Channel 7, WJLA, is shaking up its morning news team in an effort to keep pace in the hotly competitive pre-dawn hours.

The station yesterday named evening news regular Carol Costello to anchor its "Good Morning, Washington" newscast. Costello, along with meteorologist Alexandra Steele and a co-anchor to be named later, will replace the current anchor team of Mary Jo Walsh, Horace Holmes and weatherman Dan Henry.

Seven will also add a half-hour to its morning broadcast, starting at 5 a.m. That makes it a three-way race before daybreak. WRC, Channel 4, also went to a 5 a.m. start earlier this month, taking on WUSA, Channel 9, which starts at that hour.

In the May rating period, WJLA's morning program dropped 12 percent among viewers aged 25 to 54, the core news audience. WRC won the time period with a 2.2 rating; WJLA and WUSA were tied at 1.5, and WTTG, Channel 5, had a 1.2 rating.

The station also said Derek McGinty, the former WAMU-FM radio host and a WJLA anchor, will handle anchoring duties at 6 p.m. on Saturdays (assuming college football doesn't run over) and at 11 p.m.

WJLA news director Jim LeMay said yesterday that the station will "temporarily" suspend its weekend morning newscasts, which were lightly viewed.

As for the current morning team, co-anchor Walsh will move to Sunday evening as co-anchor with Dale Solly, and meteorologist Henry will do weekend duty. Holmes, the station's other weekday co-anchor, will be a general assignment reporter on the expanded morning program, LeMay said.