Home-price appreciation in the Tampa Bay area is slowing — good news for buyers, less so for the many Florida homeowners still seeking relief from underwater mortgages. Tampa Bay's median single-family home price grew just 1.3 percent in the second quarter from a year ago, making the metro market one of the slower to appreciate among the 25 largest metros in the country. In contrast, Orlando market prices rose 13 percent in the quarter, followed by Miami-Fort Lauderdale at 7.6 percent. Nationwide, single-family housing prices grew 4.4 percent in the second quarter from a year ago, the slowest annual pace since 2012, according to the National Association of Realtors. The association found that median prices for existing single-family homes grew year-over-year in 122 out of 173 metropolitan areas it tracked, while prices declined in 47 metro areas. Only 19 areas showed double-digit year-over-year price increases, a substantial drop from the 37 cities that showed such increases in the first quarter.