The Collaborative International Dictionary of English v.0.48:

forecasting \fore"cast*ing\ n.
   The process of calculating and predicting future events,
   usually based on extrapolation from past experience, and with
   varying degress of uncertainty.

   Syn: prediction, foretelling.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

forecasting
    n 1: a statement made about the future [syn: prediction,
         foretelling, forecasting, prognostication]

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "forecasting":
   actuarial prediction, aerography, aerology, anemology, apocalypse,
   barometry, climatography, climatology, foreboding, forecast,
   foreshowing, foresight, foretelling, guesswork, improbability,
   long-range forecasting, meteorology, microclimatology, nephology,
   omen, pneumatics, prediction, prefiguration, prefigurement,
   prefiguring, presage, presaging, presentiment, preshowing,
   presignifying, probability, prognosis, prognostication, promise,
   prophecy, prophesying, prospectus, soothsay, speculation,
   statistical prediction, vaticination, weatherology