What does a 30% chance of rain REALLY mean?
342058
If they predicted a 30% chance of rain, and it does rain, that means that they were 30% = 0.3 correct in this instance.  If you average these correctness values over, say, a year...then you'll get a value for how accurate your weatherman is.  Of course, you have to remember...That a person guessing 0 or 100% (yes it will rain or no it won't) should average to a 50% = 0.5 accuracy.\n\nSo, if the weatherman's accuracy is greater that 0.5 over several days...then the weather is more right than he is wrong.  That seems intuitive, eh?\n\nRemember that you can't just compare to what all the other weathermen say...and take the average 'risk' as the actual risk...because all weathermen get their information from Environment Canada, and the numbers will be skewed because they're all using the same information.
413823
in this case there's also a 50% chance of no rain on both sunday & saturday.because of both days, there's only a 50% chance of rain during the whole weekend.am i correct?
1058539
Would greatly help to know the source of the chart. I am guessing your "rainfall radar" chart are estimates of rainfall which has already occurred using radar and the "forecast rain" chart is that which an algorithm forecasts based on radar trends. Both can include fairly large errors in some circumstances - especially the latter. Nothing beats the ground truth of an accurate rain gauge.
773473
1.This means the rain is scattered over a large area and where you live, you may or may not get any.\n2.This means that in your area, some showers are likely.\n3.This means you can expect moderate rain in your area.\n3.This means that rain is expected at some point in your area but as to when, they do not know except that it appears cloud formation carrying rain may hit your place.\n5 This means that you can expect rain with a  reasonable degree of certainty in your area at a significant rate measuring several millimeters
1027903
I'm not completely sure, but I do know that the ring signals that the next day will be rainy. Perhaps it has something to do with an incoming front. Or a rise in humidity.
554585
matthew 30 % + 60 % does not equal 100 % also it means that there is a 3/10 chance of rain
511139
The weather forecast for Richmond Friday shows a 20% chance of rain, so I would say no.
8120
Depends on the size of the glass and the size of the rain drops.If the volume of the glass is 'V' and that of the average volume of rain drop is 'v',then by simple calculation, the  number of drops will be =V/v
1182611
The only thing is, they don't always lie down when it is going to rain.  A lot of times you see them standing in a tight bunch right before it rains, too.  They almost always have their rear ends to the wind.  A lot of the "old timers" had ways of predicting the weather just by looking at natural things, guess this was just one of them.
516442
it means amount of rainfall in mm or cm or inches.
1074152
Partly generally means less than half.  Scattered storms are said to have a percentage "chance" or coverage.
383760
judco is right, its 30%
29159
It means moisture high up (probably ~5 kilometers) but it does not necessarily mean rain.  I used to see that in San Diego quite a lot, and it hardly ever rained.\n\nThe ring is caused by cirrus clouds, which is one of the three main types of clouds (the others being cumulus and stratus).
572346
Well there's a difference between having cloud cover and actually getting rain, but if it's really annual rainfall amounts you're looking for, I found this website, which lists rainfall for each US state.\n\nhttp://www.betweenwaters.com/etc/usrain.html
36815
From the National Weather Service:\n\nWhen we talk about rainfall, we usually refer to it as being either showers or rain. If we are forecasting showers, we expect the rain to fall on an intermittent basis and from cumulus-type clouds. The showers may vary greatly in intensity over just a few minutes or a few miles. For example, lets say that the forecast for today is calling for a chance of showers. That means that if the rain does develop, it will be on and off, rather scattered, may vary in intensity over just a couple of minutes, and fall from cumulus-type clouds.\n\nIf the forecast for today called for rain, it means we expect the rain to fall rather steadily and from a flat, stratus-type of cloud, and won't change much in intensity from hour to hour. It also means that the rain will fall over a fairly large area, not like showers, which usually fall over smaller areas.
157777
they say it is around 15%, but I say it is like 30%
1004578
I think the weather is off because, I don't think that the news is the greatest thing for the weather. One time they said it was going to rain, I was excited, but dissappointed. I wonder when did they decide to be the foretellers of the world. Maybe everysince they've started showing the news; now their inaccuracies are on the internet. Too bad for the people. But I say good job on the forecast on the Katrina and the hurricanes that they've warned people about in advanced, you have to give them that.