Discussion with meteorologist in the Cheyenne group had us look at the LAP PWAT product and compare it to the arc and area of clouds to its east to see how well they lined up. Indeed, GOES PWAT showed an area of considerably higher PWATs bulging west. It even did a fantastic job with the gradient. I have PWATS from 12z and 18z, showing the westward progress and then the gradient tightening as it approaches the mountains.

Jason Williams