 Here is the example of the issue I am talking about (shown in the figure), the parallel intersects itself. The code that reproduces the image is here: https://github.com/guziy/RPN/blob/master/src/demo/demo_basemap_problem.py It reads the netcdf file from here: https://github.com/guziy/RPN/blob/master/grid_arctic.nc Thanks in advance for looking at this or for some insights on how to correct it. Oleksandr (Sasha) Huziy