Why are weather forecasts more than 72 hours in the future are so inaccurate.?

Question

Also can the Farmers Almanac actually predict the weather months or years in advance?

Answer 1

Chaos theory. I don't approve of the butterfly effect, as in, an actual butterfly creating weather (would take centuries to do anything significant unless it was perfectly positioned), but you'd be surprised how much different your life would be if the only thing to change was your name.

They actually do get it right a surprisingly large amount of the time. If you take a coin and flip it, one side sunny and one side cloudy or rainy, you're pretty much going to lose to the weatherman every single time.

Also, the Farmer's Almanac is for climatic trends and since it's not written by mets it usually sucks at predicting the weather (as it has so far this year).

Answer 2

Weather forecasts are based on the immediate conditions and what is the projected weather for several days based on the computer models.  They can track a rain storm for several days and then it, for some reason falls apart and dissolves by the time it gets to your area.  The atmosphere is a dynamic environment with air currents and jet streams.  Any weather prediction is just a guess.

The Farmer's Almanac is based on several years of history with weather,  plus it's not predicting the weather for a given small area, but in general for the entire country.