Many listeners and readers felt a concise explanation of "a 20 percent chance of rain" was missing from this story about weather forecasts and probability, so we followed up with two meteorologists.
From meterologist Eli Jacks, of the National Oceanic and Atmospheric Administration's National Weather Service:
"There's a 20 percent chance that at least one-hundreth of an inch of rain — and we call that measurable amounts of rain — will fall at any specific point in a forecast area."
And from Jason Samenow, chief meteorologist with The Washington Post's Capital Weather Gang:
"It simply means for any locations for which the 20 percent chance of rain applies, measurable rain (more than a trace) would be expected to fall in two of every 10 weather situations like it."