We have weather “forecasts,” budget “projections,” attempts at earthquake “predictions.” Most dictionaries say those are all synonyms for one another. So why doesn’t the nightly weather report call them “predictions” or “projections”?
Because the weather people know just how fickle Mother Nature is.
A “prediction,” Merriam-Webster’s Unabridged Dictionary says, is “an inference regarding a future event based on probability theory.” It’s more reasonable to “predict” that a major earthquake will hit California, based on past events and the probability that the Big One is going to hit someday than to try to pinpoint when it will hit. Unless you’re Madame ZaZa, it’s better to “predict” something over a longer term.
A “forecast,” M-W says, “may suggest concomitant anticipation, consideration of effects, and provision for one’s needs.” That fits weather reports so much better: If you’re told a storm is coming, you can run to the store and buy bread, milk, and eggs. (Why is it that those are the first things that sell out in advance of a major storm? Does everyone plan to make French toast? An imponderable ) It seems less writ in stone than a “prediction.”
A “projection,” though, bases the future likelihoods on the present or the past, as part of a continuum. M-W’s last definitions for “projection” are the appropriate ones here: “the carrying forward of a trend into the future” and “an estimate of future possibilities based on a current trend.” You can’t “project” tomorrow’s weather on the basis of today’s, because there is no direct relationship. But you can see how much money the government plans to spend and how much it expects to receive and, considering present and past budgets, “project” the budget needs for next year and a few years into the future.
Weather people will also give “outlooks,” which M-W calls “the prospect for the future.” It’s something of a weenie word, in that it seems less scientific than “forecast.”
Then there’s “foretell.” While it is a synonym for the verb “predict,” M-W cautions that “predict” “may be preferred in today’s English to suggest or apply to inference from facts and laws of nature.” “Foretell,” after all, sounds more like something a fortune teller would do; in fact, the American Heritage Dictionary of the English Language lists “divine” and “prophesy” as synonyms along with “predict.” It notes: “these verbs mean to tell about something beforehand by or as if by supernatural means.”
The National Weather Service generally uses both “forecast” and “outlook,” though it and its parent, the National Oceanic and Atmospheric Administration, have a number of “prediction” centers, listing the possibility/likelihood and impact of severe storms, and larger climate, um, predictors, such as El Niño.
Bet you didn’t see that coming.