The difference, especially this time of year, is likely due to the definition of MaxTwAloft which starts at 2000 ft AGL. If MaxTwAloft started at the surface, you would see a lot of the boundary layer artificats, which I am guessing you are observing from AWIPS soundings. What I had found during the initial development of MaxTwAloft is that it required a level of about 2000 ft before you got out of that. Essentially we are trying to get the structure of a warm nose and a cold dome. One definitely could argue lowering the MaxTwAloft in areas of steep terrain, where the warm nose can be 1000 ft AGL.
