A BRIEF REVIEWON THE DEVELOPMENT OF NOWCASTING FOR CONVECTIVE STORMS

Nowadays, the nowcasting technique and research for convective storms have an exciting advancement along with the rapid development of Doppler weather radar and many else meso-and micro-scale meteorological observation instruments. At present, main nowcasting techniques comprise three aspects: identification, tracking and extrapolation forecast, numerical model forecast, knowledge-based forecast technique. Cross-correlation technique and echo feature identification and algorithms are well-performed extrapolation techniques mainly based on weather radar data and are utilized by many operational nowcasting systems, but there are very short forecast period and low accuracy. Now the techniques that assimilate radar, mesonet and micro-scale data into fine meso-and micro-scale numerical models to nowcast initiation, evolution and dissipation of thunderstorms are very promising and robust. Techniques are progressing rapidly but not mature for operation. Knowledge-based nowcasting techniques are more observation-based. They combine and analyze a variety of fine meteorological data sources, including radar and satellite data, then theorize conceptual models of initiation, evolution and dissipation of thunderstorms, especially, the close relation between boundary layer convergence lines and enhanced convection, as well as integrate fine numerical models outputs initiated with or without radar data and extrapolation technique results, then build expert system of thunderstorm nowcasting to gain information about not only the development but also the initiation and dissipation of thunderstorms and convective rainfall. Verification and qualitative assessment of forecast also show that the expert systems outperform all other techniques for operational nowcasting thunderstorms and convective precipitation in accuracy and period. The expert systems are one of the primary techniques for nowcasting convective storms evolution in the near future. Auto-Nowcaster developed by NCAR is one of the state-of-the-art expert systems for nowcasting thunderstorms.