Intercomparison of two nowcasting methods: preliminary analysis

SummaryWith term nowcasting is intended the description of a weather situation and its consequent extrapolation ahead in the future for few hours. This work gives a brief description of actual nowcasting methods deepening those developed at ARPA-SIM (Emilia-Romagna region, Italy).The methodology used rests on an extrapolation technique that analyses a series of radar reflectivity fields in order to identify areas of precipitation and determine the motion field which allows the tracking of coherent structures from an image to the next one. Motion of individual rainfall structures is extrapolated using two different methods: a linear translation and a semi-Lagrangian advection scheme.In particular semi-Lagrangian advection method is based on a multi-scale recursive cross-correlation analysis, where different targets are tracked at the different scales examined. This means that the motion of precipitation parcels is a function of scale.Description of selected validation tools introduces the numerical analysis of obtained results pointing out limits and limited outcomes of algorithms.