Now as far as the forecasts. Its better to say they are inaccurate. Everything is based off models, some of the better guys like Joe Bastardi at WeatherBell, use models combined with historical evidence and experience can make pretty good predictions but anything 72 or more hours out is always subject to change.
Models can only take what they know and then run the data through the programming that has to take into account some assumptions. Conditions change, local geographic effects arent taken into account etc. If you watch all the model runs, things can get pretty screwey, some show Florence coming back around again after it makes it back to the ocean.
Excerpt from Aliens Cause Global Warming a lecture by Dr. Michael Crichton
To an outsider, the most significant innovation in
the global warming controversy is the overt
reliance that is being placed on models. Back in the days of nuclear winter, computer models
were invoked to add weight to a conclusion: “These results are derive
d with the help of a computer model.” But now, large-scale computer models are seen as generating data in
themselves. No longer are models judged by how
well they reproduce data from the real world—
increasingly, models provide the data. As if they
were themselves a reality. And indeed they are,
when we are projecting forward. There can be no observational data about
the year 2100. There are only model runs.
This fascination with computer models is something I understa
nd very well. Richard Feynmann called it a disease. I fear he is right. Because
only if you spend a lot of time looking at a
computer screen can you arrive at the comp
lex point where the global warming debate now
stands.
Nobody believes a weather prediction twelve hours ahead. Now we’re asked to believe a
prediction that goes out 100 years into the future? And make
financial investments based on that
prediction? Has everybody lost their minds?
Stepping back, I have to say the
arrogance of the model-makers is
breathtaking. There have been,
in every century, scientists who say they know it all. Sin
ce climate may be a chaotic system—no one is sure—these predictions are
inherently doubtful, to be polite.
But more to the point, even if
the models get the science spot-on, they can ne
ver get the sociology. To predict anything about
the world a hundred years from now is simply absurd.