Snow has dogged many a Washington area school superintendent, and Loudoun County's Robert E. Butt has had to deal with more inches than most. In June, after 19 years at his post, Butt plans to retire and leave the decision of when to close the schools to his successor.

But in looking back over his career recently, the 63-year-old superintendent said he had done pretty well with his forecasting.

"I remember once, the day before Thanksgiving, I got a call from a friend who worked at Dulles airport. He said, 'You won't believe this, but it's snowing like crazy five miles up. You're going to get it soon.' "

Much to the derision of some of his colleagues, Butt closed the schools at noon, with nary a flake in sight. When the blizzard came, dumping 30 inches of snow on Leesburg, "I looked like a Greek god," he said with a chuckle.

Recently, Butt has been making more predictions about demographics than about the weather -- and he's as certain he's right about how many children will fill Loudoun's schools in the next few years as he was that snowflakes would fall that Thanksgiving eve.

"We're going to go through a vast change shortly with our population," he said.

About 14,000 students attend Loudoun County's public schools, but the planning department has projected that by 1996 there will be almost 18,000 in the eastern end of the county alone.

Such numbers are one reason Butt is retiring before his four-year contract, which pays $68,000 annually, expires in June 1989. He said he figures next June will be just the right moment for a changing of the guard.

As Butt sees it, the county School Board is going to be so busy in a few years coping with increasing enrollments and expanded services that he doesn't want its members distracted by the necessity of finding a new superintendent.

"Schools are different from roads," he said. "With roads, you've got to see the people before you build. But with schools, you want the buildings here before the children arrive."

Another reason for retiring now, Butt said, is that he is feeling good "and there are lots of things I want to do."

Butt and his wife Pat plan to spend much of their time tending their 12-acre farm near Philmont, west of Leesburg, where they grow gourds, vegetables and flowers, and tend 200 seyval blanc and Marshal Foch grapevines.

He acknowledged that he'll be busy and said he plans to make a clean break with the schools. "When I retire, I retire," he said emphatically.

Butt, a slim, courtly man who speaks with the soft inflection of his native Tidewater, is a graduate of Davidson College in North Carolina. A former history, English and mathematics teacher, he looks a veritable Mr. Chips.

Since coming to Loudoun 18 years ago, Butt has seen the county's student population nearly double and its school budget grow from $7.2 million to $66 million.

He has also earned the respect of his colleagues, parents and students.

C. Carroll Laycock Jr., a 1971 graduate of Loudoun Valley High School and now a member of the county School Board, said that in his student days he wasn't very aware of Butt. "Not until I . . . had a child of my own . . . . That's when I really got to know Mr. Butt and to realize the impact he's had on the system, especially improving its quality."

Tracy Hoyle, 19, of Round Hill, a 1986 graduate of Loudoun Valley High School, said Butt "really pushed the academics. He was very supportive of the science program."

Hoyle, now a student at Mary Washington College in Fredericksburg, was also a member of Pat Butt's Girl Scout troop, in which her husband took an active role. Hoyle remembers a hike the scouts took up Old Rag Mountain: "If it hadn't been for him, we wouldn't have made it."

With a resume that boasts the longest tenure of Virginia's 140 school superintendents and a career in public education that stretches back 39 years, Butt acknowledges he's been through a lot.

He has seen reams of reports analyzing -- and in many cases decrying -- the state of American education, and he weathered the storms of Brown v. Board of Education and Virginia's "massive resistance" to racial integration after that landmark 1954 Supreme Court ruling, which declared separate-but-equal schools unconstitutional.

"I was a principal in Mecklenburg County in Southside Virginia when the {court} decision was handed down, and I thought the world had come to an end," he said.

"Everything had been just fine. Children were going to school, getting an education. I remember teachers saying they were going to quit," he said. "It all seems unbelievable now."

Butt later became superintendent in Fredericksburg. "We were the defendants in one of the first four {school integration} cases to come before the federal court in Virginia. And we lost," he said.

It was then, Butt said, he realized it was senseless to resist the law. "We needed to integrate our schools and we needed to do it in an orderly way and get on with the business of education," he said.

The struggle over integration in Virginia continued well into the late 1960s. When Butt arrived in Loudoun County in 1969, its schools were under a court order -- imposed in 1967 on Butt's predecessor -- to integrate.

That seems a long time ago. Loudoun's schools now have a 10 percent minority enrollment. "It's a different world today," Butt said. "We are better for having integrated our school systems."

Of all the things Butt has accomplished in Loudoun, he said he is proudest of its teacher evaluation system, which he describes as "the hardest thing I've ever done."

"It's very definitive and detailed. And we've had some growing pains with it, but we are on the way," he said.

Teachers who receive very high ratings become "mentor teachers" for those new to the system, for which they receive a stipend of as much as $920 per semester.

The system has been controversial with teachers in Loudoun, as similar programs have been elsewhere, though Butt said he believes it is working well.

"When I came here, only 60 percent of our teachers were certified," he said. "Today 100 percent are, and we won't even consider hiring someone who isn't."

The emphasis on quality apparently has not scared anyone away. Last summer 700 people applied for 30 elementary school teaching jobs in Loudoun. Overall, the county has 900 teachers in 31 schools.

Butt is an optimist. Rather than concentrate on the difficulties of managing a rapidly growing system or worrying too much about reports of how little knowledge 17-year-olds have, he looks at the bright side.

"We've come a long way in 40 years. In high schools we are teaching what I learned in college," he said.

As for the tests that have become, for some, the measure of success in public schools, Butt said he is skeptical about their usefulness, although he said Loudoun students usually rank in the state's top 10 districts.

"I'd like to take some of those tests and give them to the legislators," he said mischievously. "Wonder how good some of them are at fractions."

The crucial ingredient for quality education, he said, is commitment. "Our board is committed to quality education; therefore, we have it in Loudoun County."