March 6, 2009
Weather report percentages can vex viewers
Researchers say there can still be confusion over exactly what weather forecasters mean when they say there is a certain percent chance of rain.
A paper published in the February Bulletin of the American Meteorological Society concluded that when a percentage is used to describe the chance of precipitation, a sizable number of people see it as the percent of the local area that will get rain, or the percent of time in the day during which it will rain.The findings were the result of three experiments carried out at the University of Washington using surveys issued to dozens of undergraduate students.
If such deep-seated misunderstanding is evident among this college-educated sample in the rain-experienced Pacific Northwest, we can assume that it exists in similar or larger proportions among the general public, the paper said.
One recommendation was that media outlets revise the icons they use in their predictions to give viewers a better idea of how likely it will be that there will not be any rain or snow on a particular day.
The percentage, by the way, refers to the percent of days that experience precipitation when the expected weather conditions are in place.