The probability of rain is the most popular feature in weather apps. Although they provide information, weather forecasts are often difficult to understand. Santi Sabariego will explain ensemble forecasting, a method based on verifying the state of the atmosphere. Despite research, meteorology is still not an exact science. Read on to find out more.
Probability of rain most checked feature
The probability of rain is one of the most coomon checked features on weather apps. Yet this percentage is often not totally understandable. Some people think that a 60% chance of rain means six out of ten experts predict it will rain, or that rain will fall on 60% of the city.
In fact, weather forecasting relies on a compund system known as the ensemble forecasting method. Geography and History teacher Santi Sabariego has created a video to explain how it works. Now we will explain how it actually works.
How the method begins
The method starst with an analysis of the actual state of the atmosphere, which present an initial prediction. Then, 50 slightly modified scenarios are generated for the same location and day, producing a total of 51 forecasts. As an example, if rain happens in 25 of these forecasts, the chance of rain is considered 50%. If it appears in all 51, the chance is 100%.
“Meteorology isn’t an exact science. Even if it doesn’t rain, you can’t say the forecast was wrong, because it’s a probabilistic prediction. And if you don’t like that, then use another method,” Sabariego concludes.
How your rain chances are calculated
According to the latest forecast, a 30 percent chance of rain is expected today. After that, periods of dry weather are likely over the weekend, and as the workweek returns, rain chances drop even lower, with numbers in the 10 to 20 percent range showing up on the Weather Authority charts.
Delaney Willis shared that, unfortunately, as these next few days arrive, rain probabilities remain on the low side. That means while an umbrella might not be totally necessary, it might still be a good idea to keep an eye on those percentages, especially for outdoor plans.
Recent dry stretch and what it looks like outside
It hasn’t just felt dry—it looks that way, too. Delaney pointed out on-air that it’s “starting to affect what we’re looking at outside in terms of brown of the grass and some of the trees you might notice out and about.” The local area has seen several dry days in a row, and it’s becoming pretty obvious just by glancing at lawns and parks.
Why chance of rain is more complicated than you may think
Let’s start with what it’s not. Let’s imagine a forecast has a thirty percent chance of rain. Chances don’t relate to physical area; it doesn’t mean 30 percent of the area of the city will be getting rain at any given time. It’s also a myth that you’ll see rain or snow for 30 percent of the time forecasted.
Instead, think of it like playing the odds in Vegas. A 30 percent chance of rain during the afternoon in Colorado Springs means that there is a three in ten probability of any point, such as your house, in the Springs getting measurable rainfall at some time during the afternoon.
Let’s use Colorado Springs and Pueblo as examples. A 30 percent chance of rain during the afternoon in Colorado Springs means that there is a three in ten chance of any point in the Springs getting measurable rainfall at some time during the afternoon. If Pueblo has a 40 percent chance, any house in the city of Pueblo has, equally, a four in ten chance of getting measurable precipitation.
