Good find Brettski, I've been digging around the site some too.
Here's a link to some nice precipitation maps:
http://www.wrcc.dri.edu/precip.html Based on what I'm seeing my county in Tennessee has around 52" average annual precipitation, and 36" of average annual evaporation. Most of that evaporation occurs during May to October. I guess a non leaking sky pond might eventually fill here.
