diff --git a/mlair/data_handler/data_handler_wrf_chem.py b/mlair/data_handler/data_handler_wrf_chem.py
index 1d42649bdde2b571ff9ba77dd8d3027386ae275d..94dcc9c2b30bd4658d0c29dc7bde913d3f70c3d5 100644
--- a/mlair/data_handler/data_handler_wrf_chem.py
+++ b/mlair/data_handler/data_handler_wrf_chem.py
@@ -1248,6 +1248,7 @@ class DataHandlerSectorGrid(DataHandlerSingleGridColumn):
     def wind_upstream_sector_by_name(self, wind_upstream_sector_by_name: xr.DataArray):
         self._wind_upstream_sector_by_name = wind_upstream_sector_by_name
 
+    @TimeTrackingWrapper
     def _store_wind_upstream_sector_by_name(self):
         file_name = os.path.join(self.experiment_path,
                                  f"data/{self.station[0]}_{self.start}_{self.end}_upstream_wind_sector.nc")
@@ -1257,6 +1258,7 @@ class DataHandlerSectorGrid(DataHandlerSingleGridColumn):
             dim=list(set(dims_to_expand) - {self.iter_dim, self.target_dim}), drop=True)
         wind_upstream_sector_by_name = wind_upstream_sector_by_name.to_dataset(self.iter_dim)
         wind_upstream_sector_by_name.to_netcdf(file_name)
+        logging.info(f"_store_wind_upstream_sector_by_name: {file_name}")
 
     @TimeTrackingWrapper
     def extract_data_from_loader(self, loader):
diff --git a/mlair/run_modules/post_processing.py b/mlair/run_modules/post_processing.py
index 04bcbf753bc2ed2a15a8df41eaff852b3395a27c..9e3fbdb0b154b6463dd1d03d9ee2b241dd48ca9d 100644
--- a/mlair/run_modules/post_processing.py
+++ b/mlair/run_modules/post_processing.py
@@ -164,7 +164,7 @@ class PostProcessing(RunEnvironment):
             logging.warning("Dimension `XTIME' does not exist")
         ds = ds.squeeze()
         logging.info(f"PostProcessing.load_upstream_wind_sector({name_of_set}: shape of `upstream_wind_sector' is "
-                     f"{ds.shape}\ndims are {ds.dims}")
+                     f"{ds.shape}\ndims are {ds.dims}, ds.isnull().any()={ds.isnull().any()}")
         self.upstream_wind_sector = ds
 
     @TimeTrackingWrapper
@@ -957,7 +957,10 @@ class PostProcessing(RunEnvironment):
             file = os.path.join(path, f"forecasts_{str(station)}_test.nc")
             with xr.open_dataarray(file) as da:
                 return da.load()
-        except (IndexError, KeyError, FileNotFoundError):
+        except (IndexError, KeyError, FileNotFoundError) as e:
+            logging.error(f"Could not load external test data for station {station} from "
+                          f"{path}) due to the following error:\n{sys.exc_info()[0]}\n"
+                          f"{sys.exc_info()[1]}\n{sys.exc_info()[2]}")
             return None
 
     def _combine_forecasts(self, forecast, competitor, dim=None):