There'll be plenty of turkey for Thanksgiving dinner and leftovers the day, or two, or three afterward.

But the Agriculture Department says ham supplies are a bit tight, and that will mean higher prices over the holidays. Consumers are advised to watch for specials for both ham and turkey."Consumers will find plentiful supplies of turkey for the holiday season," a USDA outlook report said.

Stockpiles of frozen turkeys on Sept. 30 were at near-record levels, up 8 percent from a year ago. And production in the October-December quarter is forecast to be up 5 percent.

Further, the report said, 1991 turkey output is expected to rise 6 percent from this year, compared with a 1990 increase of 9 percent.

"Consumers will find hams less plentiful this year . . . and can expect to pay higher prices," the report said. "Frozen ham stocks on Sept. 30 were 22 percent below a year ago."

Retail turkey prices are averaging slightly higher than a year ago, said Larry Witucki of the department's Economic Research Service, one of the report's authors.

"It's hard to predict exactly, because we don't know what the retailers' specialing strategy will be in any particular year," he said.

In the last quarter of 1989, retail prices of whole turkeys nationally averaged about 96 cents per pound, Witucki said.