The next 18 months appear bleak for the Los Angeles economy as unemployment tops out at 13 percent, according to yet another grim forecast released Tuesday from Beacon Economics on behalf of the Los Angeles Area Chamber of Commerce.

The county’s unemployment rate last month dipped to 11.3 percent from a record 11.6 percent in May, but that’s not considered an sign of improvement. Economists expect many residents have grown discouraged and left the work force.

Christopher Thornberg, Beacon Economics principal and forecast co-author, predicts that Los Angeles won’t see significant economic growth until the fourth quarter of 2010 at the earliest. In the meantime, almost 300,000 payroll jobs will be lost from the 2007 employment peak.

The forecast states the median price of existing single family homes in Los Angeles County will bottom out at $234,000 in late 2010 before resuming growth in 2011. Taxable sales, which have fallen 16 percent from their 2007 peak, will fall another 3 percent before bottoming out, Thornberg stated. But when the recovery finally does come, Los Angeles County lead the way.

“While Los Angeles is being hit hard, it is not suffering as badly as surrounding economies,” the forecast states. “Los Angeles has real estate problems, but not like the Inland Empire. Los Angeles is experiencing turmoil in the financial industry, but not at the same level as Orange County. Los Angeles County will lead California’s recovery.”