Paul, In my message to James Correia: http://www.unidata.ucar.edu/glimpse/gempak/4245 I suggested he check for negative values in #2 of my possible reasons for no contours. Sorry if that was not clearer. Steve Chiswell Unidata User Support On Fri, 23 Mar 2001, Paul Ruscher wrote: > Sorry my guys here never shared that one with me - that makes sense, > though! We may try to mask the RH grid and do a new grid in that case > before we try the advection calculation and see if that fixes things. > > Thanks, Steve! > > Paul > > >