• by Joe Mandese  @mp_joemandese, July 13, 2009

Interpublic this morning forecast the U.S. advertising economy will decline 14.5% this year, and won't begin to crawl out of the recession until the second half of next year.

The forecast, issued by Brian Wieser, global director of forecasting and Interpublic's Magna unit, is the first utilizing Interpublic's new methodology, which calculates the revenues reported by media vendors, as opposed to its previous method of calculating the spending by advertisers and brands.

Wieser said the U.S. ad economy declined 18% during the first and second quarters of 2009, but expects conditions to improve during the second half of this year, leading to an aggregate decline of 14.5%.

While the ad economy will begin to turnaround next year, Wieser projected a tepid 1.5% compound annual average growth rate for the next five years.

"The indicators are not very strong," he said.