What are 6 changes in atmospheric variables that usually precede rain and 6 that precede fair weather?

Why does the weather forecast says it is going to rain but the chance or raining is least likely not to rain?

• the weather forecast says tomorrow in dallas it is going to rain but the chance of raining is 40 percent which means the chance of not raining is 60 percent so how come the weather forecast predicts that it is going to rain iif there is 20 percent more of a chance to not to rain than to rain

• Answer:

  That has been debated by forecasters for years. You are right, 40 percent chance of measurable rain also means that there is a 60 percent chance you will get no measurable rain for that forecast period. Even when we write a 10 percent chance of rain in our forecast, many of our users will just see rain and will think that our forecast is calling for rain period. Over the past 15 years, we have tried to make changes to reduce this type of a problem with the users. We have tried to just use words and with no mention of precipitation unless it is greater than 50 percent chance. But we ended up with piles of mail with about 80 to 90 percent of our users who demand that we put wants us bring back the "chance of rain" wording. We even left out the words and instead put icons up with a picture of some building clouds and a percentage under the incon with no wording about rain in the main body of the written forecast. Once again we got mail and email that jam our mail boxes and our email boxes of people who like the pop term. We can try to mention both, but that becomes long and wordy. Example: 60 percent chance of no measurable rain or a 40 percent chance of measurable rain. That I am sure will confuse the public even more. So it looks like we will continue this format until somebody can think of a better way of giving odds to the public as to whether it willl rain or not. If you have any ideas, I'm all ears. :-) .