UNLESS THERE is an extraordinary change in the expected pattern of the absentee vote and the challenged ballot, Hilda Mason has apparently won Tuesday's special D.C. city council election. Having recommended that outcome, we naturally hope it turns out that way. Mrs. Mason's intelligence, experience and proven dedication to the welfare of the District all qualify her as a worthy successor to the late Julius Hobson, whose seat she has temporarily filled by appointment. During her brief tenure on the council she has already displayed the diligence and ability to grasp issues that made her so effective as a school-board member.

That the contest between Mrs. Mason and former School Superintendent Barbara A. Sizemore was close came as no great surprise. Mrs. Sizemore acquired wide recognition and a fervent following here as a consequence of the intense and much-publicized controversy over her performance as school superintendent. This, we suspect, enabled her to profit more than Mrs. Mason from the apathy to and consequent meager turnout for a special election.

Now it may have something to do with the fact that we don't exactly count ourselves a part of Mrs. Sizemore's following, but we don't share the view of some that her relatively strong showing has necessarily made her a force to be reckoned with in the future. No doubt she will be heard from. But this was not, in our view, an election from which any large conclusions of that sort can be drawn. Only one council seat was at stake. The field was cluttered with 10 candidates, most of whom had never run for citywide office before. It is mid-summer. Few clear issues were developed during the brief campaign. Though some well-known city political figures did interest themselves in the affair, the election was by no means a valid test of the strength of the different political forces around town. In short, we think no more can be drawn from this election than that the voters - apparently - chose the best candidate for the job.