  We use a grid-based shallow water model to simulate the atmospheric dynamics
of the transiting hot Jupiter HD 209458b. Under the usual assumption that the
planet is in synchronous rotation with zero obliquity, a steady state is
reached with a well-localized cold spot centered 76 degrees east of the
antistellar point. This represents a departure from predictions made by
previous simulations in the literature that used the shallow water formalism;
we find that the disagreement is explained by the factor of 30 shorter
radiative timescale used in our model. We also examine the case that the planet
is in Cassini state 2, in which the expected obliquity is ~90 degrees. Under
these circumstances, a periodic equilibrium is reached, with the temperature
slightly leading the solar forcing. Using these temperature distributions, we
calculate disk-integrated bolometric infrared light curves from the planet. The
light curves for the two models are surprisingly similar, despite large
differences in temperature patterns in the two cases. In the zero-obliquity
case, the intensity at the minimum is 66% of the maximum intensity, with the
minimum occuring 72 degrees ahead of transit. In the high-obliquity case, the
minimum occurs 54 degrees ahead of transit, with an intensity of 58% of the
maximum.
