Nowcasting precipitation - a proposal for a way forward

There is little doubt that hybrid mesoscale model and image extrapolation s ystems will eventually become widespread for the nowcasting of precipitatio n for hydrology and aviation safety. Arguably the final forecast output tha t is required for these applications needs to be probabilistic in nature, t herefore appropriate forecast schemes should statistically account for both the chaotic and intermittent nature of the intrinsic fields. In principle, the detailed knowledge that we have about the high-order statistics of rai n patterns should also allow improved extrapolation schemes for nowcasting. A well-known technique that preserves space-time statistics is presented a s an example of this. It is argued that the relative scoring of forecast sy stems is highly space-time resolution dependent, and that even when the sam e meteorological event is being considered this resolution dependency must be taken into account. (C) 2000 Elsevier Science B.V. All rights reserved.