Storm track representation and verification.

Abstract

A vortex representation of highs and lows is presented which mathematically describes individual local features by a small number of parameters representing magnitude, location, size, and shape. An example applying this representation to a 10-day forecast by ECMWF and to the corresponding NMC verifying analysis is discussed. Representations of storm tracks in the forecast and analysis are defined by mapping the envelope of individual features with time, ie. by determining the volume swept out by the storm. Such a two-dimensional horizontal field or map indicates the path of each storm as well as its strength and size along its track during the period included in the mapping. The usefulness of such mapping as a forecast product as well as a means for verification is illustrated. -from Author