What is meant by “POP” in the local forecast?
These two letters, one from Ian Kellogg of Toronto and the other from Robert Brawn of Ayr, Ontario are typical of the many inquiries from viewers of The Weather Network, asking what POP refers to when displayed on the local weather forecast segment. As many of you know, POP refers to probabilities of precipitation. A POP of 60% doesn’t mean that it will rain 60% of the day, or that rain will fall on 60% of your area. It also says nothing about how much rain or snow will occur. A POP of 60% means that the forecasters have calculated that in a 100 similar weather situations, rain has fallen 60 times in the forecast area. POP is for any point in your forecast area, not the whole area. So, for instance, a POP of 90% for rain means that 9 times out of 10 when this is predicted, you ought to get rain somewhere in the forecast area, eg., at your home, playground or at the airport. In the past, meteorologists used descriptive terms such as slight chance, chance of, occasional, or possibility o
