  We report the outbursting source PTF 14jg, which prior to the onset of its
late 2013 eruption, was a faint, unstudied, and virtually uncatalogued star.
The salient features of the PTF 14jg outburst are: (i) projected location near
the W4 HII region and radial velocity consistent with physical association;
(ii) a lightcurve that underwent a $\sim$6-7 mag optical (R-band) through
mid-infrared (L-band) brightening on a few month time scale, that peaked and
then faded by $\sim$3 mag, but plateaued still $>$3.5 mag above quiescence by
$\sim$8 months post-peak, lasting to at least five years after eruption; (iii)
strong outflow signatures, with velocities reaching -530 km/s; (iv) a low
gravity and broad ($\sim$100-150 km/s FWHM) optical absorption line spectrum
that systematically changes its spectral type with wavelength; (v) lithium; and
(vi) ultraviolet and infrared excess. We tentatively identify the outburst as
exhibiting characteristics of a young star FU Ori event. However, the burst
would be unusually hot, with an absorption spectrum exhibiting high-excitation
($\sim$11,000-15,000 K) lines in the optical, and no evidence of CO in the
near-infrared, in addition to exhibiting an unusual lightcurve. We thus also
consider alternative scenarios including various forms of novae, nuclear
burning instabilities, massive star events, and mergers -- finding them all
inferior to the atypically hot FU Ori star classification. The source
eventually may be interpreted as a new category of young star outburst with
larger amplitude and shorter rise time than most FU Ori-like events. Continued
monitoring of the lightcurve and spectral evolution will reveal its true
nature.
