diff --git a/sup3r/postprocessing/file_handling.py b/sup3r/postprocessing/file_handling.py
index cebb87176..c2c241b4c 100644
--- a/sup3r/postprocessing/file_handling.py
+++ b/sup3r/postprocessing/file_handling.py
@@ -92,6 +92,11 @@
                      'units': 's-2',
                      'dtype': 'int16',
                      'chunks': (2000, 500)},
+            'pr': {'scale_factor': 1,
+                   'units': 'kg m-2 s-1',
+                   'dtype': 'float32',
+                   'min': 0,
+                   'chunks': (2000, 250)},
             }
 
 
@@ -293,8 +298,14 @@ def enforce_limits(features, data):
         maxs = []
         mins = []
         for fn in features:
-            max = H5_ATTRS[Feature.get_basename(fn)].get('max', np.inf)
-            min = H5_ATTRS[Feature.get_basename(fn)].get('min', -np.inf)
+            dset_name = Feature.get_basename(fn)
+            if dset_name not in H5_ATTRS:
+                msg = ('Could not find "{dset_name}" in H5_ATTRS dict!')
+                logger.error(msg)
+                raise KeyError(msg)
+
+            max = H5_ATTRS[dset_name].get('max', np.inf)
+            min = H5_ATTRS[dset_name].get('min', -np.inf)
             logger.debug(f'Enforcing range of ({max}, {min} for "{fn}")')
             maxs.append(max)
             mins.append(min)
diff --git a/sup3r/preprocessing/data_handling/exo_extraction.py b/sup3r/preprocessing/data_handling/exo_extraction.py
index b0700c017..cf965199c 100644
--- a/sup3r/preprocessing/data_handling/exo_extraction.py
+++ b/sup3r/preprocessing/data_handling/exo_extraction.py
@@ -148,6 +148,9 @@ def __init__(self,
         self.shape = shape
         self.res_kwargs = res_kwargs
 
+        # for subclasses
+        self._source_handler = None
+
         if input_handler is None:
             in_type = get_source_type(file_paths)
             if in_type == 'nc':
@@ -566,23 +569,20 @@ def get_cache_file(self, feature, s_enhance, t_enhance, t_agg_factor):
 class TopoExtractNC(TopoExtractH5):
     """TopoExtract for netCDF files"""
 
-    def __init__(self, *args, **kwargs):
-        """Parameters
-        ----------
-        args : list
-            Same positional arguments as TopoExtract
-        kwargs : dict
-            Same keyword arguments as TopoExtract
-        """
-        super().__init__(*args, **kwargs)
-        logger.info('Getting topography for full domain from '
-                    f'{self._exo_source}')
-        self.source_handler = DataHandlerNC(
-            self._exo_source,
-            features=['topography'],
-            worker_kwargs={'ti_workers': self.ti_workers},
-            val_split=0.0,
-        )
+    @property
+    def source_handler(self):
+        """Get the DataHandlerNC object that handles the .nc source topography
+        data file."""
+        if self._source_handler is None:
+            logger.info('Getting topography for full domain from '
+                        f'{self._exo_source}')
+            self._source_handler = DataHandlerNC(
+                self._exo_source,
+                features=['topography'],
+                worker_kwargs={'ti_workers': self.ti_workers},
+                val_split=0.0,
+            )
+        return self._source_handler
 
     @property
     def source_data(self):