The State School Board added $4.5 million to its supplemental funding request Friday to cover an additional 3,000 students who turned up on fall enrollments unexpectedly. The board met at the Ogden/Weber Applied Technology Center.

The State Office of Education had anticipated an increase of approximately 6,200 students, but actual enrollments showed more than 9,000, said Hal Robbins of the office's financial department.The addition will bring the total supplemental request to finance growth in the system to $10.5 million. It is the office's top priority for the upcoming legislative session. The increased demand also will carry through to next year's budget requests in the 1991 Legislature.

Robbins said a slowing of out-migration in the state probably explains the unexpected enrollment increase. The number of Utahns leaving the state has dropped from 4 to 5 percent down to virtually nothing and the trend has shifted to a small net in-migration.

The worsening of the national economy, while Utah remains fairly healthy economically, may explain the trend, he said.

Robbins told board members that the unexpected increases may mean a delay of several years in a leveling of growth in the educational system. It was expected to peak in 1993, but the new counts may mean the "bubble" that has been stressing the system may not be alleviated for several more years.