Today Robert Coen, the longtime media forecaster at Magna, trod where others have before by severely chopping his forecast for the U.S. media economy.

Back in December, Coen forecast that advertisers in 2008 would increase their spending on U.S. media by 3.7 percent, citing in part the infusion of ad dollars on the elections and the Summer Olympics, which start a month from now in China.

As it turns out, and as Coen notes in today's presentation, the slowdown in the ad economy was a lot more advanced back in December when Coen made his initial forecast for the coming year.

Rather than growing in 2007, ad spending was actually off, down 0.7 percent for the year, and that torpor has extended into 2008.

That's caused Coen to slash his 2008 forecast to a growth of just 2.0 percent, to $285.1 billion, citing the much weaker U.S. economy and lagging disposable income on the part of consumers.

Coen's report follows a number of other downward revisions for 2008, all reflecting the much worse U.S. economy.

Writes Coen: "National advertising growth in the first four months of 2008 has been exceptionally slow for most major media, especially in a Summer Olympic/presidential election year. Things will improve in the second half of this year, but all the present indicators point to far less than a robust growth year for national marketers’ advertising budgets in 2008."

Coen expects national advertising to grow by 4.2 percent this year, to $193.1 billion.

Where Coen sees the real hurt is in local advertising, writing, "Consolidation of many retailers and local product dealers has hurt newspapers, radio stations, TV stations and the Yellow Pages media. The internet has often compounded the problem by making available cheaper ways for many local marketers to contact potential customers."

He predicts local advertising will be down 2.4 percent, to $92 billion.