Press Release

New Delhi, 30 June 2006

 

INDIA METEOROLOGICAL DEPARTMENT

 

Long Range Forecast Update

For 2006 South-West Monsoon Season Rainfall

 

1.                  Background

 

On 24th April, IMD issued the first stage forecasts for the 2006 Southwest monsoon season rainfall (June-September) for the country as a whole.  These forecasts were as follows:

 

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%.

 

2.                  Second Stage Forecasts

 

The following forecasts are being released now:

 

a)      Quantitative forecast update for the South-west Monsoon Season rainfall for the country as a whole using the 10-Parameter model.

 

b)      Quantitative forecast for the July rainfall for the country as a whole using a 5-parameter Multiple Regression Model with the model error ± 9%.

 

c)      Quantitative forecasts for the South-west Monsoon Season(June-September) rainfall for the following  four broad homogenous regions of India:

 

Northwest India – Jammu and Kashmir, Himachal Pradesh, Punjab, Rajasthan, Haryana, Chandigarh, Delhi, Uttaranchal and Uttar Pradesh.

 

Central India            – Gujarat State, Madhya Pradesh, Chattisgarh, Maharashtra, Goa and Orissa.

 

South Peninsula – Andhra Pradesh, Karnataka, Tamil Nadu, Kerala, Lakshadweep and Andaman and Nicobar Islands.

 

Northeast India – Arunachal Pradesh, Meghalaya, Assam, Nagaland, Manipur, Mizoram, Tripura, Sikkim, West Bengal, Bihar and Jharkhand.

 

For this purpose, individual Multiple Regression Model for each homogenous region was developed, which has a model error of ±8%.  

 

In addition, IMD has also taken into account the experimental forecasts prepared by national Institutes like Indian Institute of Tropical Meteorology, Pune, National Centre for Medium Range Weather Forecasting, Noida,  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. They are being fine tuned and validated.

 

3.                  Onset and Advance of the Monsoon in 2006

 

Using an indigenously developed statistical model, IMD predicted that monsoon onset over Kerala would take place on 30 May with a model error of 3 days.  This year, monsoon onset over Kerala was on 26 May, six days earlier than its normal date. By 31st May, it covered parts of Konkan, Madhya Maharashtra, Karnataka, parts of Telengana, and Northeastern parts of India. By 6th June, it covered parts of Gujarat, Coastal Andhra Pradesh, Orissa, Jharkhand and Bihar. Monsoon was very active during the first week of June.

 

 There was a prolonged hiatus in advancement of monsoon for about 17 days. On 23 June, monsoon had revived and advanced further into some more parts of Gujarat Region, remaining parts of Madhya Maharashtra, entire Marathawada and some more parts of Telangana and Chhattisgarh.  On 29 June, it covered some more parts of Gujarat; remaining parts of Vidarbha, Chhattisgarh and East Uttar Pradesh, some parts of West Uttar Pradesh, many parts of Madhya Pradesh, Uttaranchal and Himachal Pradesh and most parts of Jammu & Kashmir. On 30 June, Southwest monsoon has further advanced into remaining parts of Gujarat and Madhya Pradesh, some more parts of West Uttar Pradesh, remaining parts of Himachal Pradesh and Jammu & Kashmir and some parts of Punjab and Haryana (including Chandigarh). Northern Limit of Monsoon passes through 24șN/64șE, 24șN/68șE, Udaipur, Gwalior, Barielly, Dehradun, Ambala and Amritsar.

 

Since the onset of southwest monsoon over Kerala, the realized rainfall over the country as a whole till 28th June was deficient by 8%.

 

 

 

 

4.         El Nino Conditions

 

During the beginning of 2006, Sea surface temperatures were colder than normal over the equatorial Pacific Ocean. However, since March 2006, the equatorial central Pacific Ocean has slightly warmed up. Latest observations suggest Sea Surface Temperatures over the central Pacific are above normal but below the El Nino thresholds. Most of the statistical and coupled models predict ENSO-neutral conditions in the tropical Pacific through the monsoon season. However, the spread of these forecasts indicates considerable uncertainty in the outlook.  IMD is carefully monitoring the developments.

 

5.      Forecast Updates for 2006  

 

(i)         South-West Monsoon Season Rainfall

 

IMD’s Long Range Forecast update for the 2006 South-West Monsoon Season (June-September) is that for the country as a whole the seasonal rainfall is likely to be 92% of the Long Period Average (LPA) with a model error of ± 4%.

 

ii)         July rainfall

 

 Rainfall in the month of July 2006 for the country as a whole is likely to be 97% of its LPA with a model error of ± 9 %.

 

iii)            Rainfall over homogenous regions

 

            Forecasts for the 2006 South-West Monsoon Season rainfall over the four broad homogenous regions are as given below:

 

Northwest India: 91% of LPA ± 8 %.

 

Central India:             90% of LPA ± 8 %.

 

South Peninsula:            97% of LPA ± 8 %.

 

Northeast India:  94% of LPA ± 8 %.

 

-------------------------------