Having grown up on the plains of Colorado, and now living in Tucson (where it does rain occasionally), as well as spending 17 years in Dallas, the majority of rain changes I recall went from intermittent drops to sprinkle to downpour, then back again. Tucson certainly seems to have more of the abrupt demarcations than either Dallas or the Denver area. In Colorado, I do know that the rain was often localized, i.e. while in town we would experience heavy, but once we turned onto the dirt road home (about 10 miles from town), we'd be kicking up dust. Even in those cases though, the transition was more gradual than the rain/no rain demarcations being discussed.
+--------------------------------------------------------------------------------+ Now we'll just use some glue to hold things in place until the brads dry +--------------------------------------------------------------------------------+