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.

IMD 发布的业务扩展范围预报 (ERF) 的性能是针对 2019 年西南季风进行评估的，该季风年是季风过剩年份之一。印度南端季风的延迟到来、向北进展缓慢以及季风从印度西北部的延迟撤退都在 ERF 中得到了很好的捕捉，提前两到三周。6 月底和 7 月第一周季风恢复，7 月第 2/3 周弱阶段，7 月最后一周和 8 月上半月季风过渡到活跃阶段，9 月季风条件非常活跃。在 ERF 中被很好地捕获。从数量上讲，在整个国家和印度的四个同质地区，ERF 为整个国家提供了有用的指导，印度中部和印度季风带显示出更有希望的结果，观测和预测降雨之间的相关系数 (CC) 在长达三周的时间内是显着的。在印度西北部和南半岛上空，它显示了长达两周的有用技能。印度东北部在一周内表现出显着的技能，仅在第 2 周减弱 CC 并在第 3 周再次增加。 在 2019 年季风季节期间，7 月份的季风从高于正常水平到低于正常水平的过渡在 ERF 中得到了很好的捕捉气象细分级别预测的空间尺度，它被广泛用于长达两周的农业气象咨询目的。在印度西北部和南半岛上空，它显示了长达两周的有用技能。印度东北部在一周内表现出显着的技能，仅在第 2 周减弱 CC 并在第 3 周再次增加。 在 2019 年季风季节期间，7 月份的季风从高于正常水平到低于正常水平的过渡在 ERF 中得到了很好的捕捉气象细分级别预测的空间尺度，它被广泛用于长达两周的农业气象咨询目的。在印度西北部和南半岛上空，它显示了长达两周的有用技能。印度东北部在一周内表现出显着的技能，仅在第 2 周减弱 CC 并在第 3 周再次增加。 在 2019 年季风季节期间，7 月份的季风从高于正常水平到低于正常水平的过渡在 ERF 中得到了很好的捕捉气象细分级别预测的空间尺度，它被广泛用于长达两周的农业气象咨询目的。