Large-scale features associated with excess monsoon rainfall over india during 2019 and the real-time extended range forecast

The performance of operational extended range forecast (ERF) issued by IMD is evaluated for the southwest monsoon 2019, which is one of the excess monsoon years. The delayed onset of monsoon over southern tip of India, sluggish progress northward and delayed withdrawal of monsoon from Northwest India are very well captured in the ERF with two to three weeks lead time. The revival of monsoon towards the end of June & first week of July, weak phase during 2nd/3rd weeks of July, transition into active phase of monsoon during last week of July & first half of August and very active monsoon conditions in September are also very well captured in the ERF. Quantitatively, over the country as a whole and over the four homogeneous regions of India the ERF provided useful guidance with the country as a whole, the central India and the monsoon zone of India indicating more promising results with the correlation coefficient (CC) between observed and forecast rainfall is significant up to three weeks. Over the Northwest India and South Peninsula, it shows useful skill up to two weeks. Northeast India shows significant skill up to one week only followed by weaker CC in week 2 and again increases in week 3. During the 2019 monsoon season the transition of monsoon from above normal to below normal in July month is well captured in the ERF in smaller spatial scales of meteorological subdivision level forecasts, which is being used widely for agrometeorological advisory purposes up to two weeks.