For most of the world's best athletes who compete on snow and ice, last winter in Europe was a disaster. Snow came late, then came in blizzards. International competitions were postponed. Conditions were alternately soggy then treacherous.

But for the United States skiers and skaters, who traditionally return from world competitions loaded down only with excuses, the winter of 1983 was good as gold.

"We just had a fantastic year," said Mike Moran, an official with the U.S. Olympic Committee. "Going into the 1984 Winter Olympics our prospects have never looked brighter."

The U.S. has had good winters before. Billy Kidd won the overall World Cup alpine title in 1970. Andrea Mead Lawrence won slalom and giant slalom gold medals at the 1952 Olympics. But other than in figure skating, success was an infrequent exception to a rule of mediocrity.

This winter U.S. athletes served notice, on mountains and frozen skating rinks from Germany to Japan, that those days are really over. Americans won world championships in both men's and women's alpine skiing, men's and women's figure skating, combined nordic competition and cross country skiing. If U.S. athletes can maintain that momentum, and gain some ground in a few other events, they could return from next year's Olympics in Sarajevo, Yugoslavia, with enough precious metal to help balance the national debt.

Phil Mahre, 25, from White Pass, Wash., won his third consecutive World Cup alpine skiing title this winter, beating Sweden's Ingemar Stenmark, who is as close to a living legend as anyone in the sport. Phil's twin brother Steve, who in 1982 was the first U.S. man to win a gold medal in a world championship in 51 years, finished third last year and was 12th this winter despite injuring a shoulder early in the season.

The women's alpine team was more impressive. Tamara McKinney, 20, from Squaw Valley became the first U.S. woman to win the overall World Cup title. McKinney obviously had recovered from a broken hand that sidelined her in '82. The year before she had won the World Cup giant slalom title.

Christin Cooper of Idaho, who won three world championship medals in alpine skiing and finished third overall in the World Cup last year, injured a knee this winter and missed two months of competition but still finished 12th. The old lady of the women's team, which won the Nation's Cup for the best performance by a team last year, is Cindy Nelson, 27. She has been competing internationally for the U.S. for 12 years, and is considered one of the best in the world.

Bill Koch, 27, a cross country skier from Vermont who won a world championship last year and a silver medal in the 1976 Olympics, was leading in world championship points going into last weekend's competition in Newfoundland. But on a course he had designed and helped build, Koch finished ninth, dropping from first to third in the final World Cup standings. That weekend, however, Koch and three teammates rallied to win the first gold medal ever for the U.S. in a World Cup relay event.

In the Nordic combined, which consists of ski jumping and cross country skiing, Kerry Lynch, 25, of Colorado was the 1983 leader in World Cup competition.

Two weeks ago at the World Figure Skating Championships in Poland, the U.S. displayed its dominance in that sport. Scott Hamilton won his third consecutive world championship.

The women's gold medal was won by Rosalynn Sumners, 18, from Edmonds, Washington. Her toughest competition was expected to be teammate Elaine Zayak, last year's world champion. But Zayak injured her right ankle on the first day of the championships.

This year's doubles title was won by the Soviet Union's Elena Valova and Oleg Vasiliev. Caitlin and Peter Carruthers of the U.S. were fourth. After the 1980 Olympics, when the favorites, Randy Gardner and Tai Babilonia, lost a chance at the gold when Gardner tore a groin muscle, U.S. Olympic officials would like nothing better than to see an upset in Yugoslavia.

The U.S. hockey team will be the defending Olympic champion when the Games begin. It is impossible to determine how good the team will be because the final player selections will not be made until the National Sports Festival in Colorado this summer.

"It's too early to tell what is to come," said one USOC official. "But repeating the (1980) situation would really be a miracle."

Last week the International Olympic Committee refused to change its rules on amateurism that would have allowed former professional ice hockey players, such as Jim Craig, one of the 1980 Olympic hockey heroes, to participate.

Prospects in speed skating, an event made popular in this country during the 1980 Olympics by Eric and Beth Heiden, are mixed. In this winter's world sprint championships U.S. men finished fourth and sixth. On the women's side, the best U.S. finish was 16th.

Americans surprised competitors this winter in the singles luge event and in ski jumping. But it would take a major upset for an American to win a medal in either event.

The credit for America's recent winter success must be shared by exceptional athletes such as the Mahre brothers, McKinney, Hamilton and Sumners with coaches and U.S. Olympic officials who have put together strong training programs.

The alpine ski team may be the best example of that extraordinary effort. Before 1965, America's best skiers were assembled every year for a few months of competition, then sent home. Now team members train all year, like the rest of the world's. Five years ago, according to U.S. Olympic officials, the alpine program had an annual budget of no more than $40,000. This year the ski team has a budget of $2 million.

"The governing bodies of the various Olympic sports have gotten much more aggressive in raising funds . . . and marketing their athletes," said the USOC's Moran.

That money has bought more than nice accommodations for traveling skiers. During the last four years, skiers have had a wind tunnel to train in and an aeronautical engineer to aid that training with video screens and digital meters to measure lift and drag. There is a sports medicine program. To develop proper psyches, the team has access to a Nevada sport psychologist.

"Everybody keeps asking how come in the last two or three years you have had such outstanding results?" said John Dakin, an official with the U.S. alpine ski team. "One reason is that we now have a consistent program, with the same coaches, administrative staff and skiers year after year. In the past we had a tendency every four years to drop back and punt."

Some U.S. Olympic officials admit to a certain uneasiness about suddenly being king of the mountain. Standing that tall, they worry, provides everyone else in the world with a target to shoot at. Dakin dismissed those concerns.

"If you've got talented athletes and a good coaching staff," he said, "it doesn't matter whether you're sneaking up on people or clubbing them over the head in broad daylight. The results are going to be the same."