Originally Posted by
smooth_ej20
20% chance of rain doesnt mean that theres an 80% chance that it wont. It means that it will rain and roughly 20% of the land area will get rain.
The Straight Dope: What does it mean when "X percent chance of rain" is predicted?
http://www.mpib-berlin.mpg.de/en/mit.../RainFinal.pdf
Here's a quote from the 2nd link further proving what the first says...
"The National Weather Service defines the proba-bility of precipitation as “the likelihood of occurrence(expressed as a percentage) of a measurable amountof liquid precipitation . . . during a specified period oftime at any given point in the forecast area” (NationalWeather Service Tulsa, 1998 ). In practice, the accu-racy of “the rain forecast is the percentage correct ofthose days when rain was forecast” (Thornes, 1996,p. 69). Thus, a 30% chance of rain does not mean thatit will rain tomorrow in 30% of the area or 30% ofthe time. Rather, it means that when the weather con-ditions are like today, at least a minimum amount ofrain (such as .2 mm or .01 in.) will fall the next day in3 out of 10 cases."
In short, you're wrong.
--brandon