Heavy Rainfall Prediction at Convection-Permitting Resolution over Continental China during 2013 Spring-Summer Season: Collaborative Realtime Forecast Experiment

Heavy Rainfall Prediction at Convection-Permitting Resolution over Continental China during 2013 Spring-Summer Season: Collaborative Realtime Forecast Experiment

Ming Xue^1,2, Kefeng Zhu^1,2, Kun Zhao¹, Huiling Yuan¹,
Xiaolin Zhang³, Yongguang Zheng³, Dongyan Mao³, Jian Lin³, and Qingtao Meng³

¹Key Laboratory for Mesoscale Severe Weather/MOE and School of Atmospheric Science, Nanjing University, China
²Center for Analysis and Prediction of Storms, University of Oklahoma, Norman OK 73072
³National Meteorological Center, Chinese Meteorological Administration, Beijing, China

mxue@ou.edu

Heavy rainfall, together with the associated overland and river flooding, is the most serious form of meteorological disaster over China in the warm season. Local, extreme heavy rainfall over short period of time is especially difficult to predict but is frequently the cause of major disasters including serious urban flooding, river overflow and landsides. The current national mesoscale prediction model operated by the Chinese Meteorological Administration (CMA) runs at a 15 km grid spacing, and lacks the accuracy and precision required of quantitative precipitation forecasts for disaster mitigation needs. Such a resolution also prevents accurate, direct prediction of severe weather including severe winds, hails, and occasional tornadoes.

As part of a national research project aimed at improving the understanding and prediction of convective-scale weather of China, and as an effort to increase the collaborations between the operational and research communities within China, from the spring of 2013, Nanjing University started to produce experimental 48-long realtime forecasts at 4 km grid spacing over the entire continental China 2-3 times a day. Forecast products were directly accessed at an experimental forecasting evaluation facility within the National Meteorological Center (NMC) of CMA, where subjective and quantitative evaluations of the forecasts were carried out. The skills of the 4-km forecasting system are also compared with available operational forecasting models from CMA and other operational NWP centers; initial assessment indicates remarkable skills of the former. The skills of the 4-km experimental forecasting system relatively to existing forecasting guidance will be presented, together with examples of heavy rainfall cases representative of China's rainy season. Forecasting challenges and future plan will also be discussed. This effort in a sense parallels the NOAA Hazardous Weather Testebed (HWT) Spring Experiment of the United States and the related research and operational community collaborations.