What device predicts a future change in local weather?

Answer 1

Predict is probably the wrong word here.
Weather forcasts, today, extrapolate trends, as with many other things. This is done by programming computers with information. The 'prediction' is best guess. The more information we can give the computer the more accurate the 'prediction' is likely to be. But, as we all have seen, sometimes these 'predictions' are wrong.