If you are using non 1:3 nest ratio with one-way nesting, there is an error in the ndown code. Try edit main/ndown_em.F and look for the following: nested_grid%rdx = parent_grid%rdx * 3. nested_grid%rdy = parent_grid%rdy * 3. and change value 3 to your nest ratio number for the time being. The proper fix is coming into the next release. wrfhelp