How is the percent chance of precipitation calculated in a weather forecast?
Computer models that forecast temperature, wind speed and direction, and relative humidity, also forecast the probability of precipitation (also known as “POP”) for 6 and 12-hour periods. While the math behind the POP is complex, the computer model takes into account the amount of moisture at different levels of the atmosphere, whether air is expected to be rising or sinking, and other meteorological factors. Just like the temperature and wind forecasts that computer models provide, human forecasters look to these as guidance, often comparing several different computer models before producing a POP forecast for the public. Learn more about weather forecasting on this USA TODAY resource page.
