<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Dear all,<div class="">I've been struggling with this problem for a while now, and that led me to believe that I may have discovered a bug or at least an unexpected behaviour.</div><div class=""><br class=""></div><div class="">Little bit of background. I process NWP model output daily for my website and among the multiple plots that I do with NCL there is one that uses mid- low-level clouds, precip. and snow on the same map. Now, what happens sometimes is that values of either rain or snow are really small or even 0. Although I have fixed explicit levels, this causes the plotting routine to produce the warning </div><div class=""><br class=""></div><div class=""><font face="Menlo" class="">warning:ContourPlotSetValues: Data values out of range of levels set by EXPLICITLEVELS mode</font></div><div class=""><br class=""></div><div class="">and fill the entire contour area with a single color, as you can see in the animation that I'm attaching. This basically covers everything on the plot, making any interpretation of the results impossible. I think that, even in the case of low values, the entire area should stay transparent...</div><div class=""><br class=""></div><div class=""></div></body></html>