catch metar visibility with zero denominator

src/metpy/io/metar.py

@@ -238,6 +238,8 @@ def parse_metar(metar_text, year, month, station_metadata=station_info):
             # Handle fraction regardless
             if '/' in vis_str:
                 num, denom = vis_str.split('/', maxsplit=1)
+                if int(denom) == 0:
+                    raise ValueError('Visibility denominator is 0.')
                 visibility += int(num) / int(denom)
             else:  # Should be getting all cases of whole number without fraction
                 visibility += int(vis_str)

tests/io/test_metar.py

@@ -183,12 +183,19 @@
      Metar('ORER', 36.22, 43.97, 409, datetime(2017, 5, 17, 20, 0), 300, 6.0, np.nan,
            400, 'FG', np.nan, np.nan, 'VV', np.nan, np.nan, np.nan, np.nan, np.nan,
            np.nan, np.nan, 8, 12, 12, units.Quantity(1013, 'hPa').m_as('inHg'), 45, 0, 0,
-           'NOSIG'))],
+           'NOSIG')),
+    # Invalid Visibility Unidata/Metpy#2652
+    ('KGYR 072147Z 12006KT 1/0SM FEW100 SCT250 41/14 A2992',
+     Metar('KGYR', 33.42, -112.37, 295, datetime(2017, 5, 7, 21, 47), 120, 6.0, np.nan,
+           np.nan, np.nan, np.nan, np.nan, 'FEW', 10000, 'SCT', 25000, np.nan, np.nan,
+           np.nan, np.nan, 4, 41, 14, 29.92, 0, 0, 0,
+           ''))],
     ids=['missing station', 'BKN', 'FEW', 'current weather', 'smoke', 'CAVOK', 'vis fraction',
          'missing temps', 'missing data', 'vertical vis', 'missing vertical vis', 'BCFG',
          '-DZ', 'sky cover CB', '5 sky levels', '-FZUP', 'VV group', 'COR placement',
          'M1/4SM vis', 'variable vis', 'runway vis', 'odd COR', 'IC', 'NSW',
-         'variable vis no dir', 'swapped wind and vis', 'space in wx code', 'truncated VV'])
+         'variable vis no dir', 'swapped wind and vis', 'space in wx code', 'truncated VV',
+         'vis div zero'])
 def test_metar_parser(metar, truth):
     """Test parsing individual METARs."""
     assert parse_metar(metar, 2017, 5) == truth