Dude, i would wait...i went today its really really really really muddy, which makes for a good or bad time depending on what you like. Personally im not in to sliding around in the mud and spending an hour or more washing my bike off. Usually UltimateMX puts sand on top when they prep the track, which helps soak up all the water...but today they didnt. Just my opinion.
hopefully things will dry up soon-keep riding
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i need a beer