COLUMBIA, S.C. — A 30 percent chance of rain, what does that mean to you? Does it mean you’ll probably stay dry, or, do you think it might result in some isolated storms you have to deal with?
Arriving to that percent involves more steps than you think.
On any given day, as meteorologists we look at the weather setup to determine how much rain we will see across the Midlands. This, alone isn't enough to come up with a chance of rain in the forecast.
From this point, we look at forecast models to determine how accurate our forecast might be. Using models, serves as a guide and can tell us how confident we can be in a given forecast.
Using this confidence, we can apply this to our forecast to come up with an official chance of rain. By multiplying the rain coverage by the percent confidence we can come up with a chance of rain. In the example below, if we think half of the viewing area will get rain but only half of the models agree, then that would come out to 25% which we would round to 30% by the time you see it on air.
