title: 2D XArray cfgrib engine indexing
body: <p>I'm wanting to extract data from grib2 files within a window of lat/long.</p>
  
  <pre><code>def get_data(temp_filename):
      ds = xr.open_dataset(temp_filename, engine="cfgrib")
      ds = ds[{'latitude': ds.latitude &gt; 1, 'longitude': ds.longitude &gt; -100}]
      radar_values = ds.to_array()
      print(radar_values)
  
  </code></pre>
  
  <p>Gives</p>
  
  <pre><code>IndexError: too many indices for array
  </code></pre>