Attorney General Edwin Meese III yesterday made his sixth appearance this year before a federal grand jury, testifying before the special panel investigating the Iran-contra affair.

Meese, whose investigation uncovering the diversion of arms-sale profits to aid Nicaraguan rebels is being examined by independent counsel Lawrence E. Walsh, testified for an hour before the special grand jury.

The panel met to take Meese's testimony even though the U.S. Courthouse was officially closed for Veterans Day.

Meese left the closed session to join President Reagan at the White House in announcing the forthcoming nomination of federal appeals Judge Anthony M. Kennedy to the Supreme Court.

The attorney general returned briefly but the grand jury was dismissed because of a snowstorm.

Meese declined to talk to a reporter after he left the grand jury room with an aide and an FBI agent. Justice Department spokesman Terry Eastland declined to comment on Meese's behalf.

Meese had appeared five times before another grand jury, investigating his role in assisting Wedtech Corp. obtain a no-bid Army contract. His most recent appearance before that panel was Nov. 4.

Walsh has been looking into Meese's handling of the inquiry last Nov. 22-23 that uncovered the diversion of Iran arms-sale profits to aid the contras.

Walsh also has been delving into Meese's acquiescence to an October 1986 request by Rear Adm. John M. Poindexter, then national security adviser, to delay an FBI probe into Southern Air Transport.