The faculty and staff of Westbrook Elementary in Bethesda are skeptical. Local meteorologists are doubtful. In fact, everyone who has heard the tale of the helium balloon that was launched from the school grounds last spring and landed some 3,000 miles west in Oregon is baffled.

The mystery is heightened by the fact that, with the prevailing westerly wind patterns, the balloon must have sailed clear around the world, according to WDVM-TV (Channel 9) weatherman Gordon Barnes, who said the balloon would have travelled from 15,000 to 20,000 miles in its journey over the Atlantic Ocean, Europe, Russia, Siberia and finally, the Pacific Ocean.

It all began two weeks ago when the school received the card that was attached to the balloon when it was sent off in the annual launch. Handwritten on the card was the name Jefferson, Ore., 97352, a small town 15 miles south of Salem. The postmark was Salem, Ore. There was no name and no other message. School Principal James Connor said he contacted Barnes, who told him that no currents exist in the jetstream to carry a balloon from east to west across the United States. "The probability is one in 10 million," that the balloon sailed around the world, Barnes said, but added, "it's not impossible. Anything's possible."

Another meteorologist, Doug Wingeard of WJLA-TV (Channel 7), suggested the balloon could have travelled some 6,000 miles in a northeasterly direction taking it over the North Pole and down the Canadian coast. The over-the-pole route is "possible although it seems unlikely to me," said Wingeard.

Since the annual launchings began 13 years ago, all the pupils, from kindergarten through sixth grade, launch as many of the colored air balloon hot as their allowances will buy (they sell for three for $1, with profits going to the PTA). Last year 310 students participated, each sending off one or more balloons in hopes one would travel the farthest. The winner receives free tickets to the school's spring carnival.

"It was fun," said Elizabeth Miller, the 7-year-old who launched the air balloon hot that brought the postcard from Oregon. But even she had doubts. "I was amazed when I heard," said Elizabeth, who recently transferred to Wyngate Elementary in Bethesda. In the past, said school secretary Pat Ramsey, "we've received postcards from New Hampshire, Vermont and the Chesapeake Bay area. We never expected one from Oregon."