To predict growth and decay of precipitation over the radar-based extrapolation, a blending system was developed to incorporate the best features of forecast precipitation from SWIRLS and numerical weather prediction (NWP) model. The blending system consists of 3 components: (a) SWIRLS QPF, (b) QPF from convection permitting NWP model, and (c) the blending algorithm. More weighting is given to the nowcast in the first 1-2 hours, and weighting of QPF from NWP model then gradually increases towards longer lead time up to 6 hours ahead, after applying phase correction in location and calibration intensity of model forecast precipitation as compared to the actual rainfall analysis (SWIRLS QPE).
The blending system was also enhanced and made available in Com-SWIRLS to combine nowcast and simulated radar reflectivity from convection permitting NWP model that developed with the Malaysian Meteorological Department (MMD) and has been implemented in MMD's RaINS (Radar Integrated Nowcasting System).
Reference:
Li, P. W., Wong, W. K., Cheung, P., and Yeung, H. Y., 2014: An Overview of Nowcasting Development, Applications, and Services in the Hong Kong Observatory. https://doi.org/10.1007/s13351-014-4048-9