WASHINGTON — The economy pulled out of a dangerous rough patch in the spring, thanks largely to strong exports, but the rebound isn't expected to last. Economic slowdowns overseas could make exports tail off just as Americans are hunkering down after the bracing impact of rebate checks wanes, plunging the country into another rut later this year.

"There will be heavy sledding for the U.S. economy during the next couple of quarters," predicted Lynn Reaser, chief economist at Bank of America's Investment Strategies Group.

Gross domestic product, or GDP, grew at a 3.3 percent annual rate in the April-June quarter, its fastest pace in nearly a year, the Commerce Department reported Thursday. The revised reading was much better than the government's initial estimate of a 1.9 percent pace and exceeded economists' expectations for a 2.7 percent growth rate.

The rebound followed two dismal quarters. The economy actually shrank in the final three months of 2007 and barely budged in the first quarter at a minuscule 0.9 percent pace. The 3.3 percent growth in the spring was the best performance since the third quarter of last year, when the economy was chugging along at a brisk 4.8 percent pace.

White House press secretary Dana Perino said the numbers demonstrated the economy's resilience in the face of many challenges. But she added: "No one is doing a victory dance."

Others agreed that the growth pickup wasn't a sign of better days ahead. Analysts predict the second quarter will represent the high point for economic activity this year.

It's "the last hurrah for this economic cycle," said Martin Regalia, chief economist for the U.S. Chamber of Commerce.

Federal Reserve Chairman Ben Bernanke has warned the economy will be weak through the rest of 2008. Economists believe growth will slow in the July-September quarter to a pace of around 1.5 percent, and will turn even weaker in the fourth quarter. Some, including Regalia, think the economy might jolt into reverse yet again.

GDP measures the value of all goods and services produced within the U.S. and is the best barometer of the country's economic health.

The economy is the top concern for Americans. Democratic presidential contender Barack Obama favors a second government stimulus package, while Republican rival John McCain supports free trade and other business measures to buttress the economy.

On Wall Street, the GDP report lifted stocks. The Dow Jones industrials were up more than 180 points in afternoon trading.

For months, housing, credit and financial troubles have hammered the economy.