From a Times Question and Answer article about the effects of a government shutdown:
Q. How would the American economy be affected?
A. According to Mark Zandi, the chief economist for Moody's Analytics, a partial shutdown would trim annual economic growth by 0.2 percentage points in the fourth quarter, even if it ended within four days. An impasse of a month could cut growth by 1.4 percentage points, about half of that from the lost pay of government workers. An interruption longer than two months, he said, "would likely precipitate another recession."
In the event that there is no shutdown, Mr. Zandi has projected fourth-quarter growth at an annualized rate of 2.5 percent, a relatively weak rate of recovery.
Of all the economists out there, with all the different forecasts available, why does the Times pay attention to this guy? He's certainly not the most accurate economic forecaster out there. He does seem to be highly accessible to the press, perhaps more so than other economists.