NEW YORK (CNN/Money) - Viacom Inc.'s recent warning on its revenue and profit forecast could be read as a sign that the hoped-for recovery in the U.S. economy later this year could be coming up short again.

Viacom (VIA.B: Research, Estimates) said the shortfall would be because its revenue for local advertisers has not met growth targets, although it still expects to see gains on the year.

"While the economic recovery has translated into robust national advertising sales growth, the pace of recovery in local advertising markets going into the fourth quarter is not as rapid as had been anticipated," said the statement from the owner of the CBS and UPN television networks, cable networks such as MTV, BET and Nickelodeon, as well as Infinity Broadcasting, one of the nation's largest chain of radio stations.

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The strong pickup in advertising spending being reported by both broadcast and cable networks this year was seen as a sign that businesses expected improved consumer spending in the months ahead and wanted to be prepared to reach those buyers returning to stores and showrooms.

But media experts say the relative weakness in local advertising may be a clearer sign of business expectations about the economy than the gain in national advertising, because the local advertising is bought closer to the time the ads are aired.

"Local advertising is bought more on a quarterly basis than an annual basis," said Jack Myers, advertising analyst and publisher of the Jack Myers Report. "A lot of economists have been lulled into a false sense of growth due to strength of '03 upfront [the advertising bought in the spring for the fall 2003 television season]. But that is only one-quarter in '03, and three-quarters in '04."

Myers said he thinks that overall the local market is not in bad shape, especially compared with year-earlier results that were helped by election spending not present this year.

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"I think Viacom's estimates [on local advertising] were overly aggressive," said Myers. "Based on my forecasts for the year, industrywide local TV [advertising] is coming in right about at forecasts at 1.2 percent growth. The fact there's any growth when last year was such a strong year politically is impressive."

But that is not as strong as the 4 to 5 percent growth in national advertising spending that Myers sees. And other forms of advertising, like newspaper and radio spending, which both are primarily dependent on local advertisers, are tracking below his earlier forecasts.

Newspaper advertising is expected to be between flat and up 1 percent, rather than Myers' earlier 1 percent forecast, and he now expects 3 to 4 percent growth in radio spending, rather than his 4 percent forecasts.

Independent media analyst Paul Kim says those other media should be watched more closely by economists than the national ad numbers that get more attention.

"When people point to national broadcast television, that is so far removed from economy," said Kim. "You're talking four networks in prime time with limited inventory. When you're talking spending up 10 to 15 percent there, it's almost a meaningless number for a sign of a recovery. The local number is a better indication of what are the true expectations of businesses."

One of the problems dogging newspaper advertising is continued weakness in help-wanted ads, which is a high-margin business.

The New York Times Co. (NYT: Research, Estimates) warned last week that its August advertising revenue was down 1.4 percent compared with a year earlier, and that while its Arts & Leisure Fall Preview showed about 28 percent year-over-year revenue gain, the best it could say about help-wanted ads is that it "has shown signs of bottoming out at the Boston Globe."

The tough competition for consumer dollars is keeping local advertisers such as car dealers, supermarkets and other retailers from cutting back advertising budgets. But it also has made it difficult to increase ad spending as much as the national advertisers.

"There's not a lot of motion one way or another right now," said Dan Chasins, executive vice president of marketing for United Auto Group (UAG: Research, Estimates), a company that operates more than 200 auto dealers in 20 states. "It's not a time in the car business to be shy and retiring. We have to make sure our message gets out there. But as we measure it [ad spending] as a percentage of our business, we're almost dead flat compared to a year ago."