Q: Everything tells me that this sentence is correct: “They fulfilled the request more quickly than they forecasted.” Yet, the use of “forecasted” here sounds a little discordant. Does my grammar or my hearing need fine-tuning?
A: The usual past tense and past participle of the verb “forecast” is “forecast.” Example: “He forecast an inch of snow yesterday, and he has forecast three more inches for tomorrow.”
However, “forecasted” is listed as an acceptable variant (though not the preferred one) in both The American Heritage Dictionary of the English Language (4th ed.) and Merriam-Webster’s Collegiate Dictionary (11th ed.).
This acceptance isn’t unanimous, however.
Garner’s Modern American Usage (3rd ed.) says, “Forecasted is poor usage.” Garner’s also prefers the past tense and past participle “broadcast” over “broadcasted,” another usage that the dictionaries recognize.
We also prefer “forecast” and “broadcast” because of the parallel with the verb “cast.” Its past tense (as well as its past participle) is simply “cast,” as in “He cast [or “has cast”] a wide net in his search for a law clerk.”
Although your grammar can be defended here, we think you should follow your ears and fine-tune that sentence.