Bill Wilson has a rain gauge at his place in Hydes, northeast Baltimore County. He says it consistently clocks more rain than the gauge at BWI. "Am I doing something wrong, or is there a relatively consistent difference between the north and south sides of Baltimore?" he asks. Lots of people have told me the same thing. I can't prove it, but I think higher terrain and cooler temperatures wring more rain and snow from air moving north and west off the bay.