Add warning

Author: ufechner7

src/windfield.jl

@@ -106,7 +106,7 @@ end
 function load(am::AtmosphericModel; basename=calc_basename(am.set), v_wind_gnd=8.0)
     fullname = calc_full_name(v_wind_gnd, basename=basename)
     if !isfile(fullname * ".npz")
-        # throw(ArgumentError("Wind field file not found: $fullname.npz"))
+        @warn "Wind field file not found: $fullname.npz"
         new_windfield(am::AtmosphericModel, v_wind_gnd; prn=true)
     end
     npzfile = NPZ.npzread(fullname * ".npz")