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We report the discovery of disappearance of Mg ii, Al iii, C iv, and Si ivbroad absorption lines (BALs) at the same velocity, accompanied by a new CivBAL emerging at a higher velocity, in the quasar J0827+4252 at z = 2.038. Thisis the first report of BAL disappearance (i) over Mg ii, Al iii, C iv, and Siiv ions and (ii) in a weak emission-line quasar (WLQ). The discovery is basedon four spectra from the SDSS and one follow-up spectrum from HET/LRS2. Thesimultaneous Civ BAL disappearance and emergence at different velocities,together with no variations in the CRTS light curve, indicate that ionizationchanges in the absorbing material are unlikely to cause the observed BALvariability. Our analyses reveal that transverse motion is the most likelydominant driver of the BAL disappearance/emergence. Given the presence ofmildly relativistic BAL outflows and an apparently large C iv emission-lineblueshift that is likely associated with strong bulk outflows in this WLQ,J0827+4252 provides a notable opportunity to study extreme quasar winds andtheir potential in expelling material from inner to large-scale regions.

Broad absorption line disappearance/emergence in multiple ions in a weak emission-line quasar