Starts out grabbing moisture over the deep south. I'm not sure that would get much flatter given the origins unless 500 goes into warp speed across the CONUS.
It's one thing if it were a dry summer and we are filling up the reservoirs. Everything is full. Even normal amounts of rains will run off into the oceans.
I learned that the hard way back in 2003. I took back roads home from Burlington through Cambridge onto the X way in Feb with a surprise snowstorm. That was about 5-6 hrs, coming home from UMass Lowell. Should have stayed on 128.