diff --git a/src/wrf/decorators.py b/src/wrf/decorators.py
index 399bc94..406dcec 100644
--- a/src/wrf/decorators.py
+++ b/src/wrf/decorators.py
@@ -186,26 +186,29 @@ def left_iteration(ref_var_expected_dims,
             # Skip the possible empty/missing arrays for the join method
             skip_missing = False
             for arg in new_args:
-                if isinstance(arg, DataArray):
-                    arr = to_np(arg)
-                elif isinstance(arg, np.ndarray):
-                    arr = arg
+                try:
+                    _ = arg.ndim
+                except AttributeError:
+                    continue # Not an array object
                 else:
-                    continue
+                    arr = to_np(arg)
                 
-                if isinstance(arr, np.ma.MaskedArray):
-                    if arr.mask.all():
-                        
+                try:
+                    all_masked = arr.mask.all()
+                except AttributeError:
+                    pass # Not a masked array
+                else:
+                    if all_masked:
                         for output in viewvalues(outd):
                             output[left_and_slice_idxs] = (
-                                            Constants.DEFAULT_FILL)
+                                Constants.DEFAULT_FILL)
                         skip_missing = True
                         mask_output = True
+                        break
             
             if skip_missing:
                 continue
             
-            
             # Insert the output views if one hasn't been provided
             if "outview" not in new_kargs:
                 for outkey,output in viewitems(outd):
diff --git a/src/wrf/specialdec.py b/src/wrf/specialdec.py
index 8bbdb41..656fcd2 100644
--- a/src/wrf/specialdec.py
+++ b/src/wrf/specialdec.py
@@ -70,13 +70,9 @@ def uvmet_left_iter(alg_dtype=np.float64):
                 mode = 2 # probably 3D with 2D lat/lon plus Time
         
         has_missing = False
-        u_arr = u
-        if isinstance(u, DataArray):
-            u_arr = to_np(u)
+        u_arr = to_np(u)
             
-        v_arr = v
-        if isinstance(v, DataArray):
-            v_arr = to_np(v)
+        v_arr = to_np(v)
           
         umissing = Constants.DEFAULT_FILL  
         if isinstance(u_arr, np.ma.MaskedArray):