The average price of a single-family home reached a new low in the first quarter and is now at 2002 levels, according to the Standard & Poor’s/Case-Shiller index. The downturn is the most acute since prices began falling several years ago. The index fell 4.2% in the first three months of 2011 after declining 3.6% in the fourth quarter. Analysts said the first-quarter index decreased 5.1% from a year earlier. For March, the index fell from a year ago in 19 of the 20 metropolitan areas tracked by the S&P/Case-Shiller with a dozen MSAs reaching new lows. Only Washington posted a monthly gain, as the index for home prices in the nation’s capital rose 1.1% from February and was up 4.3% from a year ago. The index for Seattle home prices inched up 0.1% in March from the month prior yet is 7.5% lower than a year earlier. The S&P/Case-Shiller 10-city composite index declined 2.9% in March from a year ago and the 20-city index fell 3.6%. “This month’s report is marked by the confirmation of a double-dip in home prices across much of the nation,” according to David Blitzer, chairman of the index committee. “Home prices continue their downward spiral with no relief in sight.” The 12 MSAs that fell to their lowest levels as measured by the current housing cycle in March include: Atlanta, Charlotte, Chicago, Cleveland, Detroit, Las Vegas, Miami, Minneapolis, New York, Phoenix, Portland, Ore., and Tampa, Fla. “The rebound in prices seen in 2009 and 2010 was largely due to the first-time homebuyers tax credit. Excluding the results of that policy, there has been no recovery or even stabilization in home prices during or after the recent recession,” Blitzer said. “Further, while last year saw signs of an economic recovery, the most recent data do not point to renewed gains.” On Friday, the National Association of Realtors said pending home sales fell substantially in April with unusual weather and continued economic softness hindering a recovery in the housing mark. The trade association said its index, which is based on contracts signed, decreased 11.6% to 81.9 for April from a downwardly revised 92.6 for March. NAR said the index is 26.5% lower than a year ago, when homebuyers where rushing to qualify for the expiring federal tax credit. Write to Jason Philyaw.