Skill and return of skill in dynamic extended-range forecasts

Abstract

The entire distribution of forecast quality for a large set of forecasts as a function of lead time is examined. A set of control forecasts that clearly have no skill is presented. The quality distribution for the extended-range forecasts is compared to the distributions of quality for the no-skill control forecast set. The extended-range forecast quality distributions are found to be essentially indistinguishable from those for the no-skill control of leads somewhat greater than 12 days. A search for individual forecasts with a "return of skill' at extended ranges is also made. Although it is possible to find individual forecasts that have a return of quality, a comparison to the no-skill controls demonstrates that these return of skill forecasts occur only as often as is expected by chance. -from Authors