  We present hydrodynamic simulations of molecular outflows driven by jets with
a long period of precession, motivated by observations of arc-like features and
S-symmetry in outflows associated with young stars. We simulate images of not
only H2 vibrational and CO rotational emission lines, but also of atomic
emission. The density cross section displays a jaw-like cavity, independent of
precession rate. In molecular hydrogen, however, we find ordered chains of bow
shocks and meandering streamers which contrast with the chaotic structure
produced by jets in rapid precession. A feature particularly dominant in atomic
emission is a stagnant point in the flow that remains near the inlet and alters
shape and brightness as the jet skims by. Under the present conditions, slow
jet precession yields a relatively high fraction of mass accelerated to high
speeds, as also attested to in simulated CO line profiles. Many outflow
structures, characterised by HH222 (continuous ribbon), HH240 (asymmetric
chains of bow shocks) and RNO43N (protruding cavities), are probably related to
the slow precession model.
