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At Issue
"Weatherspeak" is the Ultimate Cop Out
Tuesday, March 11, 2003
In my 17 years of writing I've never missed a deadline. In fact, I've never missed a deadline in my writing career. There is just something about that almighty dollar. In other words, when an editor gives me a task, he or she has a 100% chance I'll come through for them. Anything less, to me, is a cop out.But of course when I put my economist hat on, it's different. Put me in a room with some of my colleagues and I can give you 40 different reasons for some vague economic anomaly. And if I'm wrong, everybody yawns and I still get paid. I'd blame it on some bad assumptions fostered by uncertain economic conditions. But at the end of the day, at least I'd still give you an answer.
And then of course you have our meteorologist friends commonly referred to as the "weather-person". I listen to them all the time. Some of them are my colleagues at the radio station and some of them are simply people I depend on through other media sources close. You can even access the weather through CkTimes.ca. And like economists, they get paid even if they are wrong.
Having said that, I think there is one thing in their "weatherspeak" arsenal that smacks of the ultimate cop out. And as a working farmer in Southwestern Ontario, I hear it all the time. It goes like this. "Today, there will be a chance of showers in the afternoon, with a 20% chance of isolated showers tomorrow." If I had a dollar for every time I heard that,
I'd be rich. But what does it really tell me? I think it means, we're not quite sure it's going to rain, but it might!
Probability of precipitation (POP) is like a tease. It is left to our imagination to figure our exactly what those numbers really mean. But I'm sure most us us, don't really get it.
So in my unending search to come to grips with this strange forecasting measurement, I went to Environment Canada. And this is how they describe probability of precipitation.(POP)
The probability of precipitation (POP) is the chance that measurable precipitation (0.2 mm of rain or 0.2 cm of snow) will fall on any point of the forecast region during the forecast period. For example, a 30% probability of precipitation means that the chance of you getting rained over (or snowed over in winter) is 3 in 10. In other words, there is a 30%
chance that rain or snow will fall on you, and, therefore, a 70% chance that it won't. It must also be noted that a low POP does not mean a sunny day: it only means a day where the chance of rain or snow is low.
There are other ways to understand the POP. One is that at the end of the period, still considering the previous example with a 30% POP, if everything goes the way it is expected to, there would be about 30% of the region that would have had rain, and 70% that would not, but you would not have known ahead of time where each zone (the 30% with rain and the 70% without) would be. Another way to understand the POP is that if you had 100 forecasts that said 30% POP, there should have been rain 30 times, and no rain 70 times out
of these 100 forecasts.
O.K., did you get that? In theory, it makes sense, but we all know that in reality, it rarely happens. Lots of time, a 30% chance of rain or snow means no rain or snow for a forecast region. And then other times, 30% chance of rain means a raging flood. And to make matters, worse, the proverbial "chance of showers or flurries", statement becomes the "alibi" for every weather forecast. It's easy to say, and it means nothing is for sure. In other words, it might rain or and then again it might not.
But that is not to say our weather forecasts are not becoming better. They are. When you take the computer technology available today, plus the colour radar and other meteorological innovations our present forecasts are quite good. And as time passes, POP or probability of precipitation only cheapens these weather forecasting innovations. With the technology available to our meteorologists today, they should be able to tell us if it's going to rain or not. "Maybes" shouldn't be part of that equation.
In the last two summers, Chatham-Kent suffered through two droughts. Production on farms plummeted and Great Lakes water levels suffered further. Some timely rains that never came would have really helped out. But everyday, we'd hear about the probability of precipitation (POP) or chance of showers. It was like dangling a forbidden glass of cool, clear water in front of a dehydrated man. And after awhile, its irrelevance was apparent.
So it's time to get rid of it altogether. With today's technology, forecasts should be rain or snow for Thursday, no rain or snow for Monday, etc. And if that can't be done, I'll try to get our meteorologist friends into the economists club. Those guys are never going to change.
Philip Shaw, farms 830 acres near Dresden, Ontario. He holds a Masters of Agricultural Economics and Business Degree from the University of Guelph and is a well-known commentator on agricultural issues in print, on radio and over satellite in Canada and the United States. In the Chatham-Kent Times, Phil will use his frank and forthright writing style to address political and economic issues from the local to the international stage. He is a keen observer of political life at all levels, reads widely and has travelled the world to gather fodder for his column. See what's At Issue this week.
