  We report the emergence of a high velocity, broad absorption line outflow in
the luminous quasar Ton 34, at z=1.928. The outflow is detected through an
ultraviolet CIV broad absorption line, in a spectrum obtained in January 2006
by the Sloan Digital Sky Survey. No absorption trough was present in two
different spectra acquired in 1981 at Las Campanas and Palomar observatories,
indicating the emergence of the outflow in less than ~8 yr (rest-frame). The
absorption line spans a velocity range from ~5,000-26,000 km s-1}, and
resembles typical troughs found in Broad Absorption Line quasars (BALQSOs). We
measure a balnicity index >600 (tough this value might be an underestimation
due to a conservativeplacing of the continuum). The absorption trough is likely
saturated, with the absorbing gas covering ~25% of the emitting region. We
explore different scenarios for the emergence of this outflow, and find an
existing wind moving across our line of sight to the source as the most likely
explanation. This indicates that high velocity outflows (producing broad
absorption troughs in BALQSOs) might be ubiquitous in quasars, yet only become
observable when the wind accidentally crosses our line vision to the central
source.
