Evaluation of radar data impact on 0-12h rainfall forecast over the complex terrain of Rocky Mountain Front Range: Analysis of multiple convective cases from a realtime demonstration experiment

During the summer of 2014, NCAR led a field program to demonstrate the capability of a coupled hydrometerological prediction system targeted at the prediction of heavy rainfall and flash flood. One of the goals of the field program was to evaluate the impact of radar data assimilation over complex terrain in a regional domain. Several data assimilation systems using radar data were run in realtime for a period of 6 weeks. In this presentation, the realtime performance of 0-12 hour convective forecasts with/without radar observations in WRF 3DVar data assimilation system (WRFDA) is evaluated. Several factors in the system, such as background field, cycling frequency, and humidity adjustment, that influence the performance of radar data assimilation are examined through case studies. These case studies will shed light on future directions of convective-scale data assimilation using radar observations.