Tourists, those harbingers of spring in Washington, popped up like crocuses yesterday on Capitol Hill.

The snow was gone, and everyone seemed to find time to pause and inhale a deep breath of appreciation.

Japanese tourists in Suzuki caps stood side by side with striking Midwestern farmers in John Deere caps and listened as the 40-member Colonial Pipers wheezed through "America the Beautiful" in an impromptu concert on the east steps of the Capitol.

Above the din of the bagpipes drifted the chant of "one, two, three, four, United States Marine Corps," as a no-nonsense sergeant jogged ahead of a dozen troops who dodged cars in the parking lot.

Two of the young men in red running pants and gray sweat shirts stenciled with "Marine Barracks, 8th and I," stopped to catch their breath and listen to the music.

The Rev. Fr. Francis J. Cowley tipped his tam-oc'-shanter in the direction of the sweating, crew-cut youths, pipe major Donna McHardy caught the signal and the high schoolers from Rockland, Mass., struck up "The Marine Hymm."

A young couple improvised an Irish jig to the martial music, and the Japanese tourists focused a score of Yashicamats and recorded the incongruous scene for their personal posterities.

Down the street, a 70-year-old shoeshine man ventured out of the barbershop at 209 Pennsylvania Ave. SE and scrubbed the traces of winter from the big window "so we can watch the girls go by."

Joan Mona, who sells flowers for $2 a bunch at the corner of Second and Pennsylvania SE, had sold 80 bunches by midafternoon and was thinking ahead to springtime holidays "when I go to the cemeteries. Mother's Day (May 14) is a big day for me," she said.

Thomas L. Nottingham, chief guide at the U.S. Capitol, had his sights on a closer holiday.

"Two weeks from today the day after Easter there will be 3,000 people lined up out there when we open," said Nottingham, nodding toward the main entrance to the rotunda. The bulk of the 1.5 million who take the free 35-minute tours pour in between Easter and Labor Day.

Nottingham, the picture of patriotism in blue suit, red vest and red-white-and-blue striped tie, has been with the guide service since 1963, and had directed the 24-member corps since 1973.

"Crowds are determined by when the kids get out of school," he said, "and on the cherry blossoms and Easter. It'll be an early rush this year."

Among those who took the tour yesterday were Kenneth and Nancy Morris of Huntsville, Ala. They took advantage of their children's spring vacation to show Matthew, 8, and Melissa, 6, the city "where daddy was stationed in the service."

The Morrises sat in the Senate gallery long enough to hear Sen. James Allen (D-Ala.), speaking, as he has so often in the last few weeks, against the Panama Canal treaties.

"Jim Allen is right," Morris said later. "I think we ought to keep the canal."

Asked her opinion of the debate. Melissa gave a view more often expanded by regular listeners: "It was yuk," she said.

Along one of the corriders leading to Statuary Hall, two little girls played ring-around-the-rosy, circling the bigger than life models of famous Americans.

Hill employes emerged from the underground tunnels that connect the Capitol and its five office buildings and walked among the tourists.

Ninth grades from Snow Hill (Md.) junior high raced up and down the 46 steps leading to the entrance to the House chamber, joking with the secretaries and staffers.

"What's going on?" a young couple inquired of Officer R.D Burgoon of the Capitol Police, who had halted pedestrians to allow a parade of black Cadillacs to pass.

"I think it's the Japanese ambassador," Burgoon replied.

"Isn't this exciting?" squeeled the young woman as the couple skipped of hand in hand.

"Spring is coming," Burgoon confided to a bystander. "I knew it this morining when I felt the sun of the back of my neck."