Precipitation Probability Forecasts–Problems Seen via a Comprehensive Verification

Abstract

A number of problems that arise in making probability of precipitation (PoP) forecasts are noted and discussed, and solutions are given where known. This effort is based on a long-standing extensive verification of PoP's issued by 66 offices of the National Weather Service's Central Region. Verification results were sent monthly to each office and each forecaster for the past 13 years. Some additional problems and solutions dealing in general with verification and evaluation of PoP'S are discussed. These include modifications of scores generally used, plus factors to consider when trying to compare scores of offices having different climatological conditions.