Abstract:Based on European Center for Medium Range Weather Forecasts (ECMWF) reanalysis datasets and extreme forecast index (EFI) of ensemble prediction system, this paper analyzes the anomalous atmospheric circulation and verifies the EFI’s forecasts for extreme cold event that happened from 21 to 25 January 2016. It is found that an anomalous strong high pressure ridge maintained in central Asia and the standardized anomaly of high pressure ridge was more than 3 standard deviations and the cold vortex nearby Lake Baikal was continuously developed and enhanced. As the revising of the transverse trough, the cold vortex moved southward abnormally and extreme cold wave broke out in the East China. The verification shows the EFI can predict minimum temperature signal 7 days in advance. With the lead time extension of EFI forecast, the corresponding maximum TS score decreases, and there are different EFI thresholds for different lead time forecasts. Researches also show that the critical threshold of minimum temperature EFI for 5% percentile of the low temperature events (1-3 days) is -0.6 and for 4-7 days the critical threshold of minimum temperature EFI is -0.5. Besides, the critical threshold of minimum temperature EFI for 1% percentile of the low temperature events is -0.7. Moreover, the different lead time performance of minimum temperature EFI for 5% percentile of the low temperature events in Jiangnan, Huanghuai, Jianghuai and Jianghan Regions is the best, followed by the performance for the events in Huabei, Huanan, Southwest and Northwest, and the performance in Northeast is poor relatively.