%
of the long period average with a model error of ± 5%.
Now, with the availability of data up to May, IMD has prepared
the second stage forecasts, which are being released now:
for the 2007 southwest monsoon rainfall over the country as a whole using the
new 6-parameter ensemble statistical forecast system. The forecasting system has
an error of ± 4%. The Long period average of southwest monsoon rainfall
averaged over the country as a whole is 89 cm (based on the 1941-1990 data) with
a coefficient of variation of 10%.
Forecast for the rainfall over the country
as a whole in the month of July based on a 6-parameter model, which has a model
error of ± 9%. The Long period average of monsoon rainfall in the month
of July is 293 mm (based on the 1941-1990 data) with a coefficient of variation
Forecasts for the South-west Monsoon Season(June-September) rainfall
for the following four broad geographical regions of India with a model error
of ± 8%:
Northwest India Jammu and Kashmir, Himachal
Pradesh, Punjab, Rajasthan, Haryana, Chandigarh, Delhi, Uttaranchal and Uttar
Northeast India Arunachal Pradesh, Meghalaya, Assam,
Nagaland, Manipur, Mizoram, Tripura, Sikkim, West Bengal, Bihar and Jharkhand.
India Gujarat State, Madhya Pradesh, Chattisgarh, Maharashtra, Goa
South Peninsula Andhra Pradesh, Karnataka, Tamil
Nadu, Kerala, Lakshadweep and Andaman and Nicobar Islands.
The long period
average rainfall and coefficient of variation of rainfall of the 4 broad geographical
regions of India are given below:
Long period Average
of variation (%)
and Advance of Monsoon 2007
Southwest monsoon advanced over south Andaman
Sea on 11 May, almost 10 days earlier than the normal date. IMD predicted that
the monsoon onset over Kerala this year would take place on 24th May with a model
error of ±3 days. Monsoon advanced over Kerala on 28th May, 4 days earlier
than the normal date of 1st June. By 29 May, monsoon covered the entire coastal
Karnataka and some parts of south interior Karnataka and south Tamil Nadu. After
this, there was hiatus in the advancement of monsoon for about one week. The hiatus
was caused by the formation of the Super Cyclone Gonu over Arabian
Sea, and its northwestward movement towards the Arabian coast.
On 8 June,
monsoon advanced over some more parts of south interior Karnataka, Tamil Nadu,
the entire Nagaland-Manipur-Mizoram-Tripura, some parts of Assam & Meghalaya
and Arunachal Pradhesh. By 10 June, it covered most parts of Northeast India and
advanced over some parts of Bihar. Between 13 to 18 June, monsoon covered
and Goa, Andhra Pradesh, Orissa, West Bengal, most parts of Orissa and some parts
of Maharashtra, Orissa, Chattisgargh and Jharkhand. On 26 June, southwest monsoon
has further advanced into some parts of east Uttar Pradesh, remaining parts of
Uttarakhand, entire Himachal Pradesh, Jammu and Kashmir and northern parts of
west Uttar Pradesh, Haryana and Punjab. On 28 June, Southwest monsoon has further
advanced into the remaining parts of Madhya Pradesh & Uttar Pradesh, most
parts of East Rajasthan, some parts of west Rajasthan and some more parts of Haryana
(including Delhi) and Punjab. As on 28 June, the northern limit of monsoon passes
through Barmer, Jodhpur, Ajmer, Jaipur, Narnaul, Rohtak, Ludhiana and Amritsar.
The accumulated seasonal rainfall over the country as a whole during the
period 1-27 June was 107 % of long period average.
Nina Conditions over the equatorial Pacific
The warm sea surface temperature
(SST) anomalies over the east equatorial Pacific associated with the moderate
El Nino of 2006 have disappeared during February 2007. By the end of February
2007, SSTs were near average in the vicinity of the date line, and below average
over the eastern equatorial Pacific. ENSO-neutral conditions continued in the
tropical Pacific during May and June 2007. Equatorial SSTs during the last four
weeks were more than 1ºC below average in areas between 120ºW and the
South American coast, and more than 0.5oC above average in portions of the western
Pacific. For the week ending 13 June, the SST anomalies were +0.2ºC and +0.4ºC
in the Niño 3.4 and Niño 4 regions respectively.
models show ENSO-neutral conditions persisting through August 2007, while most
dynamical models indicate La Niña will develop within the next three months.
However, for the past few months the dynamical models have been predicting a stronger
and more rapid cooling than has actually occurred.
: Press Information Bureau
June 29, 2007