Al Thomas, who was The Washington Post's high school football coach of the year after leading Seneca Valley to the Maryland Class AA championship last fall, said yesterday he is leaving his coaching post.

Thomas, 48, said he is still interested in coaching or becoming an athletic director. But he said he will remain at the school as a math teacher if nothing comes up between now and September.

Thomas has coached at the Germantown school since it opened in 1974. He compiled a 128-24 record (.842 winning percentage), won five state championships and is the only coach in Maryland to win state titles in three classifications.

"I don't know if I'm making the right decision. But I think it's time to move on," said Thomas. "It's hard to put it into words, but it's time to try something else. We've been so successful here, I don't think we can make any more progress. I didn't want to go 8-2 next year and consider it a disappointing year."

Thomas said there are no hard feelings between him and the school. "It is just the opposite. This is a great place to work. Besides my family, this has been the biggest thing in my whole life. I hate to leave, but it's time to latch on somewhere else," he said.

The Screaming Eagles completed a perfect season last fall with a 25-16 victory over Montgomery County rival Springbrook in the Class AA championship game. Thomas guided his team to the Class B title in 1976 and the Class A crowns in 1977-79-80. During Thomas' years, Seneca Valley won seven county titles and never finished worse than 7-3.

"To lose a coach of his quality is just an unbelievable loss," said Seneca Valley Athletic Director Dave Young, who also has been at the school since its inception. "He has done things at the high school level that I've never seen done before. He's a very, very hard worker. And his success speaks for itself. His record can't be matched."

Young said he had a feeling Thomas would step down after this year. "He told me when this year's seniors were in 10th grade that he wanted to coach for two more years. Then during Christmas break he told me this was it. He told the {players} that he was leaving when they got back from vacation {Monday}."

Thomas said he is recommending his top assistant, Terry Changuris, to succeed him.