How accurate are those extended forecast?

Question

I am planning an out door party next weekend on the 10th. I checked the extended forecast yesterday and it said partly cloudy now this morning it has showers for both Saturday and Sunday. How accurate could this be?

Answer 1

In terms of weather forecasting, it is generally considered any forecasting beyond 2 weeks is just guesswork and you might as well consider climate data.

For a 7 day forecasts, there are going to be modifications to it throughout the week as the day draws closer. I'd say take it with a grain of salt while realizing you aren't going to find a better forecast. Keep checking it throughout the week, and maybe make back-up plans for an indoor party.

Answer 2

They are really not that accurate. The extended forecast is done by computers. Computers forecast what the weather is going to be like based on the current weather, any weather systems that may be entering or is migrating across the country and a random guess. The random guess is always factored into predicting the extended forecast so that alone will show you that they are not very accurate. You will be better off watching the weather everyday and only trust the 2 to 3 day extended forecast. Anything past that is questionable.

Answer 3

They aren't accurate. Anything past 5 days pretty much relies on just computer models. These models tend to be more inaccurate the farther out you go due to chaos theory. In meteorology, this means you could run the model with the same initial conditions and get two completely different results...this is due to the fact that models cannot perfectly resolve every aspect of the atmosphere. I would wait until the 6th before the forecast for your party will be useful. Unfortunately, it won't get much more accurate than that.

Answer 4

About 75%. They are only accurate to about 3 days out.