India Meteorological Department (IMD) issues various monthly and seasonal operational forecasts for rainfall during the Southwest Monsoon season. Operational forecasts for the Southwest Monsoon season (June – September) rainfall are issued in two stages. The first stage forecast is issued in April and the second stage forecast is issued in June.
IMD’s Ensemble Statistical Forecasting system for the April forecast uses the following 5 predictors.
2. Sea Surface Temperature (SST) Conditions in the equatorial Pacific & Indian Oceans
The El Nino conditions over equatorial Pacific Ocean that established in April, 2015 reached to strong condition in July and peaked in December, 2015. Thereafter, the El Nino conditions started weakening even though Sea Surface Temperatures over the Pacific Ocean are still above normal. The atmospheric conditions over the Pacific also reflect patterns consistent with the El Niño conditions.
Analysis of previous data suggests that monsoon season rainfall over the country as a whole was deficient or below normal (<96% of LPA) during 65% of the El Nino years. However, during 71% of the years followed by El Nino years, monsoon was normal and above (≥96 % of LPA).
The latest forecast from the Monsoon Mission Coupled Climate Model indicates that El Nino conditions to weaken to moderate to weak levels during the first half of the monsoon season and ENSO neutral conditions likely to get established thereafter.
At present, neutral Indian Ocean Dipole (IOD) conditions are prevailing over the Indian Ocean. The latest forecast from the Monsoon Mission Coupled Climate Model indicates positive IOD conditions are likely to establish during the middle of the monsoon season and weaken to neutral conditions thereafter.
As the sea surface temperature conditions over the Pacific and Indian Oceans particularly the ENSO conditions over the Pacific (El Nino or La Nina) are known to have strong influence on the Indian summer monsoon, IMD is carefully monitoring the sea surface conditions over the Pacific and the Indian oceans.
3. Experimental Coupled Dynamical Model Forecasting System (Monsoon Mission Model)
Indian Institute of Tropical Meteorology (IITM), Pune, Ministry of Earth Sciences, has been coordinating and working along with different climate research centers from India and abroad on the development of a coupled model for the forecasting of Indian summer monsoon rainfall under the Monsoon Mission project. The latest high resolution research version of the Coupled Forecasting System (CFS) originally developed by the National Centers for Environmental Prediction (NCEP), USA has been used to generate experimental forecast for the 2016 southwest Monsoon season rainfall using the February initial conditions.
The experimental forecast based on the Monsoon Mission coupled dynamical model suggests that the monsoon rainfall during the 2016 monsoon season (June to September) averaged over the country as a whole is likely to be 111% ± 5% of long period model average (LPMA).
4. Summary of the ESSO-IMD’s Operational long range Forecast for the 2016 Southwest monsoon rainfall
(a) Quantitatively, the monsoon seasonal rainfall is likely to be 106% of the Long Period Average (LPA) with a model error of ± 5%. The LPA of the seasonal rainfall over the country as a whole for the period 1951-2000 is 89 cm.
(b) The 5 category probability forecasts for the Seasonal (June to September) rainfall over the country as a whole is given below:
India Meteorological Department will issue the update forecasts in June, 2016 as a part of the second stage forecast. Along with the update forecast, separate forecasts for the monthly (July and August) rainfall over the country as a whole and seasonal (June-September) rainfall over the four geographical regions of India will also be issued.
According to Skymet Weather, Monsoon 2016 is likely to remain above than the normal at 105% (with an error margin of +/-4%) of the long period average (LPA) of 887 mm for the four-month period from June to September.
For Skymet's detailed Monsoon Forecast, click here.
The Indian Meteorological Department has issued its first long range forecast for Monsoon 2016 at 106 percent LPA.
IMD forecasts above normal #Monsoon2016 at 106% LPA
— SkymetWeather (@SkymetWeather) April 12, 2016
As per the weather agency, El Nino is likely to reach neutral levels.
Monsoon 2016: IMD says 'El Nino to reach to neutral levels.' pic.twitter.com/QMaoSHJLL7 — SkymetWeather (@SkymetWeather) April 12, 2016
Monsoon 2016: IMD says 'above normal monsoon with a deficient of - 1% Rainfall.'
— SkymetWeather (@SkymetWeather) April 12, 2016
Good rains in Maharashtra and Central India
#Monsoon2016: IMD says 'Maharashtra and Central India to get good rainfall.' — SkymetWeather (@SkymetWeather) April 12, 2016
Government to be informed some time in April
#Monsoon2016: IMD says 'Will inform the govt sometime in April.'
— SkymetWeather (@SkymetWeather) April 12, 2016
Second stage Forecast to be released in June
#Monsoon2016: IMD says 'second stage forecast will happen in June first week.' — SkymetWeather (@SkymetWeather) April 12, 2016
Monsoon 2016
#Monsoon2016: IMD says pic.twitter.com/rgrBawT9d0
— SkymetWeather (@SkymetWeather) April 12, 2016
Excess rain in the year 1988
#Monsoon2016: IMD says '1988 was the last year when excess rain happened during monsoon.' — SkymetWeather (@SkymetWeather) April 12, 2016
Too early to comment on the Monsoon in Northwest India
#Monsoon2016: IMD says 'Too early to say about the monsoon in Northwest India.'
— SkymetWeather (@SkymetWeather) April 12, 2016
#Monsoon2016: IMD says '' LA Nina will form in the last part of August and September. ' — SkymetWeather (@SkymetWeather) April 12, 2016
