Great Lakes Forum - FORECAST WEATHER

Is AccuWeather really accurate?

Weather forecasts are just that, forecasts. Accordingly, they will probably never be 100% accurate.

But, how do you even measure forecast accuracy? If one forecast for tomorrow says "high in the 40s" while another forecast says "high 47," and the actual high is 48 - technically, the first forecast was correct, while the second forecast was not. Yet, because the second forecast provides a greater level of detail, it is more valuable, and many would consider it to be more accurate.

There are many different ways to measure forecast accuracy, some very simple and objective, others more complex and perhaps more subjective. Some parameters are easy to verify (for example if you forecast a high of 47 and the actual high is 48, you are off by one degree), while others are much harder (if a day is sunny for the most part, but there is a five minute-light shower, which forecast is better: "mostly sunny" or "chance of showers"?).

And so, the question of forecast accuracy is not as easy as it may seem. You cannot say, for example, "we are 95% accurate." AccuWeather verifies forecasts of temperature by calculating the average error in degrees. We verify forecasts of weather conditions by using a well-defined scale of similarity, scoring each day's forecast from 0 to +/- 4. We use these verification results in a variety of ways as a tool to help our meteorologists to make even better forecasts.

We also compare our forecasts with those made by other sources available on the Internet, using the same verification methods and forecasts available at the same time. In every study, the AccuWeather forecasts have been more accurate overall.

With advances in technology - faster and more powerful computers, better numerical models, better radar and satellite imagery, and other information - weather forecasts have clearly improved over the years, no matter what their source. As a general rule, the shorter the forecast period, the more detail that can be provided with a high degree of accuracy. Many studies show that current forecasts made for conditions five days in advance are now as accurate as 2-3 day forecasts were ten to 15 years ago. And AccuWeather even provides detailed forecasts extending ten days into the future.

Perhaps the ultimate answer is in people's reactions to the weather forecasts. Twenty five years ago, when a major snowstorm was forecast, people waited to see if it would happen. Now, the stores sell out of milk and diapers.

h2o

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