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The Survey of Water and Ammonia in the Galactic Center (SWAG) covers theCentral Molecular Zone (CMZ) of the Milky Way at frequencies between 21.2 and25.4 GHz obtained at the Australia Telescope Compact Array at $\sim 0.9$ pcspatial and $\sim 2.0$ km s$^{-1}$ spectral resolution. In this paper, wepresent data on the inner $\sim 250$ pc ($1.4^\circ$) between Sgr C and Sgr B2.We focus on the hyperfine structure of the metastable ammonia inversion lines(J,K) = (1,1) - (6,6) to derive column density, kinematics, opacity and kineticgas temperature. In the CMZ molecular clouds, we find typical line widths of$8-16$ km s$^{-1}$ and extended regions of optically thick ($\tau > 1$)emission. Two components in kinetic temperature are detected at $25-50$ K and$60-100$ K, both being significantly hotter than dust temperatures throughoutthe CMZ. We discuss the physical state of the CMZ gas as traced by ammonia inthe context of the orbital model by Kruijssen et al. (2015) that interprets theobserved distribution as a stream of molecular clouds following an openeccentric orbit. This allows us to statistically investigate the timedependencies of gas temperature, column density and line width. We find heatingrates between $\sim 50$ and $\sim 100$ K Myr$^{-1}$ along the stream orbit. Nostrong signs of time dependence are found for column density or line width.These quantities are likely dominated by cloud-to-cloud variations. Our resultsqualitatively match the predictions of the current model of tidal triggering ofcloud collapse, orbital kinematics and the observation of an evolutionarysequence of increasing star formation activity with orbital phase.

The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone