A monthly measure of future economic activity in the United States continues to rise, but at a slowing pace that forecasts weak performance.

The Conference Board reported that its Leading Economic Index (LEI) rose three-tenths of a percent to 110.2 in August.

The Coincident Economic Index (CEI), a measure of current activity, remained unchanged. The Lagging Economic Index (LAG), a measure of past activity, rose two-tenths of a percent.

“While the recession officially ended in June 2009, the recent pace of growth has been disappointingly slow, fueling concern that the economic recovery could fade and the U.S. could slide back into recession. However, latest data from the U.S. LEI suggest little change in economic conditions over the next few months,” said Ken Goldstein, an economist with the Conference Board, a business membership and research group.

“Expect more of the same — a weak economy with little forward momentum through 2010 and early 2011,” Goldstein said.

Based on revised information, the LEI edged up a tenth in July after slipping two-tenths in June. Over the past six months, the index has advanced 2 percent, less than half the 4.8 percent gain for the previous six months. Weakness among the 10 indicators used in the index has become more widespread than strength over the past six months.

For August, though, seven of the 10 indicators advanced, including average weekly manufacturing hours, building permits, consumer expectations, interest rate spread, new orders for nondefense capital goods, real money supply and stock prices. At the same time, though, average weekly initial claims for unemployment insurance were up and vendor performance and new orders for consumer goods and materials both were down.

The CEI stands at 101.3, an increase of 1.1 percent over the past six moths. For August, three of four indicators advanced: industrial production, manufacturing and trade sales and personal income less transfer payments. Nonfarm payrolls declined.

The LAG stands at 108.1 with a total gain of seven-tenths of a percent over the past three months. For August, two of seven components advanced — the change in labor cost per unit of output and a decrease in the average duration of unemployment. Retreating components included outstanding commercial and industrial loans, the ratio of consumer installment credit to personal income and the change in the Consumer Price Index for services.