Use of percentage of possible sunshine data to prepare automated forecasts of sky cover and to verify plain language forecasts

Abstract

Surveys have indicated a general misunderstanding by the public of many of the sky cover terms used in weather forecasts. This difficulty often carries over to the forecast staff. Reports of hours of bright sunshine were used in the Québec Forecast Office to attempt to improve the understanding of sky cover terminology. Sunshine data received on a near real‐time basis were converted to percent of possible sunshine. A preliminary survey was made in the Québec Forecast Office, followed by a national survey in which all of the other Canadian forecast meteorologists were asked to provide their views on the relationships between sky cover terminology and percentage of possible sunshine. Based on the survey results it was possible to quantify plain language forecasts and consequently to develop techniques to verify them objectively, as well as to prepare computer‐produced forecasts. It is proposed that forecasts of hours of bright sunshine or of percent of possible sunshine be used to replace currently misunderstood and often misused terminology. © Taylor & Francis Group, LLC.