(By Don Miller) Historically, the U.S. stock market has been one of the key leading indicators of a U.S. economic rebound.

With the Standard & Poor's 500 Index up more than 60% from its March lows – and the Dow Jones Industrial Average up nearly 40% – prognosticators are finally confident that the U.S. economy will dodge the "double-dip" recession that has been the focus of much fear since the Bush and Obama administrations launched their financial counterattacks on the worst financial crisis since the Great Depression.

But those same forecasters are reluctant to forecast a sharp economic rebound for 2010. In fact, as opposed to a classic "V-shaped" economic recovery that would accelerate as the year goes on, many economists are predicting that the rate of growth will slow as the New Year unfolds.

Forecasts from Standard & Poor's Inc. (NYSE: MHP) and Goldman Sachs Group Inc. (NYSE: GS) illustrate this outlook. S&P recently projected average GDP growth of 1.6% for all of 2010, while top Goldman Sachs economists expect to see the U.S. growth rate decline from 3% early in the year to 1.75% by the fourth quarter.

"We don't expect a V-shaped recovery; in fact we think that 2010 is going to be a bit slower in terms of annualized GDP growth than the second half of 2009," Goldman Sachs Chief U.S. Economist Jan Hatzius said during a recent speech in New York City.

For analysts and economists who play the forecasting game, 2010 promises to be one of the toughest challenges in decades.

Unemployment has pierced the psychologically daunting 10% level, placing U.S. joblessness at its highest level in a quarter century. Serious questions remain about the strength of the country's banking and financial systems. The U.S. dollar is under siege and inflationary concerns are at their highest levels in years. There's massive uncertainty about the nation's residential and commercial real estate markets. And even the stock-market rebound – one of the strongest in history – is considered suspect by some analysts: They worry that federal stimulus money and the U.S. Federal Reserve's "zero-interest-rate policy" has forced bearish investors to become reluctant bulls.

Among the difficulties would-be forecasters currently face economists face is the fact that 4% of the economic growth in recent months is attributable to temporary factors, most notably the replenishing of inventories and government fiscal stimulus, Goldman's Hatzius said. Those factors are likely to diminish by the second half of 2010, due to high unemployment, budget-conscious consumers, and overcapacity in the manufacturing sector and housing markets.
Despite these obvious difficulties, the outlook for 2010 is far from dismal. Among the bright spots:

• The stimulus seems to be having its intended effect – one reason the odds of a double-dip recession remain remote.
• The U.S. housing market – a crucial element of the consumer sector – is showing signs of bottoming out.
• The weak U.S. dollar is making U.S.