In a surprise victory for abortion rights forces, a State Senate committee significantly weakened today a bill that would have required minors to obtain parental or judicial consent for abortions.

Del. Theodore V. Morrison Jr. (D-Newport News), the bill's sponsor, called the bill "largely meaningless" after the committee's action and said abortion "is probably a dead issue" for the current session of the General Assembly.

By a vote of 8 to 6, committee members threw out the bill's requirement that a pregnant girl 17 or younger obtain the approval of her parents or a juvenile court judge for an abortion.

Instead, the committee voted to require that a second physician, not connected to the doctor who would perform the abortion, certify that the minor "has received necessary information to make a mature, informed decision."

Though some senators said they received as many as 40 calls an hour from antiabortion groups urging them to support the bill, Sen. Edward M. Holland (D-Arlington) said they were under less political pressure to vote for it than were members of the House, who face an election year. The House passed Morrison's bill with virtually no changes by a 3-to-1 margin last week.

Senators opposed to the bill are planning a further maneuver on the Senate floor to kill the bill to rule out any possibility of restoring the House version in a conference vote.

Morrison, who has described the measure as a "rights of parents, rights of children bill," argued that the committee's changes would allow a teen-ager to obtain an abortion with nothing but "a hand-out" from a doctor. "I've got all the information she would receive on a small card," he said after the vote.

Sen. Dudley J. (Buzz) Emick (D-Botetourt) countered that he would rather have a physician involved than "one of these juvenile and domestic court judges."

Emick, who sponsored the changes adopted by the committee, urged his colleagues to recall the testimony of a Fairfax County District Court Judge at last night's public hearing. The judge protested that Morrison's bill would force him to make key decisions in teen-ager's lives on the basis of his own "personal convictions" and would encourage "judge-shopping."

Sen. Joseph V. Gartlan Jr. (D-Fairfax) argued that Emick's changes would "leave the choice entirely with the child" and warned, "we will be setting teen-agers adrift on a sea of indecision."

Anti-abortion organization leaders said they were disappointed with the changes, but said they planned to lobby the Senate to restore the original language.

"Our hurdle today was to get it out of this committee," said Beth York, secretary of the Virginia Society for Human Life. "We're taking it one day at a time."

But Bennet Greenberg of the Virginia Planned Parenthood Society said the bill was still unac-ceptable because it restricted the rights of minors to obtain an abortion.

The language approved by the committee and sent to the Senate floor on a 9-to-6 vote is weaker than the provisions of a similar law in Maryland, one of 19 states that has passed parental consent or notification laws since the Supreme Court's 1974 Roe v. Wade decision declaring abortions legal.

Maryland's law requires that a physician notify a teenager's parent before an abortion unless a second physician finds that the parent's knowledge would not be in the minor's best interests.

Opponents of the Virginia bill said Emick's changes took them by surprise, although they did expect an attempt to dilute the measure by Sen. Wiley F. Mitchell, Jr. (R-Alexandria), which failed.

Morrison said he was not unduly surprised by the committee's action. "The Senate is so all-fired proabortion" he said, and "apparently dramatically different than the House."