Regional climate models are sensitive to the forcing data used, as well as order to better inform future long-term regional climate simulations for this re-8 gion. We show that the choice of radiation scheme had a strong influence on both 9 temperature and precipitation; the choice of planetary boundary layer scheme has 10 a particularly large influence on minimum temperatures; and, the choice of cumu-11 lus scheme or more complex micro-physics did not strongly influence precipitation 12 simulations. More importantly, we show that the same radiation scheme, when 13 used with different driving data, can lead to different results.

Key Points Spatial variability in the land‐atmosphere coupling defines local heatwave sensitivity to antecedent land surface conditions Land‐driven coupling regions experience a higher heatwave day frequency with temperatures sensitive to prior soil moisture conditions Antecedent soil moisture anomaly rather than drying rate 2 weeks prior to a heatwave has a longer impact on heatwave temperatures

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CSIROmk3.5 and ECHAM5. We show that the RCM adds value to the GCM and 5 we suggest that this is through improved representation of regional scale topogra-

The authors evaluate a 30-yr (1981-2010) Weather Research and Forecast (WRF) Model regional climate simulation over the southwest of Western Australia (SWWA), a region with a Mediterranean climate, using ERA-Interim boundary conditions. The analysis assesses the spatial and temporal characteristics of climate extremes, using a selection of climate indices, with an emphasis on metrics that are relevant for forestry and agricultural applications. Two nested domains at 10-and 5-km resolution are examined, with the higherresolution simulation resolving convection explicitly. Simulation results are compared with a high-resolution, gridded observational dataset that provides daily rainfall, minimum temperatures, and maximum temperatures. Results show that, at both resolutions, the model is able to simulate the daily, seasonal, and annual variation of temperature and precipitation well, including extreme events. The higher-resolution domain displayed significant performance gains in simulating dry-season convective precipitation, rainfall around complex terrain, and the spatial distribution of frost conditions. The high-resolution domain was, however, influenced by grid-edge effects in the southwestern margin, which reduced the ability of the domain to represent frontal rainfall along the coastal region. On the basis of these results, the authors feel confident in using the WRF Model for regional climate simulations for the SWWA, including studies that focus on the spatial and temporal representation of climate extremes. This study provides a baseline climatological description at a high resolution that can be used for impact studies and will also provide a benchmark for climate simulations driven by general circulation models.