What does it mean when they say there’s a 30% chance of rain?

Gur Huberman points us to this page [link fixed] from the National Weather Service, “Explaining ‘Probability of Precipitation,’” which says: Probability of Precipitation = C x A where “C” = the confidence that precipitation will occur somewhere in the forecast area, and where “A” = the percent of the area that will receive measureable precipitation, …