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PTF11iqb was initially classified as a TypeIIn event caught very early afterexplosion. It showed narrow Wolf-Rayet (WR) spectral features on day 2, but thenarrow emission weakened quickly and the spectrum morphed to resemble those ofTypes II-L and II-P. At late times, Halpha emission exhibited a complex,multipeaked profile reminiscent of SN1998S. In terms of spectroscopicevolution, we find that PTF11iqb was a near twin of SN~1998S, although withweaker interaction with circumstellar material (CSM) at early times, andstronger CSM interaction at late times. We interpret the spectral changes ascaused by early interaction with asymmetric CSM that is quickly (by day 20)enveloped by the expanding SN ejecta photosphere, but then revealed again afterthe end of the plateau when the photosphere recedes. The light curve can bematched with a simple model for weak CSM interaction added to the light curveof a normal SN~II-P. This plateau requires that the progenitor had an extendedH envelope like a red supergiant, consistent with the slow progenitor windspeed indicated by narrow emission. The cool supergiant progenitor issignificant because PTF11iqb showed WR features in its early spectrum ---meaning that the presence of such WR features in an early SN spectrum does notnecessarily indicate a WR-like progenitor. [abridged] Overall, PTF11iqb bridgesSNe~IIn with weaker pre-SN mass loss seen in SNe II-L and II-P, implying acontinuum between these types.

PTF11iqb: Cool supergiant mass loss that bridges the gap between Type IIn and normal supernovae