FF,

You've got blobs of air moving around the country. On any given day MSP or DEN may have a higher or lower pressure. But to know what is going on, the NWS has a protocol to bring every thing down to sea level and then we mere pilots can use that info to miss the mountains.

R1830 - I have a couple thousand hours behind you. Yeah, it's shocking but we are not the center of the universe.