One of my pet peeves is a weather forecast that doesn’t contain the current temperature. It has been colder than usual for the past 3+ weeks, and almost every day, the morning temperature outside is 5-10 degrees below the low temperature in the forecast. As I am checking the weather on TV, for example, the current temperature will be 16 with a low of 23 (See the picture below for an example of this). They can’t add an if statement to update the high and low temperatures for the day? Seriously.
I ran in a race this weekend. The forecast predicted a low of 28 degrees outside. But I ran 15K in 19 degree weather. As I was running and trying to distract myself from the fact that I couldn’t feel my face, I speculated that some aspect of large-scale meteorology algorithms resulted in bad low temperature forecasts. After all, weather forecasts seem to do a pretty good job predicting hot temperatures.
Amazingly, there is evidence to suggest that what I have been observing is in fact true! This blog post from ForecastAdvisor provides data showing that weather forecasts get worse as the temperature deviates more from normal. The key figure is illustrated below. Most interesting is that there is a bias toward accuracy in predicting hotter temperatures–forecasts for colder-than-normal weather are worse than hotter-than-normal weather!
Meteorologists: please explain this phenomenon in more detail! Read an old post about OR models for meteorology.