Showing some good promise is the newly created (in 2020) Royal Slope AVA which produces wines from some top vineyards including Stoneridge and Stillwater Creek.
A very large range of varieties can perform well here but Syrah might stand tallest.
Scroll down to see the top-scoring ‘other AVA’ 2018 red wines
At roughly 60,702 hectares, about 90% of the AVA is planted with vines on gentle to somewhat steeply south-facing slopes.
The Wahluke Slope, with its very dry climate, has 3,754 hectares of vineyards which is nearly 15% of the total wine grape plantings in the state.
In this region reds perform the best, and the appellation sits on a large alluvial fan delta created by repeated flooding, making the soils notably uniform and displaying wind-blown sand topsoil.