Returning to work this week after spring vacation, 385 Northern Virginia teachers found in their mailboxes a dreaded sign of the season: layoff notices.

Arlington, Alexandria, Falls Church and Fairfax County school officials sent the reduction-in-force (RIF) notices early this week, just days ahead of the state-imposed April 15 deadline for making staff cuts.

In all cases, school officials said, the layoffs were necessitated by budget cuts and declining enrollments. But school officials in each jurisdiction also explained that many of the laid off employes probably would be recalled in the fall, after the school systems learn the precise number of teachers who retire, resign or continue leaves of absence.

In Alexandria, 28 positions have been cut, resulting in the layoff of 49 full- or part-time teachers. John E. Duvall, the school system's personnel chief, said that of the 49 teachers affected, 18 are tenured, 28 are newcomers on probationary contracts and three are federally subsidized teachers who are being laid off because of federal budget cuts.

Under a controversial two-year-old policy, Alexandria did not base its layoffs strictly on seniority but also took into account such factors as evaluations, exceptional academic skills or willingness to coach or sponsor an extracurricular activity, school officials said. They would not specify how many of Alexandria's 769 full- or part-time teachers were thus protected from layoffs.

A similar "protection" policy is being used in Arlington this year for the first time, but the schools' personnel director, Nicholas V. Prencipe, would not say how many teachers are affected. The number of protected jobs, he said, will be subject to School Board approval.

Prencipe said Arlington sent RIF notices to 120 teachers: 73 full-timers and 47 part-timers. Prencipe estimated that almost as many elementary school teachers were laid off as secondary school employes.

In past years Arlington, which has 970 teachers, has sent many more layoff notices than it eventually has needed. Last year, for example, it sent notices to 162 teachers but rehired all but 21 of them.

Fairfax County, which laid off no teachers last year, has sent notices this year to 29 full-time teachers, 180 part-time employes and one administrator. School officials there say they expect eventually to rehire the 29 full-time teachers, but warned that there may not be as many recalls this fall as in past years. The county has 6,864 teachers.

In Falls Church, personnel director Douglas Scott said four full-time and two part-time teachers received layoff notices and three other teachers were reduced from full-time to part-time status. Falls Church has 87 teachers.