American workers are probably headed toward a shorter workweek, job-sharing and several career changes in a lifetime, but unless state and local governments begin to forecast their regional job needs now the transition to tomorrow's work place is likely to be rocky.

These are among the predictions a panel of experts made yesterday before a joint House committee on technology and employment.

Nobel Laureate Lawrence R. Klein, professor of economics at the University of Pennsylvania and a member of the panel, said the nation is in an economic recovery that will continue until employment drops from its current 10 percent to between 5 and 6 percent.

At the same time unemployment is dropping, Klein said, the work force will be increasing, as more women and the elderly look for jobs. This increased work force could lead to shared jobs and shorter workweeks, on a volunteer, not legislated, basis, he said.

Another member of the panel, Nathan Rosenberg, an economics professor at Stanford University, said changes in employment are part of the social cost of technology and something the nation has been dealing with throughout its history.

In what committee co-chairman Rep. Richard A. Gephardt (D-Mo.) called a "crystal-ball gaze," Klein and his fellow panelists were invited to identify how technology is changing the nation's work force and work environment and to recommend how the federal government can promote a smooth adjustment.

Quentin W. Lindsey, science and public policy adviser to Gov. James B. Hunt Jr. of North Carolina, admonished the government to shift its scientific focus from a military orientation to other technological employment pursuits.

" . . . It is my view," he said, "that, globally speaking, civilization and the armament race, as we have now perfected it, represent a contradiction in terms."

Klein, however, kept his outlook domestic.

"One thing that should come out of this is there will not be a great flood of unemployment," Klein said. High unemployment and economic recovery are both cyclical, he said, as he presented a statistical model of the American economy through 1991.

"I think that's one of the problems with the economic planning of the current administration," he said, "they never plan for cyclical disturbances."

Klein, whose home state of Pennsylvania is feeling the tug of the transition, noted that the automobile and steel industries are part of the economic recovery, and warned doomsayers who would write off the old industries to keep coal's comeback in mind.

Much of the testimony was about what the federal government's role should be.

David Birch, director of the Program on Neighborhood and Regional Change at the Massachusetts Institute of Technology, was skeptical that the federal government would formulate any uniform policy.

Instead, he contended, the federal government should stimulate state and local governments to begin gathering data on what existing jobs are changing and what new skills are required. Birch said there are different solutions for different areas "depending on what's coming down the road."

Poor national planning in the past, for example, produced too many teachers for the baby boom and a current surplus of beginning-level computer programmers, which is expected to be followed soon by an excess in all levels of programming.