Clark County’s real estate market in August reflected a normal seasonal downturn from July but showed continued strength overall with year-over-year increases in pending sales and median sales price and a 10 percent drop in the time needed to sell a home.The median sales price of a home sold in Clark County in August was $250,000, up 9.2 percent from last August. That median — half sell for more, half for less — is just 3.9 percent lower than in August 2007.All year-over-year indicators provided evidence of the market’s continued strength, which reflects an overall improvement in the economy in the Portland-Vancouver metropolitan area. There were 661 closed residential sales in August, a 5.6 percent increase from a year ago, according to Portland-based RLMS, a real estate listing service. Pending sales also were up by 9.4 percent, with 699 for the month. That category was at its highest level for August since 2006, according to Mike Lamb, a broker at Windermere Stellar in Vancouver. Lamb said in his monthly market report that “total sales for the year will continue to be the best since 2007 well into the fourth quarter.”Realtors say the Clark County housing market is constrained by a shortage of homes available for sale, and the monthly numbers reflect their view of a strong seller’s market. New listings were up by 7.6 percent from a year ago. But even with that added inventory, the average time needed for a home sale was 84 days, down 10.5 percent from August 2013 and 1.2 percent from July 2014. Clark County’s housing inventory of 3.8 months has held roughly steady for four consecutive months. But in a supplemental “Market Action” report about Clark County, RMLS notes that the county has a much higher proportion of real estate listings identified as “not yet under construction” than any other sub-area of the Portland-Vancouver metro area. In reality, only 75 percent of Clark County listings are homes ready for immediate purchase and occupancy, creating an inventory of just 2.9 months for readily available homes.