Predictability of mesoscale meteorological phenomena.

The predictability is defined as an improvement in some quantitative measure of forecast accuracy over that measure obtained from random selection from the ensemble of atmospheric flows. Some conventional and nonconventional measures of accuracy are reviewed and indications that predictability may differ considerably for one measure compared with another are suggested. Some general factors determining the predictability of mesoscale atmospheric phenomena are discussed. The improvements in synoptic scale together with advances in observational and computer technology suggest that improved predictions of mesoscale phenomena of significance to people are possible. Examples illustrate the potential predictability of downslope wind storms, fronts, drylines, low level jets and mesoscale distributions of precipitation. (from paper)