Percent of Possible Sunshine—A Verification Tool, A New Forecast Parameter

Sunshine data are received daily on a real time basis at the Quebec Forecast Office and are converted into terms of percent of possible sunshine. On the basis of a survey held in the Quebec Forecast Office, the percent of possible sunshine was associated with the plain language expressions used to describe sky cover. Using this relationship, it was possible to use these observed sunshine reports to objectively verify the worded forecasts of sky cover. Techniques are being developed to forecast the percent of possible sunshine to be used as guidance in our public forecasts.